Transportation & Surveying

Transportation engineering includes the design of:
    roads and highways,
    railroads,
    airports
    (in the past: canals for navigation)

There are three basic specialties in transportation engineering:
1. Planning - determine what is needed, where, when, and how to pay
2. Design - design needed support systems, with how to construct them
3. Operations - maintenance, maximize efficiency, safety considerations; modify existing designs

Important tasks of the civil engineer in these projects will include:
determining cut and fill volumes for earthwork
calculating the layout of both vertical and horizontal curves, spirals, super-elevation
how much grade to maintain optimal traffic flow?
how tight of curves and super-elevation for cars vs. semi-trucks?
what speed can be safely maintained by the drivers?
road planning - routes, bridges, turning and merging lane lengths,...
cross-section
pavement selection - concrete, asphalt; resilience to freeze-thaw
traffic controls - number of lanes, traffic volumes, signals

what are the best signal timing cycles to use? goal: minimize traffic "dead times"

An example of "design safety" considerations for signs, signals, controls:
what is best height to locate signs for visibility?
what is the best type of reflective paint to use for lane markings?
what are the most visible colors to use in construction zones?
placement and type of guard-rail?
"impact friendly" sign poles (break-away)
ditches - width, slope

SURVEYING
Surveying includes getting the "lay of the land" initially and laying out construction. Surveying skills are good for summer jobs with the highway department or geotech firms. Most of the work is in the field. Modern surveyors use "total Systems" allowing in-field calculations, which are directly fed data acquired by an Electronic Distance Measuring instrument (EDM)

Transportation:

Civil engineers involved in the field of transportation have a great impact on regional development, such as the first transcontinental railroad in the U.S.

History

  The Persians and Chinese had roads as early as 500 B.C., but these were quite primitive by Roman standards. There was a Chinese saying that "a road was good for 10 years and bad for ten thousand". In South America the Inca had a 10,000 mile network of roads that were built with a labor tax on villagers. The Inca didn't have the wheel or animal labor to help with road construction, and built everything by hand. These roads included both earthen and stone paved walkways.

  The Romans built the first government built and maintained road system. This vast road network eventually encompassed 50,000 miles to connect the Empire, covering what today includes Britain, France, Spain, Italy, Greece, Turkey, and the northern coast of Africa. Parts of this roadway are still in use after more than 2000 years. The first part of the Roman road system was constructed in 312 B.C., beginning with the 132-mile long "Appian Way" which connected Rome and Capua. The builder/engineer of this roadway was Appius Claudius. The entire road system expanded over the next 800 years and was maintained through the 5th century AD when the Roman Empire collapsed. After this time, road building became a lost art.

  From Roman road-building the term "highway" originated, due to the fact that roads were build elevated above the terrain level with ditches on both sides for drainage. The Roman roads were generally "arrow straight" with no vertical or horizontal curves. This frequently required major amounts of earthwork to cut through hills and fill low spots. Roman roadways were up to 30 ft. wide to allow two lanes of traffic in major areas, and up to five feet thick. The cross-section of the roads were cambered or arched in the center for good drainage.

  The road building process began by surveying the location of the future road by sighting and driving stakes, and the level of the roadbed determined using plumb bobs. The route was cleared of brush, drainage ditches were dug, and roadbed leveled. Next, the subsoil was compacted by hand-dragging heavy rollers. Then layers of stones were set into concrete and tamped with weights attached to poles. The upper load-bearing surface was made of thick stone slabs fitted into place, and the road was then edged with curbstones. The rock used to form the road surface were cracked rocks by alternate heating with fire and rapid cooling by dousing with cold water. In addition, over marshy areas the road was elevated on a timber framework and tree- trunks. The Romans also built arched bridges to allow the roads to span rivers. These roads were built largely by prisoners, slaves, and soldiers.

  Little advances in road building occurred from Roman times until 1775 when Pierre Tresaguet, a French Engineer and so-called "Father of the Modern Road", developed a new kind of road. This modern road was 18 ft wide and 10 inches thick, constructed by laying fieldstones edgewise and then covering them with crushed and graded rock so that the subsurface rather than thick stone slabs bore the weight of the traffic. These roads were easier and more economical to build than the Roman style, and required much less earthwork. At about the same time, John Metcalf in England also advocated the construction of lighter roads underlain by well-drained subsoil.

  The next major developments in road design were developed by Thomas Telford and John McAdam, two British engineers, who improved roads in 1820s and 30s. They used stones sorted by size that were laid in layers and compacted to a watertight surface by traffic. Since adequate drainage was a necessity, the roads were cambered and elevated (similar to the old Roman design). These roads were the standard type of until cars and rubber tires came into use in 1895.

  Other major developments important to the development of modern roads include: In 1824 Joseph Aspdin first made "Portland cement" by burning a mixture of clay and lime, rediscovering the art used by the Romans. In 1865 Portland cement was first used to pave a road in Scotland. In 1837 it was discovered that natural asphalt could be powdered when hot and compacted by a roller into a smooth, watertight pavement. Asphalt was first used in the U.S. in 1877 when Amzi Lorenzo Barber paved Pennsylvania Avenue in Washington D.C. using pitch extracted from a lake in the West Indies. This proved so successful that by late 1800's Barber's company had paved streets in Buffalo, Chicago, New York, and San Francisco.

  Few further major advances in road design and construction occurred until the end of World War II, when it became evident that America's roads were inadequate. Thus, the Interstate Highway program was started in 1956. The plan was to link every major city in the U.S. in a network of multi-lane, divided, high capacity highways. This interstate system continues to serve as the major road system in use in the U.S. today.

1-70 Glenwood Canyon: A Modern Civil Engineering Achievement

  The Colorado state legislature determined that Interstate-70, the major east-west route through Colorado should be constructed and: "...so designed that...the wonder of human engineering will be tastefully blended with the wonders of nature." This 12.5-mile project was completed in 1993, closing the only remaining gap in the coast-to-coast I-70. The Glenwood Canyon project is listed as one of the 7 engineering marvels in the Colorado and cost $450 million.

  Glenwood Canyon is more than 2000 ft deep in some places and very narrow at the bottom. Previously, a 2-lane highway, U.S. Route 6, cut through the canyon. However, to put through a 4-lane interstate, it was determined that normal cut-and-fill construction techniques could not be used because they would damage the natural beauty of the canyon, in addition to compromising slope-stability to erosion and rock slides. As a requirement of the construction process, it was determined that the highway must also be kept open to traffic, due to lack of a suitable alternate route for traffic.

  The designers of the Glenwood Canyon project were Joseph Passonneau of Washington D.C. and Edgardo Contini of L.A. Due to lawsuits by citizens, an Environmental Impact Study was required which led to design changes. Consequently the project start date was delayed about 20 years. The final road design was a two-level highway, with two lanes in each direction. The project also included a 10 ft. wide bike path by the river, rest areas, and riverside boat launches.

  For any new road project today, the project begins by investigating the proposed site for route, then mapping and surveying the area. This investigation will include test drillings to collect core samples to determine if the site is stable enough to support the structure. Materials are selected for construction based on the climate, site, function, appearance, economy. Specific function factors include the volume of traffic, kinds of vehicles, and speed of the vehicles on the roadway.

In the U.S. road travel exceeded 2.2 trillion vehicle-miles in 1993.
Current challenges include: 1. Congestion in urban areas and the challenge of suitable public transit. The average car occupancy is 1.2. Road designers try encouraging car pools through high occupancy vehicle (HOV) lanes. HOV lane on route from Boulder via US36 to Denver's I-25. In Washington D.C., all lanes on the beltway are HOV lanes during rush hours. HOV lanes can also distinguish between 2 passengers, 3 or more, etc. Enforcement is an important element to make this work.
  Public transit generally only accounts for 3% of total commuter traffic. However, in some areas higher usage has been achieved. Washington D.C.'s Metro and the San Francisco Bay's BART (Bay Area Rapid Transit) are two examples. Locally, the part-and-rides for buses to Denver, light rail to downtown, Hop and Skip for campus. These systems must have flexible rider times and stop locations for rider convenience.

2. Designing the road to handle the wide range of vehicle types. For example, most older interstates were not designed to withstand the pounding of large double-long semi-trucks. This is one reason that lower speed limits are posted for trucks, and weight stations try to ensure that over- weight trucks are not using the roads. Designing the appropriate amount of curvature and super- elevation for a small Metro or VW Bug versus an double-trailer truck is impossible. In addition, safety features on the road, such as guard-rails, barrier walls, and break-away poles cannot optimally protect drivers in all vehicle types due to differences in weight and geometry (especially height).

3. Designing safer roadways. Roadway safety can relate to a variety of issues including: vertical grades (runaway trucks, slick in ice and wind), horizontal curves (speed and tightness), barriers for when cars leave the road (guard rail, barrier walls, barrels to absorb impact and slow the vehicle before it hits a bridge support), pavement markings (visible at night and through rain, snow; reflective paint, raised pavement markings, rumble-grooves), signs (adequate warning of exits and adverse conditions, avoid confusion), on-ramp and off-ramps (lengths, grades, acceleration, right versus left), sight-lines (for passing zones, at intersections), signals and intersections (stop signs versus lights; all-red and yellow time; set timing versus on-demand), pavement type (in rain, snow and ice, freeze-thaw), maintenance cycles (during snow/ice, pavement rehabilitation). Since many of the major roads are already present, maintenance and re- design is of major importance. Most new designs are in residential sub-divisions or expansions to provide routes in major urban areas.

4. Maintenance of deteriorating roads. The main issue here is bridges. Many bridges were under- designed for supporting today's loads, capacity, etc. Also, time takes its toll. For bridge piers in rivers, scour of the water over time can erode the piling. Scheduling needed repairs while maintaining service on the roads is a major challenge. Many urban areas attempt road repairs during off-peak hours (at night) or on the weekends.

Interstate usage information can be found at the Federal Highway website
This web-site includes data on the miles of interstate and road-types per state, vehicle-miles traveled, number of deaths and accidents, etc.

Railroads:

  There is currently a decline in the railroad system in U.S., which compares to the expansion of high speed railways in Japan and Europe. Railroad design poses unique challenges including: limited vertical gradients, more careful curve design, and the track and roadbed must withstand weight of train and dynamic loads of the impact and sway of moving locomotives. In the U.S. the costs for freight movement on trains vs. trucks must be considered. Also, which type of transportation is best for passengers? Amtrak has been plagued with low rider-ship and high- profile accidents. In contrast, passenger travel in Europe and Japan is common and prevalent.

Airports:

  Transportation engineers working with airports have a variety of issues to address. The primary design issues are site selection and runway design.
    The top factors influencing the selection of the location for an airport are:
convenience to the users
social factors (noise)
utilities
land availability and cost (number of runways and length requirements, easements, clear-zones)
design and layout of the airport (orientation of runways)
airspace obstructions
atmospheric conditions (fog, wind)
coordination with existing airports (airspace)
hazards due to birds (distance to sanitary landfills, migration routes, wetlands and preserves)

    Factors affecting runway layout and orientation include:
crosswinds on the runway must not exceed 15 mph more than 5% of the time (historical wind data can be obtained from the weather bureau, which summarizes the percent of time the wind blows a given direction and velocity);
the necessary length of the paved runway and the end of runway clearance (types of aircraft, gradient or slope, temperature, altitude, length of trip for fuel weight); orientation of runways (parallel and amount of separation required, at angles to have optimal use during varying wind conditions);
number of exit ramps along the runway and routing the airplanes to the terminal).

Engineers must also design the airport terminals, roads and transportation of people to the airport, parking, etc.

Web-links to top 20 U.S. firms in transportation engineering:
http://www.ch2m.com
http://www.icfkaiser.com
http://www.hdrinc.com
http://www.hntb.com

An example of what a transportation engineer does, a quote from Katrina D. Washington, who holds BS and MS degrees in Civil Engineering and is an Engineer-In-Training working toward her Professional Engineer license:
"...an assistant resident engineer for the North Carolina Department of Transportation (DOT)... for two years...job is to monitor the progress of new highway construction projects. The DOT assigns inspectors to monitor the progress and quality of the work of the highway contractors, ensuring that it conforms to...specifications. I go out in the field to supervise the inspectors on projects that I'm assigned to and evaluate how well the contractor is progressing. On the status reports I send to the state construction headquarters, I estimate the cost of the contractor's monthly progress. These reports are used to determine how much the contractor will get paid that month. I also monitor the overruns and under-runs on the job, to ensure that we complete the project close to budget. Most projects don't run smoothly from beginning to end. I draw up all the agreements we contract on projects I supervise. I do a lot of paperwork - a lot of filing, a lot of letter writing...I supervise three inspectors."