In order to overcome irrational fear of driving, you have to take the first step of realizing that this fear is indeed irrational. Sure, traffic accidents happen, but they happen to a very small percent of the people, and even if you were involved in an accident before, there's really little chance that it will ever happen.
Once you do come to the realization that your fear of driving is irrational, you can start to figure out how to over it. And you can do it with 2 parallel processes:
1. The first thing you need to do is to realize that your fear is divided in 2: Your fear of the actual driving, and your fear of what that fear of driving is likely to make you feel. You're scared of the symptoms of the fear and not just the driving. This is a fear cycle in which your fear of another phobic attack is preventing you from taking steps to correct it. In order to begin overcoming your irrational fear of driving, you need to first be willing to face what driving may make you feel. In this way you will stop feeding your own fear and deal with the real issue of driving and your fear of it.
2. The second process you need to initiate is the baby-steps process by which you start taking small steps to face your fear. This is done by driving incrementally longer distances and facing the specific things about driving which terrify you. For instance, if you fear driving over a bridge, do it with someone else in the car with you, then do it alone over a short bridge, then a larger bridge, then a bridge spaning water. Slowly but surely, you will see that the demon is not so bad and that your fear of driving is, in fact, irrational.
Do that and you will likely see an improvement in your condition.