U-turn can save you some time but can be a very dangerous maneuver if performed at the wrong place or time. At many junctions, U-turns are prohibited and despite that, some drivers attempt them and cause accidents. FLOW can help to prevent these accidents by detecting the U-turns and providing evidence. You can get counts and various traffic reports with graphs and OD matrices so you assess the drivers'

behavior. Grouped with visual alerts or police enforcement it can deter this negative driver behavior. Read this step-by-step guide and learn how easy it is to set up U-turn detection in FLOW and how it can help you enhance road safety.

If you are new to FLOW - read this article or watch our webinar to get familiar with the basics. Links to some helpful FLOW guides can be found below.

Motion filters in FLOW

Property filters in FLOW

Spatial filters in FLOW

Set operations in FLOW

Working with time in FLOW

Using widgets to view traffic data in FLOW Insights

What will you learn from this article?

  1. How to set up live detection of U-turns

  2. How to track the number of U-turns

  3. How the data can be used

If you do not have the FLOW Insights demo kit yet, you can download it here for FREE!


First, we drag and drop a category filter to the canvas. We double-click it to open its menu and we tick boxes to select the following categories: car, light, heavy, bus, and motorcycle, and bicycle as shown below. We do this so no pedestrians are counted.

Second, we create 2 gates. The first one in the origin lane and the second one in the opposite direction lane. We name the gates “U-turn gate 1” and “U-turn gate 2”.

After the gates are created we draw a U-shaped movement going from the origin gate to the opposite direction gate. We name the movement “U-turn detection”. Next, we drag the movement over to the canvas on the right side and connect it below the category filter.

Next, we add a value widget to the movement and name it “Number of U-turns detected”. We leave the time mode as is, on the whole, history setting and click add new color on the bottom of the panel. There we select red and have it show values bigger than 0. This way we will see the number go red in the dashboard when 1 or more U-turns are detected. After that, we can also add a trajectory view widget to the category filter to have a better overview of the situation in the dashboard. For the trajectory view, we leave the default settings that are pre-selected.

We can then monitor the situation using the dashboard tab where we can see the number of U-turns detected over the recent period as well as the current situation on camera. You can also publish this event to third-party software and hardware using an open API which can then activate a warning sign and save this data to a database at the same time.


Now you know how to detect U-turns with FLOW. We offer multiple real-time solutions that run FLOW, each suitable for different use. One of them is the plug n play smart TrafficCamera which is perfect for simple scenarios similar to the one in our U-turn video. For more complex traffic scenes, there is the TrafficEmbedded which can run up to 6 cameras. You can also use any number of existing city cameras with our on-premise TrafficEnterprise solution and detect U-turns across the whole city. With FLOW you can gather U-turn violation statistics that can be an important safety indicator for a given intersection. FLOW´s real-time responsiveness and easy device connectivity with public API or I/O interfaces make it ideal for traffic control, stop sign compliance or wrong-way driving deterrence.

We hope that you have enjoyed this guide.

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Let the traffic flow - with FLOW!

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