The Utah Department of Transportation is utilizing the power of high definition, multi-beam radar to improve the efficiency of ramp metering along Interstate 15.

Project Team

Utah Department of Transportation

Project Scope

Metering systems installed at several onramps to Interstate 15 in Utah help to minimize gridlock by regulating the flow of new traffic onto the freeway during peak times and other periods of heavy traffic. At two locations, UDOT is using data from SmartSensor Matrix and SmartSensor HD to create ramp metering that adapts to actual conditions.

Problems and Challenges

Effective ramp metering requires real-time information about what is happening both on the onramp and on the freeway. This requires vehicle detection that is accurate, reliable, and versatile enough to adapt to a variety of detection locations and conditions. “One- size-fits-all” approaches aren’t always effective, because each onramp is different and may require different ramp metering methods to achieve safety and efficiency.


UDOT is testing two unique ramp metering applications that utilize Matrix and HD: At Location #1, two Matrix units are used for stop bar detection and queue monitoring. This metering system is only turned on during morning and evening hours when traffic is heaviest; when the system is active, the frequency of the metering is controlled with data from the two sensors. One Matrix (installed at the top of the ramp) detects vehicles at the stop bar and controls the signal, in real-time, based on the presence of vehicles. The second Matrix (installed at the bottom of the ramp) detects queues formed as a result of metering. When a queue gets too long, the rate at which vehicles are allowed to enter the freeway is increased to prevent backups onto surface streets. At Location #2, UDOT uses a combination of HD and Matrix units in order to respond to more unpredictable traffic patterns. A series of HD sensors continuously measure speeds and occupancy on a 22-mile stretch of freeway; if occupancy levels reach a specific threshold, then metering begins automatically. At the same time, Matrix monitors traffic queues on the onramp to ensure vehicles don’t back up onto surface streets.


Non-intrusive SmartSensors are more effective for ramp metering than other detection devices: easy to install, maintenance free and highly accurate in difficult conditions. With multi-beam, high-definition radar, Matrix is the only radar sensor capable of true presence detection, and it effectively replaces up to 12 loops required for a three-lane metered onramp. SmartSensor HD’s dual-beam, true high definition radar replaces more than 40 loops over 22 lanes of traffic and is recognized as the world’s most accurate and reliable radar sensor.

For more information on SmartSensor Matrix, click here.

For more informaton on SmartSensor HD, click here.