A traffic count is the average number of cars that travel on a given piece of roadway in a day. A good traffic count - though just one factor in predicting the success for a particular piece of property - is one of the basic elements of site selection.

Industry experts caution there is no magic number or special formula, such that if you have 20,000 cars going by you'll make X number of dollars, or if you have less than 10,000 you're going to go broke.

You will capture - that is draw in as customers - less than 1 percent of the cars that drive by your wash. But the capture rate is a function of other things beside the number of cars going by a location.

"It's important to have traffic going by, but they can keep going and not stop in," says William Berls, a Rolling Meadows, IL-based business consultant to the carwash industry. "You have to have something for them to stop for."

Capture rate also is a function of the demographics of the neighborhood and whether nearby people have the money, the time and the inclination to patronize the type of wash you intend to build.

Suppose the property were on the access road to Disneyland. You'd have terrific traffic counts - but those cars would be hurrying to a specific destination and not even remotely interested in clean cars.

The traffic count also has to be evaluated in the context of ingress and egress to the proposed location.

"You can have such a high traffic count that people can't get in or out," Berls cautions. "Oil companies learned a long time ago that those great corners with terrific traffic counts weren't so terrific because people couldn't get out of them."

If cars lining up at a traffic light block the entrance to the wash, customers may turn away.

While good volume is needed, high rates of speed on the road may discourage skittish drivers from even attempting to come in.

Alan Bussey, of Car Wash Loans, a financier of wash operations in Bedford, TX, says traffic counts have to be looked at in a broad context.

"Get the most recent numbers and then go back 10 years and get that. Get every year since then. You want to know if the number is going up or down. You also want to find out if someone is going to put in an interstate or a bypass," he says.

But all of this figuring begins with getting a correct traffic count. How can you find this number?

Companies that do civil, consulting or environmental engineering generally have the capability to do a traffic count and you easily can hire them. Of course, they will charge for it.

One way to get around the cost of having a study done just for you is to check out any sizable new construction in the vicinity of your target location. It does not matter whether it recently was completed, is under way or is projected.

Go to the city or town hall and talk to the building or planning departments - they approve and oversee new construction. Find out who did the engineering for the nearby project. If the engineering firm did traffic counts for that project, it may let you have a peek at those counts for a minimal fee.

Even if the counts are a year or two old, unless there has been dramatic development in the area, they still are valid.

A no-cost way to proceed is to ask the building or planning department to let you look at the materials that nearby projects submitted to get building or zoning permits. These documents generally are available to the public as a part of open government.

If you look through the documents - which can be lengthy - almost every substantial commercial project gives current and projected traffic count figures as a part of the permit paperwork.

A variety of state and local transportation departments keep traffic count numbers. This information can be had for free, but it may not be as up to date as you would like. Because of this, they can be a good source of historic information.

Governments do traffic studies when they are considering adding a traffic light or making road improvements like widening or reworking an intersection. They do not update counts for every road at the same rate, and may not have exactly what you need.

Start locally by contacting your town or city clerk and finding out who is responsible for this information in your community. Larger cities have their own city engineers, though some use outside engineering firms. Smaller communities may leave it up to the planning or highway department.

Be specific about the location you are considering. Have the right address and the nearest cross streets to identify the area of interest.

Information also is kept by the state transportation departments. Local officials may know who to call.

For a listing of all state transportation authorities, go to the Web site www.fanafana.com. Click on "Consumer Info; Government; North America; United States; State and Local Government." At the list of states, scroll down to "state agencies by function" and click there. Select "transportation." A listing for state agencies that deal with transportation will appear.

Be patient and be prepared to go from person to person until you get the right one.

These last suggestions are not reliable for all situations, but they may be useful to some.

In a large city, a big commercial real estate agency may have current traffic count information, particularly if it is trying to sell a nearby piece of property for a retail center or office building.

Occasionally, large newspapers maintain databanks of demographic information that they will share with members of the local business community.