State highway officials have a big plan — three big plans, actually — to reshape the Massachusetts Turnpike in Allston.

The immediate reason for the project is the need to replace the viaduct that lifts the turnpike above the commuter rail tracks along Soldiers Field Road. But officials hope to use the opportunity for more grandiose improvements: realigning the highway, creating a West Station commuter rail stop, removing the labyrinth of twisting ramps and access roads, and creating an orderly grid with new streets, paths, and possibly more parkland along the Charles River.

So far, they have three ideas about how to fix a choke-point in the so-called “throat’’ area just west of the BU Bridge, where the turnpike meets the viaduct:

■ Replace the viaduct with a section of elevated highway and shift Soldiers Field Road inland from the Charles River, at a cost of $1 billion. This approach would have the added benefit of opening more parkland along the Charles.

■ Remove the viaduct and rebuild the turnpike at ground level, while putting one set of commuter rail tracks on an elevated platform above the highway, for $1.2 billion.

■ Create a solid block of rail and roadway at ground level, for $983 million.

Whatever the eventual plan, the state anticipates breaking ground on the project in 2020.