I've done quite a bit of driving the past week, so this topic came to mind. These aren't in order, and I've probably forgotten some.
1. Double parking. It's bad enough when delivery trucks do it, although at least they have a good reason. But when some idiot blocks a lane so he can go into a convenience store or whatever, I always hope someone will plow into their car -- preferably a large truck that will completely destroy it. If I were a traffic cop, double-parkers would get tickets the instant I saw them.
2. Oblivious pedestrians. It's amazing how many people just stroll right out into traffic, often with their children. They do this even when road conditions are bad, making it harder for cars to stop quickly.
3. Unnecessary lane closures. No work is being done, there's no apparent problem with the road, yet a lane is closed. Result = bottleneck causing big traffic jam. Unnecessary lane closures often occur at the worst possible times, such as rush hour.
4. Unnecessary cops. Hey, I think I'll just sit on the side of the highway with my lights flashing and create a big traffic jam. There's no accident, nothing going on, but all the traffic will slow way down to see what's happening and because they are worried about the police.
5. Trucks. There are almost too many things to mention about why I hate driving with trucks. Trucks driving at high speed in horrible weather conditions. Trucks refusing to change lanes when I'm merging onto the highway. Trucks pulling up alongside and then turning on their turn signals to come into my lane. Trucks driving side-by-side and blocking the road. Being between a truck and a wall. Trucks that have debris flying off of them that hits my car.
6. Eternal road construction. Why does it take five years to fix certain stretches of highway? Why are certain areas always under construction that never ends?
7. Traffic lights with no sensors or different settings. It's always fun driving through a largely empty city at 1am, yet having to stop and sit at every block because the traffic lights are still set on their normal daytime timers.
8. Unsynchronized traffic lights. This is particularly annoying when combined with #7.
9. Places with no parking. I know this can't be helped in certain areas, but it's no fun at all when you are in a hurry, can't find a spot, and have to loop around the block and go through more lights and deal with one-way streets.
10. One-way streets. Again, I know these are probably necessary, but I hate them. At the place I am currently working, if I park in front of the building I need to go thru two lights and two stop signs just to get to the back of the building.