Transactions on the Built Environment vol 33, © 1998 WIT Press, www.witpress.com, ISSN 1743-3509 A model of selected ridership forecasting techniques with a limited database - a case study the central coast diegan W.E. Rice College of Business, California Polytechnic State University, San Luis Obispo, California 93407, USA Email: wrice@calpoly. edu Abstract Central to the authorization of an urban transport project is the development of a credible projection of ridership. Statistical databases are often either lacking or questionable. This paper examines the techniques employed in such an environment by detailing the methodology used to forecast ridership for an extension of passenger train service to San Luis Obispo, California, in the San Diego/Los Angeles urban corridor. Many arguments implied a strong latent demand for this service. Ridership projections were constructed to evaluate the feasibility of different service levels. The statistical analysis was predicated on historical passenger rail traffic patterns, origin/destination surveys and the assumption that ridership is population-driven Data were available with respect to the impact of additional train service, arrival and departure times and the opening of new stations. These relationships were used to modify the projections further. Once the passenger counts were determined, revenue estimates were made Projected revenues were then evaluated against the standard of short-run avoidable costs to determine economic feasibility. This paper provides a detailed analysis of the steps outlined above. Transactions on the Built Environment vol 33, © 1998 WIT Press, www.witpress.com, ISSN 1743-3509 4 Urban Transport and the Environment for the 21st Century 1 Introduction By 1968, a series of train discontinuances left the abbreviated and downgraded Daylight as the sole passenger train on California's coast line between Los Angeles and San Francisco. Thanks to last minute political maneuvers, the coast line was incorporated, in 1971, into the new federal government rail passenger Amtrak system. Most important, the Coast Starlight a new San Diego-Seattle service was established. A combination of the convenience of the many cities it served, improved amenities and an expanding population base made the Starlight a solid fiscal and ridership performer. San Luis Obispo, by 1989, was accounting for 45,000 Starlight passengers annually. Serious thought again was being given to the expansion of coastline rail service. For a brief period in the early 1980s, the State of California had provided operating support for an overnight train, the Spirit of California, between Sacramento, San Luis Obispo, and Los Angeles. A combination of politics and the failure of the Spirit to achieve the statutory fare box recovery ratio of 55% resulted in the last Spirit to run on October 1, 1983. During 1990/91, several events were merging to make increased rail passenger service to San Luis Obispo a real policy option. In 1988, the state had funded a successful extension of a San Diegan north of Los Angeles to Santa Barbara. With the establishment of a second San Diegan to Santa Barbara in October of 1990, dedicated San Diegan bus connections between San Luis Obispo and Santa Barbara were established. The San Luis Obispo passenger count was increased by more than 46%. In addition, the added convenience of the additional schedules south of San Luis Obispo was largely responsible for a 17% increase in the Starlight count. It was the statewide passage in June of 1990 of the "Clean Air and Transportation Improvement Act of 1990" which proved to be the catalyst that triggered the San Luis Obispo governmental review of rail service improvements. Concurrently, the Division of Rail of the California Department of Transportation (Caltrans) was making its own assessment of expanded coast rail service. Both efforts were coordinated. The focus now was to establish the "feasible" alternatives and develop an analysis of each with respect to its revenue/ridership potential. Transactions on the Built Environment vol 33, © 1998 WIT Press, www.witpress.com, ISSN 1743-3509 Urban Transport and the Environment for the 21st Century 5 Subsequent discussion produced a "short list" of specific alternatives to be studied. Because of a combination of both limited fiscal and operational resources, realistically the viable alternatives were those providing for an expansion of San Diegan service north of Santa Barbara to San Luis Obispo, a distance of 119 miles.* Because of population growth, four new intermediate stations were incorporated into the planning—these were Goleta, the location of the University of California; Surf, to serve both Lompoc and Vandenberg Air Force base; Guadalupe, to tap the Santa Maria Valley; and Grover Beach, in southern San Luis Obispo county. It was felt, and later verified by the ridership modeling, that the addition of these new stops would generate acceptable ridership/revenue levels. To date, only the Grover Beach station has opened. 2 Specific Service Options The "short list" of specific alternatives studied was based largely on the availability of equipment given the requirements of the already existing San Diegan corridor service between Santa Barbara and San Diego. Resource constraints made the addition of only one service feasible. The options considered were: Option 1— This provided for extending to San Luis Obispo the northbound morning San Diegan from Santa Barbara. The option would provide an early afternoon arrival with a mid-afternoon return from San Luis Obispo. The train would precede the heavily used Amtrak long distance train, the Los Angeles - Seattle Coast Starlight, It would act partly as a "relief valve" for that train by transporting the many short haul trips between San Diego and San Luis Obispo. Option 2— This option was similar to the above option. However, instead of ending in San Luis Obispo, this train would continue northward to San Francisco. It thai returns southbound, reaching San Luis Obispo at 1:06 p.m., continuing south as described above. Option J-This option extended to San Luis Obispo the evening train San Diegan from Santa Barbara. This option would provide for nearly 1:00 Transactions on the Built Environment vol 33, © 1998 WIT Press, www.witpress.com, ISSN 1743-3509 6 Urban Transport and the Environment for the 21st Century a.m. arrival in San Luis Obispo with a 5:15 a.m. departure. Option 4 -This option provided for adding a new San Diegan between San Diego and Los Angeles, which would be extended to Santa Barbara and San Luis Obispo. It scheduled an approximate 7:30 a.m. departure from San Luis Obispo, with the returning train arriving around 10:00 p.m. Option 5-This option called for the re-institution of an overnight train between Sacramento and Los Angeles via San Luis Obispo? 3 Patronage Assessments Each of these options was analyzed. The basis of this analysis rested upon passenger rail-traffic patterns and survey data developed. Although origin and destination data for the Amtrak San Luis Obispo Station was available, it was felt that this data was insufficient to meet all potential patronage scenarios. Specifically, the data did not provide the precise origins or destinations within San Luis Obispo County. For example, patrons, whose origin or destination was in the south county (Grover Beach), would fall under the general category of San Luis Obispo. Therefore, a survey of San Luis Obispo passengers was conducted from which a detailed profile of the San Luis Obispo county rail passenger was constructed to estimate patronage at all potential stations. In addition, a stratified random telephone survey designed to determine the potential for rail passenger patronage to and from the City of San Francisco and its Peninsula was conducted. This was required since there was no direct passenger rail service to these points from San Luis Obispo. To be effective, the cm site survey was designed to be brief. This was necessary due to the time sensitivity of rail passengers. Two specific procedures were established to insure the reliability of the data. First, surveys were conducted for all Amtrak services. Second, a goal was established of surveying approximately 25% of the total passengers who boarded or alighted during the survey period. A total of 222 surveys were completed. This represented 384 passengers out of a total of 1070 passengers, for a population sample of 35%. The sample size, coupled with quality assurance monitoring, insured that inferences could be drawn from the data with a level of accuracy Transactions on the Built Environment vol 33, © 1998 WIT Press, www.witpress.com, ISSN 1743-3509 Urban Transport and the Environment for the 21st Century 7 within a confidence range of 5%. The survey data was analyzed by train/feeder bus service, gender of respondents, origin/destination, reasons for the trip, frequency of Amtrak travel, San Luis Obispo County origins/destinations and prime reason for using Amtrak. From this database, a series of least-squares regressions were developed. The purpose of this statistical analysis was to establish whether there existed a statistical pattern between variables. For example, was there a statistical relationship between the train selected, and the local origin/destination and, if so, what is the level of confidence of such a relationship? Based upon this statistical technique, it was found that there was no statistical relationship between the following sets of variables: (1) The train selected and the local origin/destination. (2) The local origin/destination and the train origin/destination. (3) The reason for Amtrak travel and the gender or age of the respondent. (4) Local origin/destination and the frequency of Amtrak use. The only statistically related predictor, was the size of the party to the origin/destination. Specifically, larger parties tended to be more likely to originate from outlying areas, as opposed to San Luis Obispo.