Do you use the P Street ramp to get down to Rock Creek Parkway? If you do, it might be a good idea to tape this reminder to the dashboard of your car for a few days.

There's a policeman in your future. Also some barricades. Be alert.

When I head home at the end of a particularly hard day's work, sometimes I drive with my brain turned off. The car just seems to find its own way home. If that happens to you, too, it would be well to have a reminder in front of you as you head down the P Street ramp.

The ramp is wide enough for two lanes of traffic. The problem is that it is dangerous to permit two lanes of traffic to enter Rock Creek Parkway simultaneously. It is difficult enough to merge one new lane into the rushhour flow on the parkway.

So park authorities ordered hashmarks painted on the ramp. The meaning of the "zebra stripes" was clear enough to most motorists. "Don't drive on me." And those who stayed off the hashmarks found themselves channeled into a single lane.

There was just one small problem. Some drivers are egotists who think they are too important to wait in line with ordinary people. Instead, they zoom right past those who are waiting their turn. They go flying over the hashmarks and into the parkway, and usually force parkway traffic to yield to them. But sometimes they encounter a driver on the parkway who can't or won't yield - and then there is a crash.

James J. Redmond, superintendent of Rock Creek Park, pondered the parkway accident reports carefully and finally reached some conclusions.

There are too many accidents.

There are too many accidents at the P Street ramp.

All too often they involve sports cars and "muscle cars."

There is reason to believe that a single file of cars would enter the parkway with much less danger.

So Redmond is now taking action aimed at remedying the situation, and evidence of that action may be available to you shortly after you read these lines.

Barricades will be placed on the hashmarks to help motorist get into single file. And policemen will be stationed nearby to issue tickets to those drivers who still don't get the message.

When I called Redmond to get information about what he was doing and why he was doing it, he said to me, "As recently as February of this year, the parkway was carrying 47,000 vehicles a day. By June, that figure was down to 37,000. Obviously, the opening of the subway has taken a lot of people out of automobiles and put them into mass transit, and that's a wonderful trend, especially for those of us who think that our public parks should be recreation areas rather than highway routes.

"The thing that bothers me is that we still have a high accident rate on park roads crowded with commuters during peak hours. Our volume is down 10,000 a day, but instead of making the roads safer, that just seems to encourage some people to drive faster and take more chances. They pass on blind curves, they cross median lines and some of them simply will not wait in line to enter or leave the parkway.

"At Beach Drive, for example, where they split off to go through the Zoo tunnel, we have people who know they ought to move over into the slow lane, yet insist on zipping down the fast lane and then forcing their way into the tunnel lane at the last moment. I wish I knew how to persuade them to drive more sensibly."

"Well," I said, "If you find out how to do it, please share the secret with the rest of us."

That sort of thing goes on every morning and every evening in dozens of places where traffic slows down to enter or leave a high-speed roadway. Thus far, nobody has found a way to teach the chiselers to obey civilized rules.

However, I do have an idea I'd like to test. After I make my first million, I'd like to buy a surplus Sherman tank and take it down to the Southwest Freeway or Shirley Highway during rush hour.

Then I'd like to see some pushy guy try to force his way into my lane.