AGVs have been in use in Warehouses since the 1950s. AGV are driverless
viacals that follow wires or optics buried in the pavement. Avantages are Cheper to build and operate. Disavantages are weather in that such a system has yet to be tested in a harsh weather climate with snow and slippery pavement. AGVs could be coupled toghether were each viacal could run and turn in tandem. No expencive rail and could be as wide or as narrow as needed. Trails that are now used for bikes could be used for AGVs.
You have a point. There are a number of applications – particularly in what is now light rail transit – where automatically guided vehicles might be used to considerable advantage. There are, however, some problems, mostly (in light rail) having to do with safety. I’m sure others may think of others, but the first which comes to mind have to do with handling right of way conflicts (how do you sense that some idiot isn’t going to get in the path of the vehicle?). This is handled in the warehouse environment by restricting access to the operating area to highly trained personnel, and in other areas where they are used (such as for office supplies, office mail, medical supplies, etc.) by a combination of very low speeds and bumper protection. Not practical for transit! The second objection which comes to mind is the fail safe one: except in rather rare cases, if something goes wrong with your light rail vehicle (such as a loss of power or the like) it stays on the track. This is not true of the AGV, and some means has to be found to ensure that it stops when it loses guidance or power. These are, however, soluble problems.
For heavy freight, however, I don’t see an advantage. The problem there is the right of way. ‘Conventional’ track (rail, ties, and ballast) looks like a pretty simple system, and not much fancier than, as you say, trails used for bikes. This is not, actually, the case. Conventional track is actually a rather sophisticated integrated system, developed over the last 150 plus years, which can handle really fantastic repetitive loadings – much greater than any reasonable pavement based system (except for airport runways and taxiways – but that’s a different story). The typical axle loading of freight cars is approaching 70 tons – per axle – and up, while the typical axle loading even for heavy highway trucks is more on the order of 8 tons – a whole order of magnitude difference. Further, the rolling resistance of a train on a steel track is incredibly low. Perhaps I
Theoretically it could work. But the problem is, it would have to be all or nothing. The entire system would have to change for it to work. That’s what prevents a lot of things from happening in the aviation industry too. It either all changes, or doesn’t change at all. That’s assuming that you are talking about something that would replace the system that’s available now, and not create a one-off type of thing, like a monorail. I suppose it could work on a captive system, like say a mine RR. The Australian train/trucks are an interesting concept and actually pretty impressive. But they can get away with that, because they have roads that are very sparsely traveled, and run for great distances. If they tried running 6 trailer trucks on highways in America, all the safety groups would be up in arms.
What I am asking here is “Could AGVs play a role in transit systems and be the equvent of rail for short haul freight and Commuter servive” There is one AGV bus in Los Vegas
That’s what I like[:)]! Short questions with short answers!
Yes, AGVs could and can play a role in transit systems, but the role is somewhat limited (see my above first reply). In fact, there are some very very innovative things one can do with AGVs in transit. The biggest problem is the fail safe/fail operational requirement.
For short haul freight? Possibly… for relatively small quantities or in closely captive situations; again, see my first reply for the major freight limitations.
Commuter service? Indeed, again, in some applications.
Having said all that… for the commuter/transit role, there are really two issues: automated operation, which is becoming quite common, and elimination of the rails. In many many ways automated operation is much easier if there is a fixed, protected guideway of some kind – and for transit or other light load (relatively speaking) operations, it really doesn’t matter that much, inherently, whether the guide way is steel or concrete (consider Montreal’s Metro, for instance). However, once one abandons a mechanical guideway of whatever kind for a sensed guideway, safety and reliability issues loom rather large. These issues can, and no doubt will, be overcome. But it will take some time; I wouldn’t be too surprised if advances in sensing and computing power moved fast enough to leapfrog vehicles from the present operator guidance to fully autonomous guidance (via sensors locating the edges of the roadway lanes, for instance) with no reliance on, for instance, buried wires or optics. There are experimental cars out there today which do just exactly that, astonishingly well.
For rapid, efficient, reliable, safe movement of heavy freight, though, as I said earlier it is very
Just last night on the History Channel, there was a show about DARPA testing automated land vehicles. None of them did well and they had enormous problems when encountering obstacles they did not antcipate. The one vehicle rammed a fence post that turned out to be in concrete and damaged the vehicle a lot when it forced the post out. Then later it got hung up on a rock and spun its tires for much and for so long that eventually the vehicle caught fire.
One that drive on the roads pilot-less, like Carnegie-Mellon’s design, though seems to be ok, but it requires someone to mind it and make sure its actually doing what its supposed to be doing.
GM did a fair amount of testing on AGV technology in cars in the 60’s. At least one of their major test tracks has wire laid in place. I saw it work then, but 40 years later, we aren’t seeing much of it, are we?
Failsafe is probably the biggest problem. With a rail system, at least you have a good idea where the vehicle will go if you lose control. With a “free-roaming” AGV such as they use in warehouses, you need to know that the vehicle will stop immediately if it loses it’s track, and that it won’t develop a mind of its own and set off across the countryside. That’s especially true if the cargo is people or hazmat.
Intelligent highways is a big enough topic that it has its own development institute. Some very interesting work, particularly coming out of Carnegie Mellon in Pittsburgh.
Steering multiple trailers in road trains turns out to be a trivial control exercise: you use differential wheel braking, via the sensors and actuators used for modern antilock braking. A microprocessor or computer measures the displacements of the van ends and compensates accordingly – if you’ve seen how QuadraSteer works, you get some of the idea.
Note that single wiggly-wire can be used both to keep the trailers aligned and stable in crosswinds and to ensure that the ‘train’ itself accurately follows curves both in forward and reverse movement. This is not a particularly large investment when building dedicated guideways (like the ones previously suggested for operations over ‘abandoned railroad ROWs’)
It is very difficult to get these systems to ‘fail safe’, even if only big and reputable firms perform the (skilled) maintenance. Look for truckers to tout this technology; hopefully we can also look to responsible state and Federal officials to resist, at least on Interstates.
Note that this is ENTIRELY different from autonomous guidance – there’s still a guy behind a steering wheel controlling where on the roadway the truck cab goes; the train just follows that lead. If you think unattended steam boilers on MU’ed steam power is a plaintiff’s-bar turkey shoot, just WAIT until they hear about 4- and 5-van trucks running unattended on roads where cars, pedestrians, pets, defunct retreads, etc. are lurking. (I won’t mention terrorists, except this once!)
the best place for AGVs or “Road Trains” would be on there own right of way and in dedicated lanes for AGV buses. There would be drivers that would control speed and braking and GPS to help with dispatching. HOV and Busways in Pittsburg would ideal places to test these.
MagLev is a boondoggle. Even though massive progress has been made with the magnets and operational structure, there is still little call for something that has to go 350+mph on a ROW useful for nothing else, doing nothing but carry passengers between points that almost certainly WON’T be convenient to concentrations of housing (can’t stand the noise) or office space (can’t afford the real estate).
It’s a cute toy to demonstrate space-age technology, and a valuable thing to wow the hoi. Unfortunately, as a way to spend transportation dollars meaningfully, it lacks many important constituents of ‘cost-effectiveness’ – to say nothing of better opportunity uses for the capital, labor, and energy that would have to be expended in its construction, operation, and maintenance.
One of the key principles to remember about transportation is multiple use. Locomotives that can drag effectively down low, run fast without pounding track, and contribute great amounts of braking without using air are much more valuable than ones that only do one trick well. Add the ability to couple individual, comparatively lightweight units, sprung flexibly enough and powered at the right level to run on branch lines, into a large single ‘locomotive’ and you have something that goes many places, does many things, for the money you put into it. Does this sound familiar?
At about the same time as F/GP 7s and 9s, PRR and C&O decided to build high-speed, high-power mainline locomotives – T1, Q2, H8. Note not only that these engines seldom realized the potential their engineering provided… they ran out of perceived missions relatively early, and oops! there was nothing left for them to do on the railroad.
Build a MagLev train and it’s only good for one thing: running on its special guideway, between fixed points, transporting passengers with lots of ca$h to cover the massive fixed and maintenance costs of the system. No freight at night like the early ShinKansen lines in Japan, no par
Maglev may be a boondoggle, but what about using linear induction motors to propel light rail cars, modified freight containers & personal transport vehicles(cars) along a guideway at higher densities and speeds? Seems like a lot of the technology for this stuff isn’t in the warehouse or laboratory, it’s up and running at the amusement parks. [:)]
One big issue I see is how to deal with the stuff at the other end i.e. you could build a tunnel from Long Beach to an Inland terminal and ‘shoot’ containers through, but then what do you do with them???
I’ve liked LIMs in principle for lo these many years – one difficulty is that the reaction rail usually sticks up in the center of the track and gives clearance and switching problems, but you’d probably have separate low-speed wheel power on a system using this approach.
Back in the days we all “knew” there was a 310mph or so absolute adhesion limit, I worked up a system that used periodic magnets spaced along the track to give impetus to a superconducting countermagnet mounted on a railcar. At higher speeds, this would work without perceptible ‘jerking’, and has the advantage that very little traction power needs to be provided to the moving vehicle – e.g., no catenary, flying pantographs, 25kV arcing and spark erosion, etc. etc. There are magnetic refrigeration devices currently produced that are easily capable of handling the heat gain in the superconducting coolant (ideally LN2, but practically either LHe or LH2) on a road-practical train-borne magnet configuration.
The issue comes down, as it usually does, to one of cost vs. benefits. Adhesion wheel traction has been proven effective up to what I would consider the highest practical and safe ground speeds for ROWs near the ground or running through inhabited areas. The real-world payback period for new construction of lines capable of high speed, even if given the grade profiles of new TGV lines (8-10%) – something that isn’t practical for MagLev, btw – would be amazingly long, and without convenient access to very deep pockets like the Highway Trust Fund would be difficult even to get constructed in the first place.
“Shooting” the containers would presumably be done in ‘rakes’ of some number, not individually, and it wouldn’t be difficult to arrange some sort of multiple-track yard facility into which successive trains are directed for container transfer (and then hostled without blocking the high-speed throat). However, as folks ‘in the know’ have indicated, there are relatively few of these 'inland terminal