MPC
Research Projects (2008-09)

Identifying Number

MPC-278

Project Title

Bus-Stop Shelters: Improved Safety, Year 3

University

Colorado State University

Project Investigators

Wayne A. Charlie, PhD, PE, Professor
Richard M. Gutkowski, PhD, PE, Professor
Jeno Balogh, PhD, Affiliate Professor
Dept. of Civil and Environmental Engr.
Colorado State University
Fort Collins, CO 80523-1372
PH: 970 491-8291 FAX: 970 491-7278
Email: wcharlie@engr.colostate.edu
Email: gutkowsk@engr.colostate.edu

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 in urban areas. The U.S.D.A. Forest Service’s Healthy Forest Initiative (healthyforests.gov) is resulting in a large volume of timber products in rural areas. We 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 prior work, we tested several prototype single wall sub-assemblies using ASTM E 1886 and E 1996 test methods for impacts from hail and hurricane and tornado generated debris. An encouraging degree of success has occurred. Presently, we are conducting impact tests on two orthogonally interconnected walls of a prototype full-scale shelter for varying angles of impact to the wall and corner. The objective of this continuation is to examine missile impact loading of either an actual prototype or major features of it, for which a standard sub-assembly test does not apply. Instead, tests under impacts more consistent with the actual conditions of exposure are envisioned.

Project Approach/Methods

The main goal of this proposed continuation research is to conceive a whole structure concept based on impact test findings to date and computer modeling. The researchers propose to conduct missile impact tests using standardized cannon equipment and projectile (a 12 ft. long “2 x 4” moving at 100-130 mph). However will move from standardized missile impact tests of prototype subassemblies to conducting tests more realistic to a complete structure and compare physical test results with the computer modeling results. We will endeavor to analytically account for the variability of the potential angle of attack and probability of head-on impacts. In physical tests, a platen will be used to rotate the specimen into different horizontal orientations relative to the oncoming missile. The shape and geometry of the prototype will be configured to angular and/or curved shapes to lessen the probability of direct impact.

Contributions/Potential Applications of Research

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. Bus-stop shelters are typically very nominal structures, e.g. light metal framed, extensively glassed enclosures. They are configured to harmonize with the local area and provide the functionality of cover from normal weather exposure for waiting passengers. If these structures can offer safe refuge from hail or debris generated by windstorms and tornados, they would offer additional benefits. In urban areas, when a high wind event occurs without sufficient warning, impact resistant bus-stop can serve as emergency shelters for pedestrians caught in imminent danger due to extreme winds, high velocity rainfall and the flying debris. Improved impact strength can also provide safety from impact of errant vehicles that might hit them. Improved structural modeling contributes to better understanding of response to types of loads and field conditions. Combined with performance tests, a resulting prototype bus shelter which is highly improved for impact resistance can be a boon to emergency protection from high wind natural hazards. Placing such structures at precisely those locations where public transit rider congregate provides a logical dispersion of safe facilities within the inner urban areas and in more exposed locations on incoming/outgoing routes.

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. It is anticipated that a technical journal and/or conference paper will be prepared for submittal after completion of the project. 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, 2008 - June 30, 2009

Total Project Cost

$38,854

MPC Funds Requested

$31,898

TRB Keywords

Bus-stop shelters, hail, impact resistance, tornado and hurricane debris, timber