Evaluation of Bias in the Hamburg Wheel Tracking Device, RB00-010, 2013

As the list of states adopting the HWTD continues to grow, there is a need to evaluate how results are utilized. AASHTO T 324 does not standardize the analysis and reporting of test results. Furthermore, processing and reporting of the results among manufacturers is not uniform. This is partly due to the variation among agency reporting requirements. Some include only the midpoint rut depth, while others include the average across the entire length of the wheel track. To eliminate bias in reporting, statistical analysis was performed on over 150 test runs on gyratory specimens. Measurement location was found to be a source of significant variation in the HWTD. This is likely due to the nonuniform wheel speed across the specimen, geometry of the specimen, and air void profile. Eliminating this source of bias when reporting results is feasible though is dependent upon the average rut depth at the final pass. When reporting rut depth at the final pass, it is suggested for poor performing samples to average measurement locations near the interface of the adjoining gyratory specimens. This is necessary due to the wheel lipping on the mold. For all other samples it is reasonable to only eliminate the 3 locations furthest from the gear house. For multi‐wheel units, wheel side was also found to be significant for poor and good performing samples. After eliminating the suggested measurements from the analysis, the wheel was no longer a significant source of variation.

Letter health consultation : Manganese emissions from Amsted Rail Company, Inc. (Griffin Wheel Facility) Keokuk, Iowa (2010)

This letter has been prepared as a consultation to evaluate human health impacts from manganese emissions from the Amsted Rail Company, Inc. (Griffin Wheel) facility located in Keokuk, Iowa. We understand your concern and the concern of the Keokuk community, and want you to know that the Iowa Department of Public Health’s priority is to ensure that you have the best information possible to safeguard the health of the citizens of Keokuk. That information is included in the following discussion.

Distribution of Wheel Loads on Highway Bridges, 1968

The purpose of the research was to develop a more realistic design criteria for distribution of wheel loads on highway bridges. A comprehensive study was made of the· static load distribution in a broad range of short and medium span bridge types used by today's designers.