Access to facilities such as detention ponds and/or canals located adjacent to bridge railings is often restricted by the use of W-Beam guardrail around the facility. Often the required length of need for guardrail will not be met in order to leave access to the detention ponds open. Also, on limited occasions, these facilities are accessed by disassembling 12 ft-6 inch sections of guardrail and removing a single post. These components are reinstalled once access is no longer needed, requiring the post to be drilled and compacted or driven back in place. This adds unnecessary time and effort for workers accessing facilities behind the guardrail system. In addition, it may require possible lane closure to disassemble the guardrail section resulting in traffic congestion and safety hazards for the workers. The development of a crashworthy guardrail gate system will aid state agencies in addressing this problem. The evaluation of the guardrail gate system will be in accordance with the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) (1).

Objective

The project objectives are to:

• Develop designs for a hinge guardrail gate;
• Evaluate and optimize a final candidate design through finite element computer simulations;
• and conduct full-scale crash tests.

Benefits

The project will result in improved safety features that will be implemented through new standard detail sheets of the guardrail gate system. Additional benefits include reducing unnecessary time and effort of maintenance workers and increasing safety of the workers while accessing facilities behind the guardrail.

Products

The TTI research team will provide a final report that will include the results of the design development, computer simulation analyses, and full-scale crash testing. A final MASH TL-3 crashworthy assessment of the guardrail gate will be provided in the report. In addition, detailed drawings that can be developed into state Department of Transportation (DOT) standard sheets will be provided if the guardrail gate system is deemed satisfactory for MASH TL-3.

Work Plan

The work plan for this research includes the following tasks.

 

Task 1 – Develop Design Concepts 

The TTI research team will identify the guardrail gate design needs to meet the field and site conditions encountered by state DOTs that would benefit from a hinge guardrail gate system. If needed, a survey will be distributed to the Pooled Fund state members to gather field information and design needs. Details such as guardrail gate length, gate components and function, and others will be collected.

Three design concepts will be developed to meet the needs identified previously. Advantages and disadvantages will be developed for each design concept. A single design concept will be selected in consultation with the Pooled Fund technical representative for further evaluation in Task 2. If needed, simplified computer simulations of the design may be performed to verify aspects of the design such as strength prior to proceeding to Task 2. The simplified model of the design may incorporate simplified components, smaller model size, and other techniques to allow a quick check of the design prior to performing full-scale simulations in Task 2.

Task 2 – Computer Simulation

The research team will build a finite element computer model of the guardrail gate design concept selected in Task 1. The design concept will be evaluated according to MASH TL-3 with finite element computer simulations. This will consist of impacting the guardrail gate system design concept with the 1100C FE vehicle model and 2270P FE vehicle model. The impact speed will be 62 mph, and the impact angle will be 25 degrees. Each computer simulation will be assessed according to the MASH TL-3 evaluation criteria. Different impact locations will be considered, if necessary.

Additional computer simulations may be performed to optimize the design concept. If the design concept is determined to not perform satisfactorily in the computer simulations, then the TTI research team may consider evaluation of another design concept identified in the previous Task 1.

Once a guardrail gate system has been determined to exhibit satisfactory performance in the computer the simulations, full-scale crash testing will be performed to further evaluate the system.

Task 3 – Construction and Crash Testing

The TTI Proving Grounds will perform two full-scale crash tests on the guardrail gate system according to MASH TL-3. One full-scale test will involve a 2,420-lb passenger car impacting the guardrail gate system at a 62 mph nominal speed and a 25 degree angle. One full-scale test will involve a 5,000-lb pickup truck impacting the guardrail gate system at a 62 mph nominal speed and a 25 degree angle.

The TTI research team will assess the crash tests according to the evaluation criteria set in MASH standards

Task 4 – Final Report

The TTI research team will generate a final report of the findings from the research. The results will include the design concept development, computer simulation analyses, and full-scale crash testing. The crash test results will be reported in terms of guardrail gate system performance, vehicle stability, and occupant risk factors and will be compared with respect to MASH crashworthiness criteria. Detailed drawings of the guardrail gate system will be included in the final report for implementation into state DOT standard detail sheets.

Time Schedule

Started: May 2026
Time frame: 24 Months