Measuring Improvements in the Movement of Highway and Intermodal Freight
Highway Condition Measures
Many previous efforts identified measures of highway condition as potential indicators for freight or intermodal freight. These relate to either the degree of wear on facilities or design features that might restrict freight movement (measures reflecting congestion are discussed above either under travel time or reliability):
Measures of quality or wear:
lane-miles of high-level highway requiring rehabilitation
percent of roads with surface condition classified as good
percent of bridges in good condition
Measures related to design features:
number of at-grade railroad crossings
number of overpasses that have vertical clearance restrictions
number of weight restricted bridges
intersections with inadequate turning radii for large trailers
These indicators do not measure performance directly. They provide FHWA with information on the highway system’s ability to perform but not actually how it performs as a freight mover. Information for tracking most of these measures is available.
Measures of road quality or wear are generally available and reported to FHWA as part of the Highway Performance Monitoring System (HPMS). A weakness of these measures is that they are not specific to freight: they represent the quality of road conditions experienced by all travelers. If road conditions improve, presumably freight movement benefits, but it is not clear how much freight is affected. A way to focus on freight would be to identify a set of facilities of particular importance to freight movement and track their condition.
Impedances to Freight Movement
Measures that focus on the number of impedances to freight movement are specific to freight but tend to be somewhat narrow. One problem is that the number of facilities with impedances is probably not a good measure of impact on freight movement. Many of these impedances may not be on segments of importance to freight.
Economic Impact Measures