by SC Publisher Shannen Hayes
Sanibel has long suffered from traffic congestion, and multiple studies aimed at alleviating it have been conducted over the decades. In June, the City Council approved a proposal from Kimley-Horn to evaluate the feasibility of adding a third travel lane to the Sanibel Causeway, the sole vehicular access to the island.
The proposal was solicited in response to resident requests for a study to determine whether the causeway could support an additional travel lane to improve traffic flow and reduce peak-hour congestion for vehicles exiting Sanibel, City Manager Dana Souza said.
Sanibel experiences heavy westbound traffic in the mornings and heavy eastbound traffic in the afternoons. The congestion has negative impacts on emergency response times and the quality of life on the island.
Ian Rairden, P.E., presented Kimley-Horn’s report to the council on Tuesday, Dec. 16, which concluded it is not feasible to safely create three travel lanes within the existing dimensions of the causeway. Rairden said Kimley-Horn looked at safely restriping the bridge road and modifying the bridge structure to accommodate three lanes.
As part of this feasibility study, Kimley-Horn reviewed the current causeway cross-section against lane-width standards established by the FDOT Design Manual, the Florida Greenbook, and the American Association of State Highway and Transportation Officials (AASHTO).
The Sanibel Causeway, owned and maintained by Lee County, is a two-lane, undivided roadway that spans three bridges – one high-span and two low-level – and two man-made causeway islands. The roadway is 40 feet wide, with a 12-foot eastbound lane with a 6-foot shoulder, and a 12-foot westbound lane with a 10-foot shoulder. There are no dedicated pedestrian/bicycle accommodations on the bridge.
Rairden said the minimum roadway width is 41 feet, with an optimal width of 56 feet for three travel lanes. The feasibility study concluded that restriping the bridge is not viable because it compromises safety to an unacceptable level, exposes the county to liability, and is unlikely to receive approval from the Lee County Department of Transportation.
And widening the bridge would require significant structural changes with construction costs of up to $50 million, and potentially challenging permitting. That may make expanding the bridge financially impractical at this time, Rairden said.
City Manager Dana Souza told the council he had sent the Kimley-Horn report to Lee County DOT Director Rob Price, who concurred with the report and indicated the county was unlikely to approve either alternative due to safety, liability, and financial concerns.
Souza also mentioned the rail barriers along the causeway.
“When you look at the barrier from the outer lanes (on other regional bridges), you’ll see a jersey barrier or hard barrier compared to the Sanibel bridge, which has a rail,” said Souza. “When the causeway was being constructed, there was a desire from Sanibel not to have that hardened barrier.
“(The rail) met the construction standards for a two-lane road, but any restriping of (the roadway), if a vehicle were to hit it, the rails could be more vulnerable to failing compared to other barriers,” Souza said.
He added that Kimley-Horn understood the city’s desire to create a third travel lane on the causeway and looked at every alternative for feasibility.
Kimley-Horn Senior Planner Bill Waddill told the council that the causeway’s width is too narrow to meet even the bare minimum standard of 41 feet for a third lane. And even then, it would be under certain conditions and probably not on a bridge with a fixed barrier at the edge of the shoulder. He said the DOT wants a minimum width of 53 feet.
“I think it’s really important to think about the context of the bridge we’re talking about, and whether it is the appropriate case for the bare minimum of the most lenient standards. It is probably not the answer, and, as the city manager mentioned, the county agrees,” said Waddill.
Council Member Richard Johnson said he doesn’t see how the council could make a decision that would take the existing span at 40 feet and make it work for three lanes. “I wish I could wave a magic wand to make it happen because three lanes is exactly what we need,” he said.
Johnson added that the city should think about how to work with Lee County to add an additional travel lane. “I think we need to accept this information and recognize the hard facts and turn our attention to an alternative, which I would say is begin to approach the (Metropolitan Planning Organization) about building a third lane instead of restriping the bridge.”
Mayor Mike Miller said he agreed with Johnson. “We asked our consultants to look into the feasibility of restriping, and you’ve answered the question. So, now we are on to alternative two. It will be difficult and take years and years and years to get that much money, but we should start.”
The council agreed that the city has done its due diligence, and the only option is to redesign the bridge, which is a county issue. And the council unanimously accepted the Kimley-Horn feasibility study.
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