First of all, this is something you need to make every effort to avoid. Being late to a job interview may very well ruin any chance you have at getting a job, particularly if the position you are applying for is one that is highly sought after.
Give yourself enough time to get to your destination. Plan your route and estimate how much time it will take, then add more time so that you have a buffer. Plan for heavier traffic. You may even want to take a practice drive to the company before you have the interview just to make sure you know the route and how long it will take. To determine how much time you will need, it might help to work backwards – start with the time you need to arrive, then figure out how long it will take to drive there, how long it will take to eat, to wash and dress, and then when to wake up.
If something unforeseen happens and you know you are going to be late, take the following steps.
1. Call ahead and inform the hiring manager.
With cell phones, this is easy enough to do. Let him or her know what is going on and what time you might expect to arrive. This is just common courtesy.
2. Have a good excuse.
To have any hope of salvaging your chance at the job, your excuse better be a good one. Perhaps you encountered an accident, or someone needed assistance. Or there was some type of family emergency. If you are late simply because of poor planning or oversleeping, good luck offering that as an excuse.
3. Apologize, but only once.
You certainly want to apologize for your tardiness, offer an explanation, and explain your regret at making the hiring manager wait. Tell him or her how badly you feel, how embarrassed you are, because you know the importance of punctuality. After you have made your apology, let it go. Continually apologizing will not win you any brownie points. All it serves to do is remind the hiring manager that you were late.
4. Forget about it
After you have made your apology, put the whole thing out of your mind. You still have an interview to get through, and allowing yourself to fume over it or fret about it will only draw your attention away from where it needs to be. It is now water under the bridge. Put it behind you and focus on the interview.