Also, I'd like to see Soldiers' Field Road eastbound feed directly onto the eastbound pike - and conversely the westbound Pike allowing a direct exit onto westbound Soldiers Field Road. Combined with Back Bay exit ramps on the pike (another necessary improvement), this would eliminate the need for Storrow as a limited-access highway.
Could be easily done. The train yard extends underneath the whole length of the elevated Pike, so most of that space is going to be vacated without any practical new use. Since the viaduct has to stay due to cramped space you could easily tuck longish collector/distributor ramps underneath it taking you to/from the Pike, Soldiers Field Road, and BU Bridge/Comm Ave./Mountfort St. connector. There's already that no-man's land space/hobo park and the authorized vehicle Pike access ramp on the Storrow side which could be repurposed, so that's where you can ramp up to the Boston direction of the BU Bridge. There'd be other nooks and crannies to fit ramps going outbound. It would provide a bona fide downtown traffic siphon off of Storrow, and you'd have better ramp options on the relocated Pike to hit every direction Allston and Cambridge way with well-organized flow and no surface disruption because it's all tucked under that dank viaduct.
The only remaining tracks underneath the viaduct after the yard closes will be the Worcester Line thru tracks and the Grand Junction branch split that peels across the river. If ramps had to traverse the tracks they could either put the tracks in a short/cheap cut-and-cover tunnel box, exactly the same make as the one at Wellington where the Orange Line and Haverhill Line dip under the junction with the Medford branch freight line that has to cut across them both. Or, they could dip the road ramps quickly underneath the tracks like the Storrow underpasses at River and Western.
That's your enabler for tearing down Storrow, which could be done this way:
1) Traffic-calm Soldiers Field Road by eliminating the underpasses at River and Western and do an at-grade boulevard (with reclaimed parkland!) that segues past River onto these under-viaduct collector/distributor ramps. This keeps thru traffic off of the stoplight-heavy western half of Memorial Drive. You don't need the underpasses anymore because Cambridge St. traffic will be vastly lower in that vicinity with the Pike ramps at the tolls now near Harvard Ave. for Allston/Brookline-bound traffic and the street grid in the middle now restored.
2) Add another exit further west at the Leo Birmingham Parkway roundabout, connecting to the western terminus of Soldiers Field Road. This places egresses at either end of Soldiers Field Road so that road can distribute all Harvard-bound traffic that peels some distance away from the Pike, better-utilizes the excess capacity of some of the often-empty river roads out there, and gives quick Watertown access while taking a load off the awful Newton Corner setup where ramp congestion often backs up a half-mile onto the Pike itself.
3) Tear down all of Storrow east of River St. to Embankment Road. Re-use University Road and the eastbound Storrow lanes under the BU Bridge as your entrance from Comm Ave. and the Mountfort connector to the collector-distributor ramps underneath the viaduct. You've now got a full river roads circuit and have your Storrow-replacement alignment in place. The only eastbound traffic you're diverting to Memorial Drive is onto the largely stoplight-free eastbound portion better-designed for flow and traffic calming.
4) Put the next Pike exit at Charlesgate, replacing the Bowker Overpass on Storrow. Your traffic flow now also aligns with the feeders--Mountfort and Charlesgate--to two sides of the Emerald Necklace parkways, which have some excess capacity to tap and are already designed with traffic-calming features. You have both sides of Kenmore and Fenway flanked with exits to split up the traffic and keep it from cramming through all in one direction from the Bowker boondoggle. And you're utilizing Boylston St.'s higher traffic capacity and straight alignment to get to Mass Ave., Back Bay, and Longwood without clogging up the Kenmore area making turns at traffic lights or dealing with the crazy Bowker ramps.
5) Add an eastbound entrance-only ramp at Boylston and Cambria streets to bypass Back Bay on the Pike and complement the existing westbound entrance ramp at Newbury (which will get much higher use now as a toll-free bypass to BU/Soldiers Field Rd.). This trades off the traffic increase on Boylston from Charlesgate by peeling off thru traffic that would otherwise clog Back Bay, and keeps your Pike entrance/exit traffic from having to make turns or hit too many lights (helps Mass Ave. a lot).
6) Make all of these ramps toll-free so the locals are encouraged to use them. Keep the Allston tolls for thru traffic, and maybe reinstate the Newton tolls as trade-off for making all Allston exits free. But it's important to allow for free movement at the neighborhood level so as much of this traffic as possible is off local streets and kept well-hidden in the Pike canyon.
