V

An organized consistent arrangement of five to 15 people traveling together and sharing the expense of the commute van.

The total distance traveled in miles in a given time period.

The parabolic curve connecting the two approach grades on either side of a hill.

A series of spans carried on piers at short intervals.

Used with interchange/ramp entry traffic models, this refers to the zone that provides a buffer between the driver and the end of the acceleration lane, where the driver can either merge onto the freeway in a forced maneuver or abort the merge and begin to decelerate at a reasonable rate.

A rotary, swirling, circular motion of a fluid, like wind or water, the vortex forms a vacuum at its center that draws objects toward it; examples of vortex motion are found in tornadoes and whirlpools, including the small whirlpool formed by water draining from a sink.