Road Closures

Introduction

Our online public space permit system (TOPS) holds information on a variety of different permit types. The type which permits blocking off lane(s) or the entire roadway is called an Occupancy permit; it is called this because the user is being permitted to occupy a portion of the public right-of-way. In this case, it is a portion of the roadway.

Processing Lane/Road Closure Data

Each night, DDOT extracts permit information from TOPS and publishes this as a RESTful ESRI map service. In TOPS, a permit is typically associated to either an address or a block range. For the map service extract, each permit location is reduced to a single, representative point even though lane and road closures which are typically expressed as linear features. This single point is then snapped to the DDOT Centerline roadway GIS, where a multitude of roadway attributes are then joined. Additionally, each permit point is enriched with a variety of local DC geographical information (for example the Ward, ANC, census tract, etc).

The result is a summary of the occupancy permit that has also been enriched with roadway and a ton of other data that makes mapping and downstream analysis easier.

Issues with Road Closure Permit Data

There are some known issues that prevent the closure data from being more accurate. We have been informed that all or most of these issues should be resolved in a future version of TOPS.

The TOPS permit-related closure data has indeterminate start and end dates/times. Permits have a date range that the permit is valid for (IssuedDate and ExpirationDate), but this may not correspond to the permit holder's actual road/lane closure begin and end date. Currently, a permit holder is not obligated to tell DDOT precisely when the will begin and end the closure.
The geographic bounds/length of the closure are ambiguous. The point in the map service is an approximation of the permit location, with the permit's widths and length. The precise begin/end point of the closure is not represented in the data.
There are several other jurisdictional entities in DC that can institute road closures. They may or may not be communicating these to DDOT in a timely matter.