Midwest Guardrail System
W-Beam Barrier for the Future
The Midwest Guardrail System (or MGS Guardrail) was engineered to handle today's modern vehicles. Existing W-Beam barriers were developed many years ago when the vehicle fleet was different than it is today. These existing W-Beam barriers measure 27 5/8" to the top of the rail. When crash tested with today's higher center of gravity vehicles, many results have not been successful.
In 2001-2002, the Midwest States Pooled Fund Program, funded by 11 states, recognized the need for a new generic strong post W-Beam barrier that would be compatible with the newer higher center of gravity vehicles crash tested under NCHRP 305 Test Level 3 conditions. The result was the MGS Guardrail barrier.
The differences between the MGS Guardrail Barrier and the older W-Beam barrier are:
- The MGS top of the rail height is 31" rather than 27 5/8"
- The MGS blockout is 12" rather than 8"
- The MGS W-Beam guardrail splices occur mid-span between posts rather than at the post
Midwest Guardrail System Benefits
The MGS Guardrail Barrier is totally generic-there are no patented parts, meaning all guardrail producers can supply it. Uses the same 12" W-Beam rail section in use today.
After extensive testing, MGS Guardrail has been proven to be safe effective.
- Tested with (1'-6 3/4'' & 3'-1 1/2'') reduced post spacing
- Tested 6'' behind a 6'' curb
- Tested with flare rates as sharp as 7:1 (with pickup and small car) compared to the 14:1 (Test Level 3) recommended in the AASHTO Roadside Design Guide
- Tested at a 32'' rail height with the 1800-pound small car.
- The MGS Barrier has its own transition. Both the 2000P (4400-pound pickup) and the 820C (1800-pound small car) tests were passed with the asymmetrical Thrie-Beam section. This is the first time any W-to-Thrie transition has successfully passed.
- As part of the rewrite of NCHRP 350 [NCHRP Project 22-14(2)], the MGS Barrier was successfully tested
- With both the 5000-pound quad cab and 5000-pound 3/4-ton pickup trucks
- With the 2425-pound small car at the 32" rail height
- The MGS Barrier has a greater construction tolerance:
- Was tested to 32"
- Having all of the components of the MGS system tested at 27 5/8" allows the states to both set a construction tolerance for the rail system and to overlay the road without adjusting the system.
- Both tangent and flared terminals were tested in the MGS configuration as an option
- The MGS Guardrail Barrier offers many variables to accommodate the real-world site conditions.
- The SKT and FLEAT were successfully crash tested in the MGS configuration.
There is ongoing funding for the MGS barrier. The MGS system will be tested on a slope, with the posts set on the break line of a 2:1 slope. It will also be tested in a long span application with 3 missing posts.
Comparison Charts: Improved MGS Guardrail Barriers Terminals and Current W-Beam Barriers
Barrier Comparison | Rail Element | Rail Height | Block Size | Rail Splice |
---|---|---|---|---|
Current W-Beam Barrier Design | 12" W-Beam | 27 5/8" | 8' | At the post |
MGS W-Beam Barrier Design | 12" W-Beam | 31" | 12' | Mid span between posts |
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