The contributing editor recently had the opportunity of examining the Automated Storage and Retrieval (AS/R) at California State University, Northridge (CSUN) over a two-day period. It is an impressive technology, and well worth considering as an alternative to electromechanical compact storage or a remote storage facility.
AS/R systems are not yet widely used in libraries, but the technology is well-tested, having been used in industry for many years. Items to be stored are assigned to and placed in a bin and each bin is assigned a location; the bins are then placed in an industrial rack assembly. A large assembly may be up to 40 feet high and 90 or more feet long. A computer-controlled mini-load crane (an electrically-driven forklift-like mechanism running on floor-mounted and overhead rails in aisles between racks), moves into and out of the rack assembly removing and replacing bins. When an item is requested, the bin location is sent to the mini-load crane, which retrieves the bin and carries it to the operator. The operator, guided by a visual display on a terminal, takes the item from the bin and gives it to the requestor, or delivers it to a nearby service desk. Elapsed time for retrieval from the AS/R can be well over a minute; but, by taking advantage of the data maintained by the computer, high-demand items can be moved to the front of the rack assembly as they are used and returned to the unit. Returning the item to storage follows the same procedure in reverse and requires a comparable amount of time. In a library application, 40 retrievals per hour per operator is the maximum realizable.
Storage of 1.2 million volumes—the capacity CSUN specified—requires only 8,000 square feet, but AS/R installations normally are 25-40 feet high, and cost of space must be increased to accommodate floor-loading (a minimum of 300 PSF), ceiling height, and special electrical and data cabling requirements.
The AS/R's life expectancy is 20 years or more, although moving components will require regular servicing, and replacement of computer equipment should be anticipated at least three times during this life span period.
The 1.2 million-volume capacity AS/R at CSUN utilizes six cranes aisles, 12 end-of-aisle workstations, 13,260 bins, and an electric track vehicle delivery system. The system is controlled by a 386/33 PC and 12 terminals. Additional remote terminals (five in this case) are normally included. Equipment cost is approximately $2,220,000—a figure which includes the ETV (electronic tracing vehicle), a mechanical delivery system between the AS/R and two delivery desks.
While there is considerable disagreement among architects about the cost of building a 40-foot high chamber with a floor-loading of 300 pounds per square foot, the median cost quoted by architects consulted by the team is $200 per square foot. The total space needed to accommodate 1.2 million volumes is 8,000 square feet; thus, construction would cost approximately $1,600,000.
AS/R is most attractive when the system is installed as an integral part of a new library building, an addition to an existing library building, or in the renovation of an existing library building.
Transferring materials to be stored into the AS/R costs a minimum of $.10 per item, or $120,000 (assuming 1.2 million volume). This assumes all records are already entered into a library's automated library system (online patron access catalog and circulation system), AS/R also requires the entry of records and bin location information into the AS/R computer.
Total start-up cost for accommodating 1.2 million volumes in an AS/R is approximately $3,940,000. Ongoing costs, including building and equipment maintenance, system operators, and overhead, are approximately $310,000 a year in current dollars. Thus the total cost over 20 years would be approximately $10.1 million—approximately half of the cost of electromechanical compact storage over the same period and one-third the cost of conventional open stacks shelving.
Smaller systems are also cost effective, but the relative cost of AS/R rises rapidly for installations accommodating fewer than 600,000 volumes.
A major perceived drawback of AS/R is lack of “browsability.” The “stacks” are truly closed, with delivery from the system by staff the only form of access. CSUN has overcome many of the concerns by providing for rapid delivery of requested materials (five minutes), facilitating the placement of the request at the OPAC terminal, placing no limit on the number of items which may be requested, and by providing conveniently located carrels in which patrons may review a large number of titles. Few patrons have availed themselves of the unlimited retrieval service.
The “browsability” issue might also be addressed by providing tables-of-contents information in the online patron access catalog. If one were to assume that one-third of the items in the AS/R were monographs, and that the imaging were done in-house, the 20-year cost of the AS/R option would increase by nearly 10 percent. It is hoped that commercial tables-of-contents services, such as the Blackwell North America service described in this issue, will reduce that cost in a few years when titles in the program begin to be removed from active open stacks shelving.
[Contact: Doug Davis, AS/R Administrator, California State University/Northridge Library, 18111 Nordhoff Street, Northridge, CA 91328; (818) 885-2272 or E Mail DDAVIS@VAX,CSUN.EDU.]
