TriboroRX
From TriboroRX
Contents |
[edit] Introduction
In its 1996 Third Regional Plan, Regional Plan Association describes a rapid transit line in Brooklyn, Queens, and the Bronx that could be built almost entirely on pre-existing rail rights of way. The so-called Triboro RX (TRX for short) presents a unique opportunity to provide mobility and accessibility to New Yorkers living or working within these three boroughs, at a fraction of the cost of most transit projects of similar size. This web site documents a possible alignment for the Triboro RX, and a crude estimate of what levels of initial ridership one could expect to see if it were built. The results, as you will see, are encouraging to say the least.
| Right-of-way, near Brooklyn College and Flatbush and Nostrand Avenues [1] 
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See the Triboro RX right-of-way in Google Earth or in Google Maps.
[edit] Background
It is certainly not a new idea to study the prospect of a circumferential transit line running on an existing freight right-of-way. From the Third Regional Plan's Regional Rx proposal:
The bulk of the subway system was constructed to reach out radially from Manhattan to the outer boroughs of the Bronx, Brooklyn, and Queens to enable mass commuting to jobs in the Manhattan central business district. The high-density construction that these early subway lines made possible also generated many travel needs within the outer boroughs and between them. But the subways never catered to these needs that then had themselves created. A new transit line, the Triboro RX, running essentially perpendicular to the existing radial subway lines, would attract many outer borough transit riders, and by crossing existing lins would provide countless new intra- and inter-borough options. Twenty-three subway lines would be intersected at least once, with six others intersecting twice. Fortunately, most of the right-of-way is already available, in the form of the LIRR Bay Ridge freight line in Brooklyn (mostly 4-tracks wide), the New York Connecting Railroad in Queens, the lightly used Hell Gate Bridge between Queens and the Bronx, and the St. Mary's Park Tunnel in the Bronx, which would allow Triboro trains to reach across 161st Street to Yankee Stadium.
In the 11 years since the plan was published, there has not been any published work assessing likely ridership and travel benefits of Triboro RX, or to establish its cost-effectiveness. It would be an exciting exercise in any circumstance, but especially so in the context of Mayor Bloomberg's 2030 plan for sustainability and growth for New York City. The recent proliferation of high-quality open source geospatial database and web-enabled mapping software doesn't hurt.
[edit] Process
Given the RPA's proposal, what did this project actually consist of? Primarily, deciding on the location of the stations along this line, and then modeling the way people (commuters, specifically) would use it. Since the route is pre-determined by the existing freight rights-of-way, the former is pretty straightforward. The latter, on the other hand, involves several different data sources as input, a number of reasonable but specific assumptions, and a lot of data wrangling to produce some output.
[edit] Alignment
The primary guidelines for determining the Triboro RX alignment were:
- whenever possible, create transfers at intersections with existing subway lines
- stations should be spaced 1/2 mile apart
- stations should be located on major streets or other population or activity centers
Beyond these, the entirely subjective judgment of a born-and-raised Brooklynite (who, admittedly, has spent very little time in the areas through which this line would run) was applied. The result, shown above, is 21.8 miles of transit line with 38 stations, 16 of which have transfers to between one and five other lines.
Running from the Bay Ridge waterfront to Yankee Stadium through Central Brooklyn, Queens, and the South Bronx, the Triboro RX connects a diversity of New York neighborhoods, including Bay Ridge, Sunset Park, Borough Park, Flatbush, East New York, Brownsville, Cypress Hills, Middle Village, Jackson Heights, Astoria, and Mott Haven. While these areas vary widely in socioeconomic and ethnic terms, they share at least one important similarity -- a lack of connections to each other. Additionally, most of these neighborhoods have limited transit access to Manhattan. The Triboro RX plan and the neighborhoods it passes through are best explored using:
- this interactive map (with photos)
- or opening this file in Google Earth.
The right of way proposed for Triboro RX is the same one that would be used for feeding the Cross Harbor Freight Tunnel. Fortunately, much of that right-of-way is wide enough for four tracks, enabling local transit service to co-exist with heavy freight rail. Further discussion, questions, and downloads of the Triboro RX alignment can be found in the Alignment section.
[edit] Demand Model
Having chosen the location of Triboro RX's stations, the question remains -- how, and how much, would it be used? There are many ways to answer this question, but we begin by asking how many people would use it for their daily commute. We start here in part because the foremost use of mass transit is for commuting, but as well because nearly all of the data necessary to get a rough answer is easily, publicly, and digitally available.
The primary input used was the Census Transportation Planning Package, which actually quantifies and describes commuter flows between each pair of census tracts in the City, including their breakdown by mode (i.e. car, bus, subway, walk, etc). Given that, and the shape of the subway network, the task becomes to guess commuters' routes through the system on their way to work, how those routes would change if the Triboro RX were added, and how many new riders the Triboro RX would attract.
The model we constructed to understand commuter behavior was a simple and, in certain ways, fundamentally conservative. It consists primarily of an assumption about which subway stations serve which census tracts, and a generalized cost function of travel on the subway for comparing different routes between the same origin and destination. For the former, we use the rule of thumb that a census tract is served by a station if at least one half of the area of that tract is within one half of a mile of the station [2]. The latter is a bit more complicated, but is essentially defined by making time spent transferring and waiting for trains 1.75 times as expensive as time spent actually riding the train [3].
We have neglected to model comparative travel by other modes, access costs and times to and from subway stations, and many other elements of individual choice that affect how people make transportation decisions. For a further discussion of this model, please see the Demand Model section. A detailed discussion of our inputs, where they can be found, and how they were massaged, mangled, or otherwise transformed to fit our purposes can be found in the Data Sources section.
[edit] Results
The primary finding of this study is that approximately 76,000 New Yorkers would be expected to use the Triboro RX for their journey to work (which of course means 150,000 daily trips). 32,000 of them would be new rapid transit riders, converted from other modes of travel.
For 29,000 of the other 44,000 commuters we can make direct but conservative comparisons between their trips with and without the Triboro RX. On average, their travel time on the subway would decrease from 44.7 to 36 minutes, a time savings of 17 minutes per day (or 72 hours per year). Their median travel distance on the subway would decrease from 9.8 miles to 7.4 miles, bringing them much closer to the median 5.77 miles traveled by all subway commuters in the model.
A more in depth analysis of the effects of the Triboro RX on New York City commuting can be found in the Results section. Perhaps the most compelling presentation of our results is the following map, which shows the predicted Triboro RX riders, grouped by their census tract of origin:
[edit] Conclusion
Because of the limited nature of our model, it is impossible to make the kinds of projections that are needed for traditional evaluation of the cost-effectiveness of a mass transit project. By focusing on one specific segment of the population, commuters, who are relatively well-surveyed and predictably behaved, we have shown that the Triboro RX is worth further investigation. Because the model is so conservative, the encouraging results are really that much more, well, encouraging. We hope that those who have the data, expertise, software, and resources to evaluate it fully can take up where we have left off.
[edit] Other Sections
[edit] References
- ↑ Google Earth
- ↑ Jeff Zupan, Senior Fellow in Transportation at the RPA
- ↑ Jack Dean, Planner, MTA
