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Publication Number: FHWA-RD-01-158
Date: March 2002
Study of Adequacy of Commercial Truck Parking Facilities
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The methodology used to analyze where shortages exist or are expected to exist involved a six-step process. First, the supply of available truck parking spaces was inventoried based on a database of commercial truck stops and travel plazas and a survey of public agency rest areas. Second, a parking demand model was developed and calibrated (based on a limited data set) to estimate parking demand along highway segments.Third, demand estimates from the preliminary model were sent to States and State partners for review and comment.Fourth, the model estimates were refined, based on the partnerships’ comments, and the model was re-calibrated based on additional field data. Fifth, the new estimates were sent back to the partners for a final round of review and comment. Sixth, model estimates were refined based on the partners’ comments, and the results of the analyses were used in this report.
Note that the results of these analyses were meant to assist in developing strategies and plans to reduce or better manage any shortages. The information was not intended to provide a sufficient level of detail to define the specific location and quantity of truck parking spaces required. The design-level detail required to complete this type of needs assessment was not practical within the time frame and resources of this study. However, the supply and demand information provided at the corridor level did fulfill the goal of identifying system-level problems and needs that can serve as the bases for the formulation of policy alternatives and the conducting of a more detailed study at a later time. In fact, many of the partners used the supply and demand results described above for exactly this purpose.
The analysis conducted for this study included information compiled for 49 States and addressed all the Interstate highways as well as a significant share of non-Interstate highways that comprise the NHS. Detailed modeling analysis and truck parking space inventory were conducted for nearly 520 individual roadway segments. By comparing the estimated demand with the inventoried supply, it was possible to determine if a shortage of truck parking existed along a highway segment.
To simplify the interpretation, a rating system was developed to summarize the results of the supply and demand analysis. Dividing the estimated demand by the estimated supply for both public and private parking spaces formed a demand/supply ratio that indicated the level of utilization statewide.[b] A ratio less than one indicates that demand is smaller than supply and an apparent surplus of spaces exists, while a ratio greater than one indicates that demand outstrips supply and there is an apparent shortage.
Because of the uncertainty of the demand and supply estimates, using one as an exact cutoff for indicating whether shortages exist is not appropriate. Instead, the demand/supply ratios have been grouped into three categories, as indicated in table 15 .The first category, “Surplus Spaces,” indicates that the number of parking spaces available is likely to exceed the peak demand. The second category, “Sufficient Spaces,” indicates that the peak demand and the supply of parking spaces are nearly the same. The third category, “Shortage of Spaces,” indicates that overcrowding is likely. Because the estimates of truck parking supply indicate a range of parking spaces, several different supply values could be used in determining this ratio; the results in this report use the maximum estimated truck parking spaces.
Table 16 contains a national summary of the results using the parking space utilization classification method. These results provide a general sense of the level of unmet needs for commercial truck parking. A total of 35 States are rated as having a shortage of spaces at public rest areas, while a total of 8 States are rated as having shortages at commercial truck stops and travel plazas. When looking at a combined rating (i.e., the sum of demand and supply for both public rest areas and commercial truck stops and travel plazas), a total of 12 States are rated as having shortages.
Table 17 provides a State-by-State breakdown of these results. The “Ratio” column lists the demand/supply ratio, and the “Category” column lists the parking space utilization category for each State. The “Public” column refers to the demand/supply ratio for parking spaces at public rest areas, the “Commercial” column refers to the demand/supply ratio for parking spaces at commercial truck stops and travel plazas, and the “Total” column refers to the ratio for parking spaces at both types of facilities.
In addition to determining where truck parking shortages currently exist along the NHS, the study also attempted to estimate where future shortages might exist. Table 7 lists the expected annual growth rate for the truck parking space demand for each of the 49 States considered in this study, with values ranging from 0.5 to 4.4 percent. In section 3.0 , the expected annual growth rate for the supply of truck parking spaces is estimated at about 1 percent for public spaces and about 6.5 percent for commercial spaces. Because the estimated growth rates for parking supply are national averages and local growth will vary considerably, it is not appropriate to use these figures to generate State-specific estimates of the future adequacy of truck parking space supply. However, the following observations can be made:
Several hundred drivers provided written and verbal comments, both solicited and unsolicited, regarding the availability of truck parking. Overwhelmingly, drivers remarked that there are not enough parking spaces at either public rest areas or commercial truck stops and travel plazas, particularly during the overnight hours. Drivers also reported that more parking is needed near metropolitan areas and in certain regions of the country (e.g., Northeast, Southern California, Northwest).
Drivers were asked how frequently they encounter available parking at public and commercial truck parking facilities (table 18). Among the overall sample, only 11 percent of respondents indicated that they frequently or almost always find available parking at public rest areas and only 34 percent of respondents reported that they frequently or almost always find available parking at commercial truck stops. Forty-eight percent of respondents indicated that they only rarely or almost never find available parking at public rest areas, while only 16 percent reported that they only rarely or almost never find available parking at commercial truck stops.
Table 18. Frequency with which drivers find available parking at public rest areas and commercial truck stops.
Drivers also had the opportunity to rate how often their next stop (e.g., shipper or receiver) has available parking. The most frequently reported response (by 40 percent of the sample) was that sometimes their next stop has available parking. Thirty-seven percent of drivers reported that their next stop has available parking rarely or almost never. Twenty-three percent indicated that their next stop has available parking frequently or almost always.
Topics: research, safety, freight/goods movement
Keywords: research, safety, commercial motor vehicles, truck stop, rest area, travel plaza, truck parking, TEA-21 Section 4027 study, human factors, parking studies, parking supply, truck driver survey, parking demand model
TRT Terms: Soil mechanics--Mathematical models--Handbooks, manuals, etc, Shear strength of soils--Testing--Computer simulation--Handbooks, manuals, etc, Foundation soils, Roadside structures, Soil structure interaction, Finite element method, Impact loads, Computer models