<i>Electric powered passenger trains could easily negotiate the grade from
Old Saybrook station to a high level fixed bridge over the Connecticut
River.</i>
Realistically? A 2% or better grade, especially if the train's at speed. If modern HSTs were used, make that 4%.
<i>The channel in the Connecticut River is kind of shallow and I am
not sure how big of a boat could make it to Hartford. Got to keep it open
though for the "high rollers" to get up in there with their sail boats or all
hell will break loose. </i>
There's also oil barge and other traffic on the river. I still think tunneling under a few of these would be better long term. If it's shallow there, then a trench and drop operation could be done. For freight? Well, you'd just either have limits, or make the tunnel bigger.
<i>As for Bridgeport, on second thought, leave the bridge and the station as is and on the viaduct between old Burr Road and Jenkins Curve, dig down and build a tunnel straight out, two tracks for any train that does not need to stop at Bridgeport.</i>
A bypass tunnel here could save big time if it could run trains through at existing track speeds. It could also be done without much in the way of traffic disruption. I bet it could be done cheaper than it sounds, since there'd be a somewhat more relaxed work schedule. Most of the tunneling would be 'on land', where cut/cover can be done (cheaper). Probbably wouldn't be too much extra to make it ready for 4 tracks, so when Bridgeport's urban decay catches up with them again, the station can be relocated...
<i>Another thing, if the sub base at Groton were to be closed, I wonder how high of a bridge would be required for the remaining boat traffic at that location. </i>
I'm wondering why they need a drawbridge for submarines
<i>The biggest question at this point to me is, what is going to happen first? Will the problems be corrected before the bridges in question reach a point where they can no longer be used?</i>
The latter. These bridges are probbably at or beyond the end of their useful lives. There's likely just nothing more that CAN be done.
<i>There is no really practical alternative route at this point either if any of
these bridges become disabled. Providence and New London - no service.
Boston, well the B. & A. through Springfield is single track and not really
a practical alternative. CSX is having enough problems handling the
existing freight traffic. </i>
For all intents and purposes, Amtrak service between NYC and Boston simply won't exist. Even with regular engine changes at New Haven, the ridership fall off will be so severe that Amtrak will be in <i>serious</i> trouble. Given what the jump in ridership was after electrification (on the order of 30%), and the rise of the $10 'Chinatown' bus, plus increased airline competition...
<i>Realistically, we are in a very sorry situation so far as the entire northeast corridor is concerned.</i>
And nobody's even bothering to discuss the Baltimore tunnels, the traction power into Penn, the growing catenary and signal troubles, the age of the Amfleet, the backlog of motor failures, the bridges in Maryland, the ever flakey Portal draw...
The CT bridges aren't the only problem, they're just the one getting the attention.
If the NEC comes apart, Amtrak is dead, pure and simple. Besides losing their biggest market, congress really won't want to hear excuses as to why the US's most important rail corridor (by far) isn't functioning.