Railroads, a mode of transportation some now dismiss as antiquated, present transportation engineers with numerous technically complex challenges. Their future involves high speed passenger trains for intercity runs of medium distance. Although highways have replaced railroads as the major carrier of people and freight in the United States today, more than 300,000 miles of railroad track still remain in service, and intermodal transportation calls for rail/highway links. Faced with the increasing costs of track and rail bed maintenance, civil engineers working with railroads are often engaged in rebuilding old railroad lines and improving the combined structure of the rail, the tie, and supporting ballast beneath the track.
Railroads also continue to build new lines, often to serve new industrial and commercial facilities. Likewise, the growth in recent years of intermodal "piggyback" service, in which truck trailers are carried long distances on railroad flat cars, has led to the demand for new rail and terminal facilities. As any motorist who has waited endlessly at a grade crossing for passing boxcars and other rail cars carrying truck trailers, liquid fuel, and coal can attest, railways continue to carry a large portion of the nation's raw materials and finished goods, such as heavy industrial machinery, heavy military equipment, and automobiles.
In urban areas, railroad rights of way are being redesigned to satisfy mass transit needs. Urban mass transportation elements include the planning and design of subways, elevated rail lines, "people movers," such as those built to move people around large airports, and surface rapid transit routes. As with railroads, transportation engineers are also heavily involved in the reconstruction, renovation, and maintenance of the aging subway and elevated rail systems in cities such as New York, Philadelphia, and Chicago.
Highway engineers, primarily employed by the state departments of transportation, are responsible for the planning, design, and maintenance of highway systems and secondary roadways. The work of highway engineers begins with the planning of highways and related facilities to meet future needs created by changing population patterns and the growth of cities and towns. In this respect, their work is similar to that done by the railroad engineers during the development of rail systems more than 100 years ago.
Highway engineers must analyze basic traffic patterns and attempt to predict future traffic flows. After determining the need for highway facilities based on traffic predictions, the engineers must develop the most economical combination of highway alignment and location, while paying much attention to environmental and social impacts. Engineers also supervise the construction of embankments and fills to carry roadways across low areas, and of cuts, or in some cases tunnels, to carry roadways through hills and mountain ranges. Ask any highway engineer what's most satisfying about his or her job, and high on the list will likely be the opportunity to work against the backdrop of scenic mountains, river courses, or seacoasts. High on the list of the highway engineer's biggest challenges will likely be urban highway projects-work often done at night, under tight deadlines, in very congested conditions, and with live traffic often moving just a few feet beyond the construction site.
In addition to the planning of highway facilities and the initial excavating and grading of road beds, highway engineers must design pavements to reflect the most efficient use of asphalt, concrete, and other materials available at different prices at different locations.
All of these factors-available materials, alternate routes, environmental and social impacts, traffic demands-must be considered by the highway engineer in developing the safest and most efficient system for the lowest expenditures of money, material, and labor. Nonetheless, highway projects, particularly the construction of new highways, tend to be massive in scope, sometimes costing a billion or more dollars, involving hundreds of skilled craft workers, and millions of dollars worth of heavy construction equipment. It's all in a day's work for the highway engineers orchestrating these mega-projects.
A more specialized area of transportation engineering is the planning and design of airports and their related facilities. These include terminals, hangars, runways, taxiways, and parking aprons. As traffic volume at many airports increases, the infrastructure of the airports becomes outdated. New ways are found to more efficiently move passengers and freight. For instance, the explosive growth of commercial air delivery services over the past twenty years has created the need to accommodate hundreds of aircraft, including jumbo jets. At the same time, the mitigation of environmental hazards casts a long shadow over many of today's airport projects. Since the 1960s, the federal government has spent billions of dollars on noise mitigation alone.
A less obvious form of transportation engineering is the planning and design of pipelines to carry liquids, gases, and combinations of liquids and solids. Perhaps the most famous American pipeline is the Alaskan Pipeline, constructed to bring petroleum from the North Slope of Alaska to consumers in the Lower 48. To even approach a job of this magnitude, engineers representing many disciplines had to develop materials, adapt machines, and properly equip workers to engage in heavy construction in one of the world's coldest, harshest regions. Because a major oil spill would be disastrous in this region, one of the most environmentally sensitive regions in the world, engineers had the added challenge of ensuring that the pipeline was as nearly fail-safe as possible.
Many pipelines of great importance, sometimes rivaling the Alaska Pipeline in size and cost, have been and will continue to be planned and designed by civil engineers specializing in this area. Natural gas pipelines were constructed throughout the United States in the years following World War II to provide Americans with one of the most convenient forms of energy for use in residential and commercial beating and industrial processing. These pipelines must be kept in good repair. Even solid materials such as coal are now moved through pipelines in the form of slurries-mixtures of solids and water. Indeed, slurry pipelines account for a large portion of the pipeline projects currently being planned for future construction.
Civil engineers who specialize in pipeline transport of materials must determine the most economical alignment of pipelines, with full consideration for the possible social, political, and environmental effects of such construction. These engineers plan and design power plants, terminal facilities, receiving and discharge plants, and pumping stations associated with pipelines. These engineers work closely with structural and geotechnical engineers, as well as with other specialists in the broad field of civil engineering.
Modes of transport, whether of people or materials, may increase or decrease in importance, but transportation engineers will always be vital to the functioning of society. Approximately one out of seven engineers working in the United States is involved in transportation engineering.
