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muter response to TDM in part involves normal travel choice and decisionmaking functions, the context is one where peer (or supervisor) influences and corporate culture may be uniquely impor- tant. The "changes" involved--produced by the TDM strategies themselves--are dependent on choices by the employer or institution. Employee awareness of travel options can also be signifi- cantly affected by the organization. These managerial outcomes in turn will have been influenced by the needs being addressed by the TDM program and the laws and regulations involved (or not involved). Overall effectiveness will be a function of not only employee participation and response, but also the precursor employer participation and response. This section, along with additional topics in the "Related Information and Impacts" section, seeks to illuminate key aspects of these underlying influences on how TDM programs are likely to be implemented and how effectively they will influence travel decisions. Individual Behavioral and Awareness Considerations As alluded to previously, a commuter's travel response to TDM programs represents a complex intermixture of individual behavior presumed to conform with established travel demand theory plus less-well-understood interactions with workplace dynamics. Lifestyle and life cycle impacts also seem to be more evident than in the response to more conventional transportation system changes, either because they are in fact more important in the case of responses to TDM or perhaps because they simply have received more attention given the shorter-term focus and more indi- vidualized nature of TDM actions. This subsection starts with examining the role of tripmaker economic utility decisions and then proceeds through other layers of influences including barrier effects, interactions of the employer and employee, special considerations involved in alternative work arrangements, and employee awareness of available program elements. Time, Cost, Convenience, and Barrier Effects Travel demand theory suggests that travelers' choice of travel mode is heavily tied to the compar- ative economic utility among the alternatives. This utility is most commonly expressed in terms of travel time, travel cost, and certain measures of convenience. In this paradigm, travelers see addi- tional travel time, cost, or inconvenience as a "disutility," and make their choices in such a man- ner as to minimize this disutility. In the majority of cases facing commuters nationwide, the private automobile offers the lowest disutility. This is because its users have little difficulty accessing it at the beginning of the trip, generally pay no direct cost to use public roadways, and in most cases can park for free or at a substantial discount at the employment site. These advantages are particularly evident for com- mute trips beginning or ending in suburban areas. With such advantages, along with the conve- nience of being able to define one's own schedule of departure and arrival, it is little surprise that the majority of commuters opt to use their private vehicle. The alternative commute modes involve the effort and time constraints of participating in a carpool or vanpool, or taking the time to travel by walking or bicycling, or having to drive or walk to a transit line where there may be a wait for the vehicle to arrive--with potentially no unoccupied seat and certainly requiring payment of an often substantial fare. The situation is not helped by the fact that, once in the carpool, vanpool, or transit vehicle, the commuter is most often stuck in the same traffic congestion as the private car, minimizing any apparent advantage to switching modes. There are also related barrier effects where, for example, use of transit may not be feasible because of lack of a connection or service at the needed time. 19-79

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One thing TDM must do in order to be effective is to change the equation by making the alterna- tive modes more attractive in terms of relative time, cost, and convenience and by addressing related barrier effects. Preferential closer-in parking for carpools and vanpools, and contract tran- sit service enhancements that lessen wait for a bus, are examples of strategies with elements of time saving and enhancement of convenience. Straightforward incentives and disincentives directly address the cost component of the utility equation. Transit, vanpool, carpool, and walk/bike subsidies provide monetary savings to the employee through choice of the covered alternative commute modes. Parking pricing impacts the cost equation by enhancing the out-of-pocket cost advantage of alternative modes. The compan- ion strategy (or phenomenon, as the case may be) of restricted parking supply makes driving and parking less convenient and more time-consuming by increasing uncertainty about space avail- ability and often lengthening the walk from parking to the workplace. Commute mode choice response to travel time, cost, and certain convenience changes introduced by TDM actions may be anticipated using travel demand model relationships. Table 19-20 lists key mode choice model coefficients averaged across 19902002 modeling results from 26 urban areas across the United States. Ranges are also provided. These coefficients were assembled as part of an update to EPA's COMMUTER model (U.S. Environmental Protection Agency, 2005), outlined in the "Additional Resources" section. Each average coefficient in Table 19-20 is paired with commentary as to what it signifies with regard to how commuters weigh time, cost, and convenience factors in mode choice travel deci- sions. Convenience factors are implicit in the "Out-of-Vehicle" times: Walking implies something less than doorstep service, and waiting implies less than continuously or immediately available service. The higher these out-of-vehicle time values are the more inconvenience is implied. Table 19-20 United States 19902002 Mode Choice Model Coefficients with Interpretation Time or Cost Average Coefficient Variable Coefficient Range Interpretation of the Average Coefficients In-Vehicle Time -0.0253 -0.0113 to (In-vehicle time is the time spent driving, or (minutes) -0.0450 riding in a car, vanpool, or transit vehicle.) Walk (Out-of-Veh.) -0.0473 -0.0186 to Time that must be spent walking is roughly twice Time (min.) -0.0931 the disincentive as time spent in-vehicle. Transit Wait (Out- -0.0466 -0.0155 to Wait time (1/2 the time between transit vehicles) of-Veh.) Time (min.) -0.0978 is also about twice as onerous as in-vehicle time. Auto Commuter -0.0056 -0.0004 to One minute of in-vehicle-time is as important as Parking Cost (cents) -0.0173 4.5 of parking cost ($2.70/hour value of time). Transit Fare (cents) -0.0040 -0.0004 to Dollar per dollar, transit fares are somewhat less -0.0135 onerous (less of a disincentive) than parking cost. Notes: The coefficient ranges exclude certain values deemed by the researchers to be outliers. The researchers report historic guidelines that conflict somewhat with certain interpretations provided in this table, most notably, that 1 minute of in-vehicle-time is only as important as 3 cents of parking cost ($1.80/hour value of time). Source: U.S. Environmental Protection Agency (2005), with certain interpretations by the Handbook authors. 19-80

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Barriers to the use of alternative commute modes are not amenable to incorporation as continu- ous variables in a forecasting relationship--they are more in the "go"/"no go" realm of cause and effect. Barriers are addressed by such actions as contracting to bring transit service to an otherwise unserved employment site. Shuttles connecting suburban worksites with outlying rail transit sta- tions eliminate a barrier to employee use of time-competitive rapid transit or commuter rail ser- vices. Lockers and changing facilities address a barrier to active transportation--walking, jogging, or bicycling--by providing a place to freshen up and change out of athletic gear or informal cloth- ing prior to reporting to work. Circulator shuttles or availability of company cars addresses the perceived or actual need for a car during the day for errands or company business, making use of any alternative commuting mode more tractable. Need to drive alone in order to run errands or meet other family needs, such as childcare drop-offs and pickups en route to or from work, is a barrier effect similar to the need for having one's own car at hand during the day. En route satisfaction of travel needs is a phenomenon addressed at the end of the "Underlying Traveler Response Factors" section, in the "Trip Chaining" subsection. A travel demand modeling effort to include both time, cost, and convenience factors on the one hand, and barrier (and other) effects on the other hand, is described in the "Related Information and Impacts" section under "Modeling Studies"--"California Air Resources Board Survey and TDM Program." Facilitation and Encouragement Alternative mode use may involve new ways of doing things for the employee that are, or at least seem to be, complex. For example, formation of a vanpool is not a simple endeavor for the unini- tiated. Even forming a carpool requires hard-to-obtain information on who is commuting in about the same direction at about the same time. In addition, vanpool and carpool formation and con- tinuation involves interpersonal influences that may include possible reluctance to travel with strangers or to assume a lead role in organizing rideshare arrangements. These concerns and also uncertainty as to the risks and responsibilities involved are thought to be major obstacles to ridesharing (Pratt and Copple, 1981). Help and encouragement in crossing these thresholds, in the example of vanpooling, is the func- tion of vanpool formation and cost sharing assistance. Such programs provide facilitation through varying degrees of employer involvement in vehicle purchasing or leasing, underwriting of insur- ance and maintenance costs, or possibly providing and maintaining the vehicles themselves or arranging with another entity to do the same. For encouraging use of the broader array of alternative transportation choices, transportation coor- dinator support, on-site transit information and pass sales, and rideshare matching services all serve to overcome the information barriers, discomfort, and uncertainty associated with forming group travel arrangements or taking the leap to become a transit or walk/bike commuter. Indeed, the whole array of "Support Action" strategies, addressed at the beginning of the "Response by Type of TDM Strategy" section, are focused on facilitation and encouragement. The fear of being stranded at work in an emergency or because of unscheduled overtime is still another barrier. Guaranteed ride home is the strategy geared to addressing situations where alter- native modes can't themselves meet such off-schedule needs. A factor that has characterized a number of the most successful worksite TDM programs, but is very hard to propagate on a multi-employer basis, is a deeply supportive company culture. One of the best examples comes from the 1970s and 1980s in the form of a program with heavy vanpool 19-81

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emphasis, that of the Minnesota Mining & Manufacturing Co. (3M) in St. Paul. During this period the 3M vanpooling program attracted usage that recognized rules of thumb suggest should be improbable. It is hypothesized that the program may have been operating in a "supersaturated" mode in response to not only the 1970s energy crises but also a very special corporate enthusiasm and ethic. For a full discussion of this example, see Chapter 5, "Vanpools and Buspools," under "Response to Vanpool and Buspool Programs"--"Employer Sponsored Vanpool Programs"-- "Outstanding Employer Vanpool Programs." Alternative Work Arrangements Considerations Variable work hours arrangements are somewhat unique among TDM strategies in that the trip tim- ing decision process of the individual employee comes into full play when employees are given the discretion to choose their own work times, as with flextime. This decision process involves trade- offs among at least partially conflicting factors. A survey of California State Automobile Association (CSAA) employees early in the development of discretionary alternative work arrangements found four causal factors to be particularly important. These considerations were occupational factors (deemed important by 81 percent of surveyed employees), travel congestion effects (75 percent), social/family responsibilities (71 percent), and issues related to the use of alternative modes (92 to 36 percent depending on mode). Occupational factors relate to employee matching of work hours to the needs of the office, which include work coverage requirements such as receptionist duties. Congestion effects relate to desired avoidance of rush hour conditions in order to shorten travel times or minimize the discomfort of crowding. Social/family responsibilities include the desire to spend more productive time at home with friends and family, and such responsibilities as seeing that children get to school or day care. Modal usage factors encompass the trip coordination required to participate in vanpools and car- pools (increasingly important with increasing numbers of passengers) and to match transit sched- ules (50 percent responding important in the CSAA interviews) (Harrison, Jones, and Jovanis, 1979; Jovanis and May, 1979). Modal usage factors would vary by location--the CSAA offices were in downtown San Francisco-- and occupational factors would obviously vary in response to employer requirements. The inter- play and relative importance of factors influencing changes in travel mode in conjunction with work time shifts have been difficult to research. Outcomes in relation to individual categories of employer and institutional TDM strategy have been examined in each subsection of the preceding "Response by Type of TDM Strategy" section. Compressed work week (CWW) options introduce another dimension of travel pattern effects. They bring the opportunity and/or necessity for major non-work travel adjustments. Evidence from the federal employee experimental programs indicates that travel on the weekday off typically consists of urban trip tours of linked trips to multiple destinations, like normal Saturday travel, with trip purposes similar to the usual weekday non-work trips. Extension of weekday work trips to include intermediate linked-trip destinations becomes less common, either because non-work travel needs are met on the weekday off, or because the workday simply becomes too long for much detouring. Previous weekend travel may also be shifted to the weekday off (Cambridge Systematics, 1980; Skinner and Shea, 1981). Regression analysis of CWW schedule participation among workers under the Washington State Commute Trip Reduction (CTR) program suggests that CWW is more attractive for employees with supportive employers, long commutes, and multi-modal commutes such as drive to transit. CWW participation is less among single-mode transit and shared-ride commuters. Work in man- 19-82

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ufacturing and health care industries, along with government, was found to be a positive indica- tor for CWW choice. Work in information service/software was found to be negative for CWW, along with jobs involving management and administration (Zhou and Winters, 2008). As will be seen, the employment-related positive/negative indicators for CWW participation have major differences compared to telecommuting. Indeed, few manufacturing firms are typically found among any other forms of TDM involvement. CWW appears to work well (quite likely in non-optional applications) for industries where workers must be present at their jobs, on a regu- lar schedule. It thus may fill an important gap in the spectrum of TDM strategies. With regard to the lesser CWW participation among single-mode transit and shared-ride commuters, it is not clear if such commuters feel less urgency to work fewer days, prefer regular hours to support their choice of mode, or are more likely to give up on single-mode transit and shared-ride commuting. Telecommuting adds even more decision dimensions, because it involves an actual shift in work location away from company facilities to the home or sometimes a telework center. Examination of telecommuter trip characteristics, demographics, job types, and characteristics of their employers, along with other information, provides a basis to make inferences about factors affecting telecom- muting. The following information summarization is drawn from the literature reviews and mod- eling efforts of two California studies, one utilizing the 2002 home-based Southern California Association of Governments (SCAG) survey (Walls, Safirova, and Jiang, 2007) and the other a sur- vey of residents in eight Northern California neighborhoods (Tang, Mokhtarian, and Handy, 2007): Longer commute trip distance and time are positive indicators for telecommuting adoption. (One reviewed study found the converse, but may have included home-based-business workers, with their trip distance of zero.) Modeling success using the square of distance suggests a heightening of positive impact for particularly long commute trips. Pay parking at the workplace is a positive indicator, as is the opportunity to make more money as a telecommuter. An increase in work-related costs and substantive technology requirements are negative indicators, as is reduced salary. Both the trip distance/time finding and these cost/income findings demonstrate once again the importance of time and money in commut- ing decisions. Findings are very mixed for the effect of gender. One reviewed study suggests, based on Montreal data, that the key relationship is one of more empowerment in the workplace being a positive indicator for telecommuting. Where women have less workplace responsibility and freedom of choice, the telecommuting rates tend to be higher for men relative to women. Presence of more than one adult in the household is a positive, but findings are very mixed for presence of children. If anything, children under 6 are a neutral or positive indicator, while older children (along with household distractions) are a neutral or negative indicator. Reported results are split between health limitations not being a factor and situations of disability or parental leave being a positive indicator for telecommuting. High incomes and a college education, along with other highly correlated factors such as age, are all broadly-reported strong positive indicators for telecommuting adoption--as is inten- sive and proficient use of computers. Work in architecture, engineering, other professions, education and training, sales, and senior or middle management are all positive indicators. Employment in the arts and entertainment, consulting, finance, insurance, and real-estate industries is likewise a positive indicator for telecommuting adoption. 19-83

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Work in health care, construction, maintenance, and production, along with employment in the transportation, communication, and retail trade industries are negative indicators. A dis- tinction needs to be drawn between retail trade and sales, as the latter frequently involves home and business visits and is thus often conducive to telecommuting. Results are mixed for part-time work as an indicator. Being a contract or self-employed worker is a positive while being a full-time regular employee is a negative indicator. As might be expected, job suitability for telecommuting is a positive indicator, whereas the converse is a negative indicator, along with workplace misunderstanding and lack of man- ager support. Individual perception of a need for office discipline or desirability of face-to- face-communication or social interaction with co-workers is a negative indicator. Being a driver or driving to work is a positive indicator, along with perceiving the commute to be stressful. The influence of transit use or availability is mixed. Orientation to the family, desire for lifestyle quality improvement, enjoyment of walking, and preference for appealing outdoor landscapes are all positive attitudinal indicators for telecom- muting adoption. A non-rural residential location and preference for regional accessibility tend to be negatives. A potentially quite important finding from the SCAG survey modeling analysis is that employ- ment in an organization with 25 to 249 employees is a negative indicator for telecommuting. The researchers hypothesize that the firms of under 25 employees offer a flexibility conducive to telecom- muting, while firms of 250 and more employees are likely to have an established telecommuting program. Mid-size firms are thought not to offer either benefit, being too big for responsive flexi- bility and too small to support formal programs (Walls, Safirova, and Jiang, 2007). Both of the California studies also looked at indicators of telecommuting frequency, as distinct from telecommuting adoption. Together, the literature reviewed and the studies' original research suggest that many but not all of the same factors apply, certainly not always in similar degree, but generally in the same positive/negative relationships. Both studies in their own modeling efforts encountered more analysis difficulties with frequency than adoption (Walls, Safirova, and Jiang, 2007; Tang, Mokhtarian, and Handy, 2007). The eight-neighborhood Northern California study concluded that each of three different degrees of telecommuting frequency were associated with significantly different needs and desires (Tang, Mokhtarian, and Handy, 2007). The SCAG-survey- based analysis, in the context of having added a telecommuting program variable to the frequency formulation, found employer size not to be of importance to frequency. However, employees of firms with formal telecommuting programs were found to be 22 percent more likely to be high- frequency telecommuters (4 or 5 days a week) than others (Walls, Safirova, and Jiang, 2007). Awareness and Comprehension of Options Whatever influence the utility and characteristics of alternative commute modes have on commute mode choice is dependent on employee awareness and comprehension of the available options and support programs. In the previously mentioned 1993 study for the California Air Resources Board (CARB), a survey of 45 employers engaged in TDM programs in the Los Angeles and Sacramento areas found that a surprising percentage of the employees were unaware that their employer offered a particular type of TDM strategy. Because employees were asked to identify particular TDM incen- tives made available by their employer, it was possible to compare this knowledge with a listing of 19-84