Acceleration Mode

Main Page > Technical Documentation > Vehicle Movement Logic > Acceleration Mode

CarFollow

If a vehicle meets the following conditions:
 * is in a following status (discussed here)
 * is not stopped (velocity > 0)
 * is not stopping for a control

then an acceleration rate will be calculated to the car-following model (discussed here).

StoppingForQueue

StoppingForControl

Stopped

MaxAccel

Regardless of the acceleration mode assigned to a vehicle, the maximum acceleration of a vehicle always serves as a constraint against which other candidate acceleration values are checked. The maximum acceleration value is not static and is not user-definable. Rather, it is calculated internally as a function of numerous factors, as discussed in detail (discussed here).

If another acceleration mode is initially assigned and its resultant acceleration value exceeds that of the calculated maximum acceleration value for the vehicle, the acceleration mode will be reassigned to 'MaxAccel'. The maximum acceleration mode is typically applied in situations where a vehicle, usually a commercial truck, is attempting to maintain its desired speed on an upgrade.

MaxDecel

The default value is -19 ft/s/s. This value can be changed in the 'VehicleMovementParms.xml' file.

DesiredAccel

The default value is 4 ft/s/s. This value can be changed in the 'VehicleMovementParms.xml' file.

DesiredDecel

The default value is -10 ft/s/s. This value can be changed in the 'VehicleMovementParms.xml' file.

UnimpededNormal

In this acceleration mode, the vehicle motion is not affected by a leader vehicle or by any traffic controls.

DownstreamLinkSpeedChange

SlowingForDowngrade