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MASH Hardware Evaluation with New Proposed Test Vehicles

Description:

The Manual for Assessing Safety Hardware (MASH) requires full-scale crash testing of roadside features using worst practical impact conditions, which are supposed to be representative of the composition of vehicles involved in run-off-road crashes and roadside departure speeds and angles. Previous NCHRP projects have driven changes in standard test conditions and test vehicles. For NCHRP Report No. 230, multiple vehicle classes were added for consideration including box trucks, semi tractor-trailers, and buses. Test vehicle classes were reduced to six standardized test levels during NCHRP Report No. 350, corresponding to TL-1 through TL-6 categories, and recommended three standard passenger vehicle classes: a 1,543-lb (700-kg) minicompact car, a 1,808-lb (820-kg) subcompact car, and a 4,409-lb (2,000-kg), ¾-ton pickup truck. In the middle-2000s, MASH was introduced which updated the criteria for selecting passenger car and pickup truck standards to 2,425 lb (1,100 kg) and 5,004 lb (2,270 kg), respectively. In addition, a mid-size test vehicle was introduced, corresponding to a mid-size passenger car, weighing approximately 3,306 lb (1,500 kg). After exploratory crash-testing programs for each of these changes in test vehicle selection criteria, a narrow number of selected makes and models were informally adopted as the “preferred” test vehicle types, which offered economical and reproducible outcomes.

Recent research in publication under NCHRP Project 20-07 Task 372, Evaluation of MASH Test Vehicles, indicated a significant decline in new passenger car sales and a rise in new light truck sales since approximately 2014, driven primarily by “compact” or “crossover” utility vehicle (CUV) sales. In 2017, CUVs were the highest-selling vehicle class, and more new CUVs were sold than all passenger car classes combined. As a result, updates for the selection criteria used when selecting standardized passenger car and light truck test vehicles were recommended, and it was also recommended that an exploratory full-scale testing program be conducted to evaluate roadside hardware using the CUV class of test vehicle.

A pilot testing program evaluating existing, MASH-approved hardware using the new proposed vehicles, with emphasis on the CUV vehicle class, is needed to ensure that testing criteria remains representative of the “practical worst-case” impact conditions. Differences in the performance of these systems with the new, proposed vehicles compared to existing tests with MASH vehicles should be documented. This exploratory testing program may also better-define which vehicles are best-suited for acceptance as standardized test vehicles for future MASH testing based on availability of options, cost, and model continuity. Moreover, this exploratory testing program may identify critical behaviors from one or more of the candidate mid-size vehicle classes. If these critical behaviors represent a consistent, demanding condition for common roadside hardware, future MASH testing requirements may be adjusted to accommodate these new conditions. Lastly, the selection of preferred MASH test vehicle candidate vehicles will inform the generation of new finite element analysis (FEA) models of vehicles which will be utilized in computer simulations of roadside hardware and vehicle applications in the future.

Objective:

The objective of this research effort would be to conduct a series of full-scale crash tests of MASH-approved non-proprietary roadside safety hardware using test vehicles consistent with recommendations provided in NCHRP Project No. 20-07 Task 372, Evaluation of MASH Test Vehicles.

The outcome of this research effort will be guidance for selecting preferred standardized vehicles for the light truck, small car, and mid-size vehicle classes for recommendations to updating AASHTO’s MASH evaluation criteria's, and to select the preferred characteristics (weight, size, c.g. height, etc) of the preferred mid-size test vehicle.

Benefits:

NCHRP Project 20-07 Task 372 indicated that MASH standard vehicle selection may no longer be representative of the contemporary vehicle fleet. New vehicles tend to be larger, heavier, and taller than during the initial adoption of MASH. It is critical to ensure that roadside hardware performance during impacts does not deteriorate, causing containment failures, contributing to rollovers, or breaking apart under design impact conditions. This research effort will provide the first indications of the likelihood that existing, successfully-tested hardware will continue to be perform acceptably with the updated test vehicles. In addition, the research team or contractors will identify recommended vehicles to be developed into FEA models in future NCHRP studies which will eventually augment evaluation of hardware using the updated vehicles.

Related Research:

Several pilot testing programs have been conducted to support major revisions to full-scale crash test criteria, and usually accompanied major criteria revisions. NCHRP Project 22-07, Update of “Recommended Procedures for Safety Performance Evaluation of Highway Appurtances”, was conducted to revise the full-scale crash testing procedures, performance evaluation criteria, and full-scale crash test vehicle selection from previously-accepted NCHRP Report No. 230 guidelines and to synthesize with AASHTO’s Guide Specifications for Bridge Railings. The resulting document, NCHRP Report No. 350, unified the parameters for evaluating roadside safety hardware using standardized vehicle types and classes, unified evaluation criteria, and standardize test conditions. Subsequently, TTI conducted some testing of the standard G4(1S) configuration of W-beam guardrail using four passenger vehicles, a Chevrolet Lumina, Ford Taurus, Plymouth Neon, and Dodge Caravan, to assist with computer simulation modeling efforts. Although this program was not intended to evaluate the performance of barrier systems with non-standard test vehicles, significant instability was observed with the Dodge Caravan and the Chevrolet Lumina impact caused W-beam rail rupture at a splice, which was believed to be related to a stiff point on the vehicle and localized rail pocketing.

In the early 2000s, the Texas Transportation Institute was the recipient of NCHRP Project No. 22-14(a), to reassess the criteria and test conditions described in NCHRP Report No. 350 and to recommend updates, if any, to improve the validity of those conditions. Subsequently, the Midwest Roadside Safety Facility was the recipient of a pilot testing program under NCHRP Project No. 22-14(b) which consisted of full-scale crash testing various barrier systems using the proposed MASH vehicles and impact conditions. Systems included a New Jersey permanent concrete barrier, portable concrete barriers, G4(1S) and MGS guardrail systems, and an approach guardrail transition. Test vehicles included the new 1100C small car, two options for 2270P pickup trucks (1/2-ton quad cab Chevrolet Silverado 4x4 and ½-ton quad cab Dodge Ram 1500 RWD), and the heavier 22,000-lb (10,000-kg) single-unit truck. Results were used to identify the Dodge Ram as the preferred pickup truck test vehicle and to provide initial evaluation and acceptance of some common hardware which had been approved under NCHRP Report No. 350 impact conditions.

Tasks:

The researcher or contractor would be expected to complete these major tasks:

·Install roadside safety system identified for testing.

·Perform full-scale crash tests of prioritized hardware previously evaluated using MASH evaluation criteria and impact conditions using the new proposed vehicles described in NCHRP Project 20-07 Task 372.

·Compare results of the full-scale crash testing using the new proposed vehicles with correlated MASH full-scale crash testing results.

·Identify preferred vehicles and recommend the configurations, trim levels, or sizes are needed for developing new vehicle models using finite element analysis (FEA) methods. Note that the development of those FEA vehicle models are not within the scope of this project.

Implementation:

Research results produced during this study will serve to provide the first indication of the performance of successfully-tested MASH devices during impacts with newer, heavier test vehicles as well as a critical evaluation of the performance of devices with the growing class of CUV vehicles. Results will be documented in technical reports, journal papers, presentations to national committees and research groups involved in roadside safety (examples: AASHTO TCRS and Task Force 13, TRB’s AKD20 annual winter meeting in Washington, D.C. and during the summer meeting, presentation to TTI and MwRSF pooled fund groups) and full-scale crash test videos and post-test documentation will be published and freely available for review.

The contracting agency will also recommend specific vehicles to be modeled with FEA. These vehicle models will greatly improve the evaluation of roadside hardware using numerical simulation to aid the design and retrofit (if needed) for systems tested under MASH and NCHRP Report No. 350 to be compliant with the update to MASH and new test vehicles. The new vehicle recommendations should be consistent with full-scale crash tested vehicles used during this project to improve the validation of the final vehicle models in future studies.

List the AASHTO Committee(s) and/or Council(s) – and any other organization – that might be interested in the research results and could help support implementation.

AASHTO, Technical Committee on Roadside Safety

AASHTO, Committee on Bridges and Structures Technical Committee T-7

AASHTO, Committee on Traffic Engineering

AASHTO, Committee on Safety

Relevance:

Results of the full-scale crash testing and comparisons with existing MASH testing shall be showcased at annual meetings of the Transportation Research Board AKD20 sessions and other update venues. Examples of showcase venues include the International Roadside Safety Conference, meetings with AASHTO Task Force 13 and Technical Committee on Roadside Safety, and annual meetings of the two largest roadside safety pooled fund organizations aligned with the Texas A&M Transportation Institute and the Midwest Roadside Safety Facility.

This research will provide recommendations for updating MASH guidelines for conducting full-scale crash testing, preliminary evaluations of hardware based on the recommended update to MASH, and preferred vehicles which can be developed into finite element analysis models for future simulation-based research.

Sponsoring Committee:AKD20, Roadside Safety Design
Research Period:Longer than 36 months
RNS Developer:Cody Stolle, Filiberto Sotelo
Source Info:AKD20 Summer Meeting 2020
Date Posted:01/04/2021
Date Modified:02/10/2021
Index Terms:Sport utility vehicles, Crash tests, Test vehicles, AASHTO Manual for Assessing Safety Hardware, Crashworthiness, Barriers (Roads), Highway safety,
Cosponsoring Committees: 
Subjects    
Highways
Design
Safety and Human Factors

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