GIS Technology Supported Libraries Planning

Apollo Teng

Montgomery County Public Libraries (MCPL) recently performed a system-wide service level and future expansion study. Barbara Norland was part of the study team. She requested DIST GIS Teamís assistance in providing maps to support her project. Dr. Lian Chen of the County GIS Team performed all the support.

To plan for future expansion or constructing brand new libraries, the MCPL planners needed to know population growth pattern for the next twenty years. In this regard, the first map requested and subsequently generated shows the M-NCPPC forcasted population levels by traffic zone for the years 1995, 2000, 2005, 2010, and 2015. The five views were laid out in one map, enabling ready comparisons among the five 5-year intervals.

The second map requested was for showing libraries locations along with their respective primary service areas as defined by radii specific to each library. The library list (21 libraries) provided by MCPL contains street addresses. Approximate geographic locations were derived by matching these street addresses against the Geographic Base DIME File. The circles were generated with the library locations as the centers and their corresponding primary service radii as the radii. In the lower county areas, these circles overlapped a lot. These overlapping circels were merged into one large convoluted area representing the portions of the County which are being served by two or more libraries. The remaining circles did not overlap; they represent the portions of the County that are being served by one library, given the definition of service radius for each specific library. Finally, for those portions of the County that are not covered by any circles, they represent the under-served areas. Plotting the under-served areas on top of the population forcast maps would give the library facility planners some hints of where should the future libraries be located.

The third data item that was of interest to the study was circulation. Although circulation per sqaure footage of floor space can be calculated, we decided just to plot the total volume for each library in a combined (vertical) bar chart. Arc/Info plotting (a.k.a. ArcPlot) allows the merging of charts with map views.

According to Norland, these maps turned out to be effective tools for the planning process. With the availability of detailed planimetric (including topography), orthophoto, and property databases, the planning effort can be pushed to a higher plateau. With data such as land ownership (public vs. private), acreage, assessment, slope, soil suitability, closeness to transit lines, etc., coupled with the knowledge of under-served areas, an efficient and objective procedure can be developed to tackle the next topic of site analysis and selection, which is rather tedious in a traditional and manual mode. (A prototype of this application was developed by Barb Selbst of DIST in 1993. WSSC adopted this prototype for an in-house site selection project in 1995.)