NCHRP Report 350: Devices in Work Zones - Category 3

Barriers, .crash cushions, TMAs

  • Water filled longitudinal channelizing barricades and barriers
  • Portable concrete "Jersey" barriers
  • Crash cushions and TMAs
  • This category also includes ground-mounted signs
  • Full NCHRP Report 350 testing applies
  • Category 3 devices are subject to the full crash testing requirements of NCHRP Report 350. For Test Level 3 this means a 25 degree hit at 100 kmh with a 4400 pound pickup, and a 20 degree hit with an 1800 pound car.
  • Breakaway sign posts are tested with an 1800 pound car at 35 kmh and 100 kmh

Barrier or Barricade?

  • A "Barrier" is a longitudinal device that has met the Report 350 criteria for a redirective barrier at TL-2 or above.
  • A "Longitudinal Channelizing Barricade" does NOT redirect a vehicle. It is tested at the same speeds and angles, but the vehicle penetrates the barrier without severe forces on the occupant.

Water Filled Longitudinal Channelizing Barricade

Yodock Wall – Yodock units have been crash tested in three ways: as stand alone barricade units, as longitudinal channelizers, as shown here, and with the addition of a steel box beam rail, as barriers. When deployed like this, water filled units are a good substitute for a line of drums. They are not redirective vehicle barriers, as the vehicle may penetrate a longitudinal channelizing barricade. Forces on the vehicle occupants must be below the limits acceptable for a barrier impact.

Yodock Wall that serves as a longitudinal chanelizer

Water Filled Barriers

Water Fill Barrier - Roadguard Water Fill Barrier 2 (Triton first part) Water Fill Barrier 3 (Triton second part)

Roadguard (left) with highway kit and Triton barrier (middle, and right) internally reinforced. Both of these proprietary systems have been accepted as BARRIERS. For water filled units to actually perform as a barrier, you must have a steel framework, internal or external.

Temporary Concrete Barrier

The typical pin and loop design that has been in use for years needs to be beefed up in order to meet current crash test criteria. Failures of pin and loop designs have been caused by thin pins pulling out of the loops, loops breaking, or concrete fracturing due to lack of reinforcement. There are nearly a dozen successfully crash tested designs of portable concrete barriers, and they are posted on our web site.

loop design temporary concrete barrier 1 Pin design temporary concrete barrier 2

Temporary Barriers

  • barrier joints must provide tensile & moment capacity after Oct. 1, 2000
  • new units must meet NCHRP 350 after Oct. 1, 2002
  • used where vehicle entry to the work zone must be avoided

Temporary Barricades

  • Longitudinal Channelizing Barricades
    • Must be tested using same NCHRP Report 350 tests as for a Barrier, but the test vehicle may penetrate the device. The vehicle may not roll over, nor can the device cause excessive forces on the vehicle occupants.
    • Used where vehicle entry behind the line of devices is acceptable.

Work Zone Crash Cushions

Energite III and Quadguard CZ Sand barrel attenuators are initially low-cost but they need nearly total replacement after a hit. More sophisticated attenuators like the Quadguard CZ are quite expensive, but can be restored quickly and cheaply, sometimes without the need to replace any parts at all.

photo of 2 men with energite 3 sand barrel attenuators photo of quadguard sand barrel

Work Zone Crash Cushions

  • Sand Barrel attenuators usually require complete replacement. Should be used where you have the available width, and the frequency of impact will be low
  • More sophisticated attenuators are expensive, but easier to repair. They should be used when working widths are narrow and frequency of hits is likely to be high

Truck Mounted Attenuators

TMAs are optional devices, but in order to be acceptable for use they must meet NCHRP Report 350 Test Level 2 criteria at a minimum.

U-Mad Truck Mounted Attenuator by Albert Unrath, Inc. Safe-Stop Truck Mounted Attenuator by Energy Absorption

Federal Aid research funds were used to develop a non-proprietary work zone truck-mounted attenuator. On July 13, 1995, FHWA accepted the Connecticut Truck Mounted Attenuator as NCHRP Report 350 TL-2 Truck Mounted Attenuator.

The Connecticut DOT first tested the concept over 30 years ago and has found it to be excellent life-saving device. The CT DOT offers free plans for this generic, non-proprietary work zone safety system. Full details are linked at http://www.ct.gov/dot/ctma.

For Additional Information:

Nick Artimovich
FHWA - HSA-10
400 Seventh Street, SW
Washington, DC 20590
nick.artimovich@fhwa.dot.gov

Program Contact

Brian Fouch
Safety Design Team Leader

(202) 366-0744

What's New

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ET-Plus W-Beam Guardrail Terminal Memorandum new

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FHWA Roadway Lighting Handbook, August 2012

RwD Strategic Plan, April 2013

Updated Guidance on Sign Retroreflectivity, April 2013

Clarifying Guidance on Daytime Luminance, January 2013

Guidance for the Selection , Use and Maintenance of Cable Barrier Systems, November 2012