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U.S. Department of Transportation

Federal Highway Administration

1200 New Jersey Ave. S.E.
Washington, D.C. 20590
July 25, 2007

In Reply Refer To: HSSD/SS-151

Mr. Darrell Heald
Vice President
SHUR-TITE Products
P.O. Box 2283
Round Rock, TX 78680

Dear Mr. Heald

In your letter of December 14, 2006, you requested the Federal Highway Administration's (FHWA) acceptance of your SHUR-TITE® multiple mailbox mount at the National Cooperative Highway Research Program (NCHRP) Report 350 test level 3 (TL-3). In support of your request, you provided a copy of the Texas Transportation Institute report dated November 2006, entitled "Crash Testing and Evaluation of the SHUR-TITE® Multiple Mailbox Mount" and digital video of the crash test conducted on the device.


Mailbox supports should meet the guidelines contained in the NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features." FHWA Memorandum "ACTION: Identifying Acceptable Highway Safety Features" of July 25, 1997, provides further guidance on crash testing requirements of support structures.

Product description

The SHUR-TITE® multiple mailbox mount is designed to support as many as 4 or 5 mailboxes (depending on their size and total weight) on a support frame that is fabricated from 2-3/8 inch (60.3 mm) diameter and 0.065 inch (1.7 mm) thick steel tubing. The top portion of the support frame consists of a horizontal tube, which is welded at both ends to a 25 inch (63.5 cm) radius, semi-circular shaped tube. The bottom of the semi-circular tube is welded to a 22.5 inch (57.2 cm) long vertical tube. Two detailed drawings of the multiple mailbox support are enclosed for reference.

Test article installation

The test installation had four mailboxes mounted on its top. Two of these mailboxes were smaller, measuring approximately 9 inches by 7 inches by 19 inches (229 mm x 178 mm x 483 mm) and weighing 7 lb (3.2 kg). The remaining two mailboxes were a larger size, measuring approximately 15 inches by 11.5 inches by 23.5 inches (381 mm x 292 mm x 597 mm) and weighing 13 lb 10 oz (6.2 kg). The small mailboxes were directly attached to the standard Texas Department of Transportation bracket mount with four 1/4 inch (6.4 mm) diameter bolts.

The mailbox frame was placed into a 12 inch (305 mm) diameter by 30 inch (762 mm) deep concrete footing. At the center of this concrete footing, a 3 inch (76.2 mm) diameter by 17 inch (43.2 cm) long plastic tube socket was used for mounting the mailbox support frame. Once the mailbox support frame was inserted into the footing, it was secured in place with a plastic wedge placed between the vertical support frame tube and the plastic socket in the concrete footing.


The criteria in the NCHRP Report 350 for mailbox supports specifies that to meet TL-3 they must successfully pass tests 3-60 and 3-61. These tests involve the standard 820 kg passenger car impacting the support head-on and at the critical impact angle at a speed of 35 km/h (test 3-60) and 100 km/h (test 3-61).

Both tests were conduced on your mailbox support. In test 3-60, the test vehicle impacted the device at an impact angle of 0 degrees and with the left quarter point of the vehicle aligned with the centerline of the mount. Upon impact, the support pulled out of the ground socket as designed. Contact with the windshield was made but no damage resulted. In test 3-61, the test vehicle contacted the device at an impact angle of 0 degrees and with the right quarter point of the vehicle aligned with the centerline of the support. Upon impact, the support pulled out of the ground base as designed and the mailboxes contacted the windshield. The windshield shattered an area of 5 square feet and depressed 3.2 inches (81 mm) inward without any holes or penetration into the occupant compartment. A summary of the test results is enclosed.

Based on the crash testing results, I agree that the SHUR-TITE® multiple mailbox mount meets the evaluation criteria for NCHRP 350 TL-3 for mailbox supports and may be used at all appropriate locations on the National Highway System (NHS) when selected by the contracting authority. The SHUR-TITE® multiple mailbox mount was tested in a configuration that included two small mailboxes weighing 7 pounds (3.2 kg) each and two large mailboxes weighing 13.6 pounds (6.18 kg) each. The total weight of the mailboxes is approximately 41 pounds (18.6 kg). Alternate mailbox arrangements are considered acceptable, provided that the total weight of the mailboxes does not exceed the total tested weight of 41 lb (18.6 kg).

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

Sincerely yours,

George E. Rice

George E. Rice, Jr.
Acting Director, Office of Safety Design
Office of Safety


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