JACKSON -- When freezing temperatures led to a water main break in the city a few years ago, stopping the gushing water took hours because the shut-off valve couldn't be located. A new computerized system that maps every element of the city's infrastructure would have told workers that valve was only a few feet from the break.

The database, expected to greatly improve the mapping of the city and store more accurate information about its infrastructure, is due to be completed sometime this summer.

In March, aerial photographs of Jackson were taken with special cameras at two different altitudes. Called orthophotography, the process improves the displacement of images that occurs in aerial photographs due to camera tilt and deviations in terrain.

Surdex of St. Louis already has provided the City of Jackson with the aerial photographs and is now scanning the negatives to create a computer database of images. The resulting maps will be accurate to within 1 1/2 feet horizontally and to within 1 foot vertically.

"That kind of accuracy is very important," says Public Works Director Jim Roach.

Once the database is completed, city workers will be able to call up the exact location of any storm sewer, power pole or any other part of the city's infrastructure. And they can be confident that these locations and other information will be correct.

"There can be inaccuracies with hand-drawn maps and many possibilities for human error," Roach says.

The city spent $65,000 on the aerial mapping but expects to save money on labor.

"You can spend five times the manpower," Roach said, comparing the old system with the new.

Janet Sanders, who is an inspector in the city's Building and Planning Department, will be in charge of maintaining the database.

When developers submit plans for a new subdivision, the city also will want the plans on computer disc so they can be imported into its database.

The accuracy of the computerized mapping also should save developers money because they won't be required to survey as extensively as in the past, Roach said.

"All this should be available to citizens."

The city's maintenance programs also will be enhanced, Roach said. Workers will be able to determine the age of a power pole and the transformer, when it was last maintained and other such information with a few keystrokes.

The system can be automated so that the computer provides an alert when maintenance is needed.

Video scenes obtained with a sewer camera recently purchased by the city also can be incorporated into the database

"The idea is to be pro-active rather than reactive," Roach said.