Two Approach Guardrail Transitions for Concrete Safety Shape Barriers


Book Description

Two approach guardrail transitions for use with concrete safety shape barriers were developed and crash tested. For this study, the transition systems were attached to the New Jersey safety shape concrete barrier; however, it is believed that these transition systems could be easily adapted to the F-shape barrier with no need for further crash testing. Both transition designs were constructed with two nested thrie beam rails measuring 2.66-mm thick. The first transition design was supported by nine W150x13.5 steel posts measuring, 1,981-mm long, while the second transition design was supported by nine 152-mm x 203-mm wood posts measuring 2,134-mm long. For both systems, post spacings consisted on one at 292 mm, five at 476 mm, and three at 952 mm. A triangular-shape concrete curb was constructed below the thrie beam rail on each approach guardrail transition system. The two transition systems successfully met the Test Level 3 requirements specified in NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features."




Roadside Design Guide


Book Description

This document presents a synthesis of current information and operating practices related to roadside safety and is developed in metric units. The roadside is defined as that area beyond the traveled way (driving lanes) and the shoulder (if any) of the roadway itself. The focus of this guide is on safety treatments that minimize the likelihood of serious injuries when a driver runs off the road. This guide replaces the 1989 AASHTO "Roadside Design Guide."







Guidelines for Attachments to Bridge Rails and Median Barriers


Book Description

The objective of the research project was to collect crash test data relating to bridge rails and median barriers, to collect information about common attachments to traffic barriers, and to evaluate this information for the purpose of developing guidelines for the design and placement of traffic barrier attachments. A comprehensive review of full-scale crash testing of bridge rails and median barriers was conducted in order to establish Zones of Intrusion (ZOIs) for traffic barriers. The primary goal of this review was to identify the extent that a pickup or single-unit truck intrudes over the top of a traffic barrier during a vehicular impact.







Guardrail Performance and Design


Book Description

Barrier installations are warranted (or justified) only at highway locations where the consequence of an errant vehicle leaving the roadway is judged to be more hazardous than the impact with the barrier installation. A six degree-of-freedom mathematical model was found to be useful in describing dynamic behavior of a vehicle during impact. Predictions of vehicle and barrier behavior correlated with results obtained from full-scale crash tests. Crash conditions simulated with a computer were used to identify and evaluate vehicle static and dynamic as well as barrier parameters. Vehicle weight, yaw mass moment of inertia, and deformation constant were found to be significant.




Gravel Roads


Book Description

The purpose of this manual is to provide clear and helpful information for maintaining gravel roads. Very little technical help is available to small agencies that are responsible for managing these roads. Gravel road maintenance has traditionally been "more of an art than a science" and very few formal standards exist. This manual contains guidelines to help answer the questions that arise concerning gravel road maintenance such as: What is enough surface crown? What is too much? What causes corrugation? The information is as nontechnical as possible without sacrificing clear guidelines and instructions on how to do the job right.