A section of a freeway has a speed-density relationship as following: If density < 30 veh then speed equal to the free-flow speed. hr veh If density > 30 then assuming a linear speed-density relationship, and the hr speeds and densities of the freeway are shown in the table below: Speed (mile/hr) 45 60 Density (veh/hr) 90 60 Find: 1- Free-flow speed and Jam density. 2- The space-mean speed, flow, and density at freeway capacity.

27 …… is the average speed of all vehicles along a roadway as determined by the distance and the rünning times between two selected points. 1. Running speed 2. Posted speed 3. Operating speed 4. Design speed

1. Flow is defined as the equivalent hourly rate at which vehicles pass a point on a highway during a time period. 2. The theoretical minimum value of occupancy for a loop detector installed on a highway is 3. The vehicle headway is always less 4. Time-mean speed is equal to the arithmetic (greater/less) than the value of time gap. (arithmetic/harmonic) mean of the spot speed values.

The table below shows data on speeds and corresponding densities on a section of a rural collector road. If it can be assumed that the traffic flow characteristics can be described by the Greenberg model, develop an appropriate relationship between the flow and density. Also determine the capacity of this section of the road.