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Open access publications by faculty, postdocs, and graduate students in the Department of Civil and Environmental Engineering.
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Browsing Open Access Publications by Subject "Axle load"
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Item Effect of Increasing Axle Loads on Rail Fatigue Life(British Rail Research ( Part of the Old British Rails), 1983) Zarembski, Allan M.; Stone, D. H.; Wells, T. R.; Armstrong, R. A.This report presents an investigation into the effects of increasing axle loads on the fatigue life of tangent, continuous welded rail (CWR). Two independent studies were conducted. The first utilized a statistical analysis technique, which obtained probability distribution curves for rail defect data. The second utilized a fatigue analysis methodology for the prediction of rail service life. Both techniques have shown good correlations between calculated results and service experience. The results of both analyses show that increasing the axle load results in an increased incidence of rail defect occurrences, with a corresponding decrease in rail fatigue life for tangent CWR. This reduction is by about 40% of the life of the rail, in million gross tons (MGT), when the loading is increased from 70-ton cars (200,000 lb.) to 100-ton cars (263,000 lb.). This effect, which is seen for both heavy (132 lb.) and medium (119 lb) rail sections, is quite significant, and must be taken into account in future studies and economic analyses.Item Helping Shortlines Meet the Challenges of HAL(American Railway Engineering Association, 2001-11) Turner, R.; Zarembski, Allan M.As the American Class 1 railroads continue to move towards the new generation, 286,000-pound heavy axle load cars, the American shortline industry must now gear up to address this issue. While the current level of track and structures on shortlines is generally adequate for traditional 263,000-pound railroad cars with 33-ton axles, it is often marginal or even inadequate for the new generation 286,000-pound cars with 36-ton axle loads. Recent studies have shown that the approximately 10-percent increase in load associated with the 286,000-pound cars can translate into damage to the track structure that is as much as 20 percent higher than that caused by the "standard" 263,000-pound car1This is further exacerbated by the fact that track on shortlines is generally not of the same standard as that found on Class I mainlines with lighter rail sections, fewer crossties and smaller ballast sections. In fact, one recent study of the capital needs of the U.S. shortline industry2showed that there was a significant capital requirement for track upgrade needed by the approximately 550 shortline and regional railroads to allow them to operate the new generation heavy-axle-load equipment safely and cost effectively on an ongoing, long-term basis. This study showed that the approximately 50,000 miles of track operated by these shortline and regional railroads requires $6.86 billion to upgrade their tracks to allow for safe, effective and long- term operations under HAL equipment. Furthermore, this study indicated that for long-term operations 22 percent of rail must be replaced, 43 percent of track miles require some replacement ties and 23 percent of track miles require some ballast. Noting that the rail sections frequently found on shortline railroads are lighter rail sections, many with four-hole joint bars whose strength may not be adequate for carrying these heavier cars on an ongoing basis, it is not surprising that the largest single-cost category was found to be rail with a total projected capital cost of $3.75 billion. In order to help meet this heavy-axle-load challenge, the American Short Line and Regional Railroad Association embarked on a multi-faceted program to provide support and assistance to its members. This program included an aggressive campaign to obtain additional funds for its members to upgrade their track, including working with the FRA on its RRIF3 capital loan program and working with Congress on legislation that will provide capital grants to shortline railroads. It also included the development of tools that can be used by ASLRRA members to help them manage their current assets and more effectively deal with the new heavy-axle-load cars.Item The Implications of Heavy Axle Load Operations for Track Maintenance on Short Lines(American Railway Engineering Association, 2000-09) Zarembski, Allan M.North American freight railways have increased axle loads on high volume commodities such as grain, coal, and ore because of the significant savings in overall operating costs that result from heavier cars and corresponding higher axle loads. The resulting savings are in spite of increased maintenance of way and structures costs that result form the operation of the heavier cars and higher axle loads. Testing and subsequent experience has shown that well maintained main line track with heavy rail, sound ties, and good ballast sections can support these higher axle loads, though with an increase in the “annual” maintenance costs due to greater track component damage and shortened component lives. However, short lines often operate track with light rail sections and marginal tie and ballast condition. The effect of these increased axle loads are not as well defined for this type of track and railway operation. Yet many short lines are facing the requirement to accept these heavier cars from their main line connecting partners. The implications of this to the short line operators can be potentially very significant. This paper presents the results of two specific studies performed on two different short line (regional) railroads on the effect of heavy axle load cars on present and future maintenance of way costs. This includes the potential need to upgrade track components such as rail, as well as the anticipated increase in maintenance costs in all of the key track maintenance areas to include rail, ties, and ballast (surfacing). One of the two study railroads already permits HAL 286,000 lb. cars on one line, and is looking to permit these HAL cars on several other lines that it operates. The second short line does not currently allow HAL equipment. In both cases, this paper examines the start up, short term and long term implications of operating 286,000 lb. cars on these two short line railroads.