Developing a Research-Grade Iowa Work Zone Database

Project Details









Iowa Department of Transportation

Principal Investigator
Skylar Knickerbocker

Research Scientist, CTRE

About the research

Accurate work zone data are a challenge that all agencies face. Agency staff that want to be proactive in their work zone management are limited by the accuracy of their work zone data and are looking for ways to improve the methods of collecting their data. In Iowa, as well as most other states, work zone data are manually collected using forms or lane closure planning systems. This works well for planned work zone data but is not ideal for collecting actual work zone data from the field where the work zones are actually located and when and where lanes are closed.

Improvements to this process should collect better data without any additional undue burden on field staff or contractors by using connected temporary traffic control devices (cTTCDs) to supplement the planned work zone data with verified location and time data.

The Federal Highway Administration (FHWA) Work Zone Activity Data (WZAD) Framework and Data Dictionary were invaluable resources in identifying and establishing the data elements needed for a research-grade work zone database. The FHWA WZAD Data Dictionary was used to develop the database structure by understanding the relationships between all of the data frames and data elements. An entity relationship diagram was created to show these relationships and identify the similar data elements for the various tables in the work zone database.

With the database established, a process was developed for archiving work zone data by integrating planned 511 work zone data with data from smart arrow boards deployed in Iowa. The smart arrow boards allow for verified coordinates and times to be included in the work zone database for greater confidence in the accuracy of the data.

The archival of the work zone data is a two-fold process that is scheduled to run every five minutes and update the work zone database with any new work zone information. Part 1 of the process cleans the existing 511 field data and formats it to match the fields and data enumerations from the WZAD Data Dictionary. Part 2 takes the output from Part 1 and integrates the cTTCD data from another existing process based on the Iowa DOT’s linear referencing system.

This research identified challenges with integrating cTTCD data with planned work zone data and also identified a variety of data elements that the Iowa DOT could begin collecting in the future. The current work zone database should be viewed as a starting point and should be expanded in the future as other data become available or improved methods of collecting data are added.