An IntelliZone Smart Work Zone Management System from Quixote Transportation Safety Inc. and its Highway Information Systems Inc. (HIS) subsidiary is helping to alleviate a potentially dangerous hydroplane situation that occurred as a result of a bridge replacement work zone on I-85 near Charlotte, NC.
The bridge project resulted in eight lanes — four in each direction — of temporary pavement being put down to detour traffic around the work zone. After the temporary lanes opened, and prior to the deployment of the IntelliZone system, more than 50 hydroplane incidents had been reported, many of which were attributed to water on the roadway during heavy rains.
Since the time of deployment of the IntelliZone system in March of this year, no incidents have been reported due to hydroplane conditions.
The first attempt to correct the hydroplane problem was to lay down a second surface with permeable asphalt, allowing water to be absorbed and run off between the two surfaces. While this provided some measure of improvement, it did not completely solve the problem. Construction contractor Rea Construction requested that North Carolina Department of Transportation (NCDOT) consider reducing the speed limit. After reviewing the situation further, NCDOT opted for an automated hydroplane detection/alert system and selected QTS’ IntelliZone system.
The system allows traffic to flow at normal speed during dry conditions but alerts motorists to slow down when the system detects water on the roadway.
The North Carolina system includes two FP2000 pavement sensors that measure water depth and two precipitation sensors. Each direction of travel has one of each sensor type. The rest of the system includes two variable message signs — one for each direction, a wireless communication system and a computer for configuring and monitoring the system.
Each VMS is placed approximately .5 mi. in advance of its respective sensor location. The roadside computer collects data from the precipitation sensor and pavement sensor, makes a decision about which message to display and then automatically updates the VMS. If the pavement is dry, the VMS has a blank display. If the pavement is wet and the water level is below .24 in. (.6 cm), the VMS message is “Wet Pavement Ahead; Observe Speed Limit.” When the water depth reaches .24 in., the VMS displays “Standing Water Ahead; Reduce Your Speed.” The IntelliZone system runs autonomously and is monitored remotely via a Cellular Digital Packet Data (CDPD) link to the Internet. HIS in Durham, NC, monitors the system and collects and analyzes the data. CEG