Minimum Effective Length for the Midwest Guardrail System

The recommended minimum length for the standard Midwest Guardrail System (MGS) is 175 ft (55.3 m) based on crash testing according to NCHRP Report 350 and AASHTO's Manual for Assessing Safety Hardware (MASH) specifications. However, varying roadside hazards and roadway geometries may require a W-beam guardrail system to be shorter than the currently tested minimum length. The effects of reducing system length for the MGS were therefore investigated. The research study included one full-scale crash test with a Dodge Ram pickup truck striking a 75-ft (22.9-m) long MGS system. The barrier system satisfied all MASH Test Level 3 (TL-3) evaluation criteria for Test Designation Number 3-11. Test results confirmed that the reduced system length did not adversely affect overall system performance or deflections. Simulations that used BARRIER VII and LS-DYNA were also conducted to analyze system performance with reduced lengths of 50 ft (15.2 m) and 62 ft 6 in. (19.1 m). Both system lengths exhibited the potential for successfully redirecting an errant vehicle at MASH TL-3 test conditions. However, these reduced-length systems would have a narrow window for redirecting vehicles and would be able to shield hazards of only a limited size. Owing to limitations associated with the computer simulations, full-scale crash testing is recommended before these shorter systems are installed.

[1]  Dean L Sicking,et al.  Development of Standards for Placement of Steel Guardrail Posts in Rock , 2003 .

[2]  E F Nordlin.  DYNAMIC TESTS OF SHORT SECTIONS OF CORRUGATED METAL BEAM GUARDRAIL , 1968 .

[3]  Dean L Sicking,et al.  Dynamic Evaluation and Implementation Guidelines for a Nonproprietary W-Beam Guardrail Trailing-End Terminal , 2013 .

[4]  Dean L Sicking,et al.  Development of the Midwest Guardrail System , 2002 .

[5]  Eric F Nordlin,et al.  Dynamic Tests of Corrugated Metal Beam Guardrail , 1967 .

[6]  Ronald K Faller,et al.  Development of the Midwest Guardrail System for Standard and Reduced Post Spacing and in Combination With Curbs: Part Two , 2008 .

[7]  Ronald K. Faller,et al.  Downstream Anchoring Requirements for the Midwest Guardrail System , 2013 .

[8]  Dean L Sicking,et al.  Evaluation of Critical Flare Rates for the Midwest Guardrail System (MGS) , 2008 .

[9]  G H Powell.  BARRIER VII: A COMPUTER PROGRAM FOR EVALUATION OF AUTOMOBILE BARRIER SYSTEMS , 1973 .

[10]  Dean L Sicking,et al.  Impact Performance of W-beam Guardrail Installed at Various Flare Rates , 2009 .

[11]  Dean L Sicking,et al.  Performance of Steel-Post, W-Beam Guardrail Systems , 2007 .

[12]  Dean L Sicking,et al.  PERFORMANCE EVALUATION OF THE MIDWEST GUARDRAIL SYSTEM – UPDATE TO NCHRP 350 TEST NO. 3-11 WITH 28" C.G. HEIGHT (2214MG-2) , 2006 .

[13]  Ronald K Faller,et al.  Determination of the Maximum MGS Mounting Height– Phase II Detailed Analysis Using LS-DYNA® , 2012 .

[14]  W G Cichowski,et al.  APPRAISAL OF GUARDRAIL INSTALLATIONS BY CAR IMPACT AND LABORATORY TESTS , 1961 .