Development of Field Applied Fittings for Wire Rope Barrier and Conversion to High Tension

The objective of this project is to identify and test a new field application method for wire rope terminations. The project also provides a procedure converting low-tension wire rope system to a higher tension system. Performance of the terminations and the higher tension system was verified through a full-scale crash test. The Field Swage termination and the Epoxy Socket performed the best under dynamic and static loading conditions. Both terminations will provide the full strength of the connected with rope if installed properly. Mechanical terminations may have sufficient capacity, however, further testing needs to be done to verify and they will not release wire rope due to vibrations of wire ropes seen in high-speed videos of redirection impacts. The process of converting to high tension will require the low-tension terminals to be replaced with FHWA accepted high-tension terminals. The spring compensators will need to be removed and the terminations should be replaced. The retrofitted system met the criteria for an NCHRP Report 350 TL-3 crash test rating. However, the large size of the Epoxy Socket termination has raised questions about the system when impacted by a smaller vehicle. Therefore, it is recommended that a small car test be run on this system. The Field Swage termination should meet all criteria for TL-3 and a number of similar factory applied swage fittings have performed acceptably with both cars and pickups. Low-tension systems could benefit from the addition of a fourth wire rope to further reduce potential for vehicle underride. Data from NCAC and MwRSF indicates the lower additional wire rope should not be placed higher than 13.5 inches above grade. At the request of sponsoring states two detailed retrofit manuals were developed for retrofitting existing low-tension three wire rope systems. The first manual located in Appendix H details the conversion process to a three wire rope high tension system. The second manual located in Appendix I details the conversion process to a four wire rope high tension system. Each manual describes the retrofit process step by step in a way that it can be easily understood and followed by maintenance personnel.