Strategic Scheduling of Infrastructure Repair and Maintenance: Volume 1—Decision Tree for Steel Bridge Painting

Even for the right treatment, improper timing can have consequences: premature application (treatment is applied too early) could mean wasteful spending even if users enjoy the benefits of higher pavement condition; deferred or delayed application (treatment is applied too late) could result in higher user costs due to poor condition and even reduced asset longevity. The objectives of this research were to establish the optimal condition or timing for each of the standard M&R treatment types typically used by INDOT; quantify the consequences of departures from such optimal conditions or timings; and to establish the optimal M&R treatment schedule for each asset family. The study focused on three asset types and their treatments: Painting of Steel Bridges. A painting decision tree was developed, to serve as a framework that would enable INDOT to consider other maintenance treatment types, namely spot repair/painting and overcoating. Bridge Deck Maintenance and Rehabilitation. Life-cycle condition-based deck M&R strategies based on different trigger results were proposed and presented. Pavement Maintenance, Rehabilitation, and Replacement. A framework was established to find the optimal scheduling for multiple treatments and recommend appropriate long-term M&R strategies for flexible and rigid pavements on different functional classes

Bridge Deterioration Models to Support Indiana’s Bridge Management System

An effective bridge management system that is equipped with reliable deterioration models enables agency engineers to carry out monitoring and long-term programming of bridge repair actions. At the project level, deterioration models help the agency to track the physical condition of bridge elements and to specify when bridge maintenance, rehabilitation and replacement can be expected. Also, with reliable deterioration models, the agency can customize bridge repair or replacement schedules that incorporate element condition, functional obsolescence, and pre-specified performance thresholds. At the network level, component-specific deterioration models are useful for system-wide needs assessment over a specified future time horizon, and to quantifying the system-wide consequences of funding shortfalls or funding increases in terms of specified performance measures including average values of bridge condition and remaining service life. The bridge deterioration models that are currently in use in the Indiana Bridge Management System were developed over two decades ago. Since then, significant changes have taken place in inspection methods, technologies used, advanced statistical tools for data analysis. Also, because of the lack of reliable data, such items as the truck traffic and climate conditions were not included in past modeling efforts. In recent years, these obstacles have been minimized and therefore, there is an opportunity to update the deterioration models for the various bridge components. In addressing this research need, the present study developed families of curves representing deterioration models for bridge deck, superstructure, and the substructure. The National Bridge Inventory database was used, and the models use the NBI condition ratings as the response variable. The model families were categorized by administrative region, functional class, and superstructure material type. The explanatory variables include traffic volume and truck traffic, design type, and climatic condition, and design features. Deterministic and probabilistic models were developed

Estimation and Prediction of Statewide Vehicle Miles Traveled (VMT) by Highway Category and Vehicle Classification

Vehicle Miles Traveled (VMT) is a critical performance measure that is used extensively in highway transportation management for financial analysis, resource allocation, impact assessments, and reporting to oversight agencies. As highway revenue from fuel taxes continues to plummet and user-based taxes such as VMT fees become increasingly attractive, consistent and reliable VMT estimates have become critical for highway funding evaluation and administration. At the present time, there are several methods for VMT estimation that typically yield estimates that are inconsistent or inaccurate. This study was commissioned by the Indiana Department of Transportation (INDOT) to develop a benchmark method for VMT estimation and provide calibration factors for the VMT estimation methods. The study’s core outcome is a segment-level framework for VMT estimation For the state roads, a comprehensive database was developed which facilitates extensive aggregations of VMT by geographical scope, route, functional class, and vehicle class. For the local roads, a sample of counties of different spatial locations and degrees of urbanization were used, and cluster analysis, geographic information systems (GIS), and spatial interpolation techniques were used to expand the VMT estimates from the local road sample to the population of all counties in the state. The results of this study indicate that there is significant variation in the results from the various VMT estimation methods. The technique developed in this study for reconciling these different VMT estimates was validated using the estimate from the benchmark method (segment-level) as a basis. The implementation platform developed in this study was designed to produce outcomes that address the VMT data needs of the intended end users and stakeholders and could be enhanced in the future as and when data become available

Costs and Revenues Associated With Overweight Trucks in Indiana

This study established the unit costs of pavement and bridge damage due to overweight vehicles, and discussed issues concerning overweight vehicle e enforcement in Indiana. The study identified gaps in the existing practice and research, and established a practical framework that includes the development of asset families; establishment of realistic types and timings of reconstruction, rehabilitation, and maintenance, traffic volumes and growth projections; and damage cost estimation for each asset family and age group. The sensitivity of asset damage cost with respect to key policy and analysis variables was explored. Finally, the study examined the cost and operational issues associated with the enforcement of overweight truck policies. For pavement assets, the damage cost estimates were found to range from $0.006 per ESAL-mile on Interstates to$0.218 per ESAL-mile on non-national highways. The results also suggested that the pavement damage cost estimates are highly sensitive to the pavement life-cycle length, interest rate, rest period, and the costs and service lives of rehabilitation treatments. For bridges, an incremental-design methodology was used to assign damage cost to vehicle classes based on axle configurations and vehicle-miles of travel. Each FHWA vehicle weight group was classified into an equivalent AASHTO loading using the modified equivalent vehicle model which is based on gross vehicle weight, axle loading and axle spacing. Adopting a permit structure on the basis of gross vehicle weight only, will result in some vehicles underpaying by as much as 92% of their actual contribution to bridge damage. Finally, the study examined the cost and operational issues associated with the enforcement of overweight truck policies and made recommendations regarding equipment types and locations, staffing, and staff schedules, in order to promote cost-effective practices in weight enforcement

Updates to Indiana Fuel Tax and Registration Revenue Projections

Highway revenues both at the federal and state levels have failed to keep up with expected investments required for infrastructure preservation and improvement. The reasons for this trend include the increasing fuel efficiency of vehicles, slowing of the growth in vehicle-miles of travel, and the erosion of the purchasing power of the dollar due to inflation. Past studies on the issue of highway revenue forecasting for Indiana highways were conducted under different economic conditions than what exists today. The present study updates the revenue projections of particularly with the recognition of new CAFE Standards. The present study also updates the equations for estimating vehicle miles of travel. Impacts of alternative options for changing the fuel tax rate structure are also investigated. The present study predicted fuel tax revenues from 2012 to 2025 under the existing fuel tax rate structure and also considered possible options for changes in fuel tax rates. Fuel tax revenue from existing rate structure indicated a continuous annual decrease from 2012 to 2025 by 2.96% to 3.49% in real terms. Adopting one of the four fuel tax rate modifications would provide additional short- term revenue for a variable number of years. A 1-cent increase would offset the decline in the total fuel tax revenue only for a year after which it will continually decline every year. A 3-cent increase would provide a substantial increase in revenue in the short term but will continually decline, however, the 2025 revenue from 3-cent increase would be a little higher than the 2012 revenue level. Both inflation indexing and an ad valorem tax would also provide substantial increase in fuel tax revenue