Wednesday, June 15, 2005
Underground Automated Highway System (UAHS)
John Smart recently included a vision paper on a possible future mode of transit in the most recent issue of the Accelerating Times newsletter. Note that this issue references the availability of the audio portion of Peter Thiel's presentation on Virtual Money at last year's Accelerating Change 2004 conference, where yours truly can probably (I haven't listened to the audio yet) be heard asking the one question I worked up enough nerve to ask during the conference.
He provides a vision for a form of transportation that would relieve the most crowded cities of their surface traffic burden. He envisions a network of underground tunnels in which vehicles can travel in a completely automated fashion. The details of Mr. Smart's vision will not be explicitly repeated here. His short paper on the subject is very consumable, so interested persons should get the PDF here.
Mr. Smart's paper was not intended to be a thorough treatise on the subject of underground travel, but rather to lay out a vision of a
possible future that he believes is likely to unfold.
Similarly, my thoughts are not intended to be a result of a thorough survey of the available literature. They just happened along the way, and I'd guess that these (and probably more) questions would pop up in the brain of the average reader of this paper.
While I am yet un-opinionated ;) on the topic, I did find that it left me with many questions. What follows (in the tradition of my first PRT entry, which seems to have generated some conversation) are my notes and questions as taken during my reading of the paper.
I should note that any errors that show up in quotes I pulled below are probably mine. As for the errors outside the quotes...well I'm still looking for the person that put those there ;)
In what ways does the Underground Automated Highway System increase the "...capacity of goods and transport in our largest and highest
density cities..." that the automation of existing roadways would not?
Would it be due to additional automation that is unlikely on existing roads?
Would it be because of the supplemental real estate devoted to transportation beyond the existing infrastructure?
Or does it simply by the addition of usable lanes?
How does this system increase peak traffic capacity beyond the additional lanes it provides, that are unlikely for on-surface, or
above-surface transportation alternatives?
How does it do so by an order of magnitude?
UAHS System Architecture
Is this system strictly oriented around major hubs, or does it work for more distributed trip patterns?
Where would entry/exit points be on the UAHS, and is there potential for congestion at these points?
If you were going to have a fully-controlled environment, could you regulate the flow of air so that a one-way tunnel had air flowing through it in the same direction, reducing drag?
If an "automation test lane" is required, how much lead space is required from an exit point (from a regular highway) for a vehicle to establish its autonimity? Would the driver have to cross existing lanes from, say, a regular freeway onramp, to the far left lane? Obviously this would create its own problems if the freeway was under heavy traffic load. How does this lead space (to establish the autonomous nature of a vehicle) compare to the average commute distance? How much of the original commute waiting time might still be experienced?
Does a megalot become a location where many people would depart from the UAHS, and thus become a bottleneck?
Does a UAHS suffer from congestion for its feeder networks (roads)?
What is the trip length that UAHS would be designed for? The way it's talked about makes it sound like you'd be traveling in it for a while.
If it is true that cities saturate as described, might it be the case that UAHS' order of magnitude more supply might be overkill should it be attainable?
Future Traffic Patterns
Do we believe that traffic patterns will get more focused on fewer destinations over time, or more distributed over a wider range of
origination and destination points?
"Nearly all population growth for the foreseeable future will occur in urban areas...". Does this necessitate that they will happen
primarily in the urban core, or will they be distributed around urban/suburban areas of a city.
Crikey! 8 lanes each direction? Will future demand be that high? What does the world of transportation demand look like 100 years out?
Wouldn't increasing real estate prices in the urban core tend to drive businesses into the suburbs, thus decreasing the number of travelers to that area? Is that effect measurable? Does migration away from the suburbs create new focal destinations, or do they become relatively distributed? Presumably the latter case would be harder to service with something like a UAHS.
How are existing non-car alternatives to a UAHS inferior? What about those on the horizon?
Surely automated aerial transportation systems are not the only viable alternative to a UAHS? What are the design requirements driving this as the selection set?
Issues with ridership of transit alternatives may be due to the format of existing forms of transit: Linear, multi-stop trips, with limited flexibility in departure time and destination. Perhaps alternative transit forms like PRT or dual-mode transit would increase ridership with less financial impact.
If there is evidence that the cost ratio between surface vs. elevated vs. underground transportation costs is improving for underground transit modes (from 1:3:6 to 1:2:4.5), does the evidence support that elevated transportation costs will also continue to gain? If elevated transit took the form of small guideways (e.g. PRT), could that improve the costs to the extent that they are BELOW costs for surface transportation?
If the same dollars that it took to create UAHSs were, instead, put to improving existing road systems and dedicating lanes for automation where possible, what kind of effect might it have? Would it be enough to offset the benefits of an underground system? What if the ground-level automation included significant numbers of busses? What if this money was diverted into other transit options such as LRT, PRT, or dual-mode transit? How does one establish the average ROI for each transportation alternative?
Would the costs involved in underground construction truly become advantageous over on-surface or above-surface transportation?
Costs per cubic foot quoted ($1.50) for "mining and lining" should be reduced to costs per square foot to be more directly compared to other forms of transportation, and all supporting infrastructure costs should be added to this to provide an apples-to-apples comparison of finished, working surface area.
Is the disposal cost of tunnel ejecta included in the per cubic foot dollar figure? What is included in this figure?
What would the average cross-sectional area of a tunnel be in this system, and would that account for one-way or two-way traffic?
At $1.50/cubic foot, assuming a square tunnel 16ft on a side (which is probably an order of magnitude too small), the linear cost of digging is $384/ft. At 100ft on a side, it's $15,000 per foot. That's $2,027,520 - $79,200,000 per mile before you lay any infrastructure (e.g. roads, ventilation systems, etc).
Lane widths in the US appear to vary between 9' and 12'. Using 10' widths to make calculations easier, a 4-lane road would be about 40' wide. Assuming that shoulders would be 5' each (again for ease of calculation, 4' appears common) to provide enough ceiling clearance for vehicles traveling in the outer lanes (would be interesting to see if normal long-haul vehicles would be able to travel in these lanes, but not critical for a number of reasons such as the fact that such vehicles may not meet emissions standards enough to use a UAHS, may be redesigned to have a lower maximum height in order to use a UAHS, or may be required to travel in the middle lanes), the total width is 50'. Assuming a circular bore, with a 50' diameter, the cross sectional area would be (pi*(25)^2)), or ~1963 sq.ft. At $1.50 per cubic foot to tunnel, and 5280 feet/mile, the cost/mile is: $15,550,884 for just the tunneling.
The low cost to convert existing roadways to an Automated Highway System (AHS) ($10,000/mile) seems largely irrelevant to the UAHS argument as all savings is lost in the initial construction costs of the tunnel and roadway.
What would the average cost of a "megalot" be?
Emergency Systems and Safety
How would emergency access to such an infrastructure work?
How do various types of emergency plans (that is, for various types of catastrophic failure) compare? Also, how does the probable incident rate compare with each transportation mode?
AHS's are probably safer in general, but, to the extent that non-automated traffic runs in the same area, this safety may be
somewhat compromised. Also, there is an open question as to whether significant numbers of individuals (1 in 100 perhaps) would break out of the automatic control to try to game the system, or just plain speed. Similarly, the extent to which an automated system can handle unexpected obstacles will heavily determine how much emergency response is needed (and, potentially, the limit of wide-spread
adoption of the system). If an animal wanders on to the automated roadway, for example, how does the system react? All in all, it is
not yet apparent that any reduction in law enforcement/emergency response could actually be experienced (although it does seem likely).
Granted that automobile accidents do account for a significant number of deaths each year, but if there is no public outcry, even in the face of general knowledge of the danger, then it would seem that safety cannot be a primary motivator of change in that other safety issues will always gain priority for the dollars.
By "...eliminating visual blight and noise pollution of freeways.." is Mr. Smart suggesting that existing infrastructures will not just be supplemented, but replaced? If so, how will vehicles not presently equipped to run in an automated mode make trips that would otherwise have required a freeway?
"Productivity loss" has always seemed like a weak reason to improve transportation infrastructure. Is this productivity loss to business (in which case it would seem a result of poor worker planning than anything else; if we're talking about people arriving late on the job), or to the individual (in which case it would be tough to assign a dollar figure to the time of non-working individuals)?
How does a digging rate of 20 ft/hour compare to other transportation alternatives when all prep-for-build requirements are taken into
Are there rights-of-way that need to be purchased/otherwise accounted for for underground construction? Can underground construction be built directly from point-to-point if there is no engineering reason not to? Said differently, are there places that a Tunnel Boring Machine can't go because of political/social reasons that it might otherwise be able to navigate just fine (e.g. below a residential area)?
Among the stakeholders should be those who have a stake in alternative forms of transportation. The automobile industry. And potential system component manufacturers.
What is the likely timeline for UAVs? Likely the biggest hurdle would be social as even automated cars are likely to be able to be
overridden by a human operator in case of failure. This will probably be an issue more of perception than anything else.
How do we prevent - or is it even undesirable - reclaimed roads, should there be any, from becoming more buildings as they would seem
likely to do if real estate continues to become rarer?
It would seem that other possible futures include: the emergence of attractive transit options such as dual-mode and/or PRT that have a good deal of the positive effects (and some added ones, like less reliance on owning a car) of a UAHS with potentially smaller costs; telepresence and telecommuting taking hold requiring fewer people to go to point destinations (like the urban core) simultaneously; and the possibility that trip destinations become more diffuse rather than more concentrated, making the value proposition of UAHS less appealing.