https://icube3d.com/splineland.html

SplineLand is a plugin for Autodesk 3ds Max that helps to generate topographically accurate terrains from a set of splines and lay roads. Without SplineLand it is almost impossible to achieve such accurate results in 3ds Max. Now you can do it quickly, in just a few clicks your topographical data in form of splines can become a terrain.

CityTraffic is a plug-in for 3ds Max which helps to create car traffic flow on the roads and off-roads.

Special road editor and automatic cars setup substantially accelerates preparation of scenes for the simulation of traffic movement.
Huge variety of configurations for each car, whether it is adjustment of a suspension bracket or style of driving, give the ability to create realistic simulation.
Dynamics calculation makes movements on complicated surfaces more realistic, and the artificial intelligent system helps cars to operate independently.