Refer to: HSA-10/LS-50
Mr. Richard Foedinger
DE Technologies, Inc.
3620 Horizon Drive
King of Prussia, PA 19406-2647
Dear Mr. Foedinger:
Thank you for your letter of May 23 requesting Federal Highway Administration (FHWA) acceptance of your company's Energy Absorbing Utility Pole as a crashworthy device for use on the National Highway System (NHS). Accompanying your letter was a summary report from Southwest Research Institute and videos of the crash tests. You requested that we find the Energy Absorbing Utility Pole acceptable for use on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features."
Testing of the supports was in compliance with the Test Level 2 (TL-2) guidelines contained in the NCHRP Report 350. Requirements for crashworthy utility poles are quite different from those which apply to breakaway sign and luminaire supports. Conventional breakaway supports are covered in the American Association of State Highway and Transportation Officials' (AASHTO) Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals and call for a maximum occupant impact speed of 5 m/s in a test vehicle impacting at 35 kmh and 70 kmh. The criteria for utility poles are those found in Section 3.2.3 of Report 350 and allow up to a 12 m/s occupant impact speed in 820C test vehicles impacting at 50 kmh and 70 kmh.
Full-scale automobile testing was conducted on your company's devices. The test articles were filament wound fiberglass reinforced polyester composite utility poles fabricated by Shakespeare Composites and Electronics Division. The overall length of the test poles was 13.7 meters (45 feet), with an octagonal cross-section at the lower section of the pole that transitions to a circular cross-section a the upper section of the poles. Fiberglass composite cross-arms, also provided by Shakespeare, were mounted near the top of the poles using Shakespeare-provided mounting brackets and bolts. Pre-drilled holes were provided in the poles for cross-arm attachments.
The test articles were installed in drilled holes and backfilled with NCHRP Report 350 Standard (strong) Soil at a burial depth of 1.83 m (6 feet.) The poles were installed such that the cross arms were perpendicular to the normal direction of traffic. A 12.2 m (40 ft) long wooden utility pole was installed at a nominal distance of 140 feet on both sides of the composite poles. The wooden poles were guyed in the standard manner. Standard wires were attached to the cross-arms and tensioned between the three poles.
The mass of the test vehicles was 820 kg, and they impacted the poles on the centerline of the vehicle in all tests. The complete devices as tested are shown in the Enclosure 1. The tests are summarized in the table below:
|Test #||NCHRP 350
|Test Impact Speed||Occupant Impact Speed
|1||2-80||50.0 km/hr||10.6 m/s||1.0 m/s||13.3 gs's|
|2||2-81||70.0 km/hr||10.8 m/s||1.1 m/s||5.6 g's|
Occupant Impact Speed: Speed at which a theoretical front seat occupant will contact the windshield.
Longitudinal Ridedown: The maximum g force that the theoretical occupant will experience once contact has been made with the vehicle interior.
These composite energy absorbing utility poles were not designed to break away. These poles were designed to capture the vehicle and stop it gently enough that the velocity change and deceleration requirements were met.
There was major damage to the front ends of the test vehicles in both impacts. The poles and the vehicles remained upright, and there was no occupant compartment deformation. Velocity changes and other occupant risk measures were all within acceptable limits for utility pole tests. The results of the tests met the FHWA requirements and, therefore, the devices 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.
Please note the following standard provisions which apply to FHWA letters of acceptance:
Frederick G. Wright, Jr.
Program Manager, Safety