Learning to Drive in the NGSIM Simulator Using Proximal Policy Optimization

Table 1

State representation.

Types	The description of features
The host vehicle	Longitudinal position, lateral position, heading, longitudinal speed, later speed, lane offset, the distance to the leftmost lane boundary, and the distance to the rightmost lane boundary
The surrounding vehicles (6 nearby vehicles)	Distance, relative speed, TTC, longitudinal distance, and lateral distance