The North Carolina Department of Transportation (NCDOT) used smart work zone technology to improve traffic conditions during roadway rehabilitation work at two work zones on I-95 in the vicinity of Smithfield and Rocky Mount, North Carolina.

Portable dynamic message sign (DMS) trailers equipped with traffic sensors and wireless communications enabled traffic managers to monitor work zone traffic flow and update DMS as required to respond to traffic incidents or excessive congestion. Depending on the location and level of congestion, delay and alternate route information were posted. When no delays were detected, generic messages were posted to inform motorist of the approaching work zone (e.g., Traffic Slowing Ahead / Prepare To Merge; Real Time Traffic Info / No Delay Exits 150-141). When short delays were detected, but not long enough to recommend an alternate route, the system provided a warning message and informed motorists of the expected delay (e.g., Traffic Stopped Ahead / 15 Minute Delay). If long delays were detected, the message included alternate route information (e.g., Traffic Stopped Ahead / 20 Minute Delay / Use Exit 141 As Alt.). The traveler information posted on the DMS was also made available on an Internet website to assist travelers with pre-trip planning.

The system was implemented during the 2003 construction season (April to October). Two months after completion of the construction work, a survey was sent to 1486 local residents to assess their perceptions and acceptance of the work zone information system. The survey consisted of a short mail-back questionnaire (eleven multiple choice questions) and a cover letter from NCDOT requesting their participation. Three hundred and thirty-three (333) recipients returned the questionnaire (22.7 percent response rate), and of those, 262 remembered seeing the signs while traveling in the work zone.

RESULTS

The survey results indicated that the system information influenced route choice. Approximately 26.1 percent of respondents who saw the signs often switched route, 41.7 percent sometimes switched route, and 17.4 percent seldom switched route.