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.

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.