Santa Rosa City Hall will study an alternative design for the ambitious Museum on the Square project that would change the way drivers reach parking areas and potentially improve the economic viability of the downtown redevelopment project.

Developer Hugh Futrell, who is leading an effort to transform the city-owned former AT&T building into a 10-story mixed-use tower, wants to shift the planned parking access from Third Street on the north side of the building to Second Street on the south side.

There's just one problem — that stretch of Second Street is home to the city's transit mall, where buses are welcome but cars are not.

Futrell, whose $23 million project is seen by many as potentially providing an economic boost to the downtown, wants the city to lift the prohibition on private vehicle access and allow future residents of Museum on the Square to reach the building parking through the transit mall.

But transit officials are balking, arguing that it raises a host of operational and safety issues, particularly the need to keep buses on schedule.

"Our big thing is we want to make sure we remove obstacles to our buses running on time," said Jason Parrish, administrative services officer for the city transit department.

Adding private vehicles to an area heavily used by pedestrians and four bus services could create conflicts that have not been fully examined, Parrish said.

The current development agreement between Futrell and the city calls for

drivers to enter the building on Third Street through a two-lane

driveway that tunnels through the first floor to reach a small surface

parking lot on the south side of the building. From there, residents

would take be able to access the basement parking, Futrell said.

The agreement also says that the design may be changed if the council agrees to allow residential access from Second Street. That would be preferable to Futrell for several reasons.

One is that it would be a more attractive pedestrian environment if there is not a driveway going into the front of the building, he said.

Another is that avoiding the 20-foot-wide tunnel would increase the amount of usable square footage on the first floor by about 22 percent. That would allow the proposed restaurant to be 28 percent larger and the Sonoma County Art Museum space to be 19 percent larger.

Increasing the usable space improves the economic viability of the project and thus its chances of success, Futrell said.

"Taking that economic space out of the building has an impact of probably right in vicinity of $400,000 on us," Futrell said.

But he said the most important thing is to get the issue resolved. The design needs to be completed because the next phase involves expensive construction drawings and meetings with lenders, Futrell said.

Futrell paid for a traffic study that concluded access through the transit mall could be done safely under certain restrictions. But given transit officials' concerns, Futrell formally asked the city last month to hire an independent traffic engineer to resolve the issue.

The city council last week authorized City Manager Kathy Millison to hire a firm to do the study and report to the council in November.

The council is likely to be motivated to resolve the issue. The city redevelopment agency purchased the vacant concrete building on the southwest corner of Old Courthouse Square for $3 million 2007.

Futrell's group is proposing to transform the five-story concrete eyesore into a 10-story glass-clad tower housing a museum and restaurant on the first floor, four stories of commercial space and five new floors of apartments.

Two local companies, TLCD Architecture — a partner in the project — and software firm Metier Ltd., have agreed to be tenants in the building, which has been touted by council members as the kind of live-work, pedestrian friendly development the city needs.