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.
- 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