Centralize or Decentralize Transit?

16 02 2010

This is CapMetro’s proposal for a centralized transfer facility in Downtown Austin (starting on page 9)

Is this a good idea? And why?

(source) “Evidence underlines that the emergence of hub-and-spoke networks is a transitional form of network development rationalizing limited volumes through a limited number of routes. When traffic becomes sufficient, direct point-to-point services tend to be established as they better reflect the preference of users.”

(source) “Metro areas that have integrated their rail transit into a decentralized network structure are found to enjoy higher riding habit, higher service productivity, and better cost-effectiveness than metro areas with other network structures or modal combinations.”

Transit is moving from its traditional centralized hub-and-spoke model to one that follows the point-to-point (no centralized hub) model, where multiple “nodes” are distributed around a city (examples: Providence, Seattle, Tallahassee, Orlando, Atlanta). In input/output economic parlance, they are disaggregating clusters by increasingly expanding and diversifying their operations to locations where their investments will be most profitable. Cities that are remodeling their public transit network but are sticking to the hub-and-spoke model are creating X number of hubs throughout the city; thus these hubs are becoming, in effect, nodes (example: Los Angeles).

Advantage of point-to-point system: It minimizes connections and travel time (the more that passengers use it, the more intuitive it becomes) and increases accessibility (and greater accessibility is good).

Advantage of hub-and-spoke system: They are simple; new ones can be created easily; scheduling is convenient for passengers since there are few routes, with frequent service, so they may find the network more intuitive. An example of technology that obviates this advantage: The Chicago Transit Authority’s Bus Tracker

Disadvantages of hub-and-spoke system:

  • Because the model is centralized, day-to-day operations may be relatively inflexible. Changes at the hub, or even in a single route, could have unexpected consequences throughout the network.
  • Route scheduling is complicated for the network operator. Scarce resources must be used carefully to avoid starving the hub, and traffic analysis and precise timing are required to keep the hub operating efficiently.
  • The hub constitutes a bottleneck in the network. Total capacity of the network is limited by the hub’s capacity. Delays at the hub can result in delays throughout the network. Delays at a spoke can also affect the network.
  • People must pass through the hub before reaching their destination, requiring longer journeys than direct point-to-point trips. This is often desirable for freight, which can benefit from sorting and consolidating operations at the hub, but not for people.
  • In a spoke-hub network the hub is likely to be a single point of failure.

Conclusion

Filtering people through a hub or a series of hubs is wasteful and inefficient compared to the direct point-to-point model, which can reduce transport emissions and operational costs…Are the five sites CapMetro identifies desirably positioned and reasonably purchasable land for this to be in any way an achievable endeavor?

In any case, no matter what occurs, this is what we here at The Placemaking Institute would like to see occur with Congress Avenue

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5 responses

25 02 2010
placemakinginstitute

Does the following paragraph in any way jibe with CapMetro’s proposal for a centralized transit facility?

From today’s Statesman: “Spillar said the city wants to avoid downtown rail gridlock of the sort Dallas is now experiencing, with several rail routes converging on a single line. Spillar said it is easy to envision a future rail system with legs going north on North Lamar Boulevard, northeast toward Hancock Center, south on South Congress Avenue and southwest along South Lamar Boulevard, each with several trains an hour arriving in the central business district.”
http://www.statesman.com/news/local/expanded-urban-rail-would-run-through-downtown-on-279960.html

3 03 2010
Roger L. Cauvin

Leaving aside the centralized transit facility, theere is some food for thought on the issue of grid vs. hub-and-spoke vs. other transit configurations here:

http://www.humantransit.org/2010/02/the-power-and-pleasure-of-grids.html

10 03 2010
placemakinginstitute

Great, thanks…(Jarret runs one of the best blogs around) One thing I’ve always found interesting about Austin is that the Capitol and the UT Tower are off by 12.5 degrees, thus skewing the grid by 12.5 degrees. And this leads to the bottleneck problem just north of the Triangle as well as 51st and Airport, which is an intersection that, when commuter rail commences service, is going to become much more of a problem. The paragraph below is the one that stood out most for me:

“Why aren’t all frequent networks grids? The competing impulse is the radial network impulse, which says: “we have one downtown, everyone is going there, so just run everything to there.” Most networks start out radial, but some later transition to more of a grid form, often with compromises in which a grid pattern of routes is distorted around downtown so that many parallel routes converge there. You can see this pattern in many cities. Portland for example. Many of the lines extending north and east out of the city center form elements of a grid, but converge on the downtown. Many other major routes (numbered in the 70s in Portland’s system) do not go downtown, but instead complete the grid pattern. This balance between grid and radial patterns was carefully constructed in 1982, replacing an old network in which almost all routes went downtown.”

16 05 2010
Gewinnspiele

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i’m so pleased that i saw this site. that article was so great. thanks again i saved this blog.
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9 07 2010
placemakinginstitute

Very much glad to hear that you enjoy the site and, yes, The Placemaking Institute is about to begin blogging again.

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