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Thrie Beam Blockouts

Question
State	WI
Description Text	We would like some guidance on the appropriate blockout to use for a standard thrie beam, both for wood posts and steel posts. WisDOT is working on developing a thrie beam bullnose terminal based on the MwRSF design(report TRP-03-95-00, 6-1-2000) that was approved by FHWA (11-8-2000 letter, HSA-1/HSA-cc68). The blockout for the standard thrie beam construction from posts 9 to 12 is shown as 360 mm (14.17 in) high. Sheet 2 of Minnesota DOT's Standard No. 5-297.611 "Thrie Beam Bullnose Guardrail for Medians" (dated 8-20-2001), which is based on the approved MwSRF design uses a 22-inch high blockout.

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Description Text

We would like some guidance on the appropriate blockout to use for a standard thrie beam, both for wood posts and steel posts.

WisDOT is working on developing a thrie beam bullnose terminal based on the MwRSF design(report TRP-03-95-00, 6-1-2000) that was approved by FHWA (11-8-2000 letter, HSA-1/HSA-cc68). The blockout for the standard thrie beam construction from posts 9 to 12 is shown as 360 mm (14.17 in) high.

Sheet 2 of Minnesota DOT's Standard No. 5-297.611 "Thrie Beam Bullnose Guardrail for Medians" (dated 8-20-2001), which is based on the approved MwSRF design uses a 22-inch high blockout.

System Performance Evaluation

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Road Closure Gates
Thrie Beam Guardrails

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Date May 10, 2006
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Response
Response (active)	Per your inquiry, I have summarized several of the successful thrie beam transition tests that have been conducted according to the NCHRP Report No. 350 requirements. They are as follows: No. 1 - Wood Post - Wood Blockout 550 mm center rail height 804 mm top rail height 150 mm by 200 mm by 554 mm blockouts 150 mm by 200 mm by 1.9 m posts 0.68 m dynamic deflection TL-3 pickup truck test (404211-11) No. 2 - Steel Post - Modified Steel Blockout 610 mm center rail height 864 mm top rail height W360x33 tapered blockouts W150 x14 posts 0.71 m dynamic deflection TL-4 single-unit truck test (404211-5a) 610 mm center rail height 864 mm top rail height M14x18 tapered blockouts W6 x9 posts 1.02 m dynamic deflection TL-3 pickup truck test (471470-30) No. 3 - Steel Posts - Routed Wood Blockout 550 mm center rail height 804 mm top rail height 150 mm by 200 mm by 554 mm routed blockouts W150 x14 posts 0.58 m dynamic deflection TL-3 pickup truck test (404211-10) In summary, you can use either the long wood blocks, shortened wood blocks, or even the tapered steel blocks in combination with the standard thrie beam guardrail systems after post no. 9.

Response

Response
(active)

Per your inquiry, I have summarized several of the successful thrie beam transition tests that have been conducted according to the NCHRP Report No.

350 requirements. They are as follows:

No. 1 - Wood Post - Wood Blockout

550 mm center rail height

804 mm top rail height

150 mm by 200 mm by 554 mm blockouts

150 mm by 200 mm by 1.9 m posts

0.68 m dynamic deflection

TL-3 pickup truck test (404211-11)

No. 2 - Steel Post - Modified Steel Blockout

610 mm center rail height

864 mm top rail height

W360x33 tapered blockouts

W150 x14 posts

0.71 m dynamic deflection

TL-4 single-unit truck test (404211-5a)

610 mm center rail height

864 mm top rail height

M14x18 tapered blockouts

W6 x9 posts

1.02 m dynamic deflection

TL-3 pickup truck test (471470-30)

No. 3 - Steel Posts - Routed Wood Blockout

550 mm center rail height

804 mm top rail height

150 mm by 200 mm by 554 mm routed blockouts

W150 x14 posts

0.58 m dynamic deflection

TL-3 pickup truck test (404211-10)

In summary, you can use either the long wood blocks, shortened wood blocks, or even the tapered steel blocks in combination with the standard thrie beam guardrail systems after post no. 9.

Date May 15, 2006
Previous Views (172) Favorites (0)