Islanders will get another opportunity to weigh in on a proposed rebuild of Dockton Road next week when King County transportation officials visit Vashon and put forward five possible scenarios for the future of the aging mile-long span.

The county’s engineering consultants have analyzed the impacts the five alternatives could have on various aspects of Island life — from water quality and wildlife to transportation flow and traffic patterns. They’ll display their analysis at the April 22 open house, using a brightly colored chart that shows whether the impact is positive, negative or somewhere in between.

“All of these alternatives have plusses and minuses,” said Linda Dougherty, who heads the county’s roads division and who will be at the April 22 open house. “We’ve developed a spreadsheet that allows us — through the use of some criteria — to lay out the differences so that people can see how (the alternatives) stack up against each other.”

The analysis also contains new information. The most expensive option — a full rebuild of Dockton Road along Tramp Harbor, with a cantilevered sidewalk for cyclists and pedestrians — is now expected to cost $20 million, rather than $31 million, the original estimate.

What’s more, engineers have put forward a new proposal, a slight modification of the full build-out: By raising the road a couple of feet, engineers could rebuild the two-lane span and add a sidewalk without the expensive cantilevering — a proposal that pencils out at $17.5 million.

“I was very pleased that the staff was able to realize that if you raise the road … you gain the width you need for a sidewalk,” Dougherty said. “That’s the kind of out-of-the-box thinking I like for us to be looking at.”

Other options include closing the road and rerouting the traffic — an approach that would transform the scenic stretch into a multi-use beachfront trail. The county has two versions of that project, both of which would cost around $12 million.

The open house, the second one the county has held on the project, will give county officials a chance to report back to the community, Dougherty said, and give Islanders another opportunity to respond.

“I want everyone on the Island to feel a sense of ownership in this project,” she said.

The nearly mile-long stretch of Dockton Road that runs along Tramp Harbor has long vexed county road officials. The seawall that supports the road is nearly 100 years old and made of wood, and the county has had to make some expensive repairs to it to keep it in place and the road safe.

Two years ago, the county issued a report that named this stretch of Dockton Road one of the most vulnerable road spans in the county and put money into its six-year capital budget for an ambitious rebuild.

The funds for the rebuild were cut from the budget last winter as the county grappled with a huge deficit in its spending plan. But Dougherty said she believes the project will eventually get the green light — especially because the price tag has dropped and it appears the project can be built in two phases.

“It puts it into a more affordable range,” she said.

Meanwhile, Islanders who attended a meeting with Dougherty and other county officials to prep for the open house expressed a range of opinions about the direction the county was heading.

Some, such as Frank Jackson, a Maury Island resident, said he was troubled to see that abandoning the road was still an option the county is considering.

“This is an important lifeline to Maury Islanders,” he said. “Even people like myself who are environmentally conscious realize this would be a huge impact and would gain next to nothing.”

But others questioned the county’s inclination to build an expensive new road at a time when many are concerned about the impact of traffic on the environment. Kate Hunter, for instance, said she wonders if there’s a way to reduce the number of cars — the county puts the daily traffic count at 3,000 — that pass over that road each day

“If traffic is the problem, let’s address it,” she said.

The meeting to discuss the Dockton Road seawall project will be held from 6 to 8:30 p.m. Thursday, April 22, at the McMurray Middle School multi-purpose room.