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Thrie Beam Bridge Rail Termination

Question
State	WI
Description Text	Attached is a photo of a thrie beam bridge rail attached to a box culvert. I was told that because this is a bridge rail, it does not need to have an end treatment on the downstream end to transfer the force of an impact to the ground. Is this correct? Or should it be treated with a transition, a section of guard rail and then a terminal that has a cable attached to some ground tubes?

Question

State

Description Text

Attached is a photo of a thrie beam bridge rail attached to a box culvert.

I was told that because this is a bridge rail, it does not need to have an end treatment on the downstream end to transfer the force of an impact to the ground. Is this correct? Or should it be treated with a transition, a section of guard rail and then a terminal that has a cable attached to some ground tubes?

System Performance Evaluation

System Types
Bridge Rails

Applications

System Features

Date June 23, 2008
Previous Views (25) Favorites (0)

Attachment side (3).jpg

Response
Response (active)	My first question is whether this bridge rail can be impacted by reverse direction traffic? If yes, then the bridge end requires treatment, likely occurring from an approach rail and guardrail end terminal. If not, then we can move on to the next question. If this bridge rail was designed to redirect errant vehicles through membrane action (tensile capacity), moment transfer through rail/posts, and shear transfer, then downstream anchorage would be need to be provided. If hazard shielding is required within a few spans from the end of the barrier system but without anchorage, the rail system may not be capable of performing in an acceptable manner. For rigid bridge railing systems that provide additional strength near the ends, downstream approaches may not necessarily be needed but would need to be determined based on the individual design.

Response

Response
(active)

My first question is whether this bridge rail can be impacted by reverse direction traffic? If yes, then the bridge end requires treatment, likely occurring from an approach rail and guardrail end terminal. If not, then we can move on to the next question.

If this bridge rail was designed to redirect errant vehicles through membrane action (tensile capacity), moment transfer through rail/posts, and shear transfer, then downstream anchorage would be need to be provided. If hazard shielding is required within a few spans from the end of the barrier system but without anchorage, the rail system may not be capable of performing in an acceptable manner.
For rigid bridge railing systems that provide additional strength near the ends, downstream approaches may not necessarily be needed but would need to be determined based on the individual design.

Date June 23, 2008
Previous Views (25) Favorites (0)