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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-01-159
Date: March 2002

Model Development For National Assessment of Commercial Vehicle Parking

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The 1996 Study documented an evaluation of the adequacy of rest parking facilities serving truck drivers using the Interstate Highway System.(1)The study sought to address the perceived need for additional parking through direct observation, interviews, statistical evaluations, and demographic data collection. The research team first assessed the current status of public rest area parking for trucks nationwide and developed analytical models to estimate the demand for truck parking spaces.The comprehensive assessment of public rest areas projected a shortfall of 28,400 truck parking spaces in public rest areas nationwide.

An important component of the 1996 Study was the information obtained from a survey of truck drivers. More than 90 percent of commercial drivers surveyed perceived that there was a shortage of truck parking, particularly for long-term or overnight parking.In addition, the survey results showed some important distinctions between public rest areas and private truck stops.The majority of drivers expressed a preference for public rest areas for short-term parking, while two-thirds indicated a preference for private truck stops for long-term rest needs, thus suggesting a distinction of the facility types in terms of the needs that they serve.Although a survey of private truck stop operators suggested that about one-third planned to expand their parking facilities over the next three years, there was a concern that this additional supply may not fully satisfy the demand for public rest areas if private truck stops and public rest areas are not substitutes for each other.

The conclusion of the 1996 Study was that there was a shortfall in the number of truck parking spaces that could only be remedied by creative strategies geared toward facilitating future rest area spending decisions over the next ten years.

This TEA-21 Section 4027 study updates the 1996 Study evaluation and expands the scope to include the NHS. To obtain input on the TEA-21 Section 4027 study, FHWA sponsored the June 29-30, 1999 Rest Area Forum in Atlanta, Georgia.(4) Attendees included representatives of Federal and State departments of transportation, enforcement agencies, the motor carrier industry, private truck stop operators, commercial drivers, and safety advocacy groups. The summary of proceedings documented issues identified and recommendations made by forum participants, as well as some of the efforts that States have made to improve the availability of public rest areas.

This section summarizes some of the approaches that several States have taken to address the growing demand for safe commercial vehicle parking subsequent to the 1996 Study.

2.1 Tennessee

To learn about the parking space occupancy characteristics of trucks, the University of Tennessee conducted nighttime observational studies at all public rest areas in Tennessee for each day of the week.(5) Availability of space in private truck stops near interchanges was also examined.The results of the occupancy studies showed that the rest areas were overflowing with trucks at night, as evidenced by trucks parked along the shoulders of highway exit and entrance ramps, as well as on interchange ramps. While rest areas were overflowing, approximately 30 percent of the private truck parking spaces were not occupied, and the unoccupied private parking spaces outnumbered the trucks parked along the highways by nearly a three-to-one ratio.

To understand why some truck drivers park along the highway when there are available private parking spaces, in-depth interviews were held with five drivers.Opinions of the drivers interviewed were quite consistent. The findings were that private truck stops and public rest areas are not substitutes for each other because they meet different needs.While private truck stops are used when there is a need for fuel, a meal, or other amenities, drivers want to pull over as soon as possible when they feel sleepy. In such situations, they prefer to pull off at the nearest rest area or park wherever they can, even on the shoulders of ramps.In addition, drivers reported that it is difficult to find a convenient space in many private truck stops because the parking is not well designed, and there is a risk of minor accidents and damage when moving in and out of these parking lots (as illustrated in figure 1).

Figure 1. Example of tight parking for trucks.  Photo of a truck maneuvering into a narrow parking space.

Figure 1. Example of tight parking for trucks.

2.2 Minnesota

The Minnesota Department of Transportation (Mn/DOT) conducted several market research studies during 1997 and 1998 to improve the provision of rest area services and to expand their understanding of the views of different market segments.(6)The studies included:motorist usage surveys, focus groups, a statewide telephone survey of rest area usage and satisfaction, and commercial truck usage and nighttime parking demand analysis.

The objective of the nighttime parking demand analysis was to identify rest areas where there was a greater demand for nighttime truck parking than there were available spaces and to document the frequency of this occurrence. Sites were identified as potentially having a parking capacity problem if the average truck parking capacity used was greater than 80 percent, or if the truck parking capacity was met or exceeded three percent of the weekdays or days of the year. Based on these criteria, the study results suggested that 26 of the 50 full-service rest areas operated by Mn/DOT potentially had parking capacity problems.

Mn/DOT conducted another truck study to determine how commercial vehicle operators use the rest areas along I-94 during nighttime hours. (7)Survey hours were from 11:00 p.m. to 7:00 a.m. Monday through Friday during one week. The following data were collected:1) total vehicles on eastbound I-94 before each rest area, 2) total number of vehicles entering each rest area, 3) arrival time of each commercial vehicle entering the rest area between 11:00 p.m. to 7:00 a.m., and 4) dwell time of each commercial vehicle entering the rest area between 11:00 p.m. to 7:00 a.m. The following results were reported:

  • Approximately 14 percent of the commercial vehicles on eastbound I-94 utilized the rest areas.
  • Twenty percent of the commercial vehicles surveyed arrived before 11:00 p.m.
  • Twenty percent of the commercial vehicles surveyed departed after 7:00 a.m.
  • Over the entire week for all rest areas, the oversized lots were at or over capacity 45 percent of the time.
  • None of the rest areas were at capacity at 11:00 p.m.
  • Almost 60 percent of the commercial vehicles arriving before 11:00 p.m. stayed for five hours or more.
  • Of the commercial vehicles arriving between 11:00 p.m. and 7:00 a.m., approximately 20 percent stayed in the rest area less than four minutes.One in three stayed eight minutes or less during the survey times.

The study conclusions were that commercial vehicle drivers who arrived at the rest areas before 11:00 p.m. tended to be able to find parking spaces.Once parked, they often stayed for most of the night. Commercial vehicle drivers that arrived later in the evening, after the lots were fully occupied, stayed a much shorter length of time. Based on surveyor observation, the drivers would usually pass through the rest areas without stopping, or with only a momentary stop to look for a space, and would continue on after finding nothing available.

2.3 New York

To meet the needs of the motor carrier industry and other travelers, the New York State Department of Transportation (NYSDOT) conducted research and developed a program to refurbish the public rest area system on interstate-type highways in New York.(8)The NYSDOT rest area program included four components:1) a departmental rest area policy, 2) a departmental statewide rest area plan, 3) regional rest area plans, and 4) roadway corridor studies. The rest area policy provided for well-maintained, energy-efficient, multi-functional public buildings with climate-controlled rest rooms, hot water, drinking fountains, indoor vending machines, and tourist/travel information. The plan for the parking facilities design was to meet projected future needs and provide lighted walkways, parking areas, and drives.The regional and statewide plans addressed the spacing and number of rest areas, needs of commercial vehicle drivers, and tourist information.

As part of this research, the University of Albany conducted a survey of long-haul tractor-trailer drivers.(9)A sample of 303 drivers were interviewed at roadside safety inspection sites on Route 17 and I-87 in New York State. The results of the survey were as follows:

  • Nine out of ten drivers on each road said that more commercial vehicle parking was needed, and that changes were needed in the selection of food and beverages, the layout and spacing of parking, and the number of telephones.
  • Although the majority of drivers on each road rated the adequacy of the rest area facilities as "good" or "excellent," over 25 percent said they were "fair" or "poor." Twenty-five percent rated the safety/security of the rest areas to be "fair" or "poor."
  • Forty-two and 24 percent of drivers on Route 17 and I-87, respectively, said the distance between rest areas was too great to allow drivers to stop when they want to.
  • Winter closings of one or more rest areas would be problematic for over 85 percent of drivers on each road.
  • Seventeen and 42 percent of the drivers on Route 17 and I-87, respectively, were Canadian.
  • About two-thirds of the drivers on each road drove more than 161,000 kilometers (100,000 miles) per year, and 82 percent said that most or all trips were overnight.
  • About two-thirds of the drivers on each road reported that they usually took breaks on that road.Most of the other drivers reported taking their breaks at private truck stops.
  • The most common length of daytime rest breaks on Route 17 and I-87 was 10 minutes and 15 minutes, respectively.The most common length of nighttime stops on each road was four hours.

2.4 Iowa

In 1999, the Iowa Department of Transportation was requested by the Iowa General Assembly to conduct a study of Iowa public policy regarding overnight truck parking.(10)In response, the Iowa Department of Transportation formed a Task Force on Commercial Vehicle Parking. Members of the Task Force included stakeholders from corporate and independent trucking firms; representatives from highway user groups, academia, the enforcement community, and the federal government; and the Iowa Department of Transportation.The Task Force developed a list of four issues requiring research. The Center for Transportation Research and Education (CTRE) at Iowa State University conducted the research.

A key recommendation made by CTRE was that the State of Iowa should continue to be in the business of providing some overnight parking, as the Task Force believed that the State could not expect the private sector to meet all overnight parking demands.An additional recommendation was to prioritize locations where unmet demand for overnight parking was greatest, and to ensure future public development of new overnight parking.Several priorities for the development of future public parking spaces were set:1) evaluate existing public facilities to accommodate more truck parking, 2) use intelligent transportation systems (ITS) solutions or other media to better inform truck operators of the availability of both public and private truck parking spaces, and 3) as existing rest areas are upgraded, try to size parking to meet space demands for a 20-year planning horizon.

2.5 Michigan

The Michigan Department of Transportation and Michigan State University conducted a study of rest areas in the State of Michigan. (11)The study included an inventory and utilization study of 82 rest areas. The inventory included the number of parking spaces, facilities offered, distance from previous rest area and nearest city, operation time and parking time limits, average daily traffic and truck traffic, distance to the next interchange, and number of private parking spaces within ten miles. Observations for the utilization study were made at most of the rest areas along the interstates and U.S. routes in Michigan during the peak overnight hours. The results of the utilization study showed that although a majority of the rest areas were not full (42 percent), some rest areas were overcrowded (19 percent).

In addition, the study included the development of models of rest area utilization in Michigan.The modeling techniques used included regression and discriminant analyses. Regression analyses were run for four time periods (12:00 a.m. to 2:00 a.m., 12:00 a.m. to 4:00 a.m., 4:00 a.m. to 8:00 a.m., and 6:00 a.m. to 8:00 a.m.) using a measure of truck parking space utilization as the response variable and factors such as truck average daily traffic, number of truck parking spaces, parking space layout, and distance to the nearest city as the independent variables.

Results of the regression analyses showed that for 12:00 a.m. to 2:00 a.m., truck average daily traffic was a significant factor in explaining parking space utilization. For 4:00 a.m. to 8:00 a.m., distance to the nearest city was a significant factor in explaining parking space utilization. For 6:00 a.m. to 8:00 a.m., parking space layout was a significant factor in explaining parking space utilization. R-squared values for the linear regression models, however, were rather low (e.g., 0.359, 0.387, and 0.273, respectively). Results of the discriminant analyses show the same three factors found significant in the regression analyses to be positive contributors to truck parking space utilization.

2.6 Maryland

In late 1997, the Baltimore region began to address the need for additional truck parking spaces as a result of trucks parking illegally on highway shoulders. The Truck Rest Area Subcommittee was formed to lead this effort and consisted of representatives from the Baltimore Metropolitan Council, the Maryland Department of Transportation, the Independent Truckers and Drivers Association, the National Association of Truck Stop Operators, the Maryland State Police, and private sector participants.(12)

The subcommittee conducted a two-week, nighttime survey of truck parking at public rest areas, private truck stops, park-and-ride lots, and weigh stations along portions of the I-95 and I-83 corridors. Observers recorded the location of trucks parked along shoulders, the time of day, the number of spaces available at truck stops and rest areas in relation to where trucks were parked, and any signs along the highway indicating parking facilities.

Results of the study showed that a number of drivers were parking illegally along the interstates at night, although private truck stops had parking spaces available. Further, within the network of available rest areas, truck stops, park-and-ride lots, and weigh stations, there were enough parking spaces to accommodate current parking needs around the clock.Subcommittee members concluded that factors contributing to the truck drivers' over-dependence upon the public rest areas and the spill-over of trucks onto the highway right-of-way included: ease of public rest area access, less convenient locations of private truck stops, drivers' perceptions that truck stops are full, inadequate signage, and negative reputations of some private truck stops.

Recommendations for improvement have included: increased signage for private truck stops along the I-95 corridor, promotion of an under-used park-and-ride lot for overnight truck parking, distribution of an updated trucker's map, and improved security at various locations.Future efforts may include developing a better system for providing drivers with timely knowledge of available spaces along State highways and stricter enforcement of parking laws.

2.7 Kentucky

In 1999, the Kentucky Transportation Cabinet undertook a truck parking study.(13)The study included an extensive effort to count parked trucks overnight along all interstate highways in Kentucky.The data collection methodology used in the Kentucky study is discussed in more detail in the model calibration section of this report.

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