VKT, or Vehicle Miles Travelled (VMT) is a fundamental measure of vehicle activity, or usage - in this context, the reference is to the activity of personal vehicles. VKT measures the distance travelled by autos in a given time period in a given area. It reflects both the total number of vehicle trips and the distance of those vehicle trips (hence reductions in auto trips and auto trip distance will both reduce VKT). For example, consider one person who commutes alone five kilometres from home to work five days per week. The individual's total weekly VKT is 5 km * 2 trips / day * 5 days / week, or 50 VKT. Prior to the introduction of TDM initiatives, the person drives alone. As a result of a TDM program, the commuter now cycles three days per week and drives alone the remaining two. The TDM program has shifted two five kilometres trips, three days per week from auto to bicycle. The commuter's VKT has dropped by 30 kilometres travelled per average work week (5 km * 2 trips / day * 3 days/week = 30 VKT). In another example, an increase in the workplace parking price now might induce our commuter to drive to the nearest park-and-ride lot, and continue the trip via transit. In this case, the number of vehicle-trips remains the same, but vehicular portion of the commute distance has dropped. As another example, suppose a neighbour, who formerly drove alone to her place of work, now drives the first commuter to his place of work. So, although the first commuter continues to drive all the way, 5 days per week, she is now transporting two people, reducing their combined VKT. A reduction in VKT may be the central goal of a TDM program, or a change in VKT may be used to estimate progress against other goals. Changes in VKT are directly linked to changes in GHG and CAC emissions, as well as fuel use and other indicators