Cal Poly Pomona
and truck freeway speed limits in States in which there is a difference. California has the greatest car- truck speed difference (15 mph), although Alabama has the same differential for hazmat trucks. Actual travel speeds vary according to levels of congestion, the time of day of travel, terrain and topography, truck size and load, and truck driver behavior. Peak period congestion can be avoided with travel during non-peak periods, but scheduling and hours of service needs may necessitate travel during the peak. The diagram in Figure 5 shows freeway speeds along the I-10 freeway westbound in the Los Angeles area during the morning peak on a weekday in September 2000. It is evident that the 47 mph assumption would not be applicable to travel along this route at this time of day. The indication is that a more flexible measure of travel speed should be used. One recommendation would be to use different peak and non-peak speeds, along with speeds that are reflective of different geographical areas. Regarding the latter, Table 8 shows year 2005 peak period freeway speeds (calculated, not empirical) in selected very large, large, medium and small urban areas in the U.S. Of the 85 urban areas listed, 23 had freeway speeds less than 47 mph, with the lowest being San Francisco-Oakland (39.4 mph), Chicago (39.1 mph), and Los Angeles-Long Beach-Santa Ana (34.7 mph). Since these data are compiled annually as part of the Urban Mobility Report series (e.g., Schrank and Lomax 2007), this is accessible information that could rather easily be adopted by trucking companies.
Alabama Arkansas California Idaho Illinois Indiana Michigan Montana Ohio
70 70 70 75 65 70 70 75 65
70* never implemented, 65 or less still in effect
70-80 mph day/65 mph night
Table 7. Truck Speed Limit Differentials
5 mph differential, effectively 60 55 is still posted in most locations
Statutory car speed limit
Statutory truck speed limit 55 (hazmat only) 65 55 65 55 65 60 65 65 on Ohio Turnpike, 55 on all other freeways.
70 mph day/65 mph night
<accessed on Sep. 17,
60 day/55 night
SOURCE: http://en.wikipedia.org/Wiki/Speed_limits_in_the_United_States. 2008>
Toll Costs. Trucking companies have expressed concern about the effects of an increasing number of toll facilities on overall operating expenses. Toll roads have existed for some time in the eastern U.S., but there is a growing number of toll facilities in the western U.S. Fundamental measures might include the proportion of operating expenses devoted to tolls, the total toll costs paid, total toll road mileage, and total toll road mileage as a percent of total mileage.