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NCHRP-1013 MGS Short Radius System

Question
State	IN
Description Text	INDOT is considering adopting the NCHRP-1013 MGS Short Radius System. We have seen that Washington DOT has already created a standard drawing. On the Standard Drawing they give an option where the curved system does not connect to a concrete barrier but rather a run of standard MGS W-beam guardrail/end treatment (sheet one of the attached PDF, Plan View Matchline A (see note 12)). Could you give an opinion of whether there would be enough tension developed in the system to make this an acceptable modification to consider?

Question

State

Description Text

INDOT is considering adopting the NCHRP-1013 MGS Short Radius System. We have seen that Washington DOT has already created a standard drawing. On the Standard Drawing they give an option where the curved system does not connect to a concrete barrier but rather a run of standard MGS W-beam guardrail/end treatment (sheet one of the attached PDF, Plan View Matchline A (see note 12)). Could you give an opinion of whether there would be enough tension developed in the system to make this an acceptable modification to consider?

System Performance Evaluation
MASH

System Types
Approach Guardrail Transitions (AGTs)
Stiffness and Height Transitions
W-beam Guardrails

Applications
Midwest Guardrail Systems (MGS)

System Features
W-Beam

Date May 26, 2026
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Attachment WADOT_MGS_W-Beam_Curved_Guardrail_System_Details_C20.44-00_e__1_.pdf

Response
Response (active)	We did not design the NCHRP-1013 MGS short radius system, so I am not completely familiar with its function and limitations. As such, we may not be able to give the best answer to that question. Connection of the primary roadway side of the system to a bridge end and AGT would tend to provide a much stiffer response for compressive and tensile loading on redirective impacts on the side of the system and/or capturing impacts on radius of the system. So, there may be concerns that the performance of the system is altered in the end terminal configuration shown. I do not believe that they tested redirective impact along the side of the system with the end terminal configuration shown. A second issue would be that the test systems used a secondary w-beam on the backside of the primary side barrier to mitigate the impact of vehicle on the radius of the system parallel to the primary roadway. The end terminal configuration shown does not have that backside rail. This may affect the safety performance of the system. It may be best to contact Dhafer Marzougui (dmarzoug@gmu.edu) at GMU regarding the design variations in order to get his thoughts. He and GMU worked on that design effort and may be better equipped to address that issue.

Response

Response
(active)

We did not design the NCHRP-1013 MGS short radius system, so I am not completely familiar with its function and limitations. As such, we may not be able to give the best answer to that question. Connection of the primary roadway side of the system to a bridge end and AGT would tend to provide a much stiffer response for compressive and tensile loading on redirective impacts on the side of the system and/or capturing impacts on radius of the system. So, there may be concerns that the performance of the system is altered in the end terminal configuration shown. I do not believe that they tested redirective impact along the side of the system with the end terminal configuration shown. A second issue would be that the test systems used a secondary w-beam on the backside of the primary side barrier to mitigate the impact of vehicle on the radius of the system parallel to the primary roadway. The end terminal configuration shown does not have that backside rail. This may affect the safety performance of the system. It may be best to contact Dhafer Marzougui (dmarzoug@gmu.edu) at GMU regarding the design variations in order to get his thoughts. He and GMU worked on that design effort and may be better equipped to address that issue.

Date June 10, 2026
Previous Views (35) Favorites (0)