Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

In North America, refrigerated semi-trailers are commonly used to transport large volume of produce. They are equipped with refrigeration and air circulation systems to provide an optimum transit enviromnent for the produce. Air circulation plays a vital role in maintaining produce temperature during transport. Its performance is greatly affected by the availability of air channels through and around the load. / This study is an attempt to evaluate the performance of the air circulation system. Air temperature data was gathered from 20 mixed loads of produce transported in trailers having a variety of accessories and using different loading patterns. Pearson correlation coefficient was used as an indicator to describe the air distribution inside the semi-trailers. The results showed that the air distribution inside semi-trailers is generally not uniform. In most cases, the areas that received little amount of airflow were the middle section along the length and width, and the middle and bottom sections along the height of trailers. The variability in the results precluded any determination of the effect of trailer accessories and loading patterns on the air distribution.

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Transport costs can account for a significant portion of the total production costs in an agricultural system. In order to ensure maximum efficiency of a transport operation, the transport manager is required to select a suitable vehicle and choose the best route. This is a complex process as vehicles should not be selected based solely on lowest capital cost, but with several variables taken into account. In order to determine an optimal haulage system and to aid the decision making process, a computer model called SimTrans has been developed. SimTrans simulates a haulage vehicle travelling on any given route under normal vehicle operating conditions. The model produces a set of simulated vehicle performance results and a summary of trip details. The vehicle input parameters and route details can be modified to enable the user to simulate different vehicle configurations on alternate routes. The SimTrans model was used in this research project as it provides a comprehensive output of simulated results. However, under certain conditions there is variance between actual and the simulated vehicle performance in SimTrans, particularly with the gear selection routines. The primary objective of this research was to refine, calibrate and validate the current SimTrans model. An initial investigation focused on diesel engine management systems for heavy-duty commercial vehicles and how these systems affect a vehicle's performance. This investigation was aimed at gaining an understanding of how performance data could be gathered directly from the onboard vehicle electronics of a haulage vehicle. A data logging system was developed to measure and record certain operating parameters of a haulage vehicle during operation. The system was installed on a Mercedes Benz 2637 and the vehicle was driven on two alternative routes between the Eston Sugar Mill and a loading zone near Mid-Illovo. The Mercedes Benz 2637 used for the vehicle tests was simulated in SimTrans using identical operating conditions of route and speed limits. By comparing the observed and simulated data sets, errors particularly with gear selection routines were identified. The SimTrans model was modified such that these errors were corrected and a new gear skipping routine was added. The modified SimTrans model was validated through a comparison of a new set of simulated results with the observed data. The modified model showed significant improvement in simulation accuracy over the previous version of SimTrans. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2007.

Although the original intent of this study was to do a pre-and post-deregulation assessment of rail rates per ton-mile, the results using post-deregulation data show a significant decrease in rail rates between 1981 and 2000. While accounting for changes in shipment characteristics, savings for wheat, barley, com, oat, and soybean shippers were 63.80%, 69.17%, 49.07%, 67.97%, and 59.36%, respectively. Rate savings over time for an average 1981 shipment were 45%, 55%, 38%, 45%, and 36% for wheat, barley, com, oat, and soybean shippers, respectively. Analysis regarding the effects of deregulation of rail rates on com, soybean, and wheat on a regional basis shows that rail rates not only differ across commodities, but also among regions. In general, it was found that grain producers within regions that had higher levels of intermodal competition had lower rates than their counterparts with lower levels of intermodal competition. Distribution of benefits as a result of market-based pricing has varied among regions, and these variances are increasing over time.