F-Line to Dudley
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The state's incredible disappeared 2024 fantasy Indigo did no traffic modeling whatsoever on whether the Grand Junction could even handle Indigo-spec frequencies. Based on what the Worcester-North Station peak-direction only study showed, chances of ever attaining 15-20 minute frequencies on the GJ without doing more harm than good to local street traffic look poor at best. Somewhat contrary to conventional wisdom, Broadway fared much worse than Mass Ave. on queue backups...though Mass Ave. was hardly a picnic.
This runs headfirst into the same problems as in many previous fantasy maps:
Further, reference the Worcester-NS commuter rail study. Schedule times over the Grand Junction are 1:1 equal with an Orange Line transfer @ BBY during all non- crush load hours, and Red transfer @ SS to Kendall is likewise equal when the Red Line isn't suffering under load. It's within the 2-minute schedule padding margin for error. An upgraded Grand Junction's top speed truly is that low because of the extremely sharp curves and grade crossings. This is why the Worcester study proposed zero off-peak or reverse-commute service, and only specced 5 unidirectional A.M. peaks to North Station and 5 unidirectional P.M. peaks from North Station. Directs at any other time including the later peak hours near shift-changes offered no added benefit over Orange or Red transfers. Thus, the only problem they addressed was Orange and Red's fast-decaying reliability under load. A problem that could be fixed for ALL hours of the day, including peak, with the necessary Orange and Red signaling and platform upgrades through downtown and long overdue radial relief builds like Red-Blue. In fact, on the off-peaks keeping stiff Worcester (or Indigo-Riverside) to the southside terminals was better overall at attracting ridership than forking the route in Allston for off-peak directs...simply because frequencies > one-seat.
^^The supposed convenience of a direct gets very overrated if it costs true Riverside Indigo any frequencies into BBY or SS. Frequencies are king. Diluting frequencies is a problem. And, again, doodling with mainline train service on the Grand Junction is not a good use of resources if it defers any effort away from fixing Orange's and Red's attrition under extreme load. This is a solution in search of a question, not an easy answer to a burning need. We only get answers by doing the dirty work on downtown congestion, and the Grand Junction only becomes a scalable solution if the mode gets outright changed to LRT or BRT where steeper-grade crossing eliminations at Mass Ave. and signal management can be shared with the roads at Main + Broadway.
Rest of it isn't as fatally flawed on the RR mode as the Grand Junction, but there are still unsolvable problems at:
Sullivan. . .
Eastie. . .
But worst of all, the schedule is going to be unmanageable on a DMU with how many speed restrictions it has to pass through en route. Only the mainline portions of the Worcester Line and Eastern Route are going to allow the vehicles to rev up to track speed between stops. It's 20-30 MPH in the entire middlesection on the Grand Junction + 10 MPH through the terminal district. Then probably not more than 20 MPH with the airport terminal spur if it has to be viaducted or run on an at-grade side reservation through extremely dense thickets of service driveway curb cuts and access road grade crossings. 15 minute turnarounds are going to be impossible with those performance extremes segmenting a single schedule. I think you'll be lucky to make it 25 min. frequencies, which is not useful at all.
There's no permanent solution here except real-deal Urban Ring. That's why none of the UR study options ever made passing mention of a DMU.
This runs headfirst into the same problems as in many previous fantasy maps:
- The corridor works tremendously better on light rail or BRT because every intersection can have a proportionally shared traffic light cycle. This is the only way to make the grade crossings manageable.
- Mainline rail always has the complete and total right of way at grade crossings. No exceptions, because mainline rail must make no assumptions of different rules for different vehicle types at a crossing. So traffic will always stop dead for the train, at any time there's a train, and obey the default crossing timings. And that is the sum total difference between fouling the heaviest-traffic crossings such that flushing the resulting queues locks up Kendall Sq. and LRT/BRT being able to prevent those backups by obeying the road signaling.
- Time-separation exemptions can't be sought to get around this problem because the service schedules being proposed here intermingle with mainline traffic on the Worcester Line and Fitchburg Line at either end.
- Eliminating the problematic grade crossings is impossible on RR mode. There is not enough run-up space at recommended grades for new construction to eliminate Mass Ave. or Broadway. Main can't be eliminated at all because of the air rights overhang. Tunneling under the Red Line at Main is impossible because of the risk of storm drain effect breaching the Red tunnel at the landfilled shoreline of the ancestral Back Bay, should the Charles Basin suffer a breach from sea level rise in the Harbor. Main St. is Cambridge's pre-1900 ancestral shoreline. It's impossible to run in a cut at Mass Ave. because that's deep in the heart of the 1900-05 landfilling and likewise at risk for becoming a canal in a Charles Basin flood event. The only way you can eliminate Mass Ave. is with an LRT/BRT overpass. Main will never be eliminable. Broadway...*maybe* on trolley. But there are no "Yeah, but. . ." super-Crazy Pitches that get this separation done for a DMU. We've wasted page after page and map after map on prior discussions slamming heads into wall trying to create a boondoggle big enough for mainline rail grade separation on the Grand Junction. It is physically impossible...because the waterproofing considerations for sea level rise and Charles Basin mitigation make it permitting-impossible. As well as patently insane when LRT overpasses are physically possible for every crossing except Main at billions less than DMU grade separation.
Further, reference the Worcester-NS commuter rail study. Schedule times over the Grand Junction are 1:1 equal with an Orange Line transfer @ BBY during all non- crush load hours, and Red transfer @ SS to Kendall is likewise equal when the Red Line isn't suffering under load. It's within the 2-minute schedule padding margin for error. An upgraded Grand Junction's top speed truly is that low because of the extremely sharp curves and grade crossings. This is why the Worcester study proposed zero off-peak or reverse-commute service, and only specced 5 unidirectional A.M. peaks to North Station and 5 unidirectional P.M. peaks from North Station. Directs at any other time including the later peak hours near shift-changes offered no added benefit over Orange or Red transfers. Thus, the only problem they addressed was Orange and Red's fast-decaying reliability under load. A problem that could be fixed for ALL hours of the day, including peak, with the necessary Orange and Red signaling and platform upgrades through downtown and long overdue radial relief builds like Red-Blue. In fact, on the off-peaks keeping stiff Worcester (or Indigo-Riverside) to the southside terminals was better overall at attracting ridership than forking the route in Allston for off-peak directs...simply because frequencies > one-seat.
^^The supposed convenience of a direct gets very overrated if it costs true Riverside Indigo any frequencies into BBY or SS. Frequencies are king. Diluting frequencies is a problem. And, again, doodling with mainline train service on the Grand Junction is not a good use of resources if it defers any effort away from fixing Orange's and Red's attrition under extreme load. This is a solution in search of a question, not an easy answer to a burning need. We only get answers by doing the dirty work on downtown congestion, and the Grand Junction only becomes a scalable solution if the mode gets outright changed to LRT or BRT where steeper-grade crossing eliminations at Mass Ave. and signal management can be shared with the roads at Main + Broadway.
Rest of it isn't as fatally flawed on the RR mode as the Grand Junction, but there are still unsolvable problems at:
Sullivan. . .
- You can't claim the third Orange Line track for a RR capacity expansion at Sullivan station because of the Community College-Sullivan viaduct that carries Orange. It inclines down to level within feet of the southern tip of the Sullivan platform. There's not enough room to turn out and claim Track 3 for Indigo. This means a commuter rail station must occupy the existing highly congested tracks shared by Haverhill/Reading and Newburyport/Rockport. The Western Route is already capacity-pinched by the Eastern Route's bigger capacity appetite, so plunking a mainline station at Sullivan starves Indigo to Reading of slots. That junction on the Somerville side of the river is the #1 capacity limiter.
- You can run 15-min. turnarounds to Reading if certain upgrades were made to that junction (i.e. a 2 x 2 track split for contiguous double-track to the foot of the Mystic bridge next to Assembly, instead of the current 1 Western x 2 Eastern). Plus other basic passing track upgrades further outbound, and punting the North Wilmington-Haverhill thru trains to the more capable Lowell Line + Wildcat. But pinch that junction further with a Sullivan CR station, and headways to Reading top out at much wider and less useful spacing.
- You can't use the outer Yard 10 freight tracks at Sullivan with a DMU to sidestep the Eastern/Western mainline split because of the speed restrictions of passing through Boston Engine Terminal and the freight wye to get there. Passing through Brickbotton would be a hideous schedule drain because those tracks are entirely inside yard limits capped at 5-10 MPH. And, the duck-under tunnel required to hop under the Orange Line to hit the Eastern Route before the bridge would be convoluted, require long inclines, be very speed-restricted by need for a slight curve and lack of running room for climbing the very steep grade of the Mystic Bridge so soon after the portal, and extremely expensive. Those outer tracks are easily claimable by LRT/BRT Urban Ring where the duck-unders to hop sides of the OL tracks can be steeper, simpler, and faster for those more nimble vehicles.
Eastie. . .
- It is possible to snake tracks along the Haul Road on the Eastie side of the river. Only part of the old retaining wall-framed RR cut was excavated for the truck haul road, with much of the latter-era earthen embankment retained. Widening the East Boston ROW out to its full dimensions with full retaining walls creates ample room to squeeze 2 tracks next to the realigned truck + SL Gateway pavement. A light rail Urban Ring would do exactly this. It is also possible to run mainline street-running rail--single-track, at least--over the Chelsea St. bridge without having to build a parallel drawbridge. It would be hideously slow, but street-running (or swallowed-sidewalk running) is allowed on new-construction bridges very similar to Chelsea River.
- However, there is no path into Logan-proper on mainline rail. Never was, never will be. Not with the available bridge underclearances from the Mass Pike for slipping over the Blue Line, not with the clearances on the terminal underhangs, and not with the space available next to the access roads. You definitely can't hang a schedule on street-running mainline rail if it has to go all the way to the terminals; what works for zipping across one movable bridge isn't a solution the rest of the way. If this were an LRT/BRT terminal loop you could build a relatively lightweight and low-profile viaduct to maintain the grade separation. Building a loop for a 263,000 lbs. mainline railroad minimum spec is going to be ghastly expensive, and require massive rebuild of the area around the terminals access roads to attain the clearances.
- Transpo Bloggers' Golden Rule #18: Mainline rail airport connectors are O-V-E-R-R-A-T-E-D. Read Alon Levy & others on this. They are money pits that don't generate the ridership, but conventional wisdom is utterly addicted to them in the face of empirical reality. What's justifiable and works quite well on a relatively low-profile mode like SL1 just doesn't draw ridership on a mainline deviation. Especially one that has as many slow painful zones as this tarted-up DMU ring. Don't take my word for it; read the reams of damning evidence online.
But worst of all, the schedule is going to be unmanageable on a DMU with how many speed restrictions it has to pass through en route. Only the mainline portions of the Worcester Line and Eastern Route are going to allow the vehicles to rev up to track speed between stops. It's 20-30 MPH in the entire middlesection on the Grand Junction + 10 MPH through the terminal district. Then probably not more than 20 MPH with the airport terminal spur if it has to be viaducted or run on an at-grade side reservation through extremely dense thickets of service driveway curb cuts and access road grade crossings. 15 minute turnarounds are going to be impossible with those performance extremes segmenting a single schedule. I think you'll be lucky to make it 25 min. frequencies, which is not useful at all.
There's no permanent solution here except real-deal Urban Ring. That's why none of the UR study options ever made passing mention of a DMU.