Elevators

Tall buildings these days only have stairs because they are required by fire codes. If they were not required, I suspect many buildings would not have them at all. They consume floor space that could be otherwise be rented. But why has not anyone done anything about elevators? We will have a 50 story building with several elevator shafts that run all the way to top and each shaft is dedicated to one car. Imagine if streets were like that. One bus per lane all the way from Portland to Seattle.

We need an elevator system with autonomous cars, that is elevator cars that can ascend or descend on their own without depending on cables, counterweights and rooftop machinery. Instead of having a bank of ten elevators a tall building could get by with two elevator shafts: one for cars going up and one for cars going down. Each shaft would hold five or so cars. When climbing cars reached the top, they would be shunted over to the downshaft. When the descending cars reached the bottom, they would be shunted back to the upshaft. They would in effect follow a circular pattern.

I have no doubt that such an elevator could be designed and built and could be just as safe as our current elevators. Since floor space is at such a premium, and our current elevator system is so obviously inefficient, and a more efficient design could be built, the question is, why hasn't it been done? Okay, maybe it has, and I just haven't heard about it. In any case, what can be done?

Well, it's political. Someone is going to have to champion the idea, sell it to some financial backers. And not only are there going to be expenses for development and testing, but a whole bunch of rules, regulations, and probably even some laws are going to need to be changed, and that is going to require a whole different skill set than that needed to design and build it. And then you have the insurance companies. Proving the safety of the elevator cars to the insurance industry is going to be strenuous ordeal. Finding someone who is willing to fight this battle on all fronts is going to be difficult.

Let us leave aside the political and regulatory issues for the moment and return to how such an elevator system could be constructed. My favorite, and the most difficult technically, would be to use linear induction motors. The elevator shafts would have bus bars carrying electrical current. The cars would have linear motors that would react with the magnetic field generated by the current in the bus bars to propel the vehicle. The cars would derive their power by induction from the bus bars as well. Ascending cars would draw current from the system, and descending cars would push current into the system. No moving parts, a perfect system. But such technology may currently be beyond our capabilities.

All cars would need some kind of fail-safe so in case of power or other equipment failure they would stop where they were and be locked into the shaft so they could not fall. This kind of mechanism is what made elevators successful in the first place.

A technically easier method would be to equip each car with an electric motor, a speed reducer and a set of drive wheels. Like the previous idea, the elevator shaft would be equipped with bus bars running the entire length (height) of the shaft. The car would have brushes to pick up electrical current from the bus bars to drive the motors. All of the components for this kind of drive could be ordered from a standard industrial supply.

To reduce the amount of current being carried by the bus bars, we could include a tow rope, something like what you find at a ski resort. When a car starts to ascend the motor would start turning the drive wheels. When the car reached the speed of the tow rope it could clamp on and the rope would haul the car up, almost to it's destination when the motor would come on line again, the car would release its' clamp and it would come to a smooth stop at the requested floor. The tow rope would operate continuously and would guided by two large wheels, one at the top and one at the bottom of the shaft, much like a ski lift.

Of course you would need a sophisticated control system to dispatch the cars and keep them an adequate distance apart, but there are lots of smart people out there who could design such a system. The trick will be finding someone who can marshal the right people and deliver a correctly functioning, reliable system. Diebold is not it. I am sure there are companies that can do this, though it is very difficult to determine which companies are actually competent and which ones are just blowing smoke.