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OCR for page 78
In Hawaii, the state department of transportation conducted a satellite telecommute demonstra- tion project in which it established a telework center in Mililani, Oahu, located 20 miles from down- town Honolulu. Seventeen employees participated in the demonstration (seven public sector and 10 private sector). An evaluation found that 93 percent of the employees experienced a reduction in number of work trips and an average drop in fuel consumption of 29 percent. Travel time sav- ings averaged 7.4 hours per week (Giuliano, 1992). An important 1990s synthesis-type study on telecommuting aimed at providing a framework for more accurately estimating the travel benefits associated with telecommuting. A model proposed on the basis of this synthesis accounts for two essential factors when attempting to estimate telecommute VMT savings: 1. Determining the amount of telecommuting that occurs on a given day. 2. Determining the actual vehicle miles of travel avoided as a result of a telecommute event. In addressing the first factor, cross-sectional data from various telecommute programs (includ- ing Puget Sound and the state of California) were used to conclude that about 16 percent of all employees are in a type of occupation where they can reasonably telecommute, that 50 percent of these will want to telecommute, 76 percent of these will actually participate, and--based on an average frequency of 1.2 days per week--about 24 percent will telecommute on a given day. When these proportions are jointly accounted for, the model projects that about 1.5 percent of the work- force could and would telecommute on a given day (Mokhtarian, 1998). In terms of the second factor, telecommute day VMT reduction, the study points out that not every telecommute event results in a VMT reduction equal to the commute trip length. The rea- sons are that not all of these trips are otherwise made as drive-alone, that some workers actually drive in to the worksite for all or part of their telecommute day, and that there may also be an increase in non-work trips taken that day. The analysis estimates that about 82 percent of telecom- muters normally drive alone--compared to a national average for all commuters of 73.2 percent in 1990--and that about 6 percent will actually commute on the telecommute day. These estimates suggest that a telecommute day only eliminates a vehicle trip 76 percent of the time (82 percent drive alone less 6 percent actually commuting). When taken together with the proportion of the workforce that would telecommute on a given day, the evaluation framework estimates that the average daily VMT reduction per employee achievable with a (regional) telecommuting program would be 0.5 miles on an average round trip by SOV of 43 miles, or roughly 1 percent. In light of these calculations, the researcher concludes that it would be unlikely that a TDM pro- gram based purely on telecommuting would ever reduce travel sufficiently to obviate the need for new transportation capacity. Also, if certain assumptions are made in the model with regard to res- idential relocation or induced demand enabled by telecommuting, the travel stimulation effects could equal or exceed the VMT reductions from telecommuting (Mokhtarian, 1998). UNDERLYING TRAVELER RESPONSE FACTORS The travel response of commuters to TDM initiatives involves many of the same underlying indi- vidual behavioral and decision processes found to influence response to most types of transporta- tion system changes. In the case of TDM, however, there are more layers of factors involved. Some are fairly unique to TDM. The environment is relatively atypical as well. While individual com- 19-78