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SIZE MATTERS ... IN AN AVS/RS

January 30, 2017

Just how big a vehicle can fit in an Automated Garage?

Donald R. Monahan

Yes, size does matter when it comes to the design of an automated vehicle storage/retrieval system (AVS/RS). Let me explain:


The automated transport carriers must fit a wide range of vehicle dimensions, ranging from 8-foot-2-inch-long with a 6-foot-2-inch wheelbase for the Smart car, up to 21-foot-7-inch-long for the Dodge RAM 2500/3500 Crew Cab pickup truck with a 14-foot-1-inch wheelbase.


Parking facilities are generally designed for the light-vehicle population, which includes automobiles, pickup trucks, passenger vans, and SUVs that are less than 7,000 lbs. curb weight.


It’s not economical to design parking structures for the largest vehicles in the light-vehicle population. Most AVS/RS projects limit the vehicle length to 18 feet.


The NPA’s Parking Consultants Council advocates using the 85th percentile vehicle dimensions in the light-vehicle population. This design vehicle is 6-foot-7-inch-wide by 17-foot-1-inch-long through 2010 auto sales.


According to data for the 2014-2015 model years, several extended cab pickup trucks greatly exceed an 18-foot length limitation. Among those are the Toyota Tundra, Ford 250/350/450 series, Nissan Titan Crew Cab, Chevrolet Silverado Double Cab, GMC Sierra Crew Cab, and Dodge Ram 2500/3500 Crew Cab. Even the Chevrolet Suburban and GMC Yukon XL 2500 SUVs are 18-feet-8-inches long.


Basic carrier systems


There are two basic carrier systems in an AVS/RS.


• One uses pallets supported on the floor by short legs at the four corners. The slightly elevated pallet allows the carrier to slide under the pallet, pick it up with the vehicle on top and deliver it to a storage space.


This system is less susceptible to variations in the length or width of the vehicle. It also has the advantage of eliminating problems with broken tail pipes or other debris under the vehicle. The disadvantage is the need to manage all the pallets for each storage space, as well as to replenish empty pallets to the entry compartment after a vehicle has been stored. Cleaning the pallets of slush, snow and road salts can also be a challenge in northern climates.


• The other carrier system uses a dolly to slide under the vehicle and has folding arms that wrap around the tires of the vehicle, which lifts the vehicle slightly off the floor and transports the vehicle to a storage space. The dolly needs to expand or contract in order to fit the wheelbase of the vehicle to be stored.


There is a practical range of vehicle lengths that can be accommodated with this carrier system. On one AVS/RS project, the shortest wheelbase that could be accommodated was 93 inches (7-feet, 9 inches). This limitation then could not accommodate the Chevrolet Spark, Fiat 500, Scion iQ and Smart car.


However, these vehicles represent less than 0.7% of the light-vehicle population. The largest wheelbase for an 18-foot-long vehicle is 10 feet, 10 inches.


Flexibility


There is a fair amount of flexibility in the physical design of an AVS/RS project. Column spacing is established based on the vehicle width and the number of stalls in the clear span between columns. There is then not much, if any, flexibility to accommodate vehicles with different stall widths on other floors.


A database of vehicle dimensions for 2014-2015 model years indicates that 99.8% of light vehicles are 6-foot-8-inches-wide or less. This dimension does not account for protruding mirrors. Also, 54% of light vehicles are 6-foot-wide or less.


AVS/RS facilities have a lot of flexibility with regard to floor-to-floor height at different levels. 2014-2015 data indicate that 50% of the light-vehicle population is 5-foot-high or less. Of the vehicles that are 18-foot-long or less, the maximum height is 6-feet, 8 inches. Similarly, 85% of the light-vehicle population is 5-foot, 8 inches or less. Therefore, different floors can accommodate different height vehicles.


Different length vehicles can also be accommodated in portions of the AVS/RS storage compartment. Again, data for 2014-2015 model years indicate that 50% of the light-vehicle population is 15-foot-8-inches-long or less. Also, 30% are 15-foot-long or less.


Custom-designing an AVSRS facility to allocate different size vehicles to different areas in the storage compartment can greatly improve parking efficiency and lower construction costs. However, the more variability included in the design of which vehicles must go to certain areas can increase the software challenge to manage where vehicles are stored. (Also, the local vehicle population may not match the proportion of certain models to the national statistics.)


Parking Consultant Donald R. Monahan, a 38-year veteran of Walker Parking Consultants, is now Principal of Parking-Xpert.com. Contact him at don.monahan@comcast.net.



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