BACKGROUND
    In 1996, the Washington State DOT 3-strand cable guardrail was subjected to NCHRP Report 350 test designation 3-10. The test involved an 820-kg passenger car impacting the guardrail at post 12. The impact speed was 99.7 km/h and the vehicle impact angle was 20.4 degrees relative to the guardrail. The guardrail performed acceptably by redirecting and containing the vehicle. The two rear mounted cables went under the vehicle and the vehicle became entrapped between the front and rear cables. The cable guardrail met all evaluation criteria set forth for NCHRP Report 350 test designation 3-10.
    In October of 1998, NCHRP Report 350 test designation 3-34 was performed on the New York cable terminal. This test involved an 820-kg passenger vehicle impacting the terminal at the critical impact point (CIP) at a speed and angle of 99.3 km/h and 14.7 degrees, respectively. FHWA and TTI determined the CIP involved the right front corner of the bumper of the vehicle impacting the cables in the region where they sloped downward to attach to the concrete anchor block. The New York cable terminal allowed the vehicle to gate through the end of the installation with minimal damage to the vehicle. The New York cable terminal performed acceptably according to criteria specified in NCHRP Report 350 test designation 3-34. On the basis of this test and other tests previously conducted by New York State DOT, the New York cable anchorage terminal was approved by FHWA for use on the NHS.
    In February 2000, officials at FHWA decided the installation constructed for the test of the Washington 3-strand cable guardrail should incorporate the New York cable terminal. A 145 m long test installation of Washington 3-strand cable guardrail was constructed in accordance with Washington State Department of Transportation standard drawings modified to include a New York cable terminal on each end. Posts were installed in drilled holes and backfilled with NCHRP Report 350 standard soil. The Washington 3 strand cable guardrail with New York cable terminal performed acceptably for NCHRP Report 350 test 3-11.
    A number of the high tension cable median barriers have been successfully tested at both TL-3 and TL-4 under NCHRP Report 350. TL-3 is a 3/4 ton, 2000 kg, pickup impacting the system at 100 km/h and 25 degrees. TL-4 is an 8000 kg single unit truck impacting the system at 80 km/h and 15 degrees. The systems have a variety of post configurations and spacings. While there is some variation on the cable strength and installed modulus of elasticity, overall dimension and construction are 19 mm, 3 x 7 wire ropes.
    Recent accidents in the state of Washington have indicated potential problems for field applied fittings in wire rope systems. Additionally, when low tension systems are compared to high tension systems, maintenance appears to be a larger issue with lower tension systems.

OBJECTIVE
    The objective of this project is to identify and test a new field application method for wire rope terminations. The project will also evaluate the benefits and consequences of converting the low tension wire rope systems to a higher tension system. Performance of the terminations and the higher tension system will be verified through a full scale crash test.

BENEFITS
    This project will provide performance and safety enhancements to states for use where low tension wire rope systems have been previously installed.

IMPLEMENTATION
    If acceptable test results are achieved, appropriate methods for replacement of end terminations will be provided. Appropriate tensions in conjunction with any system modifications, required for the higher tension, will also be provided.

WORK PLAN
Task 1 -- Identify and Test Alternate Termination Methods
    The researchers will identify and obtain alternate termination methods and will review alternatives with the project technical representative. Prototypes will be secured and tested statically and dynamically. TTI would assess the ability to utilize 2 different termination methods found to be acceptable when tested in Task 3.
Task 2 -- Assessment of Issues Related to Conversion to a High Tension System
    The researchers will assess the impacts of additional tension on the existing system. This assessment would evaluate the connection of the cable to the posts with the current J-bolts as well as the removal of the spring compensating devices
Task 3 -- Perform Full-Scale Vehicle Crash Test on High Tension System with Alternate Wire Rope Terminations
    The researchers will perform test Modified 3-11 of NCHRP Report 350 (2000P vehicle, 100km/h, 25 deg) on the selected design. Length of test installation will be 145 m (consistent with the original NCHRP Report 350 test of the low tension system. TTI will provide the test facility, test vehicle, instrumentation of the vehicle, high-speed film, video, still photographs, and a final report suitable for submittal to Federal Highway Administration (FHWA).
Task 4 -- Develop Detailed Procedures for Retrofit of Existing Hardware
    The researchers will develop detailed instructions with photos and illustrations that would be geared to Maintenance Technicians. These instructions would also include equipment requirements and vendors that can supply this equipment.

   
CRASH TESTING

   A full-scale crash test was performed on the prototype cable guardrail on July 11, 2008. Following are video clips of the crash testing: