3/1/06Michael Dixon1 CE 578 Highway Traffic Operations Lecture 17: Freeways Basic Sections Application

3/1/06Michael Dixon2 Objectives Existing condition evaluation Alternative design evaluation

3/1/06Michael Dixon3 Freeway Characteristics Terrain = levelNumber of lanes = 2 Volume = 3200 vphInterchanges per mile = 2 % HV = 20%Urban area % RVs = 0%Peak hour factor = % unfamiliar driversLane width =11 ft Right shoulder = 6 ftLeft shoulder = 4 ft Lowest acceptable LOS = C

3/1/06Michael Dixon4 Variable Values

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3/1/06Michael Dixon7 Define the speed-flow curve: –By interpolation on Exhibit 23-3, we know that our speed curve will lie between the FFS = 55 mph and FFS = 60 mph curves. –Using the equations below Exhibit 23-3, we can arrive at a more precise solution (not necessarily more accurate). The conditions are met for the second equation.

3/1/06Michael Dixon8 Calculate the speed: Through the interpolation method, it looks like the speed will be somewhere between 62 mph and 63 mph.

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3/1/06Michael Dixon10 Evaluating the Alternative Design See MathCad solution to adding a lane on- line