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- A highway engineer is involved in the application of engineering formulas and ideas for the design and construction of highways and roads.
- An airport engineer applies engineering formulas and ideas in the construction and design of terminals, runways, control towers, taxiways, hangers, and lighting systems.
- A railway engineer is involved in the application of engineering formulas and ideas in the design and construction of railroads for commercial and commuter trains.
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| In the process of designing a highway or road, the engineer must consider several variables. These variables include:
Design Vehicle - Engineers most often base their design upon one of the four basic types of design vehicles: Passenger Cars; Buses; Trucks; and Recreational Vehicles. The design vehicle is used in intersection controls such as turning radii, stopping distances, acceleration lengths, sight distances, and turn bay lengths.
Speed Design - This is the maximum speed limit at which the highway is to be operated. Speed design will most often control the vertical and horizontal alignments of the highway.
Volume - Volume is normally measured as ADT (Average Daily Traffic) or DHV (Design Hourly Vehicles). The ADT is used to determine structural elements of the highways such as clear zones and pavement depths. The DHV is used to design specific elements of the highway such as intersection capacity and signalization requirements.
Highway Capacity - Capacity must considered for the proposed design so that maximum free flow of traffic maybe obtained. Economical or environmental restrictions may restrict capacity flow.
Pedestrians - If pedestrians are to use the adjoining areas of the highway, accommodations must be made such as sidewalks, barrier curb, crosswalks, special signalization, and handicap ramps.
Bicyclist - If bicyclist are expect to use the highway, the engineer may add additional width to the travel lanes or sidewalk to accommodate their movements.
Safety - Safety must be considered in all aspects of design including superelevation rates, drainage, clear zones, stopping sight distance, decision sight distance, and passing sight distance.
Environment - The engineer must take into consideration the impact that the roadway may have upon local wild life and habitat. Environmental studies are most often performed before the design of the highway to assist the engineer in the decision process.
Economic Analysis - Economical designs must be considered to determine the most cost-effective method of design. Budget of the governing authority as well as local resources will influence design criteria. |
| The design elements in a highway can be classified into on of the following areas: cross section; horizontal alignment, vertical alignment, drainage, erosoin control, utilities, traffic control devices, noise barriers, fencing, and maintenance of traffic.
- Cross sectional elements includes pavement, lane widths, shoulder widths, clear zones, curb and gutter, drainage sideslopes, medians, frontage roads, noise control, roadside controls, tunnels, pedestrian facilities, bicycle facilities, turnouts, and parking.
- Horizontal elements includes maximum superelevation rates, minimum degree of curve, sight distances, offtracking, and curve transitions.
- Vertical alignment elements includes terrain, maximum grades, minimum grades, climbing lanes, passing lanes, and emergency escape ramps.
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