Connecticut Truck Mounted Attenuator - Portable Crash Cushion
CTMA
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FHWA approves Connecticut Truck Mounted Attenuator as NCHRP Report 350 TL-2 Truck Mounted Attenuator Originally approved under NCHRP 230 in the mid 1970's. Approved under NCHRP 350 on July 13, 1995. Free downloadable plans below. |
 CTMA In-house fabrication and repair of this highway safety system have saved taxpayers an estimated $1.3M versus commercially-available truck mounted attenuators. The CTMA's have been in service protecting workers since the 1970's when the CTMA was first approved for use on the National Highway System. Today, one-hundred thirty-four (134) CTMA units are in service on Connecticut highways. Repair History for period 1999 to 200 |
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The Federal Highway Administration (FHWA) has approved the Connecticut Truck Mounted Attenuator (CTMA) for use on the National Highway System. The July 13, 1995 FHWA approval letter is linked to this Web page. The ConnDOT crash test program report on the CTMA is linked to this Web page for viewing. |
The CTMA consists of four 24-inch (610-mm) diameter steel cylinders supported between a steel guide frame that attaches to a shadow truck, and an aluminum impact plate assembly with aluminum channels that slide into steel tubes in the guide frame during impact. The steel cylinders are A53 Grade B seamless steel pipe (API 5L steel pipe - oil and gas transmission line pipe, water pipe and water well casing.). Three cylinders have 1/4-inch wall thickness and the fourth has 3/8th0inch wall thickness. |
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The cylinders rest on the lower rail. |
View of truck mounted attenuator. |
CTMA detaches from the truck and can be rolled about on four retractable casters. |
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View of the four collapsible cylinders, which are bolted together. |
Close-up of bolted connection. Cable provides power to lights on the impact plate. |
The cylinder nearest the mounting plate is cylinder number 1. |
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When the CTMA is detached from the truck it rolls on retractable caster wheels. |
Side view of retractable caster wheel. |
Crank for retractable caster at the chassis mounting plate. |
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The CTMA frame attaches to the chassis beneath the truck. |
The lower rail slides safely into these tubes and under the truck chassis when the attenuator is hit. |
View of the CTMA frame and mounting plate |
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Connecticut's one-hundred thirty-four (134) were fabricated by Department personnel in the Office of Maintenance. The current-year cost for labor and materials to fabricate a CTMA is $5,000. For more information, contact Charles A. Drda, P.E. [P (860) 594-2606 ] Below are free "downloadable plans". |
The CTMA meets "Test Level 2" performance requirements for truck-mounted attenuators, which were established by the Transportation Research Board [National Research Council] through the National Cooperative Highway Research Program, NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features." |
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TRB Transportation Research Record 679 explains the development of the CTMA in the 1970's by Dr. John F. Carney III, then a professor at the University of Connecticut. |
TRB Transportation Research Record 833 describes the original crash testing of the CTMA under NCHRP 230 standards. |
Downloadable Plan Sheets for CIAS
| Adobe Portable Document Format (PDF) | Microstation Design File Format (DGN) |
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