The city of Tulsa announced Monday two finalists in the Arkansas River pedestrian bridge design competition. They are The Gateway Bridge, above left, and The Crossing Bridge, above right. Renderings provided by the city of Tulsa

The city of Tulsa has asked the Arkansas River pedestrian bridge design finalists to provide two final designs — one that could be built within the city’s $24.5 million budget for the project, and one that would cost $35 million, Mayor G.T Bynum said Thursday.

Bynum announced Monday that the Arkansas River Pedestrian Bridge Selection Committee had narrowed its choices of bridge designs to The Gateway Bridge and The Crossing Bridge. The new pedestrian bridge will connect to A Gathering Place for Tulsa park at approximately 29th Street and Riverside Drive.

Meanwhile, the city’s cost estimates for the bridge finalists range from $29.3 million to $56 million, according to an analysis done by HNTB on behalf of the city.

Bynum said those preliminary cost estimates helped make clear the need to explore additional funding options. He described the $24.5 million the city budgeted more than a year ago for the project “a general approximation” of what the city believed the bridge would cost.

“Through the whole (bridge design selection) process, what became clear to us —  to me, at least —  is that the number we have been working from, it could end up being the final budget and would be great if it is,” Bynum said. “But to get a once-in-a-century, world-class bridge that goes next to the greatest park gift in the history of the country, we may need some flexibility on the amount that we have to work with.”

Where the extra $10 million would come from has not been determined.

“We haven’t even started meeting about where those sources might be, whether that is public funds at a number of different levels of government, or whether that is private funds,” Bynum said.

But the mayor made clear all options will be pursued. He noted that many of Tulsa’s greatest icons,  including the BOK Center, the Golden Driller and the Performing Arts Center were  built with a combination of funding sources.

“I don’t see why we would just assume that this bridge would be any different,” he said. “Now that we have a better handle on the general approximation of what the costs are, I want us to leave no stone unturned on funding opportunities to pay for whatever design is ultimately decided to be the best for Tulsa.”

Bynum told The Frontier in March that the city plans to stick to its $24.5 million budget.

“Unless somebody can come to the table with another funding source that they are willing to add onto that, we have a very clearly defined budget that we have to work within,” the mayor said then.

Bynum on Thursday said the city has stuck to that number and “may very well end up doing that in the long run” if other funding sources materialize.

The potential need for more money to construct the bridge and the city’s willingness to explore all funding options, including private sector and foundation donations, could potentially complicate the bridge selection process  — or at least the public’s perception of it.

The Gateway Bridge design was created by Michael Van Valkenburgh Associates, the same firm that designed A Gathering Place for Tulsa park. The $400 million park is being paid for by the George Kaiser Family Foundation with financial assistance from other community donors.

Michael Van Valkenburgh Associaties worked with the city for about a year to come up with a pedestrian bridge design before Bynum opened the process to the public in March. Jeff Stava, who is overseeing construction of the park for GKFF, sits on the 13-member Bridge Selection Committee appointed by Bynum.

So the city finds itself with two finalists, MVVA working on behalf of GKFF, and KKT Architects of Tulsa, and one of the finalists is among the city’s most generous benefactors.

Asked whether he was concerned that GKFF’s potential to donate funding to the pedestrian bridge project would affect the selection process or the public perception of it, Bynum said he would be in a better position to answer the question in 30 days.

“I don’t know what are funding options are today,” he said. “Again, the decision for me is going to be based on the best bridge we can build.”

He added: “I would say it is super important to me that every submission has a fair and equal opportunity to be weighed in this, and I think that has been the case so far. And as long as I am mayor in this process, that will be the case moving forward.”

Stava was not available for comment Thursday morning, but in an interview with The Frontier earlier this week he praised the city for keeping the process fair to all parties.

“The city is really trying to keep a level playing field for this competition, which I respect,” Stava said.

Bynum’s proposed 2018 general fund budget of $269 million is less than 1 percent more than the city’s 2017 general fund budget and does not include any funding for the pedestrian bridge beyond the $24.5 million the city has already identified for the project.

The city actually has $27.5 million budgeted for the pedestrian bridge project, but $3 million of that has been set aside for contingency. The three major funding sources are the Improve Our Tulsa capital improvements program ($7.7 million); a federal TIGER grant ($4.7 million); and Vision Tulsa sales tax ($15 million).

The city of Tulsa is in the process of selecting a bridge design for the new Arkansas River pedestrian that will replace the existing bridge at approximately 29th Street and Riverside Drive. DYLAN GOFORTH/The Frontier

According to the city’s estimates, The Gateway Bridge would cost between $29.3 million and $50.5 million to build, and The Crossing Bridge would cost between $33.6 million and $56 million.

The estimates were compiled over a two-day period based on interviews with the designers and the “constructability” of the proposed bridges, said Paul Zachary, the city’s director of Engineering Services. Due to time constraints most, if not all, of the design submissions were delivered to the city without detailed engineering plans.

Zachary said two factors explain the wide range of the cost estimates.

“Number one was the (unknowns about) construction materials and structural supports, and two, are we working with cofferdams? Are we working with water running down the river, etcetera?” Zachary said “How you did that greatly affected your means and methods on how you would build that bridge.”

In short, until city officials have a better understanding of the finalists’ plans for their bridges, they will not know what the exact costs will be. The finalists, meanwhile, must address the feedback their proposals received from the public while keeping the project within the city’s $24.5 million and $35 million budgets.

That’s why the city is giving the finalists 30 days to work with the city to shore up their plans and cost estimates.

“There are ways to value engineer that to reach the budget,” said Nick Doctor, the city’s director of community development and policy. “This 30 days is designed to give those firms the time to take a hard look at their designs and figure out how you can engineer that to reach that cost point.”

Bynum said the city will use the same 30-day window to explore all its funding options. He noted, for example, that four trails will tie into the new bridge.

“Are there federal trail grants available out there that we could use to put towards this?” he said. “If so, I would like us to pursue that.”

The public process for selecting a pedestrian bridge design began March 20 when Tulsans were invited to submit their design proposals. The city received 234 design ideas. The Arkansas River Bridge Design Selection Committee then narrowed the field to four finalists. Nearly 3,000 people went online to comment on the finalists.

The city initially planned to rehabilitate the 113-year-old pedestrian bridge and add a second deck in time for the opening of A Gathering Place in early 2018. But that idea was scrapped in late 2014 after an inspection uncovered deficiencies in the bridge that make the planned reconstruction impractical and cost-prohibitive.

When the city opened the pedestrian bridge design process to the public in March, Bynum set out three criteria by which the designs would be judged: that they relate to A Gathering Place for Tulsa and the natural surroundings of the area; accommodate pedestrians and cyclists; and be no more expensive than the $24.5 million the city has budgeted for the bridge.