2013 Session: 440

• Dynamic Evaluation and Implementation Guidelines for a Non-Proprietary W-Beam Guardrail Trailing-End Terminal
  Abstract: Most state Departments of Transportation (DOTs) use simple adaptations of crashworthy guardrail end terminals, which typically include breakaway posts and an anchor cable, for downstream anchorage systems. The guardrail safety performance for vehicular impacts occurring in close proximity to these simplified, downstream anchorage systems is not well known. Further, the Length of Need (LON) for the downstream end of these systems has yet to be adequately determined. This research project assessed the safety performance of the Midwest Guardrail System (MGS) for impacts occurring in close proximity to a non-proprietary trailing-end guardrail terminal under the Test Level 3 (TL-3) conditions of the Manual for Assessing Safety Hardware (MASH). The two research objectives were to: (i) determine the end of the LON for impacts with light pickup trucks and (ii) investigate potential risks for a small passenger car to become unstable when impacting the downstream end of the MGS anchored by the non-proprietary trailing-end terminal. Numerical simulations were carried out to identify the most critical impact location for the 1100C small car and the end of the LON for the 2270P pickup truck. Two full-scale crash tests were performed under MASH modified test designation nos. 3-37 at the identified critical conditions for the small passenger car and the pickup truck. Although considerable snag of the 1100C vehicle occurred, occupant risk values and vehicle stability were still within acceptable limits. The crash test with the 2270P pickup indicated that the end of the LON was located at the sixth post from the downstream end post. Guidelines were proposed for installing the MGS to shield hazards in close proximity to the tested non-proprietary trailing-end terminal.
  Authors: Mongiardini, Mario; Faller, Ronald K.; Reid, John D.; Sicking, Dean L.
  Authors: Mongiardini, Mario; Faller, Ronald K.; Reid, John D.; Sicking, Dean L.
  Year: 2013
  Document Type: Paper
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-5277
• Midwest Guardrail System Without Blockouts
  Abstract: The Midwest Guardrail System (MGS) has been shown to provide exceptional redirective capability in standard and many special applications. However, the roadway width required to install a guardrail system with a blockout is not always available. In response, a non-proprietary non-blocked MGS was developed and successfully crash tested according to the testing standards established in the Manual for Assessing Safety Hardware (MASH). Results from the 1100c small car and 2270p pickup truck tests are compared between the blocked and non-blocked version of the MGS, and it is concluded that the blocked MGS performs better than the non-blocked MGS. As a result, it is recommended that the non-blocked MGS only be used in places where roadway width is a limiting parameter. But, if width is not restricted, it is still recommended to use a blockout as designated in the design drawings of the standard MGS.
  Authors: Reid, John D.; Faller, Ronald K.; Bielenberg, Robert; Lechtenberg, Karla A.
  Authors: Reid, John D.; Faller, Ronald K.; Bielenberg, Robert; Lechtenberg, Karla A.
  Year: 2013
  Document Type: Paper
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-0418
  Practice-Ready: Yes
• New MASH-Compliant Guardrail System for Placement on Slope
  Abstract: The 2002 American Association of State Highway and Transportation Officials (AASHTO) Roadside Design Guide recommends that w-beam guardrail be installed with the back of the guardrail post positioned 2’ in front of a slope break. In rolling and mountainous terrain or in locations with restrictive environmental conditions, it is often difficult to provide this width. As a result, designers must evaluate trade-offs between reduced shoulder width and guardrail installations that are less than optimal. In many instances, guardrail is installed with longer posts to provide adequate soil embedment. In the most restrictive site conditions, the post lengths are excessively long and complicate system installation and maintenance repairs. The research team used crash simulation and finite element analysis, followed by full scale crash testing to explore system performance with standard w-beam guardrail components. The project focused on designs that minimized post length. A 31” high w-beam guardrail system with 8 foot long posts, spaced on 6’- 3” centers met MASH test level 3 criteria, when placed with the face of rail over the slope break point on a 2H:1V fill slope.
  Authors: Abu-Odeh, Akram; Albin, Richard B; Olson, David K.
  Authors: Abu-Odeh, Akram; Albin, Richard B; Olson, David K.
  Year: 2013
  Document Type: Paper
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-5221
  Practice-Ready: Yes
• MASH Tl-2 Guardrail-to-Bridge-Rail Transition Compatible with 31-in. Guardrail
  Abstract: Many state Departments of Transportation (DOTs) are in the process of updating their guardrail standards to comply with the AASHTO Manual for Assessing Safety Hardware (MASH) and guidance issued by the Federal Highway Administration (FHWA) on guardrail height. The new guardrail system will provide increased capacity and improved impact performance relative to the previous design. A key feature of the new system is an increase in rail mounting height from 27 inches to 31 inches.A common application of guardrail is shielding motorists from hazards at bridge approaches including the end of the bridge rail. When a flexible approach guardrail is attached to a rigid bridge rail, a transition section is needed to properly transition the stiffness from one system to another. A nested thrie beam transition system has been successfully tested to MASH guidelines and is compatible with 31-inch approach guardrail. However, it is cost-prohibitive to use this high-speed, Test Level 3 (TL-3) transition on all roadways. A low-cost transition was successfully evaluated under NCHRP Report 350 Test Level 2 (TL-2) impact conditions. It is considered suitable for use on lower speed roadways that have traffic conditions appropriate for the use of TL-2 safety hardware. Use of this system has resulted in significant savings in material and installation cost compared to high speed transitions. However, this TL-2 W-beam transition is 27 inches tall and is not compatible with the new 31 inch guardrail systems. The objective of this research was to develop a transition that is suitable for use on lower speed roadways, less expensive and complex than the current high-speed (i.e., TL-3) transition designs, and is compatible with 31-inch guardrails. A low-cost guardrail-to-bridge rail transition was successfully developed and tested under MASH Test Level 2 conditions. It is compatible with a 31-inch guardrail and can connect to rigid concrete bridge rails. It is considered suitable for implementation on roadways that have traffic conditions appropriate for the use of TL-2 safety hardware. Use of this system provides significant savings in material and installation cost compared to the high speed transition system.
  Authors: Bligh, Roger P.; Arrington, Dusty; Meza, Rory
  Authors: Bligh, Roger P.; Arrington, Dusty; Meza, Rory
  Year: 2013
  Document Type: Paper
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-5298
  Practice-Ready: Yes
• Midwest Guardrail System Without Blockouts
  Authors: Reid, John
  Authors: Reid, John
  Year: 2013
  Document Type: Presentation
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-0418
• New MASH-Compliant Guardrail System for Placement on Slope
  Authors: Abu-Odeh, Akram
  Authors: Abu-Odeh, Akram
  Year: 2013
  Document Type: Presentation
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-5221
• MASH Tl-2 Guardrail-to-Bridge-Rail Transition Compatible with 31-in. Guardrail
  Authors: Bligh, Roger
  Authors: Bligh, Roger
  Year: 2013
  Document Type: Presentation
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-5298
• Dynamic Evaluation and Implementation Guidelines for a Non-Proprietary W-Beam Guardrail Trailing-End Terminal
  Authors: Mongiardini, Mario
  Authors: Mongiardini, Mario
  Year: 2013
  Document Type: Presentation
  Subject: Design; Safety and Human Factors
  Session: 440
  Paper Number: 13-5277