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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-213

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U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Ave. S.E.
Washington, D.C. 20590

December 22, 2010

In Reply Refer To:
HSST/B-213

Mr. Daren Copeland
Varley and Gulliver Limited
Alfred Street, Sparkbrook
Birmingham, UK B12 8JR

Dear Mr. Copeland:

This letter is in response to your request for Federal Highway Administration (FHWA) acceptance of a roadside safety system for use on the National Highway System (NHS).

Name of system: Proprietary VGAN 300 Aluminum Permanent Bridge Barrier
Type of system: Post and Tube Railing Mounted on Reinforced Concrete Curb
Test Level: NCHRP Report 350 Test Level 4 (TL-4)
Testing conducted by: Texas Transportation Institute (TTI)
Date of request: September 30, 2010
Drawing Designator: SBA07d

You requested that we find this system 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.” (NCHRP Report 350)

Requirements
Roadside safety systems should meet the guidelines contained in the NCHRP Report 350. FHWA memorandum “ACTION: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

Decision
The following device was found acceptable, with details provided below:

Description
The Varley & Gulliver proprietary aluminum bridge railing system was mounted on a reinforced concrete curb. Overall length of the entire system was 29.3 m (96.0 ft) with posts spaced at 2.44 m (8.0 ft) for a total of 12 bays, 13 posts. The posts were cast A444.0 T4 aluminum and were anchored with four M20 stainless steel bolts. Extruded 6082 T6 aluminum tubes were used for the railing. They were a flattened elliptical shape. The two lower rail elements were 152 mm (6.0 inches) in the long direction and 98 mm (3.8 inches) in the short direction and 5 mm (0.2 inch) wall thickness. The upper or pedestrian rail was 114 mm (4.5 inches) in the long direction and 85 mm (3.3 inches) in the short direction with 3 mm (0.12 inch) wall thickness. Splices were achieved with 6 mm (0.24 inch) wall thickness internal tubular sections in the main rails and 4 mm (0.16 inch) wall thickness internal tubular sections in the upper or pedestrian rail. The extruded rail elements had key way section on the lower back side that allow bolts to be placed in the key way and provides longitudinal adjustment.

The concrete foundation was specified to be 5800 psi and was 6318 psi at the time of the test and was anchored to the apron with “L” shaped bars welded to existing rebar. All rebar was specified to be 60 ksi. Steel reinforcement bar stirrups, 16 mm (0.6 inch) diameter, were placed at 150 mm (6.0 inches) on center with eight spaces under the post location and four spaces at 310 mm (12.2 inches) on center between the posts. There were 12 evenly spaced 16 mm (0.6 inch) diameter longitudinal bars in the foundation. Threaded inserts were placed in the concrete with templates. After the posts were bolted into the inserts, an epoxy grout pad was cast at each post support location. The four anchor bolts on one post upstream of impact, the impact post, and one post downstream of impact were instrumented with strain gages to measure force transmitted to the bolts.

Details of the VGAN 300 bridge rail test article are enclosed within this correspondence.

Crash Testing
The Proprietary VGAN 300 Aluminum Permanent Bridge Barrier was crash tested at the test facilities at TTI Proving Grounds Riverside Campus according to the following NCHRP Report 350 TL-4 tests for the evaluation of longitudinal barriers as described below.

NCHRP Report 350 Test Designation 4-10 with an 820 kg small passenger vehicle impacting the critical impact point (CIP) of the length-of-need (LON) of the bridge rail while traveling at an impact speed and angle of 100 km/h and 20 degrees. The purpose of this test is to evaluate the overall performance of the LON section, in general, and occupant risks, in particular.

NCHRP Report 350 Test Designation 4-11 with a 2000 kg pickup truck impacting the CIP of the LON while traveling at an impact speed and angle of 100 km/h and 25 degrees. The test is intended to evaluate strength of the section in containing and redirecting the 2000P vehicle.

NCHRP Report 350 Test Designation 4-12 with an 8000 kg single-unit box-van truck impacting the CIP of the LON while traveling at an impact speed and angle of 80 km/h and 15 degrees. This test is intended to evaluate the strength of the LON in containing and redirecting the heavy test vehicle.

The target CIP for each of the aforementioned tests was determined according to the information provided in NCHRP Report 350. For the test with the small car and the pickup, the CIP was determined to be at post 4. Post 4 is upstream of the first splice in the system. The CIP for the test with the single-unit box-van truck was determined to be 1 ft downstream of post 4. Crash Test summaries of each of these tests are enclosed within this correspondence.

Findings
The FHWA concurs to the submitted physical crash testing of the Proprietary VGAN 300 Aluminum Permanent Bridge Barrier to the proposed TL-4 designation. Therefore, the Proprietary VGAN 300 Aluminum Permanent Bridge Barrier meets the TL-4 impact conditions and evaluation criteria for a NCHRP 350, and is acceptable for use on the NHS when requested by a highway agency.

Please note the following standard provisions that apply to FHWA letters of acceptance:

 

Sincerely yours,

/* Signature of Michael S. Griffith */

Michael S. Griffith
Director, Office of Safety Technologies
Office of Safety

Enclosures

Page last modified on June 24, 2011.
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