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Re: When considering the alternatives-Induced demand?
Author: BOB2
Date: 12-14-2020 - 00:01
The assumption that additional capacity will create "induced demand", in congested urban areas with auto trips, or as a basis for rail extensions is largely a myth, as we see little travel "behavioral" evidence of a "Pfarfeggnuggin" effect. People make most trips to do things that add value to their lives within a finite real time/travel time "budget" within which to accomplish them.
What we sometimes see, which seems to "mimic" evidence of this claim of supposed "induced" demand, is that when we add a new travel "capacity" choice, it is usually to accommodate excess highly "suppressed" travel demands, in already severely congested locations with significant existing travel time delay. These "changes" in observed volumes, in a "new" corridor and/or modal alternative, are, most often, just a shift of existing trips to a more efficient choice. That is, a five hour LA-SD peak trip on I-5, versus 3 hours on LOSSAN, a 710 tunnel under South Pasadena, that "cuts" 20 miles off of a trip from La Canada to Orange County or South LA County, and saves 50 minutes of peak period "time" for the same trips. What people really do is shift from the longer route/mode to the shorter more "efficient" choice-they don't decide to make a "new" supposedly "induced" trim, because it is now more "fun" to drive.
I would suspect from the observed evidence in this case, that the primary reason for the "relatively" smaller rail passenger share, south of Portland, in the Willamette Valley, is: 1) that they are not as total travel time trip competitive, with a much more distributed (off line) population base, has not reached that point of time competitiveness with the current levels of urban/rural congestion on I-5, and 2), the comparatively poor service levels offered (wait time/transfer time/access time are known to have a higher "disutility" multiplier than "in-vehicle" travel times). As Bill Gates and his pal Steve Ballmer used to always say: "Faster, better, cheaper"... It is the same economic formula for serving travel demands, regardless of mode...
What we sometimes see, which seems to "mimic" evidence of this claim of supposed "induced" demand, is that when we add a new travel "capacity" choice, it is usually to accommodate excess highly "suppressed" travel demands, in already severely congested locations with significant existing travel time delay. These "changes" in observed volumes, in a "new" corridor and/or modal alternative, are, most often, just a shift of existing trips to a more efficient choice. That is, a five hour LA-SD peak trip on I-5, versus 3 hours on LOSSAN, a 710 tunnel under South Pasadena, that "cuts" 20 miles off of a trip from La Canada to Orange County or South LA County, and saves 50 minutes of peak period "time" for the same trips. What people really do is shift from the longer route/mode to the shorter more "efficient" choice-they don't decide to make a "new" supposedly "induced" trim, because it is now more "fun" to drive.
I would suspect from the observed evidence in this case, that the primary reason for the "relatively" smaller rail passenger share, south of Portland, in the Willamette Valley, is: 1) that they are not as total travel time trip competitive, with a much more distributed (off line) population base, has not reached that point of time competitiveness with the current levels of urban/rural congestion on I-5, and 2), the comparatively poor service levels offered (wait time/transfer time/access time are known to have a higher "disutility" multiplier than "in-vehicle" travel times). As Bill Gates and his pal Steve Ballmer used to always say: "Faster, better, cheaper"... It is the same economic formula for serving travel demands, regardless of mode...
