When it's time for Dad (or Mom) to stop driving, you may know it before he does. While no one relishes the idea of hanging up the car keys, helping your parent do it could avert a disaster.

On average, 500 older adults are injured and 15 die each day in car accidents according to the National Highway Traffic Safety Administration.

“There’s no specific age at which it’s time to stop driving,” says Christine Moll, PhD, chair of the department of counseling and human services at Canisius College in Buffalo, New York and a past president of the Association for Adult Development and Aging in Alexandria, Virginia. “But going through stop signs, changing lanes without checking for blind spots, dents to the car, traffic tickets, inability to remember routes — all those are indications.”

The road to getting Mom or Dad to park the car for good can be bumpy. Pave the way with kindness and respect. Some tips:

1. Set the wheels in motion early. Bring up the issue before it becomes one. Ask your parent if he’s thought about giving up driving one day and how he feels about it.

2. Try some car talk. Moll suggests starting a conversation in the car. If you notice your mother is driving too slowly or your father keeps forgetting to signal before turns, tactfully mention it. When you’re behind the wheel, bring up your own struggles. Say, “I find it hard to see at night. How about you?” or “Wow, I’m so tired when I have to drive at the end of the day. Does that happen to you?”

3. Recruit some backup. “Sometimes the authority of a professional carries more weight than a family member’s concern,” says Moll. If your parent’s doctor suggests giving up the keys, you can be an empathizer rather than the devil. To develop a relationship with the doctor, offer to go with Mom or Dad to appointments to be “another ear.” Quitting driving can come up naturally as part of other issues you’re discussing. An older person may also be more receptive to another concerned pro, such as a clergyman or attorney.

4. Team up for retraining. To help an aging parent recognize he’s no longer driving safely, suggest signing up together for a refresher driving course, like the AARP Smart Driver Course. Ask the instructor for a constructive critique of your parent’s driving as well as yours.

Another option: an online driving assessment, such as AAA’s Senior Defensive Driving Program. One enticement: By taking any defensive driving course, your mom or dad may earn an insurance discount.

5. Put on the brakes slowly. Going cold turkey can be tough. Besides, your parent may not need to quit altogether. He may be fine driving during the day or to familiar destinations. Together, pinpoint situations that bring on nervousness or anxiety. Come up with alternatives to driving in those cases, such as using public transportation or riding with someone else.

When even local daytime driving becomes a problem, find out if the community has a senior van service or a cab company that provides discounts for seniors. Your mom or dad may even feel better about giving up the keys in the company of others who are enjoying a shared ride.

6. Be tough if you must. If it’s clear a parent is a danger on the road, don’t hesitate to insist he park the car for good. One respectful approach: Tell him it would make you really sad if he got hurt, or hurt someone else, in an accident. Says Moll: “This plants the thought without putting your parent on the defensive. You’re not just holding out your hand for the car keys.” 

Dorothy Foltz-Gray is an award-winning health writer and author of "Make Pain Disappear" (Reader’s Digest Health Publishing) and "Alternative Treatments for Arthritis" (Arthritis Foundation).