An analyst for Pittsburgh's Gaming Task Force said Harrah's has "woefully underestimated" the traffic jams its proposed Station Square casino would create along Carson Street.

Chuck Wooster, a traffic engineer working pro bono for the task force, was asked to review traffic projections submitted by the three outfits competing to win the city's lone slot machine casino license.

At the group's meeting yesterday, Mr. Wooster said Harrah's traffic projection appears to misjudge the number of cars that would visit Station Square.

"I don't buy it," he said. "It's woefully underestimated."

Harrah's Entertainment, the largest casino operator in the world, is teaming with urban developer Forest City Enterprises. They are competing against Isle of Capri and the Penguins, which want to build a casino and a new arena in the lower Hill District, and Detroit businessman Don Barden, who wants to add one of his Majestic Star casinos to the North Shore.

Forest City's Abe Naparstek took issue with Mr. Wooster's criticism.

"The last thing we would ever do is choose a site that doesn't work," he said in an e-mail. "Station Square is the only site that benefits from all modes of transportation -- roadway, interstate highway, light rail and water. We are very confident in the site's accessibility; otherwise we would not be making this billion-dollar investment."

Mr. Wooster, president of David E. Wooster and Associates, doesn't concern himself with investment size -- he just studies traffic projections. And he says the Isle of Capri proposal is the most palatable of the three, purely from a traffic standpoint.

Meanwhile, the Station Square site is inherently problematic, because it's on a narrow strip of land, with little room for road expansion or traffic remediation.

"You've got a mountain on one side and a river on the other," he said.

Beyond geographic and road constraints, Mr. Wooster said he took issue with Harrah's traffic study methodology, noting that Harrah's curiously predicted the highest patronage and revenue of the three proposed casinos, but the lowest amount of vehicle traffic during Saturday peak hours.

For that hour, Majestic Star is predicting 3,470 vehicle visits, Isle of Capri sees 3,558 visits, and Harrah's projects just 1,536.

"I'm not quite sure how that happened," Mr. Wooster said.

A traffic impact study, for a casino or any other new attraction, is a complex equation that considers a number of variables: the number of passengers per vehicle, the ratio of people arriving by foot or public transit, peak usage hours for existing traffic and more.

On most of these counts, Mr. Wooster said, he believes that Harrah's traffic engineers weren't using numbers standard to the industry, and didn't provide enough data to back up their unusual estimates.

For example, Harrah's expects an average of 2.5 passengers in every car that visits the casino. That's higher than the average used by the two other outfits. A lower per-car occupancy would translate into more traffic.

Jerry Wentzel, an analyst from California-based DKS Associates, defended the numbers that his firm compiled. The estimate of 2.5 people per car is based on the current average occupancy of cars visiting Station Square, he said.

The average is higher, Mr. Wentzel said, because the Harrah's casino -- unlike casinos in Las Vegas, Mississippi and elsewhere -- will charge for parking, which encourages car pooling among customers.

"Very few people [will] come by themselves," he said.

Mr. Wooster also objected to Harrah's "capture" rate -- the number of people who are already visiting Station Square, presumably for shopping or dining, who will walk over to the casino. The capture rate seems unreasonably high, and has the effect of depressing traffic totals, he said.

Rebuttal from Mr. Wentzel: The capture rate of 20 percent is reasonable, and in fact, lower than the proposed capture rate for some Philadelphia casinos.

Last, Mr. Wooster said Harrah's was projecting an unusually low ratio of drive-up visitors -- only 70 percent of casino customers would come by car, according to Harrah's estimates, while 30 percent were projected to either walk or use public transit, like light rail or bus. Mr. Wooster said the split should probably be closer to 90-10.

From Mr. Wentzel: The split is reasonable. Also, included in the 30 percent are patrons who drive to the city but park "remotely," either Downtown or on the North Shore. They then complete the last leg of the trip by foot or bus.

Mr. Wooster, a recreational hockey player and Penguins fan, said all of the applicants would have to tweak their traffic plans, especially the portions relating to specific traffic improvements and their estimated costs.

The city task force was appointed by former Mayor Tom Murphy to review the casino proposals and, eventually, make recommendations to the city government.

The task force is still far away from endorsing one plan over the others, said Anne Swager, who co-chairs the group.