MGS Midwest Guardrail System
W-Beam Barrier for the Future
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.
The differences between the MGS Barrier and the older W-Beam barrier is:
- The MGS top of rail height is 31" rather than 27 5/8".
- The MGS blockout is 12" rather than 8".
- The MGS W-Beam rail splices occur mid span between posts rather than at the post.
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 350 Test Level 3 conditions. The result was the MGS Barrier.
MGS (Midwest Guardrail System)
W-Beam Barrier - Benefits
- The MGS Barrier is totally generic, no patented parts meaning all guardrail producers can supply it. Uses the same 12" W-Beam rail section in use today.
- The MGS Barrier was tested with (1'-6 ¾" & 3'-1 ½") reduced post spacing.
- The MGS Barrier was tested 6" behind a 6" curb.
- The MGS Barrier was tested with flare rates as sharp as 5:1 (with pickup and small car) compared to the 14:1 (Test Level 3) recommended in the AASHTO Roadside Design Guide.
- The MGS Barrier was tested at a 32" rail height with the 1800 pound small car.
- The MGS Barrier has its own transition. Both the 2000P (4400# pickup) and the 820C (1800# 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 ¾ ton pickup trucks.
- As part of the rewrite of NCHRP 350 [NCHRP Project 22-14(2)], the MGS barrier was successfully tested with the 2425 pound small car at the 32" rail height.
- The MGS Barrier was tested on a slope with the posts set on the break line of a 2:1 slope.
- The MGS was tested in a long span application with 3 missing posts.
- The MGS was tested 5-ft from the break-line on a 8:1 Slope.
- The MGS Barrier has a greater construction tolerance. The MGS tested to 32" and having all of the components of the 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.
- The MGS Barrier has both tangent and flared terminals tested in the MGS configuration as an option.
- The MGS barrier offers "many" variables to accommodate the real-world site conditions.
The SKT and FLEAT were successfully crash-tested in the MGS configuration. Shown below is a comparison of the improved MGS Terminals and today's terminals:
|Barrier Comparison||Rail Element||Rail Height||Block Size||Rail Splice|
|12" W-Beam||27 5/8"||8"||At the post|
|12" W-Beam||31"||12"||Mid span
|End Terminal Rail
|Splice 1||Splice 2||Splice 3||Splice 4|
at post #3
at post #5
at post #7
at post #9
Betw. Posts 3&4
Betw. Posts 5&6
Betw. Posts 7&8
Betw. Posts 9&10
- Drawing of Wood Post SKT-MGS terminal
- Drawing for Wood Post FLEAT-MGS terminal
- Drawing for Steel Post SKT-MGS terminal
- Drawing for Steel Post FLEAT-MGS terminal
- FHWA letter CC-88D (January 29, 2010)
- FHWA letter CC-88C (December 10, 2009)
- MGS Newsletter written by the Engineers at the
Midwest Roadside Safety Facility (MwRSF)
- MGS Barrier Report
- March 1, 2005 MGS Barrier
- March 8, 2005 SKT & FLEAT MGS Terminals