Max Deflection without Horizontal Curve

Civil & Environmental Engineering gen discussion Traffic
#1

QUESTION
This does not seem to be covered in AASHTO, but I’ve seen two equations used to determine the max deflection that can be used without a horizontal curve:

  1. arctan(1/design speed)
  2. arctan(60/design speed^2)

What is the appropriate criteria & reference to use for this situation? My application is a 4-lane local road with 35mph design speed.

REPLIES

ACtrafficengr
You could use the MUTCD taper equations

V > 45 mph L = WS2/60
V >= 45 mph L = WS

and plug 1 in for W to give you a rate.

SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=156698
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