Facing growing pressure to bring projects in on budget, transportation managers?such as those at the Jacksonville Transportation Authority (JTA)?have found that using off-the-shelf spreadsheet and database applications like Microsoft's Excel and Access are no longer robust enough to estimate the cost and scope of large-scale projects.

"JTA didn't have a rigorous system for developing consistent, reliable cost estimatesfor its complex construction projects," says Greg Day, a full-time onsite estimating consultant for the agency. "Their engineers' estimates were hit-and-miss compared against the actual contractor bids."

Two software providers?Gainesville, Fla.-based Info Tech, Inc. and Long Beach, Calif.-based Earth Tech, Inc. ?have added applications that allow estimators to quickly perform more complex financial analyses based on factors like engineering models, the price and performance of various materials, and unanticipated design changes.

Using Earth Tech's Tracer program, public engineers in Georgetown, Conn., for example, took a little more than two hours to calculate a project for a $3.28 million bond issue. The software-generated estimate was within 5% of a manual estimate.

Although such products have been on the market in one form or another for nearly two decades, this generation of cost estimating applications is more user-friendly and compatible with the companies' other applications, such as Info Tech's subscription only Web site that compiles and publishes the bid history of state projects, allowing users to compare their bids against past bids on similar projects by other agencies throughout the state.

Estimates are created for the year in which construction is expected to begin on a project based on inflation rates. New versions of the applications typically are released annually to reflect the latest inflation rates.

The Department of Public Works in Prince William County, Va., used Tracer to develop estimates for 10 proposed transportation improvement projects for a 2006 bond referendum. The projects, which were bid out separately, totaled $319 million. Slated for the rapidly growing area just south of Washington, D.C., they encompassed everything from widening a six lane arterial roadway to building a newfour-lane collector street.

Some of those projects are years from implementation, but the software can adjust cost estimates if errors in the original specifications are discovered after a project has begun or if a unique jobsite challenge?such as a sinkhole?occurs during construction.

One function allows users to factor in risk in regard to changes in the market rate of materials or equipment and available funding. Alternative analyses, for example, could reveal that roadway composition should change from asphalt to concrete based on possible price spikes in commodities such as oil, asphalt, and steel. Similar to the cells in a spreadsheet file, users refine the original estimate by reflecting those changes in the program's input parameter value.

Models built into such applications also illustrate what assumptions were made when previous estimates were performed.

Without these capabilities, "it's always a major challenge for agencies to come up with that first estimate when there are so many variables and options open to planners and designers to determine the specifics of a project," says Jeff Hisem, an administrator in the Ohio DOT's Estimating Office. "The problem is that the estimate doesn't always represent what the project finally turned out to be."

Jacksonville used Info Tech's Webbased Appia on a 2-mile project that widened a four-lane road to six lanes and replaced two, two-lane draw bridges. "The engineer's estimate was $65 million," says Day. "We had two contractors bid on the project, and the bids were $64.6 million and $65.6 million."

The software is most popular with state and county agencies, and public works departments in large urban areas.

"Small local agencies don't let the number of projects we do, so they build their own database or use the state's DOT database," says Roger Bierbaum, contracts engineer with the Iowa DOT. "If you're only doing a dozen or so projects a year, it isn't worth the effort to implement estimation software.

"In the past, if we had a contract with 100 items, we'd manually look up the history of all those items," says Bierbaum, whose department uses Appia. "Now the computer can do in half an hour what it used to take half a day to do."