I am working on the Kearney Bypass project. I believe they've discussed with you our concern with head-on crashes at an interchange on this project. I have attached some drawings of the area.
A description of the pdf files is given below:
Grading and paving of the current design may be flexible to achieve the distance we need for the crash cushion/impact attenuator.
I've attached my recommended configuration for the sand barrel crash cushion. It takes a lot of barrels to protect such a wide area!
Some key items to note:
(1) Barrels are 3 ft in diameter and should be spaced 6 in. apart.
(2) The gray line in the drawing represents the 24 in. clear space recommended between sand barrels and the hazard .
(3) The black line has the same dimensions as the yellow hatched area on your drawings.
(4) The head-on impact scenario requires 6 rows of barrels to safely stop errant vehicles " thus the 21 ft length shown in your drawing (yellow hatching) needs to be extended 1.5 ft to 22.5 ft.
(5) Most rows contain only 1 type (weight) of barrel, but there are 2 exceptions. Rows 2 and 3 have lighter barrels on the ends. This is designed for end in impacts (not necessary for on ramp, but included to make system symmetric.
The rows break down as follows
Row 1: 31 " 200 lb. barrels
Row 2: 31 " 400 lb. barrels and 2 " 200 lb. barrels (1 on each end)
Row 3: 29 " 700 lb. barrels and 2 " 400 lb. barrels (1 on each end)
Row 4: 23 " 1400 lb. barrels
Row 5: 15 " 2100 lb. barrels
Row 6: 7 " 2100 lb. barrels
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