THE PANEL OF experts tasked with redesigning a 1,500 foot stretch of the Massachusetts Turnpike and rail tracks running along the Charles River has thrown a new wrinkle into the plans, coming up with a concept that would keep the highway and trains traveling along the ground while elevating a section of Soldiers Field Road.

The plan, a takeoff on the so-called hybrid model that will be one of three options presented in a report to Transportation Secretary Stephanie Pollack on Friday, would also allow a wider pedestrian and bike path along the Charles while increasing green space.

“The report won’t be perfect… but it will be awfully close,” joked Jack Wright, an engineer with Weston & Sampson who is leading the Independent Review Team that is drawing up the designs and fashioning the report by the Friday deadline. “We could spend another year and I don’t think we’d be closer to having a moment where we say, ‘Aha, here’s the answer.’”

The team of engineers and architects was given 90 days to come up with drawings based on recommendations from a state Draft Environmental Impact Report for the estimated $1 billion project. The report had three options for the stretch of road that climbs and curves around a fallow area of land owned in part by the state, Harvard University, and Boston University. Tearing down the old viaduct regardless of which option Pollack picks will open up much of the land on the northern side of the Pike for Harvard to develop.

Ilyas Bhatti, an engineer on the review team and former commissioner of the Metropolitan District Commission who now teaches at Wentworth Institute of Technology, said the plans are for construction to begin in 2021 and be completed in four years.

One of the options is to remake the highway much the way it already is, with an elevated structure carrying Mass Pike traffic over heavy rail and commuter train tracks as well as rebuilding Soldiers Field Road so the four lanes would run below but alongside the westbound side of the Pike. It would create the widest lanes on the Pike at 12 feet.

That option would not require taking any land from BU but would use the existing footings for the viaduct and run the trains underneath, potentially creating noise problems. And, while it allows for expanding green space and the Paul Dudley White Path, it would be the most difficult design to build pedestrian and bicycle access across the elevated structure from the BU side.

Another option would leave all vehicles and trains at grade level, eliminating any elevated structures and running the Grand Junction Line, the tracks carrying the heavy commercial trains, raised up on fill. The at grade option would require taking up to seven feet of land from BU over about a 500-foot stretch and would have the most impact on the Charles, with part of the river getting filled in to accommodate the White Path.

Wright told the several dozen transportation and neighborhood advocates who gathered Wednesday evening in Brighton for the presentation that BU has been involved in the discussions all along the way.

“They’ve certainly been cooperating and continue to be cooperative,” said Wright, who had previously worked with transportation officials on the redesigned Green Line Extension. “We’ll find out how much cooperation costs later.”

The third option the team was given was the hybrid model that initially had the Grand Junction Line raised up on a viaduct with everything else at or below grade, with the eastbound Pike traffic running underneath. The option required taking BU land but the impact on the Charles would be minimal.

But the team drew up another hybrid alternative that would run the commercial trains on the ground while elevating Soldiers Field Road on a smaller viaduct running over the four westbound lanes on the Pike. The smaller viaduct would create an even larger green space and allow for a wider pedestrian and bike path along the Charles.

Not everyone was taken with the new design. Richard Dimino, president and CEO of the nonprofit A Better City, advocated for the at grade option and recommended looking into a “high line” structure for the White Path that would make it easier to connect with a pedestrian overpass while minimizing the infringement on the Charles.

Dimino also urged the team to reconsider the timeline that allows for 30 days for comments but does not permit the draft report to be influenced by the suggestions. He also pushed Wright to include more precise cost estimates for people to gauge what the better options would be for cost and “constructability.”

Former transportation secretary Fred Salvucci, who was the mastermind behind the Big Dig, the last major highway reconstruction of this magnitude, said eliminating the curve is a paramount priority for the redesign, something he said the hybrid and grade level models do but not the viaduct alternative.

He also lobbied for the Legislature to pass a bill that would mandate green space set-aside before any design is approved.

“The way to fix that is at the front end of the project,” Salvucci said during a question and answer period of the presentation. “You can say ‘this much is going to be green, there’s no fooling around.’ It should be built into that statute so there’s no reduction in green space.”

The draft report will be given to the Department of Transportation on Friday and then made public during the board meeting on October 15. Beginning October 17, there will be a 30-day comment period and Pollack is expected to decide soon after. The report will include pros and cons of each of the designs but will have no recommendations or preferences.