Survey of Transportation Revenue Forecasting State DOTs are becoming more reliant on nongas tax revenue sources - but the methods for forecasting these sources are not well developed or consistent, and federal funding is uncertain. DOTs have no
clear precedent for what to do.
40 states
responded to the survey.
How does your state DOT forecast future revenue?
Good forecasting IS good planning. Accurate forecasting of future transportation revenue provides baseline information needed for responsible system management.
Which revenue types are routinely forecast? State gasoline per-gallon tax
36
State diesel per-gallon tax
36
Consensus of Simple experts extrapolation
Econometric regression
Are methods documented, rather than informal only?
Yes 11 No 28 Unsure 1
13
State General Fund Tolls
8
3 Local tax
TxDOT maintains an interactive online tool that allows users to see the effects of changes to policy, fuel price, and demographics. Arizona introduced a Risk Analysis Process that relies on probability analysis and an independent evaluation of the model’s variables. The process results in a series of forecasts, with specified probabilities of occurrence, rather than a single estimate.
31
Vehicle license/ registration fees State sales tax
Washington’s forecasting process uses multiple econometric models for each major source, continually updated for better accuracy.
33
Federal allocations to state
14 Other
17
Other includes investment income, weight distance tax, ferry boat fees, etc.
Best Practice States Oregon’s econometric model uses 6-8 explanatory variables, with 225 stochastic equations updated every 6 months.
Respondents:
State transportation revenues are stagnant and declining.
Benton Heimsath, MURP Advisor: Dr. Martin Wachs Client: Caltrans
OR WA TX AZ
“Currently using unsupported software. It would be nice to generate “what if” scenarios with more ease.” “The biggest challenge is the uncertainty of funding, especially at the federal level.” “Forecasts have been very accurate, except in recessionary periods.”