U.S. Interstate Highways’ Effects on the Environment

The U.S. system of cross-country highways came into being when President Dwight Eisenhower signed the Federal-Aid Highway Act of 1956. On June 30 of that year the New York Times reporter John Morris wrote of the event, “President Eisenhower set into motion a record $33,480,000,000 road-building today by signing the bipartisan authorization bill that Congress sent him Tuesday. Sinclair Weeks, secretary of commerce, immediately announced the allocation of $1,125,000,000 among the states for the first year of what he called ‘the greatest public-works program in the history of the world.’ ” Secretary Weeks may have overstated the magnitude of the 42,000-mile (67,592-km) highway network to be built, but the interstate system nevertheless made an impact on lifestyles and businesses for years to come.

The U.S. interstate highways provided a different type of roadway from state roads and local thoroughfares because the entire network contained only about 16,000 interchanges that drivers use for entrance or exit. This design made travel more efficient for drivers by avoiding traffic lights and busy intersections. As the highways reached across the nation
throughout the 1950s and 1960s, they also began to exert a subtle effect on the environment.

The interstates—north-south routes have increasing odd numbers from west to east; even-numbered east-west routes increase from south to north—made personal travel, business trips, and trucking more convenient and faster. The interstates improved travel so much in fact that they contributed to urban sprawl from city centers; densely populated suburbs have grown up near many interchanges. Though the interstate highways made life easier for communities and commerce, they also led to the following environmental issues:

1. car and truck exhaust
2. animal and plant habitat destruction
3. animal and plant habitat fragmentation
4. blocked wildlife migration corridors
5. wildlife road kills
6. noise
7. high fuel consumption

In addition to the environmental ills mentioned here, the interstate highways have probably helped build the U.S. car culture in which more people depend on personal cars than on mass transit. The highways surely changed the way American society matured between the 1950s and 1970s as people became more mobile and the country seemed to become
smaller. (Interstate highways also gave birth to the fast food restaurant industry.) The National Geographic writer Robert Paul Jordan said of the interstate system at the height of its construction, “Americans are living in the midst of a miracle. A giant nationwide engineering project—the Interstate Highway System—is altering and circumventing geography on an unprecedented scale.” Jordan’s description captured the importance
of today’s interstate highways, but the highway system’s progress also brought with it a decline in the health of the environment. 

Vehicle Surface Technology

In addition to aerodynamic shape, lightweight components, and optimized engine efficiency, car designers can improve a car’s overall efficiency by modifying the vehicle’s surface. Moving objects have drag due to skin friction, which is the interaction of a surface with the air moving over it. Auto industry engineers therefore must reduce skin friction drag in order
to increase fuel efficiency. The rougher a vehicle’s surface, the more drag the vehicle experiences. By eliminating even microscopic rough spots in a car’s paint coating, engineers help conserve fuel.

New coatings that cover a vehicle’s paint have been investigated to reduce skin friction drag. For example, thin plastic coatings overlaid on paint can affect the roughness of a vehicle’s surface and so affect drag. The best coatings create a smooth surface for airflow and resist scratches and corrosion, causes of surface roughness. A smooth surface then allows air to pass over the vehicle in laminar sheets, meaning that streams of air line up in parallel sheets as they move. Turbulent air, by contrast, contains eddies and swirls that cause skin friction drag.

Engineers study the boundary layer of air just next to a vehicle’s surface to determine why most of the boundary layer contains laminar flow but some parts contain turbulence. The German physicist Ludwig Prandtl introduced the idea of boundary layers in 1904 and explained that the friction between a moving object and air (or water) developed only in the thin boundary layer that existed very close to the surface. Scientists since Archimedes (287–212 b.c.e.) have pondered the way flow moves over and around solid objects, but Prandtl’s boundary layer theory proposed that all flow does not behave the same in the presence of a surface. Prandtl explained that flow nearer a surface moves slower than
flow farther from the surface: “A very satisfactory explanation of the physical process in the boundary layer between a fluid [or airflow] and a solid body could be obtained by the hypothesis of an adhesion of the fluid to the walls . . . If the viscosity [thickness of a fluid] was very small and the fluid path along the wall not too long, the fluid velocity ought
to resume its normal value at a very short distance from the wall. In the thin transition layer however, the sharp changes of velocity, even with small coefficient of friction, produce marked results.” In other words, air sheets close to the solid surface move at slower speeds and contribute to skin friction drag more than the airflow outside that boundary layer,
which moves at normal speed.

Surfacing engineering now focuses on substances to increase airflow at the boundary layer. Engineering experiments have discovered that a little roughness at certain points along the boundary layer actually helps with airflow by weakening the boundary layer–surface association. For this reason, some cars contain rough outer body components just under
the doors and below the radiator grill. Specialists in surface science now study the structure of sharkskin, which reduces a shark’s drag and allows it to speed through the water. Sharkskin contains a series of tiny rigid ridges called riblets that feel rough to the touch but greatly reduce drag in

Surface coating technology is a specialty in vehicle design and engineering. Surfaces should reduce drag and assist airflow. All sources of turbulent air movement, which decrease aerodynamics, must be eliminated or corrected. The vortex generator is a simple row of fins that smooth the airflow off the back of a vehicle where turbulence is common.

water by interacting with the skin-water interface. The German engineer Volkmar Stenzel has been creating lacquers for vehicles and watercraft based on this riblet effect, sometimes by building the riblet structure into the lacquer itself. Stenzel said, “Our trial lacquer is based on the chemistry used in aviation paints.” Surface engineering to improve the aerodynamics
of a moving vehicle therefore remains an intricate science that borrows from technologies used in aircraft and watercraft. New vehicles will require the best combination of smooth surfaces, flow-direction surfaces, and vehicle shape.

Power

Power is the rate in which energy converts into work. Combustion vehicles use mechanical power produced by the engine, and this power comes from the engine’s force and velocity:

power = force × velocity

Alternative fuel cars, such as gasoline-electric hybrids, must possess features that maintain power while reducing fuel use. These attributes enable alternative fuel cars to compete with traditional gasoline cars.

The engine supplies power, and the vehicle moves. The engine’s cylinders burn fuel, usually gasoline, in a process called combustion and convert the fuel’s energy into motion (the turning of the engine’s crankshaft). Regardless of the type of fuel a vehicle uses—gasoline, diesel, electricity, a fuel cell—carmakers express the vehicle’s power as horsepower, which is a unit that describes the rate at which work is done. One horsepower equals 746 watts and stands as an internationally recognized unit to measure power. (Engineer James Watt came up with horsepower in the 1700s based on his interpretation of how much work a horse could do in one minute. By Watt’s calculations, one horse could pull 330 pounds [150 kg] of matter 100 feet [30 m] in one minute: 1 horsepower = 33,000 foot-pounds per minute.) A typical vehicle uses 20 horsepower to travel at 50 miles per hour (80 km/h) for one hour. Today’s combustion engines produce 120 to 270 horsepower, a range that gasoline-electric hybrid cars and the newest prototypes also attain.

It may be hard to decide whether powerful cars preceded superhighways or superhighway systems led to more powerful cars. The following “Case Study: U.S. Interstate Highways’ Effects on the Environment” examines an often overlooked component of transportation.

Aerodynamics

Car designers must satisfy customers’ tastes while at the same time incorporating new technologies that improve aerodynamics. Aerodynamics is the physics that enables things to move through the air with minimal resistance, also called aerodynamic drag or wind resistance. Designers shape the outer body of cars to get the best aerodynamics and also design the interior to minimize the wind noise a vehicle creates when moving at high speed. The aerodynamic models sold today take into account both exterior and interior reactions of the vehicle with the air it moves through. The automobile industry uses computer modeling and wind tunnel testing to achieve the new model’s desired performance.

Aerodynamics engineering for cars focuses on two main components of drag: ground effects and rolling resistance. Ground effects are design features that reduce lift and wind resistance. Car designers shape a car so that more air flows smoothly over the car’s top than flows across the underside. Such a design also includes structures that reduce the turbulence of the air moving over the car and off the tail. In most vehicles the junction between the roof and rear window contributes to turbulence. For this reason new fixtures have been introduced to cut this turbulence and improve airflow, a process engineers call “tripping the airflow.” The following components trip the airflow on various new car models:

1. turbulator strips—thin metal strips that lessen the small layer of turbulence that occurs between any surface over which air flows
2. vortex generators—small teeth attached to the roof above the rear window to even the airflow speed over a vehicle
3. diffusers—undercarriage components that direct airflow away from the wheels to increase a downward force on a vehicle
4. shortened fairings—body parts that direct airflow around the tires

Efficient Vehicle Design

The first stage in new vehicle design begins with research on the needs and desires of drivers, government regulations on emissions, and new technologies for improving performance. Each of these facets must also align with the intangible aspect of how a car’s looks will appeal to car buyers. Obviously, new car design involves large teams of experts in all of these specialties who must coordinate their work in a way that results in a feasible
prototype car.

Car designs include features to reduce drag as they move. Many of the features such as window shape, roof shape, and rear spoiler help airflow over the car. Side spats and a mostly flat undercarriage reduce pockets where air can swirl and decrease the car’s aerodynamics. Vehicles also contain lightweight materials on their surfaces that allow smooth airflow over the car’s body.

Rather than depend solely on drawings—even sophisticated computer drawings—automakers build prototype models of all of their most promising car designs. Building a prototype car is a complex job that requires a skilled team. Prototype builders follow a design blueprint to create a full-sized fiberglass shell, windshield, and lights. Computeraided
design (CAD) has greatly increased prototype building by allowing for design changes on the computer before building the actual car mock-up. CAD programs also create images of the vehicle’s interior controls, seats, and options. Engineers use CAD programs to make upto- the-minute design changes, and then the prototype team adjusts the model to agree with those changes. The entire process is called virtual prototyping, and, in addition to car designers, trucks, aircraft, ships, pleasure boats, and mass transit vehicles use it. This technology has helped increase the accuracy of converting a concept into a real design
that will succeed on the road.

The Automobile Industry

The automobile industry consists of a massive enterprise that plans and designs cars and
light trucks and produces, distributes, markets, and sells these products. The industry sells
about 75 million cars worldwide in a year; the United States purchases more than 11 million cars each year. The United States also produces about 25 percent of all cars made worldwide. Only Japan makes more cars than the United States, but China has been closing the gap fast and may soon overtake U.S. carmakers. Car manufacturing supports many other industries, primarily the oil industry. Makers of engines, plastics, metals, fabrics, leathers, tires, and small components of car bodies, plus recyclers, service stations, and businesses that install sound systems and other add-ons all depend on the car industry for their income. The automobile industry, which controls the development-to-sale process, combines with all the other associated industries to form the more all-encompassing automotive industry.

The first automobile built to carry passengers arrived in 1801 due to the inspiration of the
British inventor Richard Trevithick. Through the 1800s, vehicles self-propelled by steam engines became common. The French inventor Étienne Lenoir and the German engineers Eugen Langen and Nicholaus August Otto worked on building a combustion engine to run on fuel and replace steam, a move intended to make cars more powerful. By 1876 Otto developed a four-cycle combustion engine that would be the precursor to today’s engines. In 1913 the American Henry Ford invented a conveyor belt to take components directly to workers on a car assembly line, and from this point onward, American automakers would dominate the automobile industry for the next 75 years.

The development of the combustion engine and Ford’s innovative mass production promised a bright future for the automobile industry. The U.S. automobile industry dominated world markets until the 1980s when Japanese automakers mounted a strong challenge to American models. In 1970 the Clean Air Act brought new laws for car emissions, but the automobile industry learned to sidestep most of the regulations with a few minor concessions, such as the catalytic converter that made combustion more efficient. (Catalytic converters also caused a switch to lead-free gas because the devices did not work on leaded gas.) The act’s 1990 amendments forced automakers into taking further steps toward inventing clean-running engines that produced less hazardous emissions than earlier models. Today the automobile industry continues to adjust to tighter restrictions on exhaust emissions, led by California with the strictest emissions laws.

An Arab oil embargo in 1973, fuel crises throughout the 1970s, and rising fuel prices in the
2000s have been events that put pressure on the automobile industry to find more avenues
toward fuel efficiency. In all these instances, however, automakers reacted to new requirements rather than led the way in innovation. In 2009, a faltering world economy put pressure on automakers to accept President Barack Obama’s new fuel legislation. “They [automakers] can feel the political winds changing,” said lawyer David Doniger of the Natural Resources Defense Council. “They need government aid to stay in business. When you have your hand out for help, it’s hard to use the same hand to thumb your nose at the federal government.”

Temporary fuel crises certainly affect the auto industry and car sales, but a more overwhelming threat to the industry’s conventional way of doing things comes from deep underground. The crude oil that the oil industry taps and turns into fuel will not last forever. The auto industry cannot wait until the last drop of oil comes out of the Earth before it reacts. Mike Millikin, the founder of the Green Car Congress, and the environmental writer Alex Steffen wrote in 2006, “The auto industry was built on a seemingly endless supply of gasoline, but it is now becoming increasingly clear that the end is, in fact, in sight.” The end of oil should not signal the end of the auto industry, but to avoid going extinct this industry’s leaders must plan for the future now.

Drag and Energy Loss

The Ford Model T had little need for aerodynamic styling when it rolled onto the road in 1908; it never ran faster than 45 miles per hour (72 km/h). Today’s high-performance cars reach 180 miles per hour (290 km/h), although drivers on open highways usually travel closer to 70 to 90 miles per hour (113–145 km/h). A Model T’s blocky frame would not withstand today’s speeds even if it were engineered to travel that fast. Cars today have
designs that reduce wind resistance and drag, both of which cause a vehicle to use more power and more fuel to maintain speed.

Aerodynamic drag consists of forces that work against a vehicle’s forward motion. Examples of things that increase a car’s drag are the following: shape, area, density, speed, incline, viscosity (density of the air), and surface friction. Aerodynamic drag accounts for about 20 percent of the energy consumed by most car models. For this reason engineers study drag in all new vehicle designs to optimize energy efficiency.

All cars, ships, boats, and airplanes have been designed based on a drag coefficient (Cd), which is a unitless value used to describe the aerodynamics of a vehicle in motion. Put another way, Cd describes the relationship between the air’s motion and a vehicle’s motion. Car drag coefficients range from 0.25 to 0.45, with sleek Corvette-style cars on the low end of the Cd range and boxy Hummers at the high end. Usually only the newest prototypes achieve a Cd of 0.25, although the Prius measures 0.26. Car designers and engineers reduce drag and therefore enhance fuel efficiency by the following actions:

1. remove sharp corners from the body design
2. reduce the frontal area
3. remove extra components such as spoilers and roof racks
4. avoid wide tires
5. increase windshield angle
6. remove high axle to lower the car’s body

The best way to reduce drag in a well-designed vehicle is to reduce driving speed. Cars use up most of their energy overcoming the effects of drag that increases disproportionately at higher speeds, meaning a small  increase in speed causes a large increase in drag. Car designers have used race cars as examples of low-drag design. Race car design incorporates
two critical factors for achieving high speeds with a minimum amount of drag: stability and downforce. At speeds of more than 200 miles per hour (322 km/h), race cars must have adequate stability and downforce, which keeps the car from going airborne, a situation called lift. Passenger vehicles travel at speeds that remove the risk of lift, and they remain stable at legal speed limits. Auto industry engineers nevertheless consider stability
and downforce with each new design.

New Vehicles Emerge

One reason why energy-efficient cars have not dominated the automobile market originates in resistance to change, either by manufacturers or by consumers. Small minor changes always gain acceptance faster than drastic changes, and so the world’s push toward environmentally sensible cars has come in baby steps. An increasing number of drivers in North America and Europe now accept new electric cars and gasoline-electric hybrid cars because they know these models cause less harm to the atmosphere than conventional combustion-engine cars. But these alternative choices remain only a small proportion of the total vehicles on roads today—the automobile industry continues to refer to alternative vehicles as a “segment” of the industry.

Automotive engineers have a formidable challenge ahead of them: to transform alternative vehicles from a novelty choice to the main type of vehicle car buyers want. In time, alternative vehicles may become the only type of vehicle on the road. To do this, engineers must combine their skills

Alternative vehicles that rely on fuels other than gasoline or diesel fuel have become increasingly numerous on
public roads, but they still make up a small percentage of total vehicles. Ethanol-powered cars comprise almost
half of all alternative vehicles; about one-quarter run on liquefied gas. This Honda at a hydrogen filling station
may represent the next generation of alternative fuel vehicles. (National Hydrogen Association)

in developing new ways to power vehicles with designers’ skills in making the vehicles appealing to buyers.

A new generation of vehicles will contain one or more of the following features: an alternative fuel engine; aerodynamic design; a frame composed of all recycled materials; and smaller size. The best opportunity to see examples of new vehicle designs occurs at international auto shows. Ron Cogan, the editor of the Green Car Journal, said in 2007, “The international car shows are a window to what the designers are thinking, and I began seeing actual designs for efficiency.” Cogan and other car experts have been hoping for a zero emission vehicle as the first major breakthrough in car redesign since the hybrid vehicles emerged in the 1990s. Cogan said of the zero emission vehicle, “No one knew it could be done until General Motors unveiled ‘Impact I.’ ” The zero-emission Impact I appeared in early 1996, but shifting state emission laws complicated the Impact I’s rollout
and it never became a marketable car for the public. In other words, the car’s engineering succeeded and its design may well have succeeded, but complicated pollution laws scuttled its future.

Automotive engineers and car designers can refer to Toyota’s Prius to learn how a radically new car concept can become a success. The Prius was the first highly marketable green car, a car designed to cause little or no harm to the environment. The Prius arrived in 1997 with an engine containing components that used either gasoline or electric power, and the vehicle switched back and forth between these two energy sources in a single trip; this new idea was called a hybrid vehicle. A hybrid is any vehicle that uses more than one type of energy source in converting fuel into motion. Several car manufacturers have since built their own hybrid models, and consumers have been enthusiastic toward giving up conventional vehicles

Car designers and engineers have tried to develop alternative fuel cars that resemble
conventional combustion engine cars. By designing according to a traditional
appearance, new models will appeal to car buyers who want fuel savings but are
reluctant to buy unusual-looking cars. This 2008 Honda Civic GX uses compressed
natural gas as fuel and can refuel from a specialized appliance kept at home. (Honda
Media Newsroom)

 

for them. Jim Motavelli wrote in 2008 for E, the Environmental Magazine, “[Toyota] has 80 percent of the U.S. hybrid market, and the majority of those sales are the brilliantly designed Prius. The fourdoor Prius caught on both because of its incredible fuel economy—48 miles per gallon [77 km/h] in the city and 45 miles per gallon [72 km/h] on the highway—and because its unique styling makes an environmental statement about its owner. It looks like a hybrid.” The latest green cars have built upon the principles of the Prius and incorporate many of its technologies.

Automakers produce concept cars to test
innovations in fuel use, aerodynamics, materials,
and design. These models are not ready for
highway use, but the innovations they possess
might become part of cars in the future. The
car pictured here is the Aptera made by Aptera
Motors, Inc. This model is completely electric. The
company has also developed an electric/diesel
hybrid Aptera, which gets 330 miles per gallon
(140 km/l). (Aptera Motors, Inc.)

 Most hybrid vehicles like the Prius still depend to some extent on gasoline. Fuel efficiency in these cars relates to the means in which they conserve gasoline. Next-generation green cars, however, will move beyond gasoline altogether. Ron Cogan pointed out, “If you look at the
big picture, at some point we will exit from oil.” New cars will combine alternative-fuel engines with designs that maximize energy-use efficiency. The table on page 72 describes some of the prototypes (also called concept cars) that car manufacturers have unveiled in an effort to create a truly new car. Whether these ideas succeed or fail may not be as important as the fact that big automakers were willing to attempt completely new car designs.

Getting prototypes off the drawing board and onto the road requires cooperation among manufacturers, suppliers, retailers, and government. The Green Car Congress has stated, “The path to sustainable mobility is complex, with numerous competing and complementary approaches to alternative energy sources, production, distribution and applications; fuel and power-train

options; materials; safety, economic and environmental considerations
and trade-offs; policy issues; and different time lines for research, development
and deployment.” The role of carmakers is explored further in the following sidebar “The Automobile Industry.”

Innovations in Personal Vehicles

Innovations in personal vehicles come from two directions: (1) vehicle designs that increase fuel efficiency—the distance a vehicle can travel per volume of fuel—and (2) fuels that replace gasoline and diesel and so reduce the emission of greenhouse gases. The trick in achieving success in both innovations resides in the automobile industry’s ability
to remain profitable while it reinvents the car. Global warming has already reached deadly levels for some ecosystems, so automakers must understand that beginning the process of redesigning personal vehicles cannot be delayed.

Why are personal vehicles so critical to the health of the environment? Cars, sport utility vehicles, and small trucks produce about 50 percent of the greenhouse gases in the atmosphere. Cars and pickup trucks in the United States contribute to half that amount even though these vehicles make up 30 percent of all the world’s cars and pickup trucks. These vehicles produce the greenhouse gases nitrogen oxides, sulfur dioxide, and  carbon dioxide, which all trap heat in the Earth’s atmosphere. This global warming has caused, and continues to cause, plant and animal species to disappear because they cannot adjust to habitats that have changed due to warmer temperatures. Warming alters the plant life and prey-predator relationships in ecosystems; food sources disappear; invasive species
enter ecosystems and destroy them. Vehicles, industries, and residential buildings all contribute to this warming effect.

Alternatives to Travel

Any action that eliminates unnecessary travel helps build sustainable communities by conserving natural resources, but environmental engineers will likely have a hard time deciding what constitutes unnecessary travel. People travel for the following main reasons: daily commutes, business travel, and vacation travel. Business and recreational travel may
be difficult to curtail because these preplanned trips affect the health of the economy. Daily commuters certainly help the economy too, but their repeated trips along familiar routes offer the best opportunity for adopting new technologies.

The transportation consultant Alan Pisarski hinted at a new way of commuting in a 2004 USA Today article: “Pisarski suggests that building more roads or mass transit options, such as trains or buses, would only encourage more long-distance commutes. The real change, he says, will be when companies build away from the metropolitan centers.” A complete
reinvention of transportation may emerge in the next 50 years. On a small scale, vehicles will still exist, so any new designs to save fuel will grow in importance. On a larger scale, the public and businesses will need to rethink how they travel and why they travel. Any major redesign in transportation for the future will emphasize the use of advanced telecommunication technologies.

Telecommuting is the process of working all or part of the normal workweek from home. Technology already exists that makes wireless telecommuting possible and increasingly common: computers, phones, hand-held communication devices, and fax machines. New technologies in virtual commuting can enhance the telecommuting experience for both employees and employers. In virtual commuting, a worker creates a lookalike image called an avatar viewed on a computer screen to participate in meetings with other employees. The three-dimensional images connect the worker to a main corporate office or other businesses. Virtual commuting may be able to create communities where no corporate headquarters exist; every worker resides at a remote site and communicates with others electronically. Any telecommunications process that connects people working in remote sites is called in-world meeting.

Virtual commuting enables people to sit side by side in an imaginary meeting room, give slide presentations, and communicate by speaker phone or in an online chat room. Companies retain the option to rent remote office space for occasions when employees must meet in person. Rather than commute all the way to headquarters, these employees would take shorter trips to the satellite offices and telecommute together from there to the main office.

Video conferencing offers the same conveniences as virtual commuting, but participants communicate using cameras and talk to each other via a television, projection screen, or computer screen. An A. G. Lambert executive told the San Francisco Chronicle in 2007, “It’s about being able to have a natural experience even if you’re not sitting in the same room.” Sean M. Grady explained in his book Virtual Reality, “Virtual reality came into being in the mid to late 1980s, following decades of research into ways to remove the hardware wall
between computer users and computer data.” Both video conferencing and virtual commuting have a bright future when, or if, corporations redesign how they do business.

Telecommuting offers an excellent way to reduce
greenhouse gas emissions. Engineers continue
to develop innovations that reduce the sense of
distance between a telecommuter and the central
office. In many instances, as pictured here, a
telecommuter requires uncomplicated technology:
a computer, phone, fax machine, scanner, and a
reliable Internet connection.

Large companies feel comfortable with traditional central offices filled with worker cubicles.
The telecommunications industry must therefore make in-world meeting technologies as attractive as possible to break tradition. Linden Laboratories in California designs virtual communities for businesses so that each business creates a telecommuting system that meets its particular needs. The virtual communities take place on Second Life, a program that allows multiple users to share and edit documents, access public or private company space, and meet in virtual rooms set up to resemble the real-life conference room at headquarters. A computer industry analyst Claire Schooley noted in the Chronicle, “You have so much work that is done on the computer today. They [virtual technologies] make it very easy to connect.” As with so many of the changes needed in transportation, breaking old habits presents the biggest challenge of all.

Clean Ships

Oceangoing ships move tons of raw materials and finished products between continents, and intercontinental shipping has become more important as economies have become more globalized. Despite their role in a healthy economy, large cargo ships and oil tankers also cause air pollution and water pollution. Pollution from oceangoing ships comes from four sources: (1) exhaust; (2) ballast water, which is water that ships draw into empty tanks to provide stability and then dump out as the ship enters port; (3) fuel leaks and oil spills; and (4) dumped wastes. Laws dating back to the 1970s address air and water pollution but have ignored the wastes discharged from large ships. Residents of port cities, however, have known for some time that their air has been fouled mainly by ships. “These ships are essentially floating smokestacks,” Vickie Patton, an attorney at the Environmental Defense Fund, told USA Today in 2004. Another concern is that ships produce more sulfur oxide and nitrogen oxide gases than CO2, and the sulfur and nitrogen compounds contribute more to global warming than CO2 does.

Shipping causes two additional hazards to the environment: (1) the introduction of invasive species and (2) water pollution. Many invasive species that have infiltrated ecosystems around the world arrived in ballast water. Hundreds, perhaps thousands, of invasive species from microbes to fish and plants have traveled via ballast water. Cargo ships, tankers, cruise
ships, tugs, and smaller boats also foul waters with small but constant fuel leaks, large oil spill accidents, and accidental or intentional waste-dumping. The shipping industry therefore has two critical issues to address: (1) the need to build new clean-running ships to replace older, dirtier vessels, and (2) stricter adherence to laws against emissions, fuel spills, and illegal dumping. Unfortunately, very few laws exist to regulate ballast dumping. Governments can help by passing laws to require the shipping industry to clean up its current operations and seek new technologies to circumvent the ballast problem.

Washington’s Port of Seattle has taken the initiative with a plan to require that all ships that regularly enter the port convert from dieselpowered engines to clean ships. This of course will be an enormous undertaking for two reasons: (1) many thousands of ships currently cruise the world’s oceans, and (2) the majority of ships are registered with countries that may not make the environment a priority. Despite the challenges, the Port of Seattle has been specific in what it expects from clean ships. First, vessels in port will be allowed to plug into onshore electric power sources rather than burn fossil fuels. Second, ships may be required to burn lowsulfur fuel while at berth and perhaps while at sea. Third, the shipping
industry should continue its recent push to convert to diesel blends that reduce fossil fuel combustion. Fourth, current ships can be retrofitted into more energy-efficient designs. Fifth, the efficiency of operations at terminals should be improved to speed loading and unloading and so reduce the time ships wait offshore.

As the old generation of ships disappears and a new generation takes its place, shipbuilders will pursue the following objectives, listed in order of their feasibility:

1. better shapes to reduce drag
2. low-drag paints and finishes
3. new propeller designs
4. clean-burning fuels
5. onboard emissions scrubbers
6. hull air-blasters to reduce hull-water resistance
7. hybrid vessels

In 2008 the Christian Science Monitor writer Gregory Lamb discussed an even more innovative approach than the previous options: “When the cargo ship Beluga SkySails left the port of Bremen, Germany, in January, it carried with it a high-tech version of an ancient means of propulsion. During its 11,952-nautical-mile [22,135-km] voyage to Venezuela and
back, the ship launched a giant kite from its bow, sending it hundreds of feet into the air to capture the stronger and more consistent winds found above. The 1,720-square-foot [160-m2] kite, controlled by onboard electronics, exerted enough pull on the ship to provide about 20 percent of the engine power required for the journey.” This approach was certainly innovative, but hardly practical for today’s global shipping industry. Nevertheless,
transportation always has room for people with inventive ideas to help the environment.

The Austrian engineer Michael Frauscher may have hit upon a more practical solution than huge sails. Frauscher builds hybrid recreational boats that run on electricity when starting or idling or when underway at slow speed. These boats then transition to regular fuel combustion when they reach higher speeds outside the harbor. “Everybody knows about

More than 80 percent of transportation greenhouse gas emissions in the United States
comes from on-road vehicles. Light trucks, or light-duty trucks, are sport utility vehicles,
pickup trucks, and vans. Heavy-duty vehicles are commercial trucks, trucks with more
than two axles, and buses.

hybrid cars,” Frauscher said in the San Francisco Chronicle in 2008, “but hybrid boats are different.” Since most of the pollution from boats comes when they are in harbor, the hybrid boat has been designed to first solve this problem. San Francisco has added new ferries to its existing fleet that burn a blend of biodiesel (fuel made from biological sources) and low-sulfur fuel to reduce dangerous emissions by 85 percent lower than federal emissions requirements. Hybrid technology as well as low-emissions fuels may signal the next wave in cleaner ships.

The World’s Growing Car Culture

The social observer Ivan Illich wrote in 1974, “The model American male spends more than 1,500 hours per year on his car; driving or sitting in it, parking or searching for it; earning enough to pay for the vehicle, the tolls, the tires, the insurance or highway taxes.” Things may have changed little since then other than American women joining men in the love for their cars! The situation is known as car culture in which a society’s activities—economy and recreation—revolve around the car, but so too do people’s sense of style, wealth, or identity.

The car culture is composed of the production of automobiles but also includes car-related products, fuel production, fuel consumption, and car travel for work, school, shopping, and vacation. Of the fuel consumption component of car culture, President George W. Bush declared in 2006, “Here we have a serious problem: America is addicted to oil, which is often imported from unstable parts of the world.” Bush made a valid point; the United States consumes nearly one-fourth of the world’s oil.

The car culture flourishes in the United States more than any other nation for two reasons. First, the United States has ample land that allows dispersed cities to continue spreading outward. (The United States, Canada, and Australia—countries with large open spaces—own the highest number of cars per person in the world.) Second, the United States’ historically low gasoline prices have not hindered people from driving places
where they could walk or take a bus. Now other parts of the world have begun to follow the U.S. lead. China’s expanding middle class, for example, purchases a large portion of the world’s new cars, and, as a result, China now experiences the same ills caused by too many cars that the United States does. Though most people in China’s 1.3 billion population do not own cars, car ownership has grown 300 percent in a mere six years. The Beijing Web site engineer Zhu Chao told the Washington Post reporter Maureen Fan in 2008, “I’ve been to Sichuan, Shandong and Jilin provinces, and I plan to spend Chinese New Year driving to Yunnan. I really like what the car brings to my life—convenience, freedom, flexibility, a quick rhythm. I can’t imagine life without it.” Zhu Chao could have been speaking for almost any American.

Freight Transport

Railroads have been a major mode of cross-continent transport since the mid-1800s. In 1869 the Union Pacific and the Central Pacific railroads met at Promontory Summit in Utah to complete the United States’ first transcontinental railroad. That single event launched a generation of rail cargo shipments and passenger travel. Today, the U.S. freight railroad industry operates on almost 145,000 miles (233,000 km) of tracks and carries about $37 billion of freight. Freight trains carry mostly coal (21 percent of their traffic), containers or truck trailers (14 percent), and chemicals (12 percent).

The Federal Railroad Administration (FRA) has cited four benefits to the environment from trains: (1) railroads are more fuel efficient than trucks, and fuel efficiency improves each year; (2) a locomotive emits about one-third the greenhouse gas emissions (gases and particles) as a truck carrying the same tonnage over an equal distance; (3) freight railroads
lessen truck traffic congestion in cities; and (4) rail transport of hazardous chemicals has a better safety record than truck transport of the same chemicals. The U.S. Environmental Protection Agency (EPA) additionally stated in its 2006 report Greenhouse Gas Emissions from the U.S. Transportation Sector that, although transportation accounts for more than 30
percent of total greenhouse gases, locomotives contribute only 2 percent to that total.

Despite the advantages cited by the railroad industry, new rails have been difficult to build due to expense and state and local regulations. Many people oppose any new tracks running through their neighborhood. Much of the FRA’s work today centers on improving the safety of existing railroads that cross places that are becoming increasingly populated. These safety precautions include the use of horns in populated areas, slowdown requirements in city limits, and improved train-traffic crossings.

The rail industry has worked to reduce locomotive emissions by attaching new scrubbers to the engine exhaust systems. A scrubber is a device that burns and filters soot from locomotive exhaust. In 2006 Mark Davis spoke for the Union Pacific Railroad by explaining, “It’s [scrubbers] part of our industry’s continued effort in looking for cleaner, more fuel
efficient locomotives. We looked at 14 different filtering technologies and this one [a silicon carbide–based filter] made the most sense and best fit the rail industry’s needs.” Locomotive scrubbers represent an essential first step in building cleaner railroads.

Train fuel efficiency has improved more than 80 percent since 1980 according to railroad transportation company CSX Corporation. The CSX vice president Lisa Mancini praised the railroad industry in 2008, saying, “Freight rail is safe, secure, efficient and sustainable. Through dedication and cooperative investment it is possible to achieve a balance between
freight rail—which drives our nation’s economy—and passenger rail— which carries our nation’s citizens.” In order to fulfill Mancini’s vision, freight transport will likely focus on the following objectives in the near future: (1) further increases in fuel efficiency; (2) equipment for reducing hazardous emissions on current locomotives; (3) development of clean-air locomotives; and (4) design of shutdown systems to reduce fuel waste and emissions when idling.

Freight transport by trucks increased dramatically as the new U.S. interstate highways were built in the 1950s. Trucks now carry 58.2 percent of goods by weight compared with 12 percent carried by train. But trucks and rail lines carry about equal amounts of goods in terms of tonmiles, meaning the miles needed to transport a ton of goods. Trucks tend
to transport materials of much higher per-ton value than trains. Trains carry new cars coast to coast, but they also deliver hundreds of tons of raw materials to industry. These materials—coal, chemicals, solvents, resins— have a lower per-ton value than many of the finished products carried by trucks. Though North American transport depends on trucks, the trucking industry must confront the same issues as personal vehicles regarding emissions. Large diesel trucks contribute up to 40 percent of the nitrous oxides (a greenhouse gas) and as much as 60 percent of all particles emitted by vehicles that end up in the atmosphere. Trucking therefore needs to make a concerted effort toward cleaner alternative fuel vehicles as much, if not more, than personal vehicles.

Roads

and the road’s length. Smooth roads reduce the power vehicles need to maintain their speeds by reducing surface-tire rolling resistance. Environmental engineers therefore design durable roads that can carry heavy loads without cracking or wearing, yet give vehicles a smooth driving surface. Asphalt and concrete meet these needs but they also affect the environment in negative ways. Asphalt comes from the crude oil refining process, so it consumes nonrenewable fossil fuels, and the production of concrete’s main ingredient, cement, accounts for 7 to 8 percent of the world’s carbon dioxide emissions. New road building in sustainable communities will therefore focus on three areas for improvement: (1) alternate road materials; (2) road planning; and (3) road use.

Road planning and design work hand-in-hand with alternative materials to reduce roads’ carbon footprint. For example, gas-wasting designs such as long cloverleaf entrances and exits on freeways can be phased out and replaced with shorter but safe entry and exit lanes. Newer roads also improve water conservation with drainage ditches that catch runoff and
channel the water to wastewater treatment plants. Future road materials may soon be used in which a porous surface allows rainwater to seep into the earth and thereby reduce the burden on treatment plants.

Road planning also involves study on the ways people use roads. Commuters today follow very different driving patterns than commuters of a decade or two ago. The U.S. Department of Transportation’s Bureau of Transportation Statistics (BTS) has conducted a study that related a region’s economy to driving patterns. The BTS found a recent rise in the
proportion of daily “stretch commuters” or “extreme commuters,” meaning they travel more than 50 miles (80 km) each way to work every day in trips that take 90 minutes or more. Stretch commuters make 19 out of 20 of these trips in personal vehicles rather than mass transit. Housing costs have often contributed to these lengthening commutes due to the “drive until you qualify” syndrome. The MSNBC reporter Allison Linn wrote of a familiar circumstance in 2008: “For Dollie Kinkead, the economic turmoil gripping the country translates into an 80-mile [129 km] drive each workday from a house she can’t sell to a job she thinks she’s lucky to have.” Environmental engineering can help alleviate this bleak picture, but factors in society obviously play competing roles.

Long commutes may not be as fixable as finding new technologies in road building and planning. Austroads is an association of Australian and New Zealand road and traffic experts that takes a three-pronged approach to road-planning: (1) drivers’ needs; (2) economics; and (3) the environment. This organization wants to foster sustainable roads, meaning
roadway construction that reduces resource consumption, improves landscape and air quality, does not cause water or noise pollution, and

The typical combustion engine converts gasoline to motion efficiently at speeds higher
than 35 miles per hour (56 km/hr) with steady driving to avoid fast accelerations. Fuel
efficiency decreases in many cars at higher speeds.

protects habitats. Austroads has taken on all of these goals while providing resources for building quality thoroughfares for drivers and mass transit. Austroads’s chairman Alan Tesch explained in the organization’s latest annual report (2007–08), “A total of 41 projects were completed [in the past year] and 29 research reports and technical reports published. There were also 15 guides published . . . The guides are intended to be used by road authorities in Australia and New Zealand as a complete package of technical information that applies a consistent standard to road building . . .” Austroads also offers technical resources on road
design, planning, maintenance, and operation.

In the United States, engineers have reexamined two road designs: cloverleaf interchanges and traffic circles. A cloverleaf contains four loops and one or two bridges called overpasses that enable drivers to switch from one roadway to another without stopping at a traffic light. These designs decrease time spent idling at lights, but they also lengthen driving distance.
Traffic circles (called roundabouts in other countries) allow traffic to flow without stopping at interchanges between two or more roadways. Circles have offered an efficient traffic control device for many years until the 1980s when heavy traffic overwhelmed many circles. Densely populated New Jersey, for instance, once depended on more than 100 traffic circles statewide to ease traffic flow, but the state has gradually removed many of its busiest
circles that slow traffic rather than speed it up.

Environmental engineers today develop ways to
decrease fuel waste while maintaining safe roads.
This interchange in Fort Worth, Texas, in 1958,
seemed like a well-designed answer to navigating
the country’s new interstate highway system. This
design called a cloverleaf, however, requires extra
driving and road-building materials so it may not
be the best choice for helping the nation reduce its
total fuel consumption. (TexasFreeway.com)

 

Air Travel

Air travel fuel efficiency has improved in the last 30 years more than threefold, and since 2000 fuel conservation in the airlines has improved by almost 25 percent. The U.S. passenger fleet has made even better strides when measured in revenue passenger miles (RPM), which equals one fare-paying passenger carried one mile. The U.S. RPM per gallon of fuel has more than doubled since 1978. Passenger and freight airlines made this remarkable progress in fuel efficiency by using the following methods:

Engineers design advanced transit systems to meet the particular needs of a city and its surrounding communities. The goal of advanced transit is to speed travelers to their destinations with superior efficiency. Future advanced transit projects will include safe routes for pedestrians, bicycles, and motor scooters, and they will provide electricity for recharging electric-powered vehicles during the workday.

1. single-engine taxiing
2. selective engine shutdown on ground delays
3. better weight distribution
4. cruising longer at higher altitudes
5. shorter, steeper approaches to cruising altitude

Aircraft engineers may always struggle to simultaneously solve fuel efficiency and emissions because high-altitude flights give better fuel efficiency, but slower aircraft cruising at lower altitudes emit less CO2. Airline industry engineers, nevertheless, have other opportunities that can complement each other for reaching better overall efficiency, such as the following:

1. improved navigation and weather forecasting systems to calculate most efficient routes
2. fuel-efficient engines and aircraft
3. winglets to reduce air drag and reduce fuel use 3–5 percent
4. new paints to reduce heat absorption, which requires extra energy for cooling
5. airport power hookups rather than use of onboard auxiliary power when at the gate
6. innovations in current kerosene-type jet fuel that comes from crude oil
7. aircraft innovations to reduce noise pollution

Redesigned hubs (a centralized heavy-traffic airport) and better flight scheduling should also reduce resource waste. For instance, a typical airport may run the following operations in a single day: (1) jet fuel arrives by pipeline or truck to a storage site; (2) airport hydrant system distributes fuel to the terminals; (3) hoses carry the fuel from the terminal hookup to individual planes; and (4) refueling trucks carry fuel to remote terminals. These systems work well enough, but newer designs will extract savings by relying less on trucks or by changing an airport’s capacity to fuel more airplanes from a single fuel tank. Airports have
already changed configurations to allow more planes to land and take off without ground delays, which saves fuel on the ground and in the air. The Air Transport Association of America has stated its view on fuel efficiency: “Beyond the numerous, diverse, successful measures that U.S. airlines have taken and continue to explore to conserve fuel, the
single biggest advance in fuel conservation, and emissions reduction, will come from reform of the U.S. air traffic control system, which continues to rely on 1950s technology and procedures.” Clearly, the airline industry has a broad horizon of opportunities for improving society’s use of natural resources.

Can Bicycles Make a Difference?

Bicycle commuting requires similar thoroughfares as those used by pedestrians. That is, bicycle routes must be safe, well-lighted, wellpaved, inviting, and go where the traveler wants to go. The benefits of using a bicycle to replace cars in most commuter trips should be familiar to almost everyone: bicycling promotes health; bicycling reduces air and noise pollution; bicycles do not use fossil fuels; bicycling relieves traffic congestion, which burns more fuel; and bicycles do not require much space to park—about 20 bicycles can park in a single car parking space.

Bicycling Life, a Web site devoted to bicycles as an alternative mode of travel, has noted that bicycling gives added benefits beyond good health: bicycles are inexpensive for owners and for city infrastructure; high-quality bicycles include more advanced material and power technologies than cars; and in urban centers bicycles reach their destinations faster than
cars, but bicycling has not become part of global industry. The last point refers to the wariness that many people feel toward giant corporations that have close ties to government. In 1955 General Motors chairman Charlie Wilson proclaimed, “What is good for General Motors is good for America.” At the time, Wilson made a valid point because the country’s economy and car-oriented culture brought new post–World War II conveniences
and wealth. But the auto industry also grew into a huge enterprise that collected as many critics as it did supporters. The bicycle industry, by contrast, supports local businesses and has not become tied to political agendas.

A new bicycle culture in the United States may take different forms that will all help the environment. First, commuters can substitute bicycles for cars whenever possible. Bicycle travel may be point to point or it may be composed of partial trips in which a bicyclist rides to a subway or bus station and then travels part of the route on mass transit that also carries the bicycle. Second, bike-sharing works the same as car-sharing: More than one person makes use of a single bicycle in a day, either free or with a small rental fee. After a few hours, the rider returns the bicycle to the same drop-off/pickup location. Bike-sharing in Paris, France, outshines any other place in the world for efficiency. In 2008 the Time reporter Kristina Dell wrote, “It’s hard to walk more than two blocks [in Paris] without running into a bike rack, which helps explain why the program has already yielded a 5 percent drop in car traffic. Paris has also removed lots of parking spots to make way for bike stations.” Lyon, France; Copenhagen, Denmark, and Barcelona, Spain, also run successful bike-sharing programs. By comparison, Washington, D.C.’s program has 120 bicycles and only 10 stations. A third bicycling option involves the use of electric bicycles, also called e-bikes, that run on power levels much lower than those consumed by cars—150 watts of electrical energy versus 15,000 watts for a car.

Bicycles certainly make a difference in preserving the environment, especially if people combine bicycling with other sustainable activities. To help bicycling grow and make a true impact on the environment, some of the following issues must be resolved: (1) safety for bicyclists in heavy vehicle traffic; (2) building more bikeways; (3) options in bad weather;
(4) theft prevention; and (5) developing respect between drivers and bicyclists. As the Time reporter Dell pointed out, “With gas prices skyrocketing and carbon-footprint consciousness going mainstream, more and more cities are betting that Americans are finally ready to make biking part of their daily commute.” Dell’s prediction has already come true in many cities and towns where a small but dedicated subpopulation of commuters has made the bicycle their primary mode of travel.

Commuter Rails and Buses

Commuter rails and buses offer the advantage of carrying many commuters on the same vehicle on a single trip so that fewer personal cars crowd the roads. Commuter rails have evolved over the past 100 years to encompass a variety of styles seen in cities today. Some large cities contain more than one mode, and almost all large U.S. cities contain at minimum a bus system and a rail system. The table on page 49 explains the types of rail systems in use in the world today; all have in common the requirement of running solely on set routes determined by preexisting tracks.

Heavy rail refers to railroads that carry freight and passengers coast to coast. Some railway lines combine freight cars and passenger cars, but others such as Amtrak trains run mainly for long-distance travelers and commuters. Local commuter rails, such as New York’s Long Island Railroad (LIRR), cover shorter distances, and, in many instances, these local lines
bear the majority of rail travel in a metropolitan area. For instance, the LIRR carries almost 300,000 commuters each weekday and is the busiest commuter railroad in North America.

The difference between heavy rail and light rail can be difficult to understand at times because many light rail systems serving cities and suburbs resemble long-distance commuter rails. The following two principles have helped clarify the difference between light and heavy rail, but even these principles have exceptions and may be thought of as merely rough rules of thumb. For instance, most subway riders board trains from a platform.

1. Light rail travels 10 miles per hour (16 km/h), up to 60 miles per hour (96 km/h), and heavy rail travels faster than 60 miles per hour.
2. “On heavy rail, you board the train from a platform. On light rail, you board the train from the ground.” (engineer Harry H. Conover)

Trolleys, streetcars, and trams differ from rails because they usually travel at low speeds, and they often receive electric power from lines above the car. These modes alleviate some downtown congestion, but they may also contribute to traffic congestion in certain places such as crossings.

Light rail covers longer distances from outlying areas to city centers and presents the best features for getting people out of their cars and onto mass transit. Light rails usually travel on tracks in which the electrical power comes from a dedicated power rail in the track, sometimes called the third rail. Traffic design engineers now develop light rail systems that
share some of the characteristics of streetcars and trams, such as routes along mixed traffic streets, dedicated rights of way, exclusive corridors, or in the middle of major thoroughfares.

Light rails are easier to build than heavy rails and have lower operating costs. These advantages enable engineers and local governments to plan convenient routes to reach commuters yet avoid wetland and woodland environments. Light rail and subway systems hold great potential for conserving fuel in urban areas and reducing harm to the environment, especially by incorporating the following points:

1. different types of systems to expand commuter choices
2. convenient stations
3. convenient commuter-hour scheduling
4. on-time performance
5. minimize breakdowns
6. preservation of open space

Commercial bus lines strive for similar objectives as light rail systems, that is, moving large numbers of people swiftly on a single vehicle. Longdistance bus companies such as Greyhound run intercity bus lines, while transit buses (also called urban or city buses) serve neighboring towns or a single large city. Buses have two advantages over light rail: (1) buses often serve rural communities where no other mass transit system runs, and (2) bus routes can be changed according to a community’s needs. Like light rail, buses carry as many as 100 passengers on a single vehicle (also called a motor coach, omnibus, or autobus), which spares roads and fuel, but they also congest urban traffic and produce emissions. Unfortunately,  buses have a long history of running on diesel fuel or gasoline and so have contributed to greenhouse gas buildup.

Towns in the United States have made efforts to convert their public buses and school buses to cleaner technologies. Lynn, Massachusetts, for example, plans to retrofit by 2010 all its 5,500 school buses so that filters clean pollutants out of engine exhausts. Ed Coletta, spokesperson for the state’s Department of Environmental Protection, said, “These buses are
going to be used long into the future, and we want to make sure they’re emitting as few gases as possible.” Lynn joins hundreds of other communities that have tried to balance the advantages and disadvantages of buses with a hopeful future.

New clean technologies can apply to vehicles in addition to transit, school, and shuttle buses. The DOE’s Energy Efficiency and Renewable Energy Program keeps track of various public transit fleets that have made similar inroads into pollution control and alternative fuels: delivery services, long-haul trucks, refuse haulers, taxis, rental cars, and police vehicles. All of these vehicles offer the advantage of belonging to fleets that return to a central base so that mechanics can assure the vehicles receive proper maintenance and fueling. The following table describes innovations that are rapidly emerging in public bus fleets.

Advanced transit represents a new type of bus or rail travel that uses more than one technology for the purpose of conserving energy and fuel. For example, a community that is trying to use energy and resources in a sustainable manner may develop an advanced transit system, also called light transit, that contains the following features:

1. a network of interconnected mass transit routes for buses, light rail, and heavy rail
2. dedicated commuter lanes
3. alternative fuel-powered fleets
4. electrical power hookup stations in addition to the fleet’s base station
5. express routes to bypass local station stops
6. emphasis on speed throughout the network
7. accommodation for bicycles in all fleets
8. easy and fast line switching, including long platforms and wide doors

Using the features above, advanced transit can meet its goals of eliminating inefficient schedules and excess fuel consumption, all while providing an enjoyable experience for riders. To do this, future advanced transit systems will likely include vehicles that are not yet common in today’s mass transit, such as trams, light-duty buses, dedicated bicycle
and scooter routes, and extensive use of car- or bike-sharing in city centers.

Pedestrians and Parking

The cleanest and healthiest way to traverse neighborhoods and the downtown is as a pedestrian. Many European and U.S. cities have made safe walkways to help pedestrians get to their destinations, but other places have become notorious for their lack of amenities for walkers. As people stop walking and increase their use of cars, not only does the environment receive more air pollution but people’s health also declines.

Reid Ewing’s research team at Maryland’s National Center for Smart Growth reported in 2003 in the American Journal of Health Promotion that U.S. urban sprawl contributed to obesity, high blood pressure, hypertension, heart disease, and diabetes—results that seemed to point to the lack of walking done by people in the study. Ewing explained in a 2006 interview published on ScienceWatch.com, “Using health data from the Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance System, this study
showed that American adults living in sprawling counties walk less, weigh more, and are more likely to be obese, and are more likely to suffer from high blood pressure than otherwise comparable adults living in compact counties (after accounting for individual socioeconomic and behavioral differences). This was the first study to show a link between urban form and the U.S. obesity epidemic.” Ewing’s study highlighted the often overlooked fact that mode of travel affects health and even the country’s healthcare costs.

European engineers have designed walking centers in several cities, including Copenhagen in Denmark, Cologne in Germany, Montpellier in France, and York in England. City planners can either design new car-free zones that admit only pedestrians and bicyclists or close off streets for periods of time to create temporary car-free zones. The sidebar on page 46 “Can
Bicycles Make a Difference?” takes a closer look at bicycles’ contribution to sustainable communities. Of course, roping off streets to exclude cars requires additional steps such as setting up access for business deliveries and providing parking for cars that reach the perimeter of the car-free zone. Redesigning cities to improve transportation is therefore a large task.

Parking availability has an important impact on the environment also mainly because it helps gets cars off the road quickly, allowing drivers to turn off their engines. Conversely, congestion caused by lack of parking spaces creates streets backed up with idling engines that emit exhaust. Multistory parking structures are better than large parking lots, which
cause the following problems:

1. remove large amounts of land from nature
2. contribute to rain runoff and soil erosion
3. absorb oils, fuels, and road salts that then wash away with runoff
4. hold heat and contribute to warming cities

Environmental engineers design new ecologically friendly parking garages to reduce the harm that sprawling parking lots have caused to the environment. The table on page 46 describes innovations for new community parking garages.

In California, the Santa Monica Civic Center parking garage provides convenient parking with many of the attributes listed in the table on page 46, plus additional innovations. Santa Monica’s garage is the nation’s first Leadership in Energy and Environmental Design (LEED)–certified parking structure because of these innovations: a storm water drainage and
treatment system for use in the sprinkler system; use of recycled construction materials; coatings and paints that produce a minimum of toxic vapor–producing substances; surface
glazing that promotes heating and cooling efficiency and reflects light to reduce electricity use; rooftop solar panels that generate onethird of the garage’s energy needs; and energy-efficient mechanical systems. The CNN reporter Desa Philadelphia noted, however, in 2008, “Those features weren’t cheap: the $29 million price tag for the car park is about $10 million more than for comparable garages. Santa Monica estimates that its parking structure will be profitable within fifteen years [of its construction].” Even parking garages have a place in sustainable communities if planners manage the costs carefully.

Conveniently located parking structures
help ease traffic congestion by reducing
the time a driver spends searching for
downtown parking. Garage builders
often include energy-saving lighting,
architecture that admits daylight, and
recycled building materials. This Ecoplex
parking garage in West Palm Beach,
Florida, included several principles of
green building in its construction and
use. (Tilt-up Concrete Association)

 

Fuel Efficiency

Fuel efficiency is the capacity to produce the greatest amount of work energy from the least
amount of fuel input. In vehicles, this is called fuel economy. Fuel economy arises from the
relationship between two types of energy: potential energy contained in a volume of fuel and kinetic energy associated with the vehicle’s motion. When a car burns fuel, the car’s potential energy decreases but its kinetic energy increases. Car designers try to design models that maximize this conversion so that most of the fuel’s potential energy turns into kinetic energy and little excess energy disappears as heat.

Improved fuel efficiency will come from two components: the type of vehicles produced
by car manufacturers and driving habits. Car engineers adjust the following characteristics to improve fuel efficiency: vehicle design, vehicle body’s materials, and engine design. Vehicle designs and materials that increase the car’s efficiency of movement help increase a car’s miles per gallon (MPG), which is the main value that describes fuel efficiency. Aerodynamic design, lightweight materials, and an efficient combustion system all combine to increase MPG. Meanwhile, drivers must do their part by following the advice of the U.S. Department of Energy (DOE) regarding fuel-efficient driving. The DOE has estimated that certain driving styles can save on fuel use by the percentages shown in the following list:

1. observe speed limits, 7–23 percent
2. avoid rapid acceleration and braking, 5–33 percent
3. avoid excessive idling
4. remove excess weight, 1–2 percent
5. use cruise control
6. use overdrive gears
7. keep engine tuned, 4 percent
8. replace dirty air filters, 10 percent
9. keep tires at recommended pressure, 3 percent
10. use vehicle’s recommended grade of motor oil, 1–2 percent
11. use trunk for storing items rather than roof rack, 1–2 percent
12. choose drive times to avoid peak congestion
13. combine trips
14. select vehicle based on fuel economy
15. buy a gas/alternative fuel hybrid car

All of the recommendations on this list cause few inconveniences for drivers and are easy adjustments to make. Drivers need only be willing to change their behavior in minor ways to help reduce harm to the environment and also save on their fuel expenses.

Personal Vehicles

Typical car advertisements illustrate the strong connection Americans have with their cars. Car ads often feature a vehicle cutting through mountain passes, speeding along coasts, or taking hairpin turns—never with another car in sight. Though these ads promote an association between driving and nature, cars actually threaten nature in many ways. Automobiles and trucks pollute the air with greenhouse gases and particles. Vehicles also create traffic congestion, which leads to additional pollution and prompts communities to build more roads. Then the domino effect increases urban sprawl.

Mass-produced road vehicles pioneered by Henry Ford changed lifestyles forever. Ford’s innovation increased mobility and opened a new world of careers, learning, and communication, but it also soon produced congestion. Engineers worked diligently to design smooth roads for faster travel, plus traffic lights, bridges, and other deployments to keep cars moving. In the car’s early history as now, drivers tussled with the thorny problem of getting around slow traffic. In the 1940s, engineers began planning divided highways in the United States to keep traffic moving; passing lanes allowed faster vehicles to overtake slower drivers. The divided highways, also called freeways, next included overpasses so that
drivers could move through interchanges without stopping or even slowing. When urban sprawl accelerated in the late 1940s after World War II, city planners sat down with engineers to map out more roads based on patterns of trip origins and common destinations. New roads would bring, they thought, two rewards: income from vehicle and fuel taxes and a solution to congestion.

It is difficult to say whether new roads and rails encouraged urban sprawl or urban sprawl created the need for more roads and rails. In either case, additional road-building within the past few decades has not reduced congestion and, in many places, bad traffic has increased. The economist Robert Samuelson has been credited with the theory that “cars expand to fill the available concrete.” People might choose to decrease their driving either because of its environmental impact or due to rising fuel costs. However, Colorado State representative Claire Levy pointed out to the Denver Post in 2008, “The average person can reduce their driving by only a small amount since it is impossible to get to work, school, church, or shopping centers without a lengthy drive.” It seems as if Americans have become inextricably tied to their cars.

Economics influences driving patterns, as Representative Levy implied. Fuel costs often affect drivers’ choices in personal vehicles, carpooling, or mass transit, but housing costs also play a part in transportation. Housing costs near the center of desirable cities such as San Francisco, New York, Denver, or San Diego force families to seek housing they can afford, houses that exist only in outlying areas. As a consequence, the number of commuters and the distances they travel to city-based jobs increase as housing costs in a metropolitan area increase. The USA Today writers Debbie Howlett and Paul Overberg explained in 2008, “To afford a house in a neighborhood with good schools, low crime
and Saturday morning youth soccer, extreme commuters keep highpaying jobs in the big cities and buy houses well beyond the traditional metropolitan area. In California’s Antelope Valley, across a mountain range from Los Angeles, commuters call it ‘driving until you qualify.’ ”

The Zipcar car-sharing program at the University of North Carolina at Chapel Hill
allows borrowers to reserve a car online on an hourly basis. An electronic reservation
system remotely unlocks the vehicle at the time the reservation starts. Zipcar offers
several on-campus pickup and drop-off stations. Several cities have experimented with
similar car-sharing programs as well as bicycle-sharing to decrease traffic congestion
and reduce overall emissions. (GlobalExchange.org)

(The New Yorker’s Rick Paumgarten once explained, “ ‘Drive until you qualify’ is a phrase that real estate agents use to describe a central tenet of the commuting life: You travel away from the workplace until you reach an exit where you can afford to buy [qualify] a house that meets your standards.”) Mass transit has had a difficult time keeping up with these lengthening commutes.

Civil and environmental engineers understand that some drivers will not forsake their cars, and taking drivers out of cars may in fact hurt the global economy. The auto industry supports thousands of other businesses and also serves as a major recycler of metals. Many aspects of the world’s economy—a mobile workforce, taxes, jobs, and tourism—depend on cars too much to ignore. Car-sharing programs offer a good compromise to the abundance of single-driver cars. In these programs, drivers register with a car-sharing enterprise in their city and reserve a car at a set location and then leave the car with its keys once they are finished driving it. The next car-sharer takes the vehicle from there. The automotive analyst Thilo Koslowski told the Boston Globe in 2007, “The next generation of drivers
may have a little bit different view of how to meet basic transportation needs—they may not need to own a vehicle.” For the present, car-sharing is not offered in every city so it has room to grow. But car-sharing’s appeal lies in its potential to reduce the total number of cars on the road while allowing drivers the independence they enjoy.

Urban Transportation Systems

Efficient and attractive mass transit systems can greatly help in breaking the car habit. Some cities struggle with transportation systems that have noisy, polluting equipment that runs behind schedule and requires passengers to change vehicles to continue their routes. Clearly, commuters will not be eager to leave their cars for this experience. Other cities have built transit systems consisting of new vehicles that burn fossil fuel alternatives

Curitiba, Brazil, has built an admirable advanced transit system. The system designates separate roads for buses and long nonstop car commutes, point-to-point public transit routes, and local routes that speed the travel of people who do not need to enter the city center. The city now has what many consider the world’s best bus system supported by well-planned highways and bus stations. Curitiba has also built extensive routes for bicycle commuting.

and that run on well-planned routes. Curitiba, Brazil, for example, emphasized transportation in 1969 when it embarked on a project to become an ecological city. Curitiba planned walkways, bicycle paths, bus routes, and car thoroughfares that complemented each other and took large numbers of commuters quickly into and out of the city center. The detail-oriented system in Curitiba even included extra-wide rail doors and platforms to
allow more people to board and disembark at the same time.

Mass transit’s main advantage over other modes of transportation resides in its ability to carry many passengers in a single vehicle. Despite this obvious benefit to the environment, mass transit must overcome many problems that hamper it in the United States and other countries, as summarized in the following table.

Future mass transit systems will need to fix the problems of noise, pollution, inconvenient routes, and poor performance, but new systems must also improve in other ways. People value certain intangible qualities such as convenience, safety, and cleanliness. Many individuals simply do not like mass transit’s strict schedules, predetermined stops, and the feeling of riding in close quarters with hundreds of strangers. U.S. lifestyles also do not mesh well with mass transit schedules for the following reasons: (1) many people work long overtime hours and do not feel comfortable taking mass transit during nonpeak hours after dark; (2) mass transit does not lend itself to drop-offs and pickups at daycare facilities;
and (3) mass transit is difficult to coordinate with extra trips linked with work commutes, such as shopping, medical appointments, and school schedules. Some rural areas have no access at all to mass transit even if riders would be willing to use buses and trains.

Perhaps the biggest hurdle to mass transit in the United States relates to habit. Some Americans see their cars as extensions of their identity. Developing countries, by contrast, have depended on mass transit as their main means of travel to work and recreation. The Institute for Transportation and Development Policy (ITDP) based in New York City and
Wohltorf, Germany, has developed the following primary focus areas for breaking the car habit:

1. developing high-quality, low-cost mass transit infrastructure
2. planning for and advocating cycling and walking
3. strengthening bicycle and other nonmechanized vehicle industries

Of the three ITDP goals listed here, high-quality and low-cost mass transit will be key to ushering people from their cars and onto buses and rails. Mass transit must outcompete cars by offering outstanding service.

This means improvements in comfort and safety, frequency of service, speed, and ease of transfer from one line or mode to another. Australia has focused on these things to make recent enhancements to its mass transit, and, as a result, transit systems have become profitable for large cities such as Sydney, Melbourne, and Brisbane. Mass transit improvements that have worked for Australia and that are now being adopted by other countries are the following:

• walk or cycle routes leading to park and ride transit stops
• mass transit vehicles that accommodate bicycles
• single ticketing system for an entire metropolitan area
• extensive suburban routes
• dedicated bus-only roads with overpasses at intersections
• buses with driver-activated priority at intersections
• feeder buses that link neighborhoods to express routes

Sydney, Australia’s “T-way” transit system has used several of the improvements listed above to reduce some travel times by up to an hour. Yet even with these advantages, large countries like Australia and the United States do not maintain the mass transit ridership seen in densely populated European countries. In Brisbane, Australia, citizens take an
average of 20 rail trips each year, while in Switzerland citizens take about 530 rail trips per year. Zurich, Switzerland, has developed a bus and tram system that is one of the best in the world, based mainly on the provision of separate roads for mass transit. In the early 1990s Zurich converted some of its streets to pedestrian and public cars only, removed some curbside parking to help traffic flow, raised tram tracks to avoid congested areas,
and reduced the number of legal left turns—Swiss drivers drive on the right side of the road as in the United States. In addition, public transport vehicles control 90 percent of the traffic lights, which helps transit drivers make the route more efficient with less slowdowns.

No place on Earth is a mass transit utopia. Australian mass transit runs well, but still has its pitfalls; Zurich’s system did not arise overnight and would likely be prohibitively expensive in the United States, with its much larger area. (The size of the New York metropolitan area alone is one-fourth the area of Switzerland.) American Public Transportation Association spokesperson William Millar told the USA Today reporter

European cities have developed the most efficient train stations in the world. Europeans travel by train more
frequently than travelers in the United States. This station is Gare du Nord in Paris, France, which is the busiest rail station in Europe and one of the busiest in the world. (iStockPhoto.com)

Marisol Bello in 2008 that “only 5 percent of [U.S.] workers commute by public transit . . . and no more than 20 percent of households has easy access to buses or trains.” If countries like the United States are to achieve sustainability in natural resource use, it will take a new commitment by people to mass transit, but also at a cheaper price tag. Joe Giuletti of the South Florida Regional Transportation Authority said in the same news article, “At a time that ridership is at an all-time high and people are desperate to use mass transit we are in a terrible spot.” Mass transit remains a very tough test for the next generation of environmental engineers.