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Kearney Bypass Crash Cushion/Impact Attenuator

Question
State	NE
Description Text	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: Kearney Bypass 60 scale.pdf is a plan view of the area at a 60 scale. This exhibit has a few dimensions and leaders describing the linework. Kearney Bypass 30 scale.pdf is a plan view of the area at a 30 scale. Kearney Bypass section.pdf shows sections of the roadway as a truck is traveling south over the bridge and to the 3-way intersection. The first section (option 7) shows what we are proposing " a jersey barrier on the outside of the shoulder, but probably with a reinforced slope of 1:1.5. Grading and paving of the current design may be flexible to achieve the distance we need for the crash cushion/impact attenuator. The attached drawing (at a scale of 1:40) is a simplified sketch of the south section of the interchange. In order to allow for WB-62 truck turning movements, the current design provides about 21' for a crash cushion/impact attenuator in front of the jersey barrier. Please let us know if there is a device that will protect or lessen head-on impacts within this limited space.

Question

State

Description Text

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:

Kearney Bypass 60 scale.pdf is a plan view of the area at a 60 scale. This exhibit has a few dimensions and leaders describing the linework.
Kearney Bypass 30 scale.pdf is a plan view of the area at a 30 scale.
Kearney Bypass section.pdf shows sections of the roadway as a truck is traveling south over the bridge and to the 3-way intersection. The first section (option 7) shows what we are proposing " a jersey barrier on the outside of the shoulder, but probably with a reinforced slope of 1:1.5.

Grading and paving of the current design may be flexible to achieve the distance we need for the crash cushion/impact attenuator.

The attached drawing (at a scale of 1:40) is a simplified sketch of the south section of the interchange. In order to allow for WB-62 truck turning movements, the current design provides about 21' for a crash cushion/impact attenuator in front of the jersey barrier. Please let us know if there is a device that will protect or lessen head-on impacts within this limited space.

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Date August 11, 2009
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Attachment Kearney Bypass.jpg

Response
Response (active)	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

Response

Response
(active)

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

Date August 11, 2009
Previous Views (86) Favorites (0)

Attachment Kearney Bypass - Sand Barrels.pdf