A vocal group in the East Link light-rail planning process says it has the answer to Bellevue and Sound Transit’s financial dilemma.

The two organizations have worked tirelessly to find ways to cut at least $60 million in costs, for which Bellevue would be on the hook. The new report by Building a Better Bellevue, which previously advocated for rail lines on the east side of Interstate 405 away from the preferred route on 112th Avenue where many of the group’s members live, posits that running the train underground through a bored tunnel could lead to a savings between $160 and $275 million.

The current route runs at surface level on Bellevue Way and 112th with a raised crossover from the east to the west side of the street. This route has been approved by the Bellevue City Council, Sound Transit Board and the federal authorities.

Building a Better Bellevue’s route would exit Interstate 90 and use the South Bellevue Park and Ride as envisioned by the current alternative, but it would then dip underneath Bellevue Way, and cross underground. The bored tunnel would then run along 108th Avenue Northeast all the way through a downtown tunnel. It would then exit a tunnel near Northeast Sixth Street, a cheaper option currently being discussed by the Bellevue City Council.

This route is similar to the C3T underground tunnel route in initial planning documents when the project was being envisioned. According to Sound Transit documents, the C3T alternative would have the train come out of the tunnel on Northeast 12th Street, right in the middle of Bellevue’s Hospital District. This was the preliminary drawback for the City Council at the time. This iteration of the route has the train exiting the tunnel in downtown, and running through the Hospital District as agreed upon by Bellevue and Sound Transit.

Proponents of the route agree that tunneling through the city costs more, but the tradeoffs more than make up for the difference.

“We acknowledge it costs more,” said Joe Rosmann, spokesman for Building a Better Bellevue. “It costs $148 million more to do tunnel as opposed to their current plan. But it’s all the other things that don’t have to be done where the real savings is going to be.”

According to the group’s estimates, eliminating a station between the South Bellevue Park and Ride and downtown, along with fewer property acquisitions and mitigation measures add up to the $275 million savings.

But many remain skeptical of the plan. Bellevue councilmember and Sound Transit Board Member Claudia Balducci called the plan an “extraordinary claim.” She said it would be great if the study turned out to be correct, but she was wary of the conclusions because options had been studied tirelessly, and results never showed tunnels to be the cheapest option.

“We’ve looked at a lot of underground options over the last five plus years, and every one single one has proven to be among the most expensive, sometimes by hundreds of millions of dollars,” she said.

Nevertheless, Balducci said, staff from both Bellevue and Sound Transit will examine the study. She said both boards need to find the right balance of considering all possible options and keeping the project on a good timeline for opening.

Sound Transit responded to the study as well, saying the claims of savings in terms of reduced costs for contingencies, and the elimination of mitigation were unfounded.

“The savings they are claiming are mostly resulting from assumptions of reduced scope, professional services, and contingencies without a clear basis,” Sound Transit said in a statement.

Sound Transit studied a deep bore alternative, according to the statement but it came out to be more than $200 million more expensive. Unless the board says otherwise, Sound Transit does not plan to further pursue this suggestion.

Rosmann said the study was conducted over a six-month time span. It was put together primarily by Bill Popp, a transportation consultant, and Al Cecil, a Building a Better Bellevue member and retired Boeing engineer. Cecil said he examined the track in 100-foot increments for estimating costs, using Sound Transit’s figures.