In fact I haven't played simutrans for a while......
Just downloaded v102 (Executable+pak128) but found that it was unable to show traffic even if 'traffic density' was set to 16.
I did have traffic displayed in older versions......
I'm using Windows Vista.
Thanks a lot for your kind help~
If you have the timeline enabled, and you are in an early year before cars are available, then you will not see any cars.
I've set the starting year to 2050 but it still didn't work unfortunately......