Credit: Photos: Steve Ellis

Left: Team members working on Washington, D.C.'s, turn-restriction project last year entered information about each intersection into tablet PCs. Right: Information from each day's field survey was easily uploaded into the server.

A geographic information system (GIS) now provides detailed information on every intersection in the nation's capital. Washington, D.C.'s, Department of Public Works Solid Waste Management Administration (DPW-SWMA) uses both routing software and new turn-restriction information to increase production and save resources.

Last year, GeoDecisions, Camp Hill, Pa.—a spatial information technology company— completed the turn-restriction project for the District of Columbia's Office of the Chief Technology Officer (OCTO). The application was designed to be used by OCTO, DPW-SWMA, and the D.C. DOT (DDOT). It contains data on more than 20,000 intersections and approximately 1100 miles of streets and alleys throughout the District of Columbia area.

“Like most cities, Washington, D.C., had some turn restriction data, but it was not complete or mapped,” said Ed Wells, OCTO's project manager. “We concluded that a field survey had to record both physical restrictions and posted signs.”

The DPW-SWMA relies on this comprehensive data to balance workloads and optimize crew deployments for garbage truck routing, snowplow mapping, and street sweeping. The turn restriction data also supports basic routing for DPW and DDOT, using RouteSmart (a program that finds the quickest or shortest route) and ESRI routing software.

The hardware used to collect data consisted of Toshiba tablet PCs and Trimble Pathfinder Pocket global positioning system (GPS) receivers, allowing data collectors to display and edit necessary data. The customized data collection screen was designed to give users the ability to display each intersection and fill in the appropriate sign or barrier restriction in the pull-down menu, minimizing collection time and reducing errors.

After the application was created, the second phase of the project involved recording turn restrictions for every intersection in the District. Field collection teams—comprised mostly of students from the University of the District of Columbia—performed this labor-intensive work. Equipped with one tablet PC, a GPS unit, and an operation manual, each two-person data-collection team was responsible for completing assigned sites, divided into 461 areas by the OCTO GIS department. Collectors relied on pull-down menus on the tablets to record regulatory-sign text, such as “Between 8 a.m. and 4 p.m.” or “Except Buses,” and to correctly record physical turn restrictions, such as “median or barrier.” The field collection teams returned to the District of Columbia office daily to upload the raw data into the turn-restriction project server.

Based on the input to RouteSmart, a table was developed to provide a control type, restriction type, and delay value for each turn within the District. As data were collected and processed for each collection area, the application was updated, street by street.

District of Columbia agencies already are experiencing the benefits of the project. For the first time, the DDOT Traffic Safety Administration has access to a current and complete list of one-way streets and turn-restriction locations. The turn-restriction application permits DPW-SWMA to optimize collection routing across the district and increase the effectiveness of nontrash collection, snow removal, leaf pickup, street and alley cleaning, mechanical street sweeping, and litter-can collection.

“For one day, DPW used the prototype application to allocate and route the calls automatically,” said Dave Kohler, DPW's GIS manager. “For the first time, two supervisory clerks did not spend half the day sorting 300 sheets of paper by hand. The drivers returned an hour and half early and asked for the next day's batch.”

Public works agencies will continue to use the updated DDOT street files and the newly developed turn-restriction tables for emergency routing and for updating OCTO's Emergency Atlas and Citizen Atlas. From garbage-truck collection areas to emergency routing, the turn-restriction collection application and survey project offers a comprehensive and unprecedented street-by-street perspective of the Washington, D.C., area.

Steve Ellis is director of commercial solutions and Quinn Dinsmore is communications coordinator with GeoDecisions.