This can happen because one has analyzed transportation needs and rearranged trips to be more efficient.  Some possible choices:

•  As a business, reorganizing deliveries by neighborhood/area to conserve time and fuel. 
• One might re-engineer the way a business operates to discover that exchanges that once happened in person were better handled through the mail or on-line

• By employees working from home some proportion of the time.
• Group errands in a particular part of town into one trip, rather than several.