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Welcome to the Roadway Centerline wiki page!  This is an exhaustive 'deep-dive' of the inner workings of the DDOT GIS team's main reason for existence:  the centerline. 

GIS Centerlines

We maintain centerline-based roadway data for all roads and alleys open to traffic within the District of Columbia.  DDOT uses a linear referencing system (or LRS) to maintain both the centerline/road GIS as well as the various attributes and characteristics about that roadway.  There are 3 major components of our LRS-based centerline GIS:

From these 3 components, we derive a multitude of other data and products for many uses.  Some of the more popular ones are:

  • Street Segment Centerlines -  used by the Master Address Repository
  • Roadway Segment Centerlines  - will eventually be used as the common base routing network layer.
  • Intersection Approaches - used by Safety Data team for MIRE (see below)
  • Cross-section Data - complete view of our roadway elements as a cross-section.
  • Network Analysis Layer - (coming soon)

How We Update the Centerline and Other Data

  • Construction updates from Protrack+
  • Notifications from the public/other agencies

How We Check our Centerline and Other Data

  • Checks on Centerline
  • Checks on Cross-sections
  • Checks on Parking Data


In the years since it's inception, the simple centerline has changed quite a lot.  Read a bit more about the origins of the DDOT centerline:  from paper-based engineering drawings and ROW cards in the DC Office of the Survey all the way to our modern-day LRS.  We've come a long way and it's interesting to understand where we've been.  Visit the DDOT Centerline Legacy page for more.