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03 September 2010


Dear JVH:

Let's set aside your comments about the space efficiency for a second. Anyone who has designed enough automated parking systems, knows there is little point refuting that claim.

So, while I too loathe the infamous and misleading "1-minute retrieval" claim that is often used to berate our industry by those predisposed to do so, in this case, I think you are taking what appears to be an off-handed comment by a developer and using it to paint the industry with broad brush strokes.

First, I am sure you can see that you yourself quoted the developer as saying "it will be possible to recover a car within one minute." If you simply read the words, can you really find fault with that statement? The developer didn't say "process a car" or "turnover a car" he said "recover a car." (You should know, for the record, that it is quite possible to recover a car in 60 seconds or less. Naturally it depends where it is located, but it is possible nonetheless.)

As you correctly pointed out, it is the human "dwell" time that makes the 1-minute number unrealistic. However, that is not what the developer said - he said "recover."

I am sure if you ask that developer in a more exacting manner you would get a more realistic answer. For example you could ask, "What is the average amount of time it takes from the time a person requests their car to the time they drive away and that parking bay is available for another driver?" You may also ask, "What is the highest number of vehicles per hour your system has ever handled inbound & outbound in one hour."

While I am certain all of the resulting answers will be higher than the 1-minute claim would suggest. I would also be willing to bet that if you went and observed the daily operation of their existing facilities and interviewed the tenants of the buildings they serve, you may just be surprised (not happily I suspect) to learn that they actually enjoy using the system every day.

Why else would a real estate developer be planning to buy another system? Tenants, residents and real estate brokers all talk to each other, so if the system provided a poor experience, don't you think the developer would choose not risk the significant capital investment he is making in a new building on a technology that will further tarnished his reputation? I know it goes against the deeply-held beliefs of the American parking establishment, but people actually like parking in well designed automated parking systems.

I also read Don's comment, and while more balanced, it too surprisingly painted a scenario in which patrons may have to wait 10 minutes for their car. Ironically, Don is one of the parking consultants who taught us how to realistically plan throughput to meet the peak 15 minutes of the day. What was missing from Don's statement and yours was the qualifier, "If a system is properly planned to account for dwell time that sort of delay should never occur."

I hope you will accept my invitation to spend a few minutes in a Web-conference so I can walk you through the time studies we use to estimate system throughput. I think you may find it interesting (and perhaps reassuring) to see how much detail we use to estimate system throughput and transaction times.

I agree that the parking efficiency in floor area per stall are grossly high. Normal efficiency for automated parking is about 225 square feet per stall (21 sq. meters per stall). Automated parking consumes half the volume as a conventional, ramp access garage, but you have to add the cost of the machinery to the building cost. However, basement parking construction costs can be very high, which makes the smaller automated garage more cost competitive. As for the service rate, one must consider the dwell time which is the time to gather up one's belongings, children, pets, etc, vacate the vehicle, and activate the storage system. The dwell time averages about 45 seconds for familiar users or longer for unfamiliar users. Also, if ten people arrive at approximately the same time to retrieve their vehicle, the system may not have enough transport devices to accommodate ten cars at once. The tenth person in line may have to wait as much as ten minutes or more to get their vehicle.

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