A twolane facility with 11 feet lanes has concrete barriers

A two-lane facility with 11 feet lanes has concrete barriers on both sides at the outside of the paved way shoulder. The design speed is 40 mph with the minimum horizontal curve radius of 600 feet. What would be the minimum shoulder width that can be provided that meets the stopping sight distance requirements?

Solution

Given data:

Width of the each lane = 11 feet

no of lanes =2

Design speed = 40mph = 64.374 kmph

radius of curve = 600 feet = 182.88 meters

Extra widening for sholders is We= Wm+Wps

Wm= Mechanical widening= (nl²/2R) where n= no of lanes, length of wheel base (6.1m), R= radius of curve

Wps=Psycological widening=(V/9.5R^0.5) where V= design speed

Wm=(nl²/2R)= (2*6.1²/2*182.88) = 0.203 m

Wps=(V/9.5R^0.5)= (64.374/9.5*182.88^0.5) = 0.5 m

total widening = 0.203+0.5=0.703 m

= 2.306 feet