Monday, August 31, 2009

Duplicate Address




Last week David & I went for the field research to check the location of 3233 15th Place SE as it was appearing at two locations.

Unfortunately 3233 15th Place SE was on two buildings ….may be 30 meters away. One for a cemetery and another for a new townhouse that looked unoccupied.

MAR team took initiative on this and informed DCRA to correct the address for of one of them; may be townhouse as that is the newly issued address as compare to the cemetery.
This kind of case is unusual and may create nightmare for address related services like getting mail and in emergency situations. However, one good thing is that the MAR team is taking good care of unusual address pattern/locations including duplicates. :)


Monday, August 24, 2009

Square, Suffix, Lot (SSL)


Today's topic is the Master Address Repository (MAR) and Square, Suffix, Lot. One of the goals of the MAR is to establish a better relationship between addresses and SSLs (property identifier). For a plethora of information regarding Square, Suffix and Lots check out the Vector Property Map (VPM) website. Also see Office of Surveyor which is tasked with maintaining the official map of property boundaries in Washington, DC. The Search Real Property Assessment Database is used to search and display real property assessment records, use the on-line public information database.


What is the relationship between an address and an SSL (property record)?

It is a many to many relationship. One SSL (Square, Suffix, Lot) can have multiple addresses located on it. This often includes garden style apartment complexes as well as corner addresses with separate addresses facing each adjacent street. One address can also sit upon multiple properties. One single family residence can sit upon multiple lots. The address records only contain one 'base' SSL (usually comes from OwnerPly). The cross reference table contains the many to many relationship between an address and an SSL. Some addresses do not have an associated SSL (such as some metro entrances or many addresses on Federal property). In, the address table, each address record will only be associated with one SSL. That SSL will be the base SSL, which is the SSL under which the address point is located.


What is the Address / SSL Cross Reference Table?

The Cross Reference table stores the relationship between an address and an SSL (property identifier). The relationship between these two items is a many to many. It stores over 200,000 records. One SSL (Square, Suffix, Lot) can have multiple addresses located on it. This often includes garden style apartment complexes as well as corner addresses with separate addresses facing each adjacent street. One address can also sit upon multiple properties. One single family residence can sit upon multiple lots. The address records only contain one 'base' SSL (usually comes from OwnerPly). The cross reference table contains the many to many relationship between Address ID and SSL. Some addresses do not have an associated SSL (such as metro entrances or many addresses on Federal property).

How is the Address / SSL Cross Reference Table maintained?

The Address / SSL Cross Reference Table is maintained by an automated process that is run each weekend. The table is completely repopulated each and every weekend. The table is created based on the following sources:
  • Vector Property Map (VPM)
  • Address Records
  • Condo Relate
  • Residential Unit Table
  • Integrated Tax System
  • Selected building polygons

Thursday, August 20, 2009

Place Names


The Master Address Repository (MAR) also includes place names (which we call alias names). It is important to have these place names in the MAR for multiple reasons. One reason is that many of these places do not have addresses and thus need to be located using their place name. For example the Washington Monument or the Carousel on the National Mall (see image).

The Alias (place) Table in the MAR contains names for building, historical sites, statues, metro station entrances, museums, federal buildings, hospitals, embassies, hotels and more. There are over 5,000 alias records, each of which is associated with an address. Using the MAR Sample Client alias names can be searched. Each and every alias record is associated with an address record. Multiple alias names can be associated with one address record.

Monday, August 3, 2009

***** Monthly MAR Data & Information Report: July 2009 *****


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Dataset Numbers:

Addresses: 141,728
Residential Units: 187,384
Aliases: 5,155
Street Name Alias: 1,021
Intersections: 16,359
Block: 15,826
Address / SSL Cross Reference Table: 235,456

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News:

The MAR training for Joseph Bembry, who is a DCRA Employee, had been completed. He will be reviewing and recommending new addresses. He has also been trained to directly add addresses to the MAR using the MAR Maintenance Tool.

80 roadwaysegment IDs were updated to reflect changes in the Department of Transportation's Street Spatial Database (SSD).

Sunday, August 2, 2009

Corner Buildings, Multiple Addresses


There are thousands of building located on street corners within Washington, DC. While the overwhelming majority of these buildings only have one address, some of these buildings have multiple addresses. An example of a corner building with multiple addresses is the building on the southwest corner of 7th Street & H Street NW:


  • 734 7TH STREET NW (Fuddrucker's)
  • 702 H STREET NW (small Office building with a few office suites)

One can view this location in Google Streetview. Both of these addresses are in the Master Address Repository.
Over the past few years the MAR Data Team has collected and mapped hundreds of these addresses located at corner buildings which have multiple addresses. This has been accomplished through processing millions of records which contained addresses located in Washington and through field research (site visits). Despite a large investment of time in this effort, there are still probably a few missing corner addresses.