Emboldened by a $4 million grant and a freshly completed master plan, Palo Alto is rolling ahead with design work on a new bike bridge that would span U.S. Highway 101 and give residents in the south end of the city a year-round connection to the Baylands.

The project, which has an estimated price tag of up to $10 million, is one of the most conspicuous and expensive components of the city's newly adopted Bicycle and Pedestrian Transportation Plan. Currently, residents in the southern part of the city rely on an underpass at Adobe Creek to cross the highway. The underpass is typically open for about six months a year and is subject to unexpected closures, as with the recent construction of lanes on 101.

The proposed overpass at Adobe Creek has won the support of the entire City Council as well as many in the bike and environmental communities. It gained a burst of momentum last month, when the Santa Clara County Board of Supervisors approved a $4 million grant for the project. In the next year, the city plans to conduct an environmental analysis for the new structure and launch a design competition for the bridge.

But first, the city wants to hash out the bridge's basic alignment. That was the topic the Planning and Transportation Commission grappled with Wednesday night, when it considered a menu of design options involving curvy ramps of varying lengths, shapes and locations. The option recommended by the project consultant, Alta Planning + Design, has the bridge stretching from West Bayshore Road to East Bayshore Road and then taking a turn on the east side into a corner of the baylands, just north of Adobe Creek. Other alternatives include a design that drops off users just east of East Bayshore and one that brings them to a site just north of the baylands, largely avoiding the nature preserve.

In advocating for his preferred choice, Casey Hildreth, a consultant with Alta, said the goal is to come up with a bridge that is "not seen as an intrusion into the baylands" but rather allows the baylands to be "extended over the highway and into the city." Other options would involve more turns and would require users to reverse course if they wish to reach the baylands, factors that staff and consultants believe would make the structure more appealing.

The commission did not vote on the project Wednesday, but members offered some thoughts and added one new design to the buffet of options already on the table. Commissioner Arthur Keller advocated considering a new option that would cross the highway and then, rather than swerving north toward the staff-recommended area near East Bayshore, proceed on a relatively straight eastward path toward the baylands trails.

Commission Michael Alcheck called Keller's concept a good one. He also, however, encouraged staff to pursue alternatives that "don't tread too deep into the baylands."

"I think we should be careful about our impacts on the baylands," Alcheck said. "It's not just a matter of where the bridge ends up. It's the actual construction."

Commission Chair Eduardo Martinez also had words of praise for Keller's proposed design, with its relatively simple and straight alignment. Such an approach, Martinez said, would make the structure look more cohesive.

"What makes an elegant bridge is the continuity of the structure," Martinez said, citing Golden Gate Bridge and Bay Bridge as examples.

"In the Keller alternative, they're continuous and gentle and really lend support to the idea that it's one structure and not a fragmented structure."

Martinez, an architect, was less enthusiastic about the prospect of an architectural design competition to determine the bridge's ultimate appearance. Given the fact that so many of the conditions of the project, including the ramp alignments, are predetermined, a competition wouldn't be too important, Martinez said.

"If the city engages a good bridge designer like T.Y. Lin, that does things of this nature, through the design process we'll end up with a bridge that can be quite beautiful, quite functional and quite manageable within the cost structures," he said.

Commissioner Greg Tanaka took the opposite stance and cited the bridge's prominence as a good reason for a design competition.

"I think this bridge will be a showpiece for Palo Alto. Kind of like a gateway," Tanaka said. "I like the idea of a design contest."

Even with the ongoing work and growing enthusiasm, the project is still far from a done deal. The city has committed $1 million of its own funds as a condition for the $4 million county grant. But even so, it still needs to find the rest of the funds for the project, which would cost somewhere from $6 million to $10 million.

The city's new bike plan identifies the bridge at Adobe Creek as its top-ranked "Across the Barrier Connection." Hildreth cited a recent feasibility study that projected that the new bridge would dramatically increase the number of annual trips at the crossing, raising it from the current estimated level of 43,000 to about 74,000. To accommodate the future demand, the city is also planning to improve the bike corridors on Fabian Way and Charleston Road, he said.

The goal, Hildreth said, is to complete the draft environmental analysis next spring, to begin construction in late 2015 and to complete it within two years.

"Ideally, by beginning of 2017, this would be a fully functional, 365 access over the highway," Hildreth said.