Question

13. A divided rural multi-lane highway with an AADT of 50,000 vehicles per day. A 70 mph. The peak hour factor is set at 0.8 and the directional factor, D is estimated at 0.8. The highway is required to provide a Level of Service ‘B’. Assuming the highway is to be designed for the thirtieth highest hourly volume (k= .15) during the year

Calculate the number of lanes required in each direction
Calculate the number of lanes If the highway is designed, for the fifteenth highest hourly volume(k=12).

Answer 1

as given 2nd problem k=12 is taken to get no of lanes =555.6(impossible)

D = 0.8 calculate the directional design hour volume: DDHV = K times D times AADT = 0.15 times 0.8 times 50000 = 6000 veh/hour service flow (SF) = V/PHF = 6000/0.8 = 7500 veh/h No.of lanes N = SF/cj (v/c) times f_w times f_hv times f_p times f_E f_w = 1, f_Hv = 1.0, f_p = 1.0, f_E = 1.0 cj = 2000 for standard condition (v/c)_i = 0.54 form (thirteenth highest hourly volume) standard value for both cases. N = 7500/0.54 times 2000 times 1 times 1 times 1 times 1 = 6.94 7 required lanes = 7 ii) directional design hour volume DDHV = k times D times AADT = 0.12 times 0.8 times 50000 = 4800 veh/h service flow (SF) = v/PHF = 4800/0.8 = 6000 veh/h N = 6000/2000 times 0.54 times 1 times 1 times 1 times 1 = 5.55 6 required lanes = 6 as given 2nd problem k = 12 is taken to get no of lanes = 555.6(impossible) It's not correct that's why I take k = 0.12 to get N = 6 it's possible

It's not correct that's why I take k=0.12 to get N=6 it's possible