Trips per person X miles per trip = VMT

The Vehicle Miles Traveled (VMT) per employee calculation combines the the number of people who share the trip (trips per person) with the length of the one-way commute trip (miles per trip). It reduces the person trips for employees who use high occupancy modes as shown at right.

For example: Joe commutes to work five days each week; he drives alone three days and carpools with a friend the other two days each week. His one-way trip is 10 miles.

3 drive-alone trips + 2 two-person carpool trips	X 10 miles per trip = VMT
5 potential trips per person

then,

3 drive-alone trips + (2 x 1/2 trips per person)	X 10 miles per trip = VMT
5 potential trips per person

then,

4 trips per person	X 10 miles per trip = VMT
5 potential trips per person

finally,

4	X 10 = 8 Vehicle Miles Traveled
5

Most employer programs will not affect the length of an employee's commute trip (the "miles/trip" portion of the VMT per employee equation) . But, employer programs can and do influence commute choice (the "trips/person" portion of the VMT per employee equation).

"Trips per person"

• A drive-alone trip (also includes one-person motorcycle and drive-on ferry trips) = 1 trip
• A two-person carpool = 1/2 trip per person   
• A three-person carpool = 1/3 trip per person
• A four-person carpool = 1/4 trip per person
• A five-person carpool = 1/5 trip per person
• A six-person carpool = 1/6 trip per person
• 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 person
• Trips not made because of teleworking and a compressed work week schedule and all non-motorized trips (bicycling, and walking) = 0 trip per person.