March 27, 2003

Refer to: HSA-10/WZ-135

Mr. Marc Christensen
Off the Wall Products, LLC
P.O. Box 1461
Salt Lake City, UT  84110-14461

Dear Mr. Christensen:

Thank you for your letters of June 14, August 16, and December 17, 2002, requesting Federal Highway Administration (FHWA) acceptance of your company's water-filled longitudinal channelizers as crashworthy traffic control devices for use in work zones on the National Highway System (NHS).  Accompanying your letter was a report of crash testing conducted by E-Tech Testing Services, summaries of additional tests, drawings of the individual units, and videos of the tests. You requested that we find these devices 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.” On March 12, 2003, you provided a complete final report covering the crash testing of the device as a longitudinal channelizer.


The FHWA guidance on crash testing of work zone traffic control devices is contained in two memoranda.  The first, dated July 25, 1997, titled “INFORMATION: Identifying Acceptable Highway Safety Features”, established four categories of work zone devices: Category I devices were those lightweight devices which could be self-certified by the vendor, Category II devices were other lightweight devices which needed individual crash testing, Category III devices were barriers and other fixed or massive devices also needing crash testing, and Category IV devices were trailer mounted lighted signs, arrow panels, etc.  The second guidance memorandum was issued on August 28, 1998, and is titled “INFORMATION: Crash Tested Work Zone Traffic Control Devices.” This later memorandum lists devices that are acceptable under Categories I, II, and III.

A brief description of the devices follows:

The Multi-Barrier is a rotation molded hollow plastic barricade section, which can accept water ballast.  Each high-impact, UV-resistant polyethylene section is 1219 mm (48 inches) tall and 1016 mm (40 inches) long.  Each section is 598 mm (23.5 inches) wide at the base, tapering on one side to a top width of 152 mm (6 inches).  The wall thickness is 5.1 mm (0.20) inches, and one section weighs 22.7 kg (50 pounds) empty. The specifications and drawings are given in the enclosed literature for reference.

Individual units were crash tested as Type II barricades, and found acceptable in FHWA Acceptance Letter WZ-8 date February 5, 1999.  This action, WZ-135, is to qualify the same units linked longitudinally and filled with water, deployed as a Test Level-1 (TL-1) longitudinal channelizer.


Full-scale automobile testing was conducted on your company's devices.  The crash test matrix was a modification of both the NCHRP Report 350 tests for longitudinal barriers and work zone traffic control devices.  The crash tests are summarized in the table below:

Test Number



NCHRP 350 Test #

1-10 (Pick Up Truck)

1-11 (Small Car)

Test Article

Off-The-Wall Multi-Barrier

Length of test article

30 Sections (30.5 m, 100 ft)

30 Sections (30.5 m, 100 ft)

Mass of individual units

22.7 kg (50 pounds)

22.7 kg (50 pounds)

Mass of water ballast

418 kg (921 pounds)

418 kg (921 pounds)

Vehicle inertial mass

2011 kg (4433 pounds)

826 kg (1820 pounds)

Impact speed

51.25 km/h (31.8 mph)

49.16 km/h (30.5 mph)

Impact angle

25.0 degrees

20.2 degrees

Occupant impact speed

4.78 m/s

6.78 m/s

Ridedown acceleration

-3.45 g's

-3.77 g's


Vehicle penetrated, stopped

Vehicle penetrated system

Vehicle damage

Minor, to grill and hood

Minor, to grill and hood

Occup. compartment intrusion



Windshield damage

No Contact

No Contact


As expected the vehicle penetrated the installation.  The occupant impact velocity of the small car exceeded that for a work zone traffic control device, but the occupant impact velocities and accelerations in both tests were within those specified for a barrier.

The results of the testing met the unique requirements established for water-filled longitudinal channelizers and, therefore, the device described above and shown in the enclosed drawings for reference are acceptable for use on the NHS under the range of conditions tested (Report 350 TL-1), when proposed by a State or other highway agency.

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

in-service performance reveals unacceptable safety problems, or that the device being marketed is significantly different from the version that was crash tested, it reserves the right to modify or revoke its acceptance.

Sincerely yours,

Michael S. Griffith
Acting Director, Office of Safety Design
Office of Safety