Simulate the entry of the vehicles into the roads in VANET
 

Hello,
I am using ns2.35 to simulate VANET.
When using SUMO, the mobility trace generated puts all the vehicles in the same position (same X and Y coordinates).

This causes many collisions in the simulation.
So, i want to fix the vehicles 's arrival rate and intervehicle distance in my simulation scenario.
Have you any idea about that and how it can be done.