Gregory Highway MGS W-Beam Barrier

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 Guardrail 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 guardrail 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 Guardrail 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 3/4'' & 3'-1 1/2'') reduced post spacing.
  • The MGS Barrier was tested 6'' behind a 6'' curb.
  • The MGS Barrier was 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.
  • 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-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.
  • 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 has a greater construction tolerance. The MGS Barrier 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.
  • There is ongoing funding for the MGS Barrier. The 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.
  • 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.

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