The Las Vegas and Laughlin areas of Nevada have experienced tremendous growth within the last five years. The primary mode of transportation to these resort areas from the Los Angeles area is by automobile. The Interstate 15 and 40 Freeways and State Route 58 provide access between the Central and Southern California areas to the Las Vegas and Laughlin resort areas. These major interstate routes meet and cross in the City of Barstow. Travel on these highways is heavily utilized by recreational traffic to the Nevada resorts and beyond on weekends. The traffic is heaviest in the northbound/eastbound directions on Friday afternoon/evenings, with travelers heading towards the resorts, and southbound/westbound on Sunday afternoon/evenings, with travelers heading home.

Inland Engineering Corporation was contracted by the City of Barstow to conduct a traffic impact analysis under the Congestion Management Program criteria in the County of San Bernardino for the Lenwood Road area along the I-15 Freeway in the southern portion of the City. The project area studied consists of recreational and truck-oriented commercial uses. In addition to the typical gas stations, restaurants, and truck stops that cater to freeway travelers, the area is home to two factory outlet shopping centers. The travel characteristics of the study area correspond to the peaking characteristics of the freeways.

Due to the unique travel characteristics and the impacts the freeway recreational traffic have on the City of Barstow streets, Inland Engineering Corporation chose to develop a traffic model for the City to estimate year 2005 and 2015 peak hour turn movement volumes for the intersections to be studied in the Traffic Impact Analysis. Because of its ability to model intersection peak hour delays and obtain peak hour turn movement volumes, Inland Engineering utilized TMODEL2 as the tool for its modeling efforts.

Since the area to be modeled was outside the areas modeled by the regional transportation agency, a key element to successful completion of the local model was determining the amount of through traffic in the City of Barstow, that is, the amount of traffic traveling the major highways that cross in the City but do not stop in the City. In addition to the through traffic, the amount of traffic getting off the freeway and patronizing local recreational commercial businesses before getting back on the freeway towards their ultimate destination (diverted link traffic) needed to be determined. In developing the local model, it was determined that the recreational traffic could be assigned an individual trip purpose to account for its unique travel characteristics.

To obtain this data, a video license plate survey was conducted. By obtaining license plate data at key entry and exit points to and from the City of Barstow, the license plate numbers at each entry point could be matched against license plate numbers at each exit point. For each license plate match in such a survey, the time of observation at the entry point is compared to the time of observation at the exit point to determine the travel time. Any vehicle which is within the anticipated travel time is considered a through trip. Any vehicle that exceeds the anticipated travel time by five minutes is considered a trip in which a local business in the area or along the freeway was patronized.

Inland Engineering Corporation contracted ATD Northwest of Woodinville, Washington to collect the license plate data utilizing high-speed video cameras and recorders. Five locations were identified in which to collect the data. The locations were established to correspond with the external zones to the model area. The five study locations represented the most significant of the eight roadways which traffic can enter and exit the City of Barstow (the other three roadways have an ADT less than 1000). The survey was conducted in May of 1995 between the hours of 2:00 p.m. to 7:00 p.m. on three separate days to obtain representative weekday, Friday, and Sunday p.m. peak-hour data. Video data was obtained continuously at the five locations for each travel lane entering and exiting (16 cameras).

TModel was contracted to develop a license plate matching program with input and output files which would be compatible with TMODEL2. Two program modules were created by TModel to accomplish the matching effort. The first program consisted of the data-entry program. Data entry consists of the station number, date of the survey, time of the observance, vehicle type (car, truck, bus, recreational vehicle, and motorcycles), date of license plate, and license plate number. The program creates ASCII files which we found to be easily edited and combined in any file editor program. The license plate matching program module, in standard TModel fashion, allows for flexibility in input and output parameters.

Necessary files consist of the complete license plate data file created by combining the files from the input program, and a travel-time matrix (.TTY) file created in the Trip Table Manipulation TMODEL2 module (2.3.1). The travel-time matrix consists of the anticipated travel times between each of the station combinations. The travel times were obtained by conducting floating car travel-time surveys. A variance time can be entered to allow for slower vehicles that may exceed the anticipated travel times. The flexibility occurs in the parameters to run the program for matches. The matches can be specified for a specific start and end time, vehicle type, minimum license plate length, and state. Outputs consist of a trip table for those plates which match by less than the anticipated travel time (.TTY) plus the variance time.

This trip table represents the through trips and can be viewed in the TMODEL2 Trip Table Manipulation module (2.3.2). Another output consists of a Time Frequency File (.FAC). This output allows for up to six different entering and exiting station combinations to be stored with the travel-time difference up to 90 minutes. The files can be viewed and analyzed in TMODEL2, F-Factor Editor (2.7.1), and Trip Length Frequency Distribution (2.7.3). This element was used to estimate the average trip time for those vehicles which patronized businesses in the City of Barstow. This data was informative for the City of Barstow as well as for the local model and useful for estimating the diverted link trip characteristics of recreational commercial traffic. In addition, a summary statistics file can be saved or printed which presents the total number of vehicles and number of readable license plates by vehicle type by user identified time periods. This feature allows for analysis of actual traffic volumes and obtains vehicle classification percentages for trucks and recreational vehicles to be used in roadway and freeway capacity analysis.

We found TModel to be an excellent partner in the project with the development of their License Plate Matching Program. Their user support was a key element in the successful completion of the project and in keeping those traveling through Barstow on the Crossroads to Riches.