Explanation Given: Peak hourly volume in the analysis direction is 900 veh / h . Peak hourly volume in the opposing direction is 720 veh / h . Trucks are 10 % of total volume. Recreational vehicles are 2 % of total volume. PHF is 0.94 . Lane width is 12 ft . Shoulder width is 2 ft . Access points per mile are 30 . The terrain is level. Base free flow speed is 45 mi / h . No passing zones are 60 % of analysis segment length. Formula used: The free flow speed is given by F F S = B F F S − f L S − f A .......(I) Here, B F F S is base free flow speed, f L S is adjustment for lane and shoulder width, and f A is adjustment for access points per mile. The heavy vehicle adjustment factor is given by f H V , A T S = 1 1 + P T ( E T − 1 ) + P R ( E R − 1 ) .......(II) Here, P T is proportion of trucks, P R is proportion of recreational vehicles, E T is equivalent for truck, and E R is equivalent for recreational vehicle. The demand flow rate is given by v i , A T S = V i P H F × f g , A T S × f H V , A T S ......(III) Here, P H F is peak hour flow, V i is demand volume for direction, f g , A T S is grade adjustment factor, and f H V , A T S is heavy vehicle adjustment factor. The average travel speed is given by A T S = F F S − 0.00776 ( v i , A T S + v o , A T S ) − f n p , A T S ......(IV) Here, F F S is free flow speed, v i , A T S is demand flow rate in analysis direction, v o , A T S is demand flow rate in opposing direction, and f n p , A T S is adjustment factor for percentage of no passing zones in opposing direction. The percent free flow speed is given by P F F S = A T S F F S .......(V) Here, A T S is average travel speed and F F S is free flow speed. Calculation: The free flow speed is calculated as Substitute 45 mi / h for B F F S , 2.6 for f L S , and 7.5 for f A in equation (I). F F S = ( 45 mi / h ) − 2.6 − 7.5 = 34.9 mi / h The heavy vehicle adjustment factor in analysis direction is calculated as Substitute 10 % for P T , 2 % for P R , 1 for E T , and 1 for E R in equation (II). f H V , A T S = 1 1 + ( 10 % ) ( 1 − 1 ) + ( 2 % ) ( 1 − 1 ) = 1 1 = 1 The demand flow rate in analysis direction is calculated as Substitute 900 veh / h for V i , 0

The level of service in each direction.

Traffic And Highway Engineering

5th Edition

ISBN: 9781133605157

Author: Garber, Nicholas J., Hoel, Lester A.

Publisher: Cengage Learning,

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Question

Chapter 9, Problem 22P

To determine