Center-based telecommuting has many hypothesized benefits. To determine its value as a transportation demand management strategy, however, its travel-related benefits must be established quantitatively. This research provides the first analysis of the impacts of center-based telecommuting on individual travel behavior and emissions, using travel diary data from the Puget Sound Telecommuting Demonstration Project. An analysis of personal vehicle usage for this small sample of workers showed that the number of vehicle-miles traveled (VMT) was reduced significantly as a result of center-based telecommuting (from 63.25 miles per person-day on non-telecommuting days to 29.31 miles on telecommuting days). The reductions in weekday VMT comprise significant reductions in commute-related VMT with insignificant changes in non-commute-related VMT. The number of personal vehicle trips did not change significantly. In essence, center-based telecommuters behave as conventional commuters in terms of their number of trips, but are more similar to home-based telecommuters in terms of VMT reductions. The significant reduction in VMT translates into a 49% decrease in oxides of nitrogen (NOx) emissions and a 53% decrease in particulate matter (PM) emissions comparing telecommuting days to non-telecommuting days for the small sample. Because the number of daily trips was not impacted by telecommuting, the levels of emissions associated with the cold start process, total organic gases (TOG) and carbon monoxide (CO), were essentially unaffected. Of course, region-wide impacts will be much smaller when the proportion of telecommuters in the workforce and the frequency of telecommuting is considered.

This study compares the travel patterns of three different groups of workers identified in the 1991 Caltrans Statewide Travel Survey: home-based business (HBB) workers, home-based telecommuters (HBT), and non-home-based (NHB) workers. HBB workers have the highest average daily trip rate of the three groups, while rates for HBTs and NHB workers are statistically equivalent. Differences in drive-alone trip rates and time spent traveling are similar to those of other studies, with HBTs making 0.6 (18%) fewer trips and traveling 46% less time than NHB workers. Although HBB workers have the highest work-related trip rate, the NHB group makes nearly twice as many work and work-related trips combined as the HBB group, and more than three times as many as HBTs. The temporal distribution of HBB trips is unimodal, in contrast to the traditional bi-modal distribution for NHB trips and a flat distribution (from 9 a.m. to 6 p.m.) for HBTs. The HBB group is quite heterogeneous, with distinct differences across industry in overall trip rates, freeway use, and rates by purpose.

The impacts of home-based telecommuting on travel behavior and personal vehicle emissions for participants in the State of California Telecommuting Pilot Project are analyzed using the most advanced emissions modeling tools currently available. A comparison of participants' telecommuting day travel behavior with their before-telecommuting behavior shows a 27% reduction in the number of personal vehicle trips, a 77% decrease in vehicle-miles traveled (VMT), and 39% (and 4%) decreases in the number of cold (and hot) engine starts. These decreases in travel translate into emissions reductions of: 48% for total organic gases (TOG), 64% for carbon monoxide (CO), 69% for nitrogen oxide (NOx), and 78% for particulate matter (PM). Although the authors developed the methodology to investigate the emissions impacts of telecommuting, the analysis technique can be applied to any demand management or other transportation strategy where all of the necessary model inputs are available. An analysis of the number of personal vehicle trips and VMT partitioned into commute-related and non-commute-related purposes revealed that non-commute personal vehicle trips increased by 0.5 trips per person-day on average, whereas the non-commute VMT decreased by 5.3 miles. This important finding supports (for one indicator, the number of trips) the hypothesis that non-commute travel generation is a potential negative impact of telecommuting. This finding demonstrates the need to monitor these changes as telecommuting moves into the mainstream. In this study, however, the small increase in non-commute trips has a negligible impact compared to the overall travel and emissions savings.

Center-based telecommuting has many hypothesized benefits. To determine its value as a transportation demand management strategy, however, its travel-related benefits must be established quantitatively. This research provides the first analysis of the impacts of center-based telecommuting on individual travel behavior and emissions, using travel diary data from the Puget Sound Telecommuting Demonstration Project. An analysis of personal vehicle usage for this small sample of workers showed that the number of vehicle-miles traveled (VMT) was reduced significantly as a result of center-based telecommuting (from 63.25 miles per person-day on non- telecommuting days to 29.31 miles on telecommuting days). The reductions in weekday VMT comprise significant reductions ha commute-related VMT with insignificant changes in non-commute- related VMT. The number of personal vehicle trips did not change significantly. In essence, center-based telecommuters behave as conventional commuters in terms of their number of trips, but are more similar to home-based telecommuters in terms of VMT reductions. The significant reduction in VMT translates into a 49% decrease in oxides of nitrogen (NOx) emissions and a 53% decrease in particulate matter (PM) emissions comparing telecommuting days to non-telecommuting days for the small sample. Because the number of daily trips was not impacted by telecommuting, the levels of emissions associated with the cold start process, total organic gases (TOG) and carbon monoxide (CO), were essentially unaffected. Of course, region-wide impacts will be much smaller when the proportion of telecommuters in the workforce and the frequency of telecommuting is considered.

The impacts of home-based telecommuting on travel behavior and personal vehicle emissions for participants in the State of California Telecommuting Pilot Project are analyzed using the most advanced emissions modeling tools currently available. A comparison of participants' telecommuting day travel behavior with their before-telecommuting behavior shows a 27% reduction in the number of personal vehicle trips, a 77% decrease in vehicle-miles traveled (VMT), and 39% (and 4%) decreases in the number of cold (and hot) engine starts. These decreases in travel translate into emissions reductions of 48% for total organic gases (TOG), 64% for carbon monoxide (CO), 69% for nitrogen oxide (NOx), and 78% for particulate matter (PM). Although the authors developed the methodology to investigate the emissions impact of telecommuting, the analysis technique can be applied to any demand management or other transportation strategy where all of the necessary model inputs are available. An analysis of the number of personal vehicle trips and VMT partitioned into commute-related and non-commute-related purposes revealed that non-commute personal vehicle trips increase by 0.5 trips per person-day on average, whereas the non-commute VMT decreased by 5.3 miles. This important finding supports (for one indicator, the number of trips) the hypothesis that non-commute travel generation is a potential negative impact of telecommuting. This finding demonstrates the need to monitor these changes as telecommuting moves into the mainstream. In this study, however, the small increase in non-commute trips has a negligible impact compared to the overall travel and emissions savings.

Transportation control measures are often implemented for their environmental benefits, but there is a need to quantify what benefits actually occur. Telecommuting has the potential to reduce the number of daily trips and miles traveled with personal vehicles and consequently, the overall emissions resulting from vehicle activity. This research, sponsored by the Washington State Energy Office (WSEO), studies the emissions impacts of telecommuting for the participants of the Puget Sound Telecommuting Demonstration Project. The California Air Resources Board's emissions models, EMFAC7F and BURDEN7F, are used to estimate the emissions on telecommuting days and non-telecommuting days based on travel diaries completed by program participants. This study, among the first of its kind, represents the most sophisticated application to date of emissions models to travel diary data.

Analysis of the travel diary data and the emissions model output supports the hypothesis that telecommuting has beneficial transportation and air quality impacts. The most important resuslts are that telecommuting decreases the number of daily trips (by 30%), the vehicle miles travled (by 63%), and the number of cold starts (by 44%), especially those taking place in early morning. These reductions are shown to have a large effect on daily emissions with a 50 to 60% decrease in pollutants generated by a telecommuter's personal vehicle on a telecommuting day.

Reductions of this magnitude are observed because the telecommuters in this sample are long-distance commuters, with commutes twice as long as the regional average. As telecommuting becomes more widely adopted, and the average commute length for telecommuters becomes more representative of the average, the per-capita impacts on travel and emissions reported here will decrease. Also, there a re many factors that should be considered as part of a total assessment of the air quality impacts of telecommuting. These include an analysis of the direct transportation impacts (the only impacts adressed here), as well as the indirect transportation impacts, indirect non-transportation impacts, and region-specific topographical and meteorological factors. However, the net impacts are still expected to be beneficial - a reduction in VMT and emissions.

Transportation control measures are often implemented for their environmental benefits, but there is a need to quantify what benefits actually occur. Telecommuting has the potential to reduce the number of daily trips and miles traveled with personal vehicles and, consequently, the overall emissions resulting from vehicle activity. This search studies the emissions impacts of telecommuting for the participants of the Puget Sound Telecommuting Demonstration Project (PSTDP). The California Air Resources Board's emissions models, EMFAC7F and BURDEN7F, are used to estimate the emissions on telecommuting days and non-telecommuting days, based on travel diaries completed by program participants. This study, among the first of its kind, represents the most sophisticated application of emissions models to travel diary data.

Analysis of the travel diary data and the emissions model output supports the hypothesis that telecommuting has beneficial transportation and air quality impacts. The most important results are that telecommuting decreases the number of daily trips (by 30%), the vehicle-miles traveled (VMT) (by 63%), and the number of cold starts (by 44%), especially those taking place in early morning. These reductions are shown to have a large effect on daily emissions, with a 50% to 60% decrease in pollutants generated by a telecommuter's personal vehicle use on a telecommuting day. These net savings are almost entirely due to the elimination of commute trips, as non-commute trips increased by 0.33 trips per person-day (9% of the total trips), and the non-commute VMT increased by 2.2 miles. Overall reductions in travel and emissions of this magnitude are observed because the telecommuters in this sample are long-distance commuters, with commutes twice as long as the regional average. However, even as telecommuting adoption moves into the mainstream, its net impacts are still expected to be beneficial -- a reduction in VMT and in emissions.

It is important to note that when the level of telecommuting is considered (that is, the percentage of work days that employees actually telecommute), the weekly savings are a much smaller proportion of total weekday travel. Also, these findings represent average per-capita reductions; the aggregate (or overall, regionwide) impacts are determined by scaling these reductions by the number of program participants. Thus, the aggregate effectiveness of telecommuting must take into account the number of people likely to participate as telecommuters and how often they telecommute, not just the per-capita, per-occasion impacts.