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Developing Testing Protocol for a Family of Devices - Signs, Breakaway Poles and Work Zone Devices

Description:

The joint FHWA/AASHTO implementation plan for MASH devices require highway agencies to evaluate many different designs of permanent signs, breakaway poles, and work-zone devices. The new policy by the FHWA and AASHTO required that sign supports and breakaway hardware, including breakaway poles and temporary work zone devices, installed on federal aid roadways after December 31, 2019 to have been evaluated to MASH 2016.

In a May 26, 2017 letter from the FHWA, all tests required by MASH for a given device must be performed to get an FHWA eligibility letter. Also, with FHWA’s changing role in determining crashworthiness, highway agencies and manufacturers have been left in a situation where a significant number of systems still need to be evaluated to MASH, including permanent signs, breakaway poles, and work-zone devices. For each device, up to three full-scale crash tests need to be conducted, and these crash tests can be expensive to perform. There are thousands of variations of breakaway sign support systems, luminaire supports, and work-zone traffic control devices that the state DOTs utilize. The costs of these tests will fall directly on to transportation agencies and the public. Thus, it is not feasible to test all possible combinations to MASH.

A more cost-effective to evaluate the crash worthiness of a “family” of devices and determine which tests, either full scale or using surrogate testing methods, should be conducted in order to evaluate the crashworthiness of the entire family of products. Finding a more cost-effective way to determine the crashworthiness of a “family” of devices will speed implementation of new hardware and save transportation agencies funds.

Objective:

This project will:

· Determine what critical features a surrogate or bogie vehicle should have to determine crashworthiness

· Review previous literature and research on testing signs, breakaway poles, and work-zone devices

· Define the critical traits that make a “family” of devices.

· A procedure to determine the “Worst Practical Condition” for some devices that have similar designs. For example:

o Signs that use the same support design, but are installed at different heights or with different mass signs.

o Poles made of similar materials, but at different heights or devices attached to the top.

o Traffic control devices that use similar mounting hardware but have different sign substrates for a specific type of work-zone device

· Perform testing to validate the guidance on determining the most critical tests for a family of devices.

Benefits:

Transportation agencies must start adopting MASH-approved hardware now, as the new MASH implementation policy by the FHWA and AASHTO requires that sign supports and breakaway hardware, including breakaway poles and temporary work zone devices, installed on federal aid roadways after December 31, 2019 to have been evaluated to MASH 2016. This research will aid agencies in implementing MASH hardware and allows development of hardware in a less expensive manner.

Related Research:

There have been some MASH crash tests performed on existing signs:

Schmidt, J.D., Langel, T.J., Asselin, N., Pajouh, M.A., and Faller, R.K.; “MASH 2016 Evaluation of a Non-Proprietary Type III Barricade”; MwRSF TRP-03-394-18; InTrans Project 18-535; MwRSF; 2018

Sheikh, N.M., Bligh, R.P., Menges. W.L. and Kuhn, D.L.; “Crash Test and Evaluation of 3-Ft Mounting Height Sign Support System” FHWA/TX-15/9-1002-15-1; TTI; 2016

Dobrovolny, C.S., Arrington, D.R., Bligh, R.P., Menges, W.L., and Kuhn, D.L., “MASH Evaluation of TXDOT High-Mounting-Height Temporary Work Zone Sign Support System”; FHWA/TX-16/9-1002-15-8; TTI; 2017

Dobrovolny, C.S., Arrington, D.R., Bligh, R.P., and Menges, W.L.; “Development and MASH Full-Scale Crash Testing of a High-Mounting-Height Temporary Single Sign Support with Aluminum Sign”; FHWA/TX-13/9-1002-12-5; TTI; 2013

Bligh, Roger, Menges, Wanda, and Kuhn, Darrell; “MASH Evaluation of TXDOT Roadside Safety Features – Phase I”; FHWA/TX-17/0-6946-1; TTI; 2018

Bae, S., Tate, D., Wood, T., Zuo, D., Bligh, R., Menges, W., Gonzalez, V., Griggs, D., and Yang, Q.; “Testing of Alternative Supporting Materials for Portable Roll-Up Signs Used for Maintenance Work Zones”, FHWA/TX-14/0-6639-1; Texas Tech University; 2014

Silvestri, Chiara, Bligh, Roger, and Menges, Wanda; “MASH Full-Scale Crash Testing of 4-ft Mounting Height, 24"×30" Chevron Sign Installed on 5.5H:1V Slope Ditch.”; FHWA/TX-13/9-1002-12-6; TTI; 2013.

Williams, William, and Menges, Wanda; “MASH Test 3-11 Of the TXDOT Portable Type 2 PCTB With Sign Support Assembly”; FHWA/TX-11/0-6143-1; TTI; 2011

Bligh, Roger, Arrington, Dusty, and Menges, Wanda; “Temporary Large Guide Signs”;

FHWA/TX-13/0-6782-1; TTI; 2014

Bullard, Lance, Bligh, Roger, Wanda, Menges, and Haug, Rebecca; “NCHRP Web-Only Document 157: Volume 1: Evaluation of Existing Roadside Safety Hardware Using Updated Criteria - Technical Report”; TRB; 2010

Faller, Ronald, Sicking, Dean, Lechtenberg, Karla, Holloway, James, and Schmidt, Jennifer; “Safety Investigation and Guidance for Work-Zone Devices in Freight Transportation Systems Subjected to Passenger Car and Truck Impacts with New Crash Standards”; MwRSF TRP-03-225-10; MATC-UNL: 100; Mid-American Transportation Center; 2010

The research projects above concentrated on specific devices, and crash tests were performed on these devices. Some of these efforts included devices that were crashworthy according to the crash testing and safety performance criteria in NCHRP Report 350. However, when NCHRP Report 350 work-zone devices were subjected to the new MASH crash testing , several of the work-zone sign stands produced undesirable results, including windshield and floorboard penetration and excessive windshield and roof deformation. This testing indicated that devices tested under previous NCHRP Report 350 safety performance standards may not perform acceptably with the new MASH safety performance standards, and additional analysis may be warranted.

Currently NCHRP Project 03-119 Application of MASH Test Criteria to Breakaway Sign and Luminaire Supports and Crashworthy Work-Zone Traffic Control Devices that is evaluating several systems with computer simulation and testing to MASH standards. However, this project has limited funds, and there will be a significant number of systems that will not be evaluated during this project.

There are still are significant numbers of devices that should be tested to MASH. Permanent signs with wood post supports, for example, can have the following variations:

· Post sizes (e.g. cross section, weakening of posts)

· Post height

· Number of posts

· Panel size

· Panel connections

· Panel materials

· Panel location

· Panel weight

· Auxiliary devices attached to sign (e.g. flags, solar panels, sensors, flashing lights, secondary sign…)

· Soil type

Just with these variations, there could be approximately 300 to 400 or more MASH tests required for the wood-post subset of permanent signs. Additionally, there could be hundreds more tests when including U-channel supports, perforated square steel tube supports, I-beam supports, round aluminum tube supports, and other variations that state DOTs may utilize. Work-zone signs and sign stands have even more variations that need to be evaluated to MASH. During NCHRP Project 03-119, over 553 unique systems were identified, and some of those systems have multiple variations.

Implementation:

Transportation agencies are in the process of implementing MASH hardware. This research will allow transportation agencies to implement MASH approved signs, breakaway poles, and work zone devices. Without this research, transportation agencies and manufacturers will need to test all of their wide range of products. This large cost will then be transferred to transportation agencies in their implementation MASH approved signs, breakaway poles, and work-zone devices.

Sponsoring Committee:AFB20, Roadside Safety Design
Research Period:24 - 36 months
Research Priority:High
RNS Developer:Erik Emerson, Jennifer Schmidt, and James Kovar
Source Info:2018 AFB20 Midyear Meeting, Austin TX
Date Posted:01/15/2019
Date Modified:01/25/2019
Index Terms:Test procedures, Traffic signs, Breakaway supports, Work zone safety, Work zone traffic control, Crashworthiness, Highway safety, Roadside hazards,
Cosponsoring Committees: 
Subjects    
Highways
Design
Safety and Human Factors

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