Wrong-way detection programs are being funded faster than they are being specified well. Connecticut is on its way to 400 ramp systems. Ohio, Florida, Pennsylvania, Massachusetts, and Arkansas are deploying or testing. The agencies getting results share a few decisions made before the purchase order. These are the eight questions that shape them.
If you need the background first, read how wrong-way detection systems work.
Nobody instruments every ramp in year one. Prioritize by:
Measure the ramp. A driver at 25 to 35 mph covers a 400-foot ramp in about eight to eleven seconds. The sign has to light while the driver can still see it and stop. Specify detection-to-sign activation in milliseconds, not seconds, and require the number at night in rain, since that is when wrong-way entries happen. Under 500 milliseconds is achievable with current fused sensors.
This is the false-alarm question, and it is the one most specs skip. Ask whether the system fires on a single sensor's judgment or requires two independent sensors, typically radar for direction and video for object class, to agree. Ask specifically how it handles mowers on the shoulder, pedestrians, cyclists, and headlight sweep from the adjacent ramp. Our post on false alarms explains why this decides whether the TMC still trusts the system a year in.
The detection should trigger existing ramp signs directly. Specify the interface: contact closure for simple sign controllers, NTCIP or SDLC for networked signs and DMS. Avoid any system that requires replacing working signs or a new ATMS integration project to get the first ramp live.
Three recipients, in the same instant: the driver via the ramp signs, the traffic management center, and law enforcement. The TMC alert should carry a video clip so an operator can confirm in seconds and post the mainline DMS. Specify the alert path explicitly, including what happens after hours.
Night, fog, rain, snow, and low-sun glare are the operating conditions, not the edge cases. Require all-weather, 24-hour performance in the spec and ask for evidence from a live ramp rather than a demo. Radar is what carries direction detection through weather. Video is what keeps it from firing on things that are not cars. A system that relies on one alone will have a weather gap.
Ramp projects stall on trenching and power. Favor systems that mount on an existing pole or light mast, run on PoE, and go in within an hour per ramp. That is the difference between instrumenting six ramps this season and one.
The agencies winning support for expansion report turnaround rates: how many drivers triggered the system and reversed on the ramp. Connecticut cites more than 1,000 turnarounds across its program. Ohio reports 83 percent of triggers in 2024 ended with the driver turning around. Specify logging of every event with timestamp, clip, and outcome from day one, so the program can show the number a year from now.
Omnisight's wrong-way detection was built around these questions. One FusionSensor per ramp fuses HD3D Doppler radar and AI video on the device, and both must agree on direction and object class before an alert fires. Detection to sign trigger is under 500 milliseconds. It drives existing signs and DMS over contact closure, NTCIP, or SDLC, runs on PoE, mounts on a pole in under an hour, and logs every event with a clip. The same device also handles incident and queue detection on the mainline and can feed V2X alerts to connected vehicles, so a ramp sensor is not a single-purpose purchase.
Scoping a ramp program? Talk to our team and bring your 911 wrong-way call data. It is usually the fastest way to pick the first ten ramps.
Subscribe to The Edge Brief for monthly field notes, deployment stories, and product updates.
Subscribe →