The discussions about the Treasure development shifted to traffic on Wednesday, a topic that project critics say should put the brakes on the hillside proposal.

The Park City Planning Commission delved into the traffic the project is expected to generate, but it seemed only limited progress was made at the meeting. The Planning Commission since last June primarily addressed issues related to the Treasure square footage and the overall design of the project. The panel’s struggles with the Treasure square footage was likely a preview of another difficult discussion centered on traffic since square footage and traffic are closely related.

There has been deep concern over the years of the Treasure discussions about traffic. Critics claim Old Town roads like Lowell Avenue and Empire Avenue would be overwhelmed if vehicles headed to and from Treasure used the roads. The Treasure partnership, consisting of the Sweeney family and a firm called Park City II, LLC, argue that the roads can adequately carry the traffic in combination with a broader Treasure transportation plan.

The Planning Commission inquired about a range of traffic issues, a signal that the panel will likely spend months discussing the issue. Some of the discussion centered on traffic studies centered on Treasure. The talks about Treasure have stretched for more than a decade, and there is concern that a traffic study conducted years ago no longer reflects the situation today. The earlier traffic study itself was disputed as the Treasure side claimed the numbers showed the roads could accommodate the additional vehicles while opponents argued otherwise.

Pat Sweeney, who represents his family in the discussions, said in an interview after the meeting the earlier traffic study, dating to 2004, will be updated later this winter. He said the Treasure side plans to count vehicles during Presidents Day weekend in February, which is typically one of the busiest weekends of the ski season. The developers last counted vehicles on Presidents Day weekend in 2005, he said.

“The fundamental capacity is there. Can things be improved? Sure,” Sweeney said.

The Treasure team on Wednesday told the Planning Commission everyday people consider themselves experts on traffic and the issue garners emotional responses. That is not the proper way to evaluate Treasure-related traffic, though, Shawn Ferrin, an attorney who represents the development partnership, said. The Treasure side also indicated the earlier traffic study showed the development would have a minimal impact on roads.

Matt Cassel, the Park City engineer and a City Hall staffer who will be influential in the traffic discussions, told the Planning Commission the Treasure-related traffic needs to be considered alongside other projects planned in the vicinity. He mentioned eventual development at the Park City Mountain Resort base area and City Hall’s own plans for housing along the lower Park Avenue corridor.

The Planning Commission received a little more than 30 minutes of public testimony on Wednesday in opposition to the project. Hearings have been overwhelmingly against Treasure. The speakers on Wednesday maintained the earlier traffic study was based on outdated square-footage numbers, said there needs to be further consideration of pedestrians and argued that Lowell Avenue and Empire Avenue do not function as two-way streets. The comment about Lowell Avenue and Empire Avenue appeared to be based on wintertime conditions, when snow on the sides of the roads narrow the streets.

Another speaker, John Helton, told the Planning Commission streets like Woodside Avenue and Norfolk Avenue should be considered as Treasure traffic is discussed.

“Those streets will also be greatly impacted,” Helton said.

John Stafsholt, a Treasure critic, meanwhile, said the Planning Commission should require a new study of the traffic.

Members of the Planning Commission offered a variety of comments in their first round of feedback about traffic. John Phillips, a Planning Commissioner, was concerned about safety during snowstorms and said Crescent Tram, a tiny Old Town street, would be used by Treasure traffic. He wondered whether a vehicle tunnel could be built in the area of the Town Lift to shift the Treasure traffic flow.

Adam Strachan, the chairman of the Planning Commission, said details are needed showing the anticipated traffic impacts that can be tied directly to Treasure. He said all the traffic issues cannot be pinned on Treasure.

Treasure is envisioned as approximately 1 million square feet on a hillside overlooking Old Town along the route of the Town Lift. The proposal encompasses residences, commercial square footage and convention space. The Sweeney family in the 1980s secured an overall approval for development on the Treasure land and nearby parcels and is now attempting to win another necessary permit before Treasure can be developed.