Indiana State Highway Cost Allocation and Revenue Attribution Study and Estimation of Travel by Out-of-State Vehicles on Indiana Highways

This study was commissioned by Indiana Department of Transportation (INDOT) to investigate the cost responsibility and the revenue contribution of highway users with regard to the upkeep of Indiana’s state and local highway infrastructure (pavements, bridges, safety assets, and mobility assets). The costs consisted of expenditures on construction, preservation, maintenance, and operations of the highway infrastructure. For revenues, user and non‐user sources were considered. The highway users were represented by the 13 Federal Highway Administration (FHWA) vehicle classes, and the study was based on 2009‐2012 data on expenditures and revenues. The study framework duly recognized the dichotomy between attributable and common costs. For allocating the attributable costs to the vehicle classes, equivalent single axle loads (ESALs), American Association of State Highway and Transportation Officials (AASHTO) loading equivalents, and passenger car equivalents (PCEs) were used; for allocating common costs, vehicle miles traveled (VMT) was used. For each vehicle class, the share of revenue contribution was compared to the share of cost responsibility to determine respective equity ratios and thus to ascertain the extent to which vehicles in each class may be underpaying or overpaying their cost responsibilities at the current time. The study also determined the distribution of fuel purchases and travel by out‐of‐state vehicles on Indiana’s highways; this analysis was required to further refine the results of the cost allocation and also to quantify the magnitude of any imbalance between the out‐of‐state travel and share of consumption on Indiana’s infrastructure and the revenue from such out‐of‐state vehicles. The outcome of this research is a systematic documentation of the sources and extents of highway revenues and the areas of expenditures at the local and state levels in Indiana. Pavement and bridge expenditures were found to have a dominant share of the overall expenditures on Indiana’s highway system. Classes 2 (automobiles) and 9 (5‐axle combination trucks) were found to have a dominant share of the cost responsibilities. It was determined that the user revenue sources contributed approximately 63.5% of the total state funding for highway expenditures and 36.5% were from non‐user revenue sources. The inability of user revenue sources to cover the total highway expenditure and the consequent partial reliance on non‐user sources seem to constitute a rather unstable funding situation particularly because the non‐user sources are characterized by significant variability. On the basis of the expenditures and revenues associated with the various user groups (vehicle classes) over the analysis period, this study found that inequities exist, albeit in varying degrees, among the highway user groups. Of the 13 vehicle classes, classes 1–4 were found to be overpaying their cost responsibilities while classes 5–13 are underpaying. For example, vehicle class 2 is overpaying its cost responsibility by 10% while vehicle class 9 is underpaying by 19%. The results of the equity analysis are generally consistent with those of studies carried out at other states. Also, it was estimated that the travel by out‐of‐state vehicles on Indiana’s interstates, national highway system (NHS) non‐interstates, non‐NHS and local roads are 21%, 10%, 9%, and 7% respectively, of the total travel as a percentage of VMT on those families of highway systems.