Technical Report Documentation Page 1. Report No. 398 2.Government Accession No. 3.Recipient’s Catalog No. 4.Title and Subtitle 5.Report Date Effects of Hauling Timber, Lignite Coal, and Coke Fuel on Louisiana March 2005 Highways and Bridges 6.Performing Organization Code 7.Author(s) 8.Performing Organization Report No. Freddy L. Roberts, Aziz Saber, Abhijeet Ranadhir, and Xiang Zhou 9.Performing Organization Name and Address 10. Work Unit No. Civil Engineering Program Louisiana Tech University 11.Contract or Grant No. P.O. Box 10348 Ruston, LA 71272 Sponsoring Agency Name and Address 13. Type of Report and Period Covered Louisiana Department of Transportation and Development Final Report, July 1, 2004 – March 31, 2005 Louisiana Transportation Research Center 4101 Gourrier Avenue 14.Sponsoring Agency Code Baton Rouge, LA 70808 15.Supplementary Notes Conducted in cooperation with the U.S. Department of Transportation, Federal Highway Administration 16.Abstract This study included the development of a methodology to assess the economic impact of overweight permitted vehicles hauling timber, lignite coal, and coke fuel on Louisiana highways and bridges. Researchers identified the highway routes and bridges being used to haul these commodities and statistically chosen samples to use in the analysis. Approximately 1,400 control sections on Louisiana highways carry timber, 4 control sections carry lignite coal, and approximately 2,800 bridges are involved in the transport of these commodities. Three different gross vehicle weight (GVW) scenarios were selected for this study including: 80,000 lb., 86,600 lb. or 88,000 lb., and 100,000 lb. The current GVW is 80,000 lb., the 86,600 lb. GVW is the permitted load for log trucks and the 88,000 lb. GVW is permitted for lignite coal and coke haulers. The 100,000 lb. GVW for sugarcane haulers is the highest level currently permitted by the state of Louisiana. The methodology for analyzing the effect of these loads on pavements was taken from the 1986 AASHTO design guide and involves determining the overlay thickness required to carry traffic from each GVW scenario for the overlay design period. Differences in the life of an overlay were calculated for different GVW scenarios and overlay thickness and costs were determined for a 20-year analysis period. These costs were developed for the sample on all control sections included in the study. These present net worth costs were expanded to represent the cost for all control sections carrying each commodity. A suggestion from enforcement personnel caused project staff to perform an additional analysis using one load axle at 48,000 lb. (48-kips), which is the maximum permissible tandem axle load. This analysis showed that 48-kip axles produce more pavement damage than the current permitted GVW for timber trucks and causes significant bridge damage at all GVW scenarios included in the study. The methodology for analyzing the bridge costs was developed by 1) determining the shear, moment and deflection induced on each bridge type and span, and 2) developing a cost to repair fatigue damage for each vehicle passage with maximum tandem load of 48,000 lb. Results indicate that permit fees paid by timber trucks should increase from the current $10 per year to around $346/year/truck for a GVW of 86,600 lb. when axles are equally loaded and $4,377/year/truck if 48-kip axle load are permitted. The current permit fee for lignite coal should remain at current levels. The legislature should not consider raising the GVW level to 100,000 lb. because the pavement overlay costs double over those at 86,600 lb. GVW and the bridge repair costs become significant. In many cases, the bridge costs per passage of a loaded truck amount to $8.90 meaning that the cost of bridge damage per truck per year can easily exceed $3,560. The project staff recommends that the legislature eliminate the 48-kip maximum individual axle load and leave GVWs at the current level, but increase the permit fees to sufficiently cover the additional pavement costs produced by the presence of these permitted overweight vehicles. 17.Key Words 18.Distribution Statement Overweight permitted loads, bridge damage, pavement damage, log Unrestricted. This document is available through the National trucks, coal trucks, overweight permits, overlay policy, equity, gross Technical Information Service, Springfield, Va 21161 vehicle weight 19.Security Classif.(of this report) 20.Security Classif.(of this page) 21.No. of Pages 22.Price Form DOT F 1700.7(8-72) Reproduction of completed page authorized Effects of Hauling Timber, Lignite Coal, and Coke Fuel on Louisiana Highways and Bridges by Freddy L. Roberts, Ph.D., P.E. Aziz Saber, Ph.D., P.E. Abhijeet Ranadhir Xiang Zhou Civil Engineering Program Louisiana Tech University P.O. Box 10348 Ruston, LA 71272 LTRC Project No. 05-2P State Project No. 736-99-1299 conducted for Louisiana Department of Transportation and Development Louisiana Transportation Research Center The contents of this report reflect the views of the authors/principal investigators who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the views or policies of the Louisiana Department of Transportation and Development, the Federal Highway Administration or the Louisiana Transportation Research Center. This report does not constitute a standard, specification, or regulation. March 2005 ABSTRACT This study included the development of a methodology to assess the economic impact of overweight permitted vehicles hauling timber, lignite coal, and coke fuel on Louisiana highways and bridges. Researchers identified the highway routes and bridges being used to haul these commodities and statistically chosen samples to use in the analysis. Approximately 1,400 control sections on Louisiana highways carry timber, 4 control sections carry lignite coal, and approximately 2,800 bridges are involved in the transport of these commodities. Three different gross vehicle weight (GVW) scenarios were selected for this study including: 80,000 lb., 86,600 lb. or 88,000 lb., and 100,000 lb. The current GVW is 80,000 lb., the 86,600 lb. GVW is the permitted load for log trucks, and the 88,000 lb. GVW is permitted for lignite coal and coke haulers. The 100,000 lb. GVW for sugarcane haulers is the highest level currently permitted by the state of Louisiana. The methodology for analyzing the effect of these loads on pavements was taken from the 1986 AASHTO design guide and involves determining the overlay thickness required to carry traffic from each GVW scenario for the overlay design period. Differences in the life of an overlay were calculated for different GVW scenarios, and overlay thickness and costs were determined for a 20-year analysis period. These costs were developed for the sample on all control sections included in the study. These present net worth costs were expanded to represent the cost for all control sections carrying each commodity. A suggestion from enforcement personnel caused project staff to perform an additional analysis using one load axle at 48,000 lb. (48-kips), which is the maximum permissible tandem axle load. This analysis showed that 48-kip axles produce more pavement damage than the current permitted GVW for timber trucks and cause significant bridge damage at all GVW scenarios included in the study. The methodology for analyzing the bridge costs was developed by 1) determining the shear, moment, and deflection induced on each bridge type and span, and 2) developing a cost to repair fatigue damage for each vehicle passage with maximum tandem load of 48,000 lb. Results indicate that permit fees paid by timber trucks should increase from the current $10 per year to around $346/year/truck for a GVW of 86,600 lb. when axles are equally loaded and $4,377/year/truck if 48-kip axle loads are permitted. The current permit fee for lignite coal should remain at current levels. The legislature should not consider raising the GVW level to 100,000 lb. because the pavement overlay costs double over those at 86,600 lb. GVW and the bridge repair costs become significant. In many cases, the bridge costs per passage of a loaded truck amount to $8.90, meaning that the cost of bridge damage per truck per year can easily exceed $3,560. The project staff recommends that the legislature eliminate the 48-kip maximum individual axle load and leave GVWs at the current level, but increase the permit fees to sufficiently cover the additional pavement costs produced by the presence of these permitted overweight vehicles. iii iv ACKNOWLEDGMENTS This report could not have been completed without the assistance of personnel from Districts 03, 04, 05, 07, 08, 58, 61, and 62. Personnel from district administration, construction engineering, maintenance, materials, and traffic all contributed to the successful completion of the project. Each district provided personnel to meet with project investigators to estimate the pavement cross sections for each control section in the district carrying timber. They later developed the history of pavement construction and rehabilitation, and then made traffic volume and classification counts on each control section included in the study. Without this timely assistance, we simply could not have performed the study. In addition to LADOTD personnel, representatives of the Louisiana Forestry Association developed estimates of the tonnage of timber that was hauled over each of the control sections included in the study. The authors especially want to thank Buck Vanderstein, executive director of the forestry association, for his help in coordinating the collection of this information. Representatives from Savage Industry were also very helpful in determining the amount of lignite coal hauled, the route trucks followed, and the truck configuration and weight distribution on the axles of those trucks.