In counties where the delineations of property boundaries by field surveys must be approved by a public office. as in the state of California, it may be possible for the cadastral overlay (including the supporting numerical records based on field surveys) to be tied directly to the legal documents that define the property boundaries. as they are in the cadastres of Continental Europe. This type of public register of property boundaries now occurs in two counties in Massachusetts where registration of both title and boundary includes about half of all parcels.
The development of a cadastral overlay will consist of a series of integrated operations, entailing the compilation of land-tenure information and the publication of cadastral maps. Ideally, an area will be chosen for implementing the cadastral-mapping program within which the geodetic reference framework and the large-scale base-mapping program have been established.
There may be a temptation to initiate the cadastral overlay program before an adequate base map is available. The cadastral map is a highly valuable, tangible product that can garner public recognition and support for a multipurpose cadastre initiative. Furthermore, the land-tenure overlays are an invaluable tool in developing other aspects of the cadastral program. However, such a shortcut to a cadastral map should be discouraged, for experience has shown the following:
It is often difficult subsequently to transfer the parcel information to the higher-quality, uniform large-scale mapping base; and
There is always the danger that the product may be misused with a resulting loss in consumer confidence (McLaughlin, 1975).
Another important prerequisite for a cadastral mapping program is a budget for continuing maintenance of the maps. The front-end investments in improved cadastral maps will be wasted if insufficient resources are allocated for keeping them constantly up to date. The annual cost of the technical personnel needed for this work may average more than 5 percent of the original cost of the maps. Howwver, most of the counties that have invested in the elaborate type of digital map system described in Section 3.5.3 have found their costs of map maintenance to be substantially reduced.
We recommend that the updating of cadastral overlays be scheduled so as to assure that they will reliably show any new or changed land parcels that have been in existence for two weeks or more. Where the overlays are used by the recorder of deeds to display the parcel numbers used for indexing the land-title records, this updating should occur within one week.