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Re: When considering the alternatives-Induced demand?
Author: FUD
Date: 12-14-2020 - 06:01
BOB2 Wrote:
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Your view of the issue is similar to mine when it comes to new roads. For a different mode, especially a train, it's necessary to demonstrate that enough trips will be available to justify running the service, and it doesn't matter where those trips come from. In practice, some of those trips will be relocated from highways in the corridor, and some will be trips that otherwise would not occur for various reasons.
The trips have to come from somewhere. They don't appear out of thin air, unlike what some of the "induced demand" arguments appear to claim. Where they come from helps to determine the resilience of the service to changes in conditions, and what can be charged for the service (i.e. the profit potential). Some feasibility studies address that better than others, and some (e.g. early CAHSR) don't seem to do it at all.
Finally, if a isn't congested to some degree, it's not truly filling a need. What happens if you build a road and nobody uses it? Or run a train and nobody uses it? For certain values of "nobody" of course. Obviously, it wasn't needed. The difference is that once you build a road it's there, roughly, forever (yes, there have been rare cases where a road is removed), while an unused train, and even the tracks, can be removed quickly if regulatory agencies allow it to be. In a congested urban area (i.e. people want to be there), almost any transportation facility will be used at least at a moderate level. That may not be true for interurban traffic.
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>
Your view of the issue is similar to mine when it comes to new roads. For a different mode, especially a train, it's necessary to demonstrate that enough trips will be available to justify running the service, and it doesn't matter where those trips come from. In practice, some of those trips will be relocated from highways in the corridor, and some will be trips that otherwise would not occur for various reasons.
The trips have to come from somewhere. They don't appear out of thin air, unlike what some of the "induced demand" arguments appear to claim. Where they come from helps to determine the resilience of the service to changes in conditions, and what can be charged for the service (i.e. the profit potential). Some feasibility studies address that better than others, and some (e.g. early CAHSR) don't seem to do it at all.
Finally, if a
