Should Dualmode Concepts Give Priority to Intercity Travel or
Intrametropolitan Travel Problems?
by Jim Haugen, with a response from Bill Turnbull
Questions have been raised regarding the validity of Jim Haugen's view that
should give priority to dealing with intercity travel rather than intraurban travel
problems. Here's his response, followed by a commentary from Bill Turnbull.
1. General - For 30 some years I have seen, over and over
conceptual drawings of new systems overhead structures, with just a few
vehicles on-board, located in a pristine, park-like setting; or,
alternatively, a similar system running down the median of a freeway. Either
way, the purpose is supposedly to convince viewers that such a system will be
unobtrusive when installed. Dualmode proponents must be realistic about the huge
problems of fitting such systems into an urban setting, such as those
2.1 Physical constraints
- Can you take a lane away for some new system? During the NAHSC
deliberations the freeway operators overwhelmingly said no.
- Assume that you somehow are successful in getting consideration of the
possibility of replacing the inside lane of a freeway with a new dualmode
system of some type. How do the dualmode vehicles access this inside lane?
Expensive and intrusive flyovers will be necessary to get across the
conventional traffic (and heavily congested) lanes. And, a second lane, at
least for some distance, will be needed to be able to merge and de-merge from
- How about just building on or over the freeway median? First, you must be
at least 16 feet high so trucks in an adjacent lane won't hit your guideway.
And, what are you going do about all the problems where existing arterial
streets are already crossing over the freeway - go up another 16 feet to
clear trucks on the arterial?
- And then there is the problem of running your new guideway through existing
freeway interchanges - big problem. And, of course, fitting in your own
dualmode system's interchanges - another big problem.
- And, can your system operate in its reserved lane without physical
separation to prevent it from mixing with manually driven vehicles?
- And what will on-off ramps look like and where will the space come from to
accommodate them - because you need queuing space for vehicles while having
their systems checked out and verified; and time waiting to fit into a vacant
slot coming down the guideway. And even more space will be required if you want to
form trains before entering the guideway.
- Always, costs are given in terms of $x per mile of guideway, ignoring all
the extra costs of such problems as outlined above - especially ignoring any
infrastructure engineering costs; and right-of-way acquisition costs.
- The Detroit CBD people-mover was originally estimated to cost $22 million.
By the time the guideway and stations were built and the system was up and
running it actually cost $220 million - only a factor of ten difference!
- The state runs the freeways. The governors are concerned about committing
funds to solve the congestion problems of the big city, when they have a lot
of constituents in smaller towns and rural areas. So they had better make
sure that the majority of the funds are coming from the Federal government.
And our Federal DOT has already been burned on its AHS program, as well as
historically going back to ideas like GRT (Group Rapid Transit).
- And the counties handle the arterial streets, which are going to be greatly
affected by any changes in freeway access problems. And here NIMBY (Not In My
Backyard) becomes a big a big political football.
- How do you ever get to proof-of-concept? You have to somehow prove that
this new system is (1) going to work without any catastrophes; and (2)
achieve a sufficient market to be able to pay back all its costs and then
- Although it seemed that NAHSC was trying its best to bury any possible AHS
problems, because of its conflicting role as AHS advocate, it was obvious (to
some of us) that the possibility of short headway operations had big safety,
liability and feasibility problems - for little potential gain in trip time
3. Elevated systems over arterials
3.1 Physical constraints
- Again, I never see realistic pictures showing the size and complexity
expected from stations with parking and holding areas; for on-off ramps; for
network intersections - all of which will gobble up a lot of land - land
which is tough and expensive to acquire.
- Here in Detroit we have a lot of five lane arterials with the center lane
used for turning movements, so forget trying to put an elevated guideway down
the center - unless you want to put up with the extra cost and intrusion of
straddling the entire five lanes with a support structure.
- Arterials also always have a mix of land uses, some commercial, some
apartments and condos, some private homes. Installing elevated guideway along
the edges of the arterials will bring up big land-use conflicts.
- Again, NIMBY - we have uproars over just wanting to build new bike paths
along arterials which border private homes.
- Is there any precedent for extensive installation of a network of elevated
guideways? Our historical precedent is the "El" as installed in New York and
Chicago, with very bad public images. (and yes, of course, your new idea will
have much less intrusive guideways).
- The same point from freeway related costs holds true - always, costs are
given in terms of $x per mile of guideway, ignoring all the extra costs of
such problems as outlined above - especially ignoring any infrastructure
engineering costs; and right-of-way acquisition costs.
- In the smaller jurisdictions of communities through which arterial pass you
are really going to have problems with NIMBY.
- And now the Federal government is liable to give a lot less funding support
and you have to deal with convincing taxpayers - whose usual approach to
avoiding the congestion problems is to move further away.
- PRT attempts to minimize physical and intrusion problems by focusing on
small vehicles and minimal size guideway. As a system gets more complex and
the capacity target goes up, operational problems become larger and larger -
and bring up nasty trade-offs with physical and cost problems. I have yet to
see a good, believable description of operations for any dualmode system.
Dualmode deliberations cannot begin with an inventor's dream of an overlay
system for urban areas, which doesn't come to grip with the kind of realities
I've tried to point out above. There must be a different approach and I have
some ideas (biases?) to convey in a future article.
Response from Bill Turnbull
I have no serious disagreement with most of what Mr. Haugen has to say. There are
difficulties, serious difficulties, associated with implementing any urban transit system,
dualmode included. I have no quarrel with that. Nevertheless, it is precisely in the
great urban areas where the major problems exists. I don't think we can walk away
from that. The problem of inter-city travel may well be approaching a crisis - the
crisis of intra-urban travel is here and now.
Studies suggest that the capacity of the Los Angeles freeway system will have to be
doubled in the next five decades. It is in this context that we must view the
difficulties Mr. Haugen describes. That is, in a comparison of the relative
difficulty of competing means to achieve our goals, rather than simply some absolute
recitation of the obstacles.
A single dualmode line has the potential to accommodate several lanes of freeway
traffic; perhaps as many as six to eight. Implementing dual mode is not without its
problems; but then, so is providing six to eight more freeway lanes. I think it is
not an unreasonable argument that a single dualmode line might be considerably less
expensive than 6 to 8 freeway lanes.
I look upon the initial implementation of urban dualmode as primarily an adjunct
to freeways. And yes, I would anticipate using the median where available; and, if
necessary, usurping an existing freeway lane. The problems Mr. Haugen lists such as
the requirement for under and overpasses (flyovers), merge lines, interchanges, and the
necessity of separating transit vehicles from other traffic are real and must be
addressed. However, I do not see these as insurmountable. Moreover, they are not new
issues to serious students of this topic.
I differ from most of my colleagues in that the pursuit of the latter
requirement(separation) mandates an elevated guideway. This may well be a
requirement in many instances. To require it in all instances, without regard to specific
local conditions, places an undue economic burden on any system. We must guard
against imposing any requirement arbitrarily, to be applied universally.
On one issue, I am afraid that I must disagree with Mr. Haugen completely. In his
previous submission, he discusses the difficulties of installing an urban system (as he
has more fully here) and then informs us that ". . . the potential service gains are,
at best, trivial."
I can't imagine that a commuter stuck in freeway traffic at 15 to 20 MPH (or less)
would agree that proceeding at 80 MPH (or some such number) in a hands-free, hassle-free,
direct to his destination journey would constitute only a trivial improvement. The
use of electrical propulsion, thus greatly minimizing the concentration of automotive
pollutants, would also seem somewhat greater than trivial. These are only two of the most
important; there are others that have been discussed extensively in these and other
proceedings. Indeed, Mr. Haugen list some as they apply to inter-city travel.
They apply to urban travel as well.
In the final analysis, economics will prevail. If, in the pursuit of
solutions to our many and urgent urban transit problems, a dualmode system proves (as I
believe it will) to be the economic system of choice; then the many other advantages will
prevail over political objections. This may be wishful thinking; but I, for one,
believe it deserves one hell of a try.
In this connection, much was made of faulty (and over optimistic) economic
projections; e.g., guideway cost per mile with little or no consideration of other
costs. While that may have been true, I see no need to continue the practice.
Estimates must be developed that describe the true costs (as best as can be determined) of
a specific project, not some general considerations. No one is served by a low-ball
estimate that ultimately results in a cancellation of the project (for instance, Seattle).
I guess what strikes me most about Mr. Haugen's discussion is the overriding
pessimism. No one suggests that his very real concerns should be ignored; but
perhaps, a small measure of excitement over the opportunity-to-excel might also be in
order. He does, however, offer hope. He indicated that he has some ideas
"(biases?)" that might overcome these concerns. I look forward,
enthusiastically, to considering them.
Last modified: July 14, 2001