Logistics Sprawl and Urban Freight Planning Issues in a Major Gateway City - Sustainable Urban Logistics: Concepts, Methods and Information Systems - page 59

Introducing a new scale of analysis for the spatial issues associated with
warehouses in the L.A. area, I have studied the locational patterns of logistics
facilities at the zip-code level. I have considered the warehouses in the NAICS 11
database (NAICS code 493). The data were obtained from the U.S. Census Bureau
County Business Patterns Survey. 12 This provides an analysis of the number of
establishments in all the counties and zip codes in the United States based on a
detailed breakdown of industrial sectors and according to nine employment size
classes.
The technique I have used is centrography, which is the spatial analysis of
geographical data based on descriptive spatial statistics (Isard 1982 ). This is well-
suited to identifying and quantifying sprawl patterns and providing data for their
cartographic representation. Centrographic analysis consists of finding the
weighted geometric center, or barycenter, of a geographic distribution. Once this
has been done for each data set, the ''directional distribution,'' or the spatially
weighted distance of one standard deviation of the distribution is determined. The
directional distribution provides an indication of the decentralization and direction
of movement of establishments (an establishment is defined as a facility; a single
company can have a number of establishments or sites). The mean distance from
the barycenter for each distribution is then determined. This method provides data
for a cartographic representation of logistics sprawl.
Figures 2 and 3 show two different images of the relocation of warehouses in
Los Angeles since 1998. Figure 2 shows the warehouses in the five county area,
while Fig. 3 shows the results for a wider area, which extends to San Diego and
includes San Diego County and Imperial County. It also includes Kern County in
the north where some recent logistics developments have occurred.
A centrographic analysis of the location of warehouses (NAICS code 493) was
completed for the five county area (Fig. 2 ) between 1998 and 2009. This analysis
is compared with the location of all the establishments (representing all economic
sectors) and how this has changed over time. The results are the following:
The average distance of warehousing establishments from their barycenter
increased from 25.907 to 31.963 miles, but the average distance of all establish-
ments from their barycenter remained stable, changing from 41.748 to 41.714 miles.
This means that while establishments in the L.A. metropolitan area have not
sprawled, warehouses have, moved out an average of 6 miles. This suggests that
within the L.A. metropolitan area, more truck miles are required to reach cus-
tomers (for shipments or deliveries) in 2009 than was the case in 1998. This is
''relative sprawl,'' i.e. when logistics facilities move further away than the busi-
nesses they serve for pick-ups and deliveries.

11

North American Industry Classification System.

12

http://www.census.gov/econ/cbp/index.html (last accessed on April 26, 2012).