Travel Survey Manual Appendices

Travel Survey Manual Appendices Travel Model Improvement Program Travel Survey Manual - A~~endices June 1996 Prepared by Cambridge Systematic, Inc. Prepared for U.S. Department of Transportation Federal Transit Administration Federal Highway Administration Office of the Secretary U.S. Environmental Protection Agency Appendix A The Costs of Travel Surveys The Costs of Travel Surveys Travel surveyors are almost always constrained by limited available resources. More often than not, the survey design and sampling tasks are bounded by funding limits, so the survey team needs to be able to estimate the cost of various types of surveys early in their effort. Estimating Costs Based on Previous Survey Efforts The most common source of rough cost estimates is the reported costs of previous efforts. The costs of travel survey efforts are often reported in technical papers and reports. In addition, rules-of-thumb about survey costs are commonly cited. For instance, many surveyors use a figure of $100 per completed survey for telephone-mail-telephone household travel surveys. Unfortunately, there are several problems with relying on past survey experience in estimating costs: ● The analyses rarely account for inflation; ● The analyses do not account for deteriorating cooperation rates over time; ● The analyses do not account for geographic differences; ● It is often difficult to determine which survey cost elements are included in the past cost estimates; and ● It is highly unlikely that the past efforts will include the same survey design=le-ments and sampling considerations as the survey team’s pro- posed effort. To analyze the cost of a past survey effort, the survey team needs to account for inflation. If the year of the past survey is known, then this is a fairly trivial calculation. However, this step is commonly ignored. This is particularly true with rules-of-thumb. It is impossible to lCIIOWwhether these estimates have been developed in the recent past or whether they have considered the effects of inflation. Even if past costs are adjusted for inflation, the cost estimates will not take into account the increased difficulty of getting respondents to cooperate with survey efforts. Cooperation rates and response rates are dropping --- Travel Survy Manual A-1 over time for all types of surveys, and the increased difficulty of completing surveys has a direct effect on survey cost. For instance, consider this extreme example. A 1964 home interview survey had an estimated cost per completed interview of $12. If that cost is adjusted for inflation, the estimated cost per completed interview would be about $50. In reality, the 1995 cost for a home interview survey similar to that conducted in 1964 would be much higher (almost certainly more than double) than $50 per completed survey. Response rates for these types of surveys have diminished drastically over the years to the point that these types of surveys are not generally considered to be feasible. The survey team must also be careful in using cost estimates from other locations. The availability and cost of survey worker labor differs from city-to-city. Many cities have large pools of temporary workers and University students that can be tapped for fieldwork and office jobs. Others do not. In addition, the cost of facilities and equipment are likely to be different from city-to-city. Finally, some survey locations have spe- cial characteristics that will affect the cost of the survey work. For instance, in estimating the cost of a roadside handout survey to be conducted at a barrier toll facility, the survey team should not use past survey examples in which toll collectors were asked to distribute ques- tionnaires unless the new survey effort will also be using the toll collectors. Some toll roads will require survey teams to supply fieldworkers at the toll booths, while others will prevail upon the collectors for survey distribution. The response rates and cooperation rates from different locations are also likely to be quite different, which means that the amount of survey worker labor may be significantly different in different locations. For instance, completing 1,000 30-minute telephone interviews with a 50 percent response rate is likely to cost $10,000 to $20,000 less than completing 1,000 30-rninute interviews with a 33 percent response rate. The final two potential problems with using past survey efforts as a guide in estimating survey costs are related to the way that survey costs are commonly reported. In order to use a past survey cost estimate effec- tively, the survey team must understand exactly which survey elements the estimate included. Most reported estimates are the cost to the agency of one or more survey contractors. These costs are a problem, because: . They do not include the considerable time and effort expended on the survey by agency staff; . Contractors are responsible for different survey elements in different survey efforts; ● They do not reflect the actual cost of the survey to the contractor, only the contract price. A-2 Trmel Suruey Manual Therefore, when a survey team sees a cost estimate for a past survey effort, they should seek as much detail as possible about what it includes and how it was calculated. In general, the best cost estimates for a survey effort are the costs of very recent surveys conducted in the same geo- ~aphic location. Non-transportation surveys with these characteristics are probably better measures than older transportation surveys or transportation surveys performed in different places. If possible, the survey team should enlist the assistance of a local marketing research expert to obtain abetter understanding of current local survey costs. Developing Cost Estimates from Unit Costs In addition to (or instead of) relying on past survey efforts at the begin- ning of a survey design effort, the survey team should try to develop cost estimates by considering each survey element. Fairly accurate estimates of likely costs can be developed with a little effort. Using simple spreadsheet software will allow the survey team to test different assumptions about response rates, labor and equipment costs, and different survey designs. For each type of travel survey, there are fixed and variable costs. The labor costs for interviewers and fieldworkers are almost always the most important cost elements for telephone and personal intercept surveys (either interviews or questionnaire distribution). The primary expenses for mail surveys are usually postage and printing. Table A.1 summarizes the cost components of travel surveys. The specific costs for a survey effort need to be developed based on the potential survey design(s) and on the survey team’s specific plans. The following discussion describes an example of how a survey team might estimate survey costs based on unit cost assumptions. A survey team needs to perform vehicle intercept surveys at five locations on the perimeter of a study area. Each location needs to be surveyed in one direction, and they all average about 8,000 vehicles per day in that direction. Because of past logistical difficulties with working with DMV data files, the survey team does not wish to consider a license plate survey. However they would like to compare the costs and benefits of con- ducting a roadside handout survey and a roadside interview survey. The survey team has identified a number of individuals that would be suitable for the fieldwork, so the team would like the crew to intercept platoons of five vehicles at a time, ask drivers a single screening question, and then either hand them a mailback form to complete or conduct a short interview. The survey team believes that the following efficiency levels will be achieved by the two methods: Travel Survey Manual A-3 .3 * & it 3 A-4 Travel Survey Manual m ..4 E!o VJ’ “$ z 6 Travel Sum?y Manual A-5 Handout/ Mailback Interview Average platoon assembly time (min.) 2 2 Average data collection time (min.) 1 5 Average platoon release time (min.) 1 3 Time between platoons (min.) 2 2 Total platoon cycle time (min.) 6 12 Platoons per hour 10 5 Vehicles per hour 50 25 Vehicles per day (12 hours) 600 300 Both survey methods will require automatic counting equipment, signage, and safety equipment. The anticipated site design for the handout survey will require the daily rental of $600 of equipment per survey site. The interview survey will require $800 of equipment per survey site. Based on past experiences, the survey team expects the following response from the two survey methods: Handout/ Mailback Interview Cooperation rate (respondent agrees to interview 95% 8570 or accepts questiomaire) Completion rate (respondent completes survey) 25 95 Percent of completed surveys that are usable 90 95 Percent of contacts yielding usable survey data 21 77 Tables A.2 and A.3 show the cost estimation calculations. In this case, the roadside interview survey is the more cost effective method. However, the survey team needs to weigh the reduced cost against the added traffic disruption of the method. A-6 Travel Survey Manual Table A.2 Assumptions Used in Survey Costing Example Handout/Mailback Interview Survey Survey First Each Other First Each Other Site Site Site Site . Survey Design and Analysis Senior Analyst hours 60 0 60 0 Junior Analyst hours 80 0 80 0 Administrative hours 120 0 120 0 Training Number of Supervisors 1 0 1 0 Number of Technicians 8 0 8 0 Training Hours 3 0 3 0 Survey Station Setup Period Number of Supervisors 1 1 1 1 Number of Technicians

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