Vehicle Miles Traveled (VMT)

Trips per person X miles per trip = VMT

The Vehicle Miles Traveled (VMT) per employee calculation combines the length of the one-way commute trip with the number of people who share the trip. In this way, it gives more credit for employees who use higher occupancy modes. For example, an employee in a two-person carpool with a one-way commute of 10 miles has a higher VMT (5 VMT) than an employee in a four person carpool with the same commute length (2.5 VMT).

The formula also gives extra credit for non-motorized commutes and commutes not made because of a compressed work week schedule or telecommuting. Most employer programs will not affect the length of an employee's commute trip (the "miles/trip" portion of the VMT per employee equation) since this implies that employers are either moving the worksite closer to their employees or employees are moving closer to the worksite. Employer programs can and do influence commute choice (the "trips/person" portion of the VMT per employee equation).


	How VMT is Calculated There are two components to the VMT calculation: trips per person, and Miles per trip Trips Per Person "Trips/person" is the average number of commute trips made, divided by the total potential trips. Number of commute trips depends on how many occupants rode in the vehicle used. Where: Drive alone trips (includes one-person motorcycle and drive-on ferry trips) = 1 trip Two-person carpool = ½ trip per employee Three-person carpool = 1/3 trip per employee Four-person carpool = ¼ trip per employee Five-person carpool = 1/5 trip per employee Six-person carpool = 1/6 trip per employee Vanpools of less than seven but more than two occupants are counted as carpools (see above). Vanpools of seven or more and transit (bus, train or walk-on ferry) = 0 trip per employee Trips not made because of teleworking and a compressed work week schedule and all non-motorized trips (bicycling, and walking) = 1.20 trips reduced. Each employee whose work schedule is changed so that he or she no longer commutes during the peak period = 0.20 trips reduced. Miles Per Trip "Miles/trip" is the average one-way distance employees live from work and is calculated using the average trip length to the worksite, as calculated from the survey (Question 7c).