Providence Alignments

Of all the cities served by the Northeast Corridor (NEC), Providence has the most severe alignment problem.

Providence Station: Inadequate for the purpose

Providence's current alignment is relatively new. It was installed in the 1980s, to reach a new train station replacing one being decommissioned. It is also, in every way, objectively inferior to the alignment it replaced. There are two major deficiencies associated with this alignment: (1) excessively sharp curvature in the station approach, and (2) undersized station facilities. Figure 1 shows the current alignment (in red) and the old New Haven (NH) alignment, where divergent from the modern one (in purple).

Figure 1: NEC and NH legacy alignment

Figure 2 shows the difference in curvature between the modern and historical alignments.

Figure 2: NEC and NH alignments in DT Providence

From these figures we can ascertain characteristics of the two alignments. The original NH alignment bypassed Providence city--still in use--to reach its main train station, along Exchange Terrace. There, it crossed the Woonasquatucket and Moshassuck Rivers just above their confluence into the Providence River, and diverged. One route headed north to Pawtucket, where it split into routes to Woonsocket and Attleboro. The other crossed Main and Canal streets, and ran through the East Side railroad tunnel, across the Crook Point bridge, and through Rumford and North Seekonk, returning to the NH mainline south of Attleboro. This latter route was built as a freight bypass, but it also proved an important commuter connection from Providence to Bristol and Fall River. The NEC, meanwhile, follows the old NH (originally: Boston & Providence) mainline north to Pawtucket and then east to Attleboro.

Providence Union Station: Adequately sized, unusable

Providence Station, meanwhile, was built to replace Union Station in the mid-1980s. While it improves on the curvature characteristics viz. the old NH mainline, it appears that planners never considered the superior track geometry the old freight bypass offers. Furthermore, the station was built to handle rail traffic at its nadir, and as traffic is increasing, the station is reaching capacity. Indeed, were Providence to have a fully built-out commuter rail network--one possibility is shown as Figure 3--the station would be utterly incapable of handling the demand load. Worse, its predecessor--although still in place--has seen irreparable damage against any possible return of the railroad. The ROW is unusable between I-95 and Canal Street.

Figure 3. Providence commuter rail possibility.

So we now turn our attention to what it would take to actually introduce heavy infrastructure so as to solve these stated problems. Looking to implement low-curvature routes, three options present themselves--each would have its own station facilities. None are cheap.

The waiting room is a bit...small...for a major NEC station

To see the maps I generated for this post, see linked here and here.

The Options

Figure 4. Option A: Providence-state line tunnel

Figure 4 shows Option A. This option parallels the existing NEC, but eases curvature through the construction of a cut-and-cover tunnel under US 1 to Pawtucket, and along Cottage Ave. thence to the state line. Almost incidentally, it eases the moderate curvature around Pawtucket. The diagram shows some curvature around the Blackstone crossing, as it's assumed to follow existing easements wherever available; a deep bore nullifies that.

However, this is a lengthy tunnel--the distance from downtown Providence to the state line is about the same as the length of the Philadelphia tunnel proposal I demolished at length some time ago. And while Providence's infrastructural need is greater than Philadelphia's, one look at the old NH freight bypass suggests it's not that much greater.

Figure 5. Option B: Providence River tunnel

Figure 5 shows Option B. This was the first option that drew my eye on the map--the idea is to eliminate the station curve entirely, something none of the other options do. Unlike Option A, the tunnel is of moderate length.

But also unlike any other option, this one suffers from multiple shortfalls. First, it's the only option with extensive sub-water-table tunneling. The alignment is quite literally waterside. Unlike any other alignment, an entirely new intercity station site must be built--and the best place looks to be quite literally under the confluence of the Woonasquatucket and Moshassuck rivers into the Providence. Part of this alignment lies under semi-active port facilities. And finally, this alignment has a sharp curve that just will not go away. It offers no time savings over the existing Providence bypass.

Figure 6. Option C: New East Side tunnel

Figure 6 shows Option C. This alignment would run a new deep-bore tunnel under the East Side and link up with the old NH freight bypass--with excellent track geometry--in East Providence. Its curvature, while constant, is also gentle, and it has far less length, and hence cost, associated with it than Option A.

It is still, however, a deep bore tunnel.

Figure 7. Option D: "Option-C-cheap"

Figure 7 shows Option D, or perhaps "Option-C-cheap". Like Option C, it links Providence Station with the old East Side line. Unlike Option C, it does so far closer to the city, linking a short bore tunnel under the Moshassuck and part of College Hill with the existing East Side Railroad Tunnel and running across the Crook Point Bridge.

However, in some ways this proposal reeks of a penny-wise, pound-foolish attitude. Not only does it itself have the sharpest curve of all the proposals, despite its brevity, it also fails to ameliorate the lone sharp curve on the NH alignment--at Crook Point. It is perhaps better suited to regional rail than true HSR.

Crook Point bascule bridge, abandoned 1976

Finally, please note Figure 8 below, with all four options superimposed on the legacy alignments, to give one a sense of how each of these stack up against each other.

Figure 8. All four proposals to the same scale.

Ranking the Options

Ranking is somewhat subjective, but my primary criteria, in order of importance, are

• Cost
• Length
• Curvature

As all of these proposals involve a new platform level (at the very least), we can assume that cost is fixed. What we are therefore looking at is thus cost per unit length of tunnel. Of these, Option A is (probably) the least expensive, and Option B (definitely) the most expensive. But looking at the criteria, we find

• Option A. Cost: -. Length: -. Curvature: +
• Option B. Cost: -. Length: +. Curvature: -
• Option C. Cost: +. Length: +. Curvature: +
• Option D. Cost: +. Length: +. Curvature: -

Option C clearly wins out--but it is not quite the most incrementalist approach available.  

East Side Railroad Tunnel--West Portal

That would be to start with Option D, implementing Option C as and when further funds become available--perhaps as part of a package dedicated to fixing Along the Shore's significant curvature issues in Connecticut. In the meantime, Option D offers expanded station facilities, a better Amtrak alignment, and a platform to develop better--and perhaps, eventually, comprehensive--Rhode Island rail service.

New Haven operations in MA and RI

A look at the core of Figure 3's schematic--Figure 9--displays this, with the East Side line and Option D linked up to create an S-Bahn-esque core.

Figure 9. Figure 3's core network

Conclusion

Ultimately, while Providence's future is its own, what the New Haven left behind was a framework of easements that can provide it with excellent commuter rail. And what the Northeast Corridor needs today is HSR geometry. Hopefully we can do the right, the incremental thing--reactivating the substantial underutilized/disused infrastructure, while judiciously inserting HSR infrastructure where needed. This needs Organisation vor Elektronik vor Beton to happen, though--not the Beton-first mindset our transit agencies always seem to have.