Another shortsighted project, the Beverly bridge was rebuilt 3 years ago, in hindsight they should have built it to be the same height as the auto bridge next to it negating the need for a draw.
Not enough room to incline-up to fixed level from the March St. overpass on the Salem side is the answer there. They could've tried replacing the swing with a variable-height lift and wider navigation channel so the boats clear faster when it's open, but that's it.
Mind you, we aren't talking Cos Cob on the NEC in terms of high-stakes traffic here. It's only a moderately busy waterway in summer, and boat traffic is nearly zero in winter. It's no problem for running Rockburyport RUR. B&M ran much higher overall traffic levels through here back in the day.
The only issue is this putting all eggs in Beverly's basket thing TM is hung up on. You are going to have outbound correcting pauses on the Salem main platform for openings, and are going to have to scramble a couple close-succession bunched inbound slots in recovery from an opening. With or without electrification, and with or without this "we're electrifying but 90% of the schedules are still going to be diesel" cognitive dissonance in the report. It leaves the clock-facing schedule adherence a bit on the brittle side. You have no such brittleness if you work the Salem Peabody-side turnout because pattern #3 plays the smooth-out role that buys more bandwidth for the swing bridge pauses. The only thing that makes the bridge a bottleneck is chaining it in a trio with the Salem main platforms + tunnel and winging it as an ironclad requirement for 100.00% of service. You don't need to do that. With Salem having such high potential as a breakaway bus hublet you also don't have strong reasoning for being so severe/absolutist about the Bev mandate. I mean...they're going to average :15 at Bev Depot any which way as happenstance byproduct of the Newburyport & Rockport endpoints netting :30. Just
clock-facing wise it's going to be 15 +/- 3 during heavy bridge use times with *potential* for a too-close unidirectional bunching meriting a one-off skipped or rescheduled headway. The day-long average is still :15 amidst the variability.
You're just careening self straight into trouble shouting out a mandate that it's got to be :15 on-the-minute every single time all-day or else we've failed / it's a miscarriage of "justice" / everything is horrible.
That's where TM is getting itself into trouble...on the mandate that specs Beverly or bust. In the real world people are not even going to notice the small wobble in arrivals around the bridge. And in the real world you
can hit all of that exactitude by playing the supporting options at Salem, so it's a very arbitrary difference that's small-potatoes for any above-and-beyond upside and a bit too much downside that the wobble in arrivals is going to bite them on the rigid clock-facing.
Now...if you want to sound an alarm about a drawbridge reno that SHOULD be changed into a fixed conversion, Saugus Draw rehab is in-design right now. That one is REALLY pointless, because there's all the room in the world to incline-up on both sides and if BLX-Lynn ever happens there
has to be a fixed Saugus River crossing. The correct decision there would be to buid a 2-track deck fixed replacement with 4-track piers so BLX can be slapped on later. Instead we may have a completely rehabilitated bascule with a wholly structurally-separate rapid transit fixed bridge needing to be built 15 years later 20 ft. next to it. That'll look
extremely dumb on the side-by-side comparison. Saugus Draw is a nothingburger for train traffic because GE does nothing for barge traffic anymore and the uncontrolled silt runoff from Rumney Marsh runoff is a goddamn ecological disaster that's choked the rivers off of most practical navigability in the last 50 years. Not going to impact the mainline layer-cake of services but once in a blue-moon hiccup. But, damn, is rehab-over-rebuild going to look silly-shortsighted when we have to duplicate-build the fixed BLX span right next to it on the same river.