MPC
Research Projects (2009-10)

Identifying Number

MPC-278

Project Title

Bus-Stop Shelters: Improved Safety, Year 4

University

Colorado State University

Project Investigators

Wayne A. Charlie, PhD, PE, Professor
E-mail: wcharlie@engr.colostate.edu

Richard M. Gutkowski, PhD, PE, Professor
E-mail: gutkowsk@engr.colostate.edu

Jeno Balogh, PhD, Affiliate Professor

Dept. of Civil and Environmental Engr.
Colorado State University
Fort Collins, CO 80523-1372
PH: 970 491-5048 FAX: 970 491-7727

Description of Project Abstract

Bus-stop shelters (school and public transit) typically provide, at best, only limited reduction to exposure to rain, snow, wind and direct sunlight. Most shelters provide little or no reduction in potential injury from severe storms (wind, wind generated missiles, or hail) or vehicle impacts. The proposed research effort will serve to evaluate and physically test bus-stop shelter designs, including a timber based design, to evaluate and upgrade the impact resistance of bus-stop shelters.

Project Objectives

Research objectives are to design, construct and test a prototype timber bus-stop shelter capable of providing improved safety to occupants from vehicle impacts, hail, and windstorm (e.g. hurricane) generated debris. The researchers propose to investigate multiple materials for bus-stop shelters, including timber. Based on these tests, we will evaluate the potential of recommending commercial development of the concept of "impact resistant bus-stop shelters". In the prior work, several prototype sub-assemblies were tested using procedures and a dimension lumber missile prescribed in ASTM E 1886 and E 1996 test methods for impacts from hail and hurricane and tornado generated debris. An encouraging degree of success occurred. Subsequently, we conducted impact tests on specimens comprised of orthogonally connected walls of a prototype full-scale shelter. The specimens were stiffened at top and bottom to simulate the overall stiffness of a four-sided unit. This involves testing beyond the scope of standard testing and moves in the direction of testing full structures. The researchers have conducted these tests using standardized cannon equipment and projectile, but considering the variability of the potential angle of attack by fixing specimens to an angularly adjustable base support.

Project Approach/Methods

Work done to date has led to instances of stopping or repelling missiles successfully, but infrequently and inconsistently. The successful outcomes indicate that repelling or stopping the missile involves absorption of and/or release of kinetic energy upon impact. A buffer backing material improves absorption, while freedom of the base to displace releases energy. So both means are being investigated at incrementally increased velocities so as to make adjustments and work toward stopping or repelling missiles consistently at hurricane level velocities. The proposed continuation study serves to move further in this approach to testing and ultimately toward the impact loading of an actual prototype. Computer-based structural modeling has been done at static loading conditions but the magnitude of an equivalent static load to simulate the impact force needs to be established. Thus, high speed digital camera imaging is to be used to record the impact event in a time record in order to use the impulse-momentum relationship to establish the impact force record over time, which can potentially be mathematically integrated to establish the equivalent static load needed.

Contributions/Potential Applications of Research

Bus-stop shelters should harmonize with the local area and combine simplicity, functionality, good design, and safety. In addition, if these structures can offer safe refuge from hail or debris generated by windstorms and tornados, they would offer additional benefits. Improved structural modeling contributes to better understanding of response to these increasing loads and field conditions. The research proposed will lead to a better understanding of impact resistance of bus-stop shelters leading to more realistic assumptions of a bus-stop shelter's response to impact loading. This information should be of potential benefit to designing new and upgrading existing bus-stop shelters.

Technology Transfer Activities

Technology transfer will be via an MPC technical report and an MPC Research Seminar will be presented over the Transportation Learning Network telecommunications network after completion of the project. If warranted, a technical journal and/or conference paper will be prepared for submittal. Publicity about all of the MPC projects is available through the MPC web site maintained at NDSU.

Colorado State University has an extensive database from its past research on windstorm, tornado and hurricane impact resistance of structures and similar research on blast load resistance of structures. Colorado State University also has an extensive database and computer modeling experience in modeling timber bridges and structures to static and dynamic loadings.

Time Duration

July 1, 2009 through June 30, 2010

Total Project Cost

$20,368.00

MPC Funds Requested

$11,864.00

TRB Keywords

Bus-Stop Shelters, Hail, Impact resistance, Tornado and Hurricane Debris, Timber