Help on making a traffic and predestrain system

I wanted to have a traffic and pedestrain system in my team project. I looked into many sources to how to implement this such as having the cars follow a spline path and using MassAI. The problem is the level maps are huge and so I found it intimidating to map out a spline for all the roads in the game, even considering having the vechiles move in opposite directions as well as split into different road branches. As said before, I had looked into MassAI, however I can not get the pedestrains and the vechiles behave in any matter other than to follow the path such as the player being able to knock them off the road. I also came across with a problem where the NPCs and vechiles share the same path. My situation was not helped by sources on MassAI being sparce.

Could you let me know of any free plugins, tutorials, git repositiories or other to help me in my predicament? I felt like I am stuck in a corner now.

Did you check the city example?

Yes I have. Honestly, my computer can not handle the scale of the project and crashes when I play the sample. I also do not know how to analyse the project.

Maybe check the smaller city or there is a sample only with pedestrians. That tutorial actual explains everything from scratch: Your First 60 Minutes with Mass | Tutorial