Transportation Engineering
Transportation engineering designs roadways and analyzes traffic. The exam covers horizontal and vertical curve geometry, sight distance, and the fundamental relationships of traffic flow, following AASHTO geometric-design practice.
Horizontal Curves
The degree of curve (arc definition) is D = 5,729.58/R, so larger radii give flatter curves. Superelevation banks the roadway so that a component of vehicle weight plus side friction supplies the centripetal force needed to round the curve, reducing reliance on tire friction.
Vertical Curves and Sight Distance
Crest and sag vertical curves connect grades; the rate of curvature K = L/A (length per percent change in grade) is checked against sight-distance minimums. Stopping sight distance is the sum of brake-reaction distance and braking distance, both increasing with speed.
Traffic Flow
The fundamental relationship flow = density x speed (q = k·v) links the three traffic-stream variables. Capacity is the maximum sustainable flow. These relationships size lanes, time signals, and evaluate level of service.