Federal Highway Administration
1200 New Jersey Ave. S.E.
Washington, D.C. 20590
October 25, 2007
Ms. Saundra Lautenberg
V.P. Operations, North America
177 Fieldcrest Avenue
Edison, NJ 08837
Dear Ms. Lautenberg:
In your letter of July 26, 2007, you requested the Federal Highway Administration (FHWA) acceptance of your company’s Elite bus stop sign support system for use on the National Highway System (NHS). Accompanying your request was a report from the E-TECH Testing Services. You requested that we find this device acceptable for use on the NHS under the provisions of the National Cooperative Highway Research Program (NCHRP) Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features.”
Sign supports should meet the guidelines contained in the NCHRP Report 350, “Recommended Procedures for the Safety Performance Evaluation of Highway Features.” The FHWA memorandum, “ACTION: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on testing requirements of sign supports and outlines procedures for pendulum testing and estimation of high-speed breakaway performance of sign supports from low-speed pendulum test results.
The Elite bus stop sign support system includes a 9.8 to 13.1 foot (3m to 4m) extruded aluminum (material specification 6063-T6) post, lower timetable and upper route display signs, concrete foundation with socket tube mounting option, service line or solar powered lighting, and accompanying mounting hardware. The aluminum post is weakened 18 inches (0.45 m) from the bottom with a 1/2 inch (13 mm) diameter hole through the cross section just above the foundation socket tube such that the post fractures near or below the ground level when impacted.
Test article installations
Two Elite bus stop sign support systems were tested. Each test article was configured with the “worst case” triple lower timetable display, solar light, and concrete anchor block with the tube socket option. The pendulum tested installation used a securely welded steel foundation to simulate the concrete anchor block with socket tube. In each installation the test article was assembled according to the manufacturer’s instructions and the total test article mass was
121 pounds (55 kg).
Testing was conducted to evaluate performance at the test level 2 (TL-2) conditions according to NCHRP Report 350 criteria. After consultation with the FHWA Office of Safety, it was determined that the low speed (35 km/h) compliance testing (Test 2-60) be accomplished using a pendulum test apparatus and that the high speed (70 km/h) testing (Test 2-61) be completed using the 820C test vehicle. The pendulum bogie was built according the specifications of the Federal Outdoor Impact Laboratory's (FOIL) pendulum, and the frontal crush of the aluminum honeycomb nose of the bogie simulated the crush of an actual vehicle. Tests with pendulums are acceptable for most breakaway supports with the exceptions of base bending or yielding supports.
For each test the velocity change and deceleration were both within acceptable limits. There was no appreciable stub height to measure from the ground line. The results of the pendulum test (Test 2-60) yielded a maximum change in velocity of 12.8 ft/s (3.9 m/s). The results of the higher speed 820C vehicle impact (Test 2-61) yielded a maximum change in velocity of 7.5 ft/s (2.3 m/s) and maximum ridedown acceleration of -1.2 g’s. The vehicle bumper impacted the support at 17.3 inches (440 mm) above ground level and the sign support rotated above the vehicle, made contact with the rear windshield and caused the rear windshield to shatter. A summary of the testing results are enclosed.
The results of crash testing met the FHWA requirements and, therefore, the Elite bus stop sign support system as described above and shown in the enclosed drawings for reference are acceptable for use as TL-2 devices on the NHS under the range of conditions tested, when proposed by a State. The condition of the sign supports due to the damage from impact are classified as not being repairable. For systems that will be wired in ground for power, all electrical wiring connectors must be breakaway.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
George E. Rice, Jr.
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