How ReCAP Works
ReCAP is designed to efficiently store and preserve library and archival materials. Its current plan follows the Harvard Depository model. Items are sorted by size as they arrive at the facility, added to an inventory management system that tracks their location and status, and then shelved with like-sized materials in 30' tall shelving ladders similar to the racking systems used in warehouses. Each day, items are retrieved from the storage modules and delivered to library patrons in both print and digital format, and then returned to their home location within the facility.
Materials at ReCAP are sorted by size upon arrival. Bound volumes are sorted into five groups by their dimension from spine to foredge -- A, B, C, D, and E -- and each of these is divided into High and Low groups according to the volume’s dimension from head to tail. Like-sized volumes are then placed together into trays to control for their depth from front to back cover, so that materials in ReCAP can be efficiently packed in all three dimensions. Conventional library shelving controls for size in just one dimension by grouping volumes into standard or oversized groups, and requires some free space on the edge of each shelf to allow for shifting and reshelving.
ReCAP also holds a variety of archival materials and non-print media that are housed in a variety of containers. These are also sorted to group like-sized containers together to maximize space efficiency and assigned to shelves that are closely sized to the container height. In general, materials are trayed and shelved so that they are directly adjacent along with width and depth and have only 1-2” of clearance between the top of any tray, book, or container and the shelf above. This close packing in all three dimensions provide four principal benefits: reduced rates of environmental damage, good mechanical support, limited oxygen exposure to prevent against fire, and a good ratio of building footprint to collection size. Further information about ReCAP’s preservation efforts is available in the http://recap-dev.princeton.edu/facility-storage/preservation-environment, http://recap-dev.princeton.edu/facility-storage/energy-sustainability, and http://recap-dev.princeton.edu/information-publications sections.
Accession and Verification
After sizing, materials are added to ReCAP’s inventory system. After each tray is packed, the tray is labelled with a piece count and customer code. A second staff member then checks the customer code and scans the tray barcode and the barcodes of each item in the tray to verify the count and associate the items to the tray. A third staff member then repeats the scan of the tray barcode and the item barcodes, to double-verify the correct item to tray association, customer code, and piece count.
ReCAP pulls materials three times per day, at approximately 7:30 am, 12:00 pm, and 3:00 pm. During retrieval staff are given a picklist that is sorted for an optimal path through a section of the facility. Materials are shelved on 30’ high aisles of racking accessible via an operator-elevating lift, so the picklist is sorted to allow the staff to retrieve from one vertical half of the rack from front to back, and the over vertical section from back to front.
On average, ReCAP staff retrieve one volume every 60 seconds. However, travel time between aisles and zones in the racking takes more time than pulling items within a zone, so batching and queuing requests for optimal speed is important. The first retrieval takes several minutes, but within a well-structured retrieval path, each item takes only a few seconds. The three dimensional arrangement of ReCAP allows retrievals to progress in three dimensions, as well, so that a single 30’ ascent from the bottom of the rack to the top traverses well over 6,000 volumes. This same amount of material would require around 180’ of standard library shelving.
ReCAP scans and delivers discrete sections of the materials in its holdings on request, up to about 50 pages or one specific section such as a table of contents, article, or chapter. This generally allows for same-day service, eliminated the wear and added costs of physical delivery, and keeps material secure within ReCAP’s preservation envelope. Scanners with an angled platen or overhead cameras are used in digitization to ensure that scanning does not place any significant strain on the materials.
The majority of ReCAP requests are filled via print delivery, arriving at the requesting library the next business day. Materials are packed into durable and reusable plastic totes with an integrated lid. The totes are lined on the bottom and sides with a high-density foam to protect the materials in transit and ensure that they gradually equilibrate between the storage and usage environments. When a small number of items is shipped to a particular destination, an additional loose pack of paper or foam is placed on top of the books beneath the lid to hold materials in place.
On return to ReCAP, all items are sorted onto carts for refile, by their home aisle and arrival date. This ensure ReCAP has immediate inventory control and makes it possible for items to be retrieved prior to reshelving in the storage racks. On return to their home tray, the barcodes of the tray and item are scanned to verify that they are matched correctly. Materials are batched and staged for refile and generally returned to their home tray location over a period of 1-2 weeks. Refile is the only major process at ReCAP that is not time dependent, however; accession and retrieval both have to be performed daily to meet demand.
The two stage process of initial check-in and subsequent return to shelf gives ReCAP the flexibility to adapt to peak demand and meet delivery goals under a variety of circumstances, and to make sure that refile runs are performed on batch sizes that are large enough to achieve optimal refile speed.
Audit and Inventory Control
ReCAP fills almost 250,000 requests each year. As an inventory control and audit mechanism, this assures us that we are as close as possible to zero-loss in our inventory control and perfect reliability in retrieval. Our annual retrievals surpass the "six nines" threshold of 99.9999% reliability and our margin of error for our inventory control evaluations is less than .05%.