Monday, March 5, 2012

Road Design Measurement Photos, 210 Eastbound Grand Avenue Exit


Did you crash exiting Grand Avenue 210 Eastbound at night?  You are not at fault.  According to the following paper,

Discussion Paper No. 8.A
STOPPING SIGHT DISTANCE
AND DECISION SIGHT DISTANCE
prepared for
Oregon Department of Transportation
Salem, Oregon
by the
The Kiewit Center for Infrastructure and Transportation
Oregon State University
Corvallis, Oregon 97331-2302
September 2004

The road does not provide adequate distance for you to stop your vehicle at night.

What is the significance of these pictures?  This is the exit of Grand Avenue on the 210 Freeway, Eastbound.  There are no signs on the freeway indicating that a curve is approaching.  What if you were driving at night, at 55mph?  A driver would then have to use Decision Sight Distance, because the curb is below the height of the crest of the road. This means that time would elapse before the breaks were applied because the brain would have to process the information and the drive would have to react.    Decision Sight Distace in this case, according to the paper above, at 55mph is 535ft.  Unless you could see the curb from 535ft, you would impact it.    


  The distance needed to stop on this exit is 492 ft, at a minimum, is called Stopping Sight Distance.  That is if the object, the curve, was seen. 












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