The free-flow speed at section of an expressway is 70 mph and density at flow = 0 is 120 %3D vehicle/mile.

A segment of rural freeway is being designed for a FFS of 65 mph using 11 ft lanes in a mountainous area. The lateral clearance is nominal (1 ft). The directional (i.e. one-way) design flow rate is expected to be 2,400 passenger cars per hour. How many lanes in one direction will be needed to provide at least a LOS B? Response Feedback: When FFS=65 mph and flow rate=2400 pcphpl the density=36.9 pcpmpl which translates to a LOS E. When FFS=65 mph and flow rate=1200 pcphpl the density=18.5 pcpmpl which translates to LOS C. When FFS-65 mph and flow rate=800 pcphpl the density=12.3 pcpmpl which translates to LOS B.

For the Greenshields model, the mean free flow speed on a highway facility lane equals 75 mph near zero density, and the jam density is observed to be about 160 veh/mi. Plot the q-k-u curves in proper order. Write down the speed-density, flow-speed, and flow-density equations. Find out the maximum flow, and also mark it on your diagrams. Compute speeds and densities corresponding to a flow of 2,880 veh/h, describing traffic conditions from a driver’s point of view. Calculate average headways, gaps, clearance, and spacing at CASE 1: maximum flow and at CASE 2: jam density. (Suppose the average vehicle length is 17ft)

A traffic stream is moving at a steady state when entering a mountain grade. Upon entering the grade, the speed, density and flow are 72 km/h, 25 veh/km and 1800 veh/hr respectively. On the grade, a truck drops to a speed of 15 km/h causing traffic to bunch up to a density of 85 veh/km. When the truck pulls over, traffic accelerates to the maximum flow until steady state flow conditions resume. Calculate (a) the flow of traffic behind the truck on the mountain grade (b) the jam density and free flow speed for this road (c) the density and speed when traffic resumes a steady state flow (d) the maximum flow