Material Requirements for High-Tension Cable Barriers: A Guide (2025)
Chapter: 1 Introduction
CHAPTER 1
Introduction
1.1 Background
Longitudinal barriers on the United States National Highway System (NHS) have long demonstrated effectiveness in reducing the severity of roadway departure crashes (FHWA 2020). These safety systems are classified into three main categories: rigid concrete barriers, semi-flexible metal post-and-beam barriers, and flexible cable barriers. The 2011 American Association of State Highway and Transportation Officials (AASHTO) Roadside Design Guide (RDG) Table 6.1 classifies most median barriers as generic systems, with exceptions for high-tension cable barriers (HTCB) and certain moveable barrier systems (AASHTO 2011).
Generic systems, such as strong-post W-beam barriers, feature standardized designs (e.g., SGM04a-b; see TF13 n.d.a.; TF13 n.d.b.) and conform to standard specifications (e.g., AASHTO M 180). These systems have been full-scale crash tested, and many have received a Federal Highway Administration (FHWA) eligibility letter (e.g., B-64;) indicating authorization for use on federal-aid projects (Horne 2000; TF13 2019). These generic systems can be adopted and installed by any transportation agency or competent organization.
In contrast, all current HTCB designs in the U.S. are proprietary. These systems are designed and manufactured by four companies: Brifen USA, Valtir, LLC (previously Trinity Highway Products), Gregory Highway Products, and Gibraltar Global. While the HTCB systems have all been crash tested [e.g., to NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features (Ross et al. 1993) or AASHTO Manual for Assessing Safety Hardware (MASH) guidelines (AASHTO 2009; AASHTO 2016)] and have FHWA eligibility letters, they do not have standard designs, nor is there a standard specification that covers the material requirements of all the components of these systems. There are also no standardized installation and maintenance procedures, or material testing requirements for these systems. This lack of standardization can lead to states having less understanding of the required materials and methods for their HTCB installation projects. As states install more HTCBs, they develop standard drawings, provisions, and specifications, sometimes requiring different materials or procedures from manufacturer recommendations.
The recommended HTCB Acceptance Plan developed through this research is intended to reduce state-to-state variation in specifications, level the competitive landscape during bidding, and promote consistency in HTCB installation, maintenance, and training practices.
A 2017 in-service performance evaluation (ISPE) of HTCB systems conducted by the Kentucky Transportation Cabinet (KTC) concluded that quality assurance during installation is needed to ensure standards are met, recommending additional training and guidelines for inspectors (Agent et al. 2017). A nationally recognized best practices document is anticipated to help address such issues.
1.2 Objective
The primary objective of this project was to develop a document that outlines the materials used in HTCB systems and identifies general practices and procedures used in the cable barrier industry. This document is intended to serve as a reference for state transportation agencies, allowing them to incorporate the specifications into their contracts. Where appropriate, the document refers to existing AASHTO/ASTM standards for the various components of HTCB systems. It is anticipated that this document will ensure that HTCB installations across different states conform to the current state of practice and will promote uniformity in the implementation of these barrier systems.
