MPC
Research Projects (2003-04)

Identifying Number

MPC-234

Project Title

Impact Performance Testing of Roadway Safety and Security Barriers, Year 2

University

Colorado State University

Project Investigators

Dr. Richard Gutkowski
Department of Civil Engineering
Colorado State University
(970)491-8291 or Fax: (970)491-2788
gutkowsk@engr.colostate.edu

Jeno Balogh, Visiting Scientist
Department of Civil Engineering
Colorado State University
(970)491-8524 or Fax: (970)491-8291
jbalogh@engr.colostate.edu

External Project Contact

N/A

Project Objective

The objective of the project is to develop and implement an impact test method to provide an affordable, logistically convenient preliminary performance test of roadway security barriers.

Project Abstract

A variety of portable safety and security barriers for directing traffic (public events, sports facilities, etc.) And securing private and public locations against access (courthouses, schools, etc.) Have been developed. Some higher capacity systems have been developed for use on and around high speed automobile racing tracks. Generally, the barriers are hollow, plastic composite walls and use dead weight fill (sand, water) to resist impact without interconnection to the ground. Heavier solid systems, such as a concrete Jersey Wall type configuration, are used in highway construction as well. These are much more expensive and require heavy equipment to relocate them. Few of the filled, lightweight systems have been crash tested to meet federal standards, although some users have conducted their own impact tests. Typically, manufacturers are small businesses without the resources to conduct federal tests similar to crash tests of bridge guard rails. Thus, developing a comparable impact test method to conduct dependable preliminary tests has great merit.

Task Descriptions

Full-scale impact testing is the most effective method of realistically evaluating the safety performance of guard rails, median barriers, bridge railings, crash cushions, break away supports, work zone traffic control devices, and other hardware. NCHRP Reports 230 and 350 present specific impact conditions for vehicle mass, speed, approach angle, etc., etc. for various vehicles. Impact speeds range from 20 to 60 mph and approach angles vary from 0 to 25 degrees. Dynamic tests include use of a gravitational pendulum, drop mass, or bogie vehicle. Procedures were devised to subject roadside safety features to severe vehicle impact conditions rather than to typical or average highway situations. Sometimes, static tests are used during the early stage of development when certain critical details and connections require strength/deflection evaluation.

CSU researchers have conducted preliminary performance static and dynamic pendulum tests of bridge guard rail systems. Indeed, one system subsequently survived a federal crash test done by other researchers. CSU also has the physical capability to include a bogie vehicle type of test at very high impact speed. Thus, these capabilities are being used to configure the needed impact test set-up and conduct physical tests of actual safety barriers.

A sequence of steps was planned over a two-year period. In Year 1 (Phase 1), CSU researchers configured a simplified, economic test configuration which closely realized many of the recommendations of NCHRP 350. A surrogate test vehicle was used in an inclined flume on a steep incline and produced the Impact Severity test levels required by NCHRP 350 for Level 1-3 type vehicle approval. The performance of the surrogate vehicle and flume incline and track were acceptable. However, confinement limitations at the base of the flume constrained the physical set-up of the barriers themselves. Specifically, the angle of attack was nearly head on, not angular, and the vehicle could not approach on a horizontal plane. In addition, only 3 barriers or less could fit in the area at the base of the flume.

The objective of the Year 2 (Phase 2) continuation study is to improve the test by relocating outside the flume on a to-be-constructed inclined track, using real vehicles, and avoiding the physical constraints to allow setting up a much greater number of linked barriers, so true system performance is examined. An inclined hill site adjacent to the flume provides the embankment needed. A roadway at the base of the hill and adjacent open space allow for the placement of the multiple barriers needed. The hill side topography will be examined to conceive the needed test set up.

Beds of flat bed trucks will be used to build the ramp and a curve segment will be included to enable impact in horizontal plane, at the desired angle of attack. Performance testing will then be conducted on actual security barriers using trucks (without occupants) to be rolled in a guided manner down the ramp. The outcome of the use of test set-up will be assessed using the established criteria for safely and properly conducting the test. These criteria were established in Phase I.

Milestones, Dates

Starting Date: July 1, 2003
Assess the topography of the site: August 31, 2003
Conceive the test configuration: September 31, 2003
Construct the test facility: February 28, 2004
Conduct the impact tests: April 30, 2004
Assess the performance of the test: May 30, 2004
Report on the outcomes: June 30, 2004
Ending Date: June 30, 2004

Student Involvement

One graduate student; one undergraduate student

Relationship to Other Research Projects

An MPC project on "Highly Flexible Crash Barriers" is being conducted at CSU, independently by another researcher. It focuses on basic research in regard to material response to high strain rates and numerical modeling of response to hypothetical system and possibly configuration of "soft" crash barriers for highways. Its outcome could lead to systems that could be tested in the impact test set-up devised in the work described herein on security barriers.

Technology Transfer Activities

Techniques for developmental performance testing will result. An MPC technical report will be developed and outcomes will be presented via the TEL8 teleconference system in the monthly MPC-InfoX technology exchange series with regional transportation agencies. It is anticipated that industry will be involved in the performance test phase, to lend practicality to the tests and observe outcomes for use in practice.

Potential Benefits of the Project

Recent interest in portable barriers has heightened with concern about terrorist attacks creating nationwide security needs. Indeed, the Fort Collins Army Reserve began using one of the portable barrier systems as a safety shield for its facilities. That system has also been used by the City of Fort Collins Justice Center, at the new Invesco Field in Denver, and the Platte River Power Authority's Rawhide Power Plant and its substations. A local manufacturer was also belatedly approached about potential use of portable barriers at the Salt Lake City Olympic Games site. Lack of credible performance data was a deterrent to immediate acceptance. Thus, a step toward more rigorously verifying impact performance at more affordable cost would help overcome that concern as well as encourage conduct of full federal crash tests, if needed.

TRB Keywords

Impact tests, performance tests, safety, security barriers