Sources of emissions
Commuting to MIT
Commuting activity to DUSP results in annual emissions of 80 MTCDE.
Methodology of commuting emissions
There are 199 students listed in the DUSP handbook. Assuming the same division of on/off campus housing as the rest of MIT (40% on campus, 60% off), there are 120 students commuting each day 1, plus the department staff and faculty. 1. See MIT 2004 Graduate Student Survey, available here. To calculate the total emissions from each commuting trip, we assume that the students, faculty and staff have the same travel behavior as respondents to the MIT Transportation Survey. 2. The table below presents estimated mode share, riders per mode and total emissions by mode for trips to and from campus for all DUSP commuters. 2. Mode choice data in this section comes from preliminary draft analysis of the 2006 MIT Transportation Survey; annual MTCDE for each mode comes from Groodie's assessment of MIT's emissions due to commuting, which assume average auto trip of 8.8 miles, emitting 1.163 MTCDE annually. Transit riders cause 0.149 MTCDE. Groodie, T A, A methodology for assessing MIT's energy used and greenhouse gas emissions. ME SM thesis 2004. Available via DSpace. To account for emissions from ridesharing, these trips are considered to have 50% of the emissions of drive alone: 0.807 MTCDE.
Emissions from commuting trips to MIT campus
| Students | Staff | Faculty | |
|---|---|---|---|
| Number | 198 | 26 | 39 |
| % mode share | |||
| Drove alone | 5% | 36% | 46% |
| Rideshare | 2% | 8% | 18% |
| Transit | 27% | 32% | 8% |
| Riders per mode | |||
| Drove alone | 10 | 9 | 18 |
| Rideshare | 5 | 2 | 7 |
| Transit | 53 | 8 | 3 |
| Emissions | |||
| Drove alone | 15.6 | 15.1 | 28.7 |
| Rideshare | 3.7 | 1.7 | 5.8 |
| Transit | 7.9 | 1.2 | 0.5 |
| Total emissions | 27 | 18 | 35 |
The total emissions produced by commuters are 80 MTCDE. This could be an overestimate, since some faculty and students do not attend school every day. On the other hand, some people drive from further away than 8.8 miles so the distorting effects may negate each other.
Limitations
This analysis does not provide any adjustment for faculty or staff who work part time, or students who come in more or less frequently. It also assumes that there is a single annual emission for each mode of transport, rather than a gradient depending on distance or modes chosen. More sophisticated analysis of the travel survey data could provide distance information, to be combined with emissions info from the MBTA or other sources.
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