Safer Streets With LiDAR

Utah is implementing LiDAR technology at intersections to create real-time 3D maps that improve detection and safety for pedestrians and cyclists.

What is LiDAR?

We are always looking for ways to make our roads safer, especially for people who are walking, biking, or using scooters. One of the newest tools we are using is called LiDAR.

LiDAR stands for Light Detection and Ranging. It sounds complicated, but you can think of it like the sonar that bats or dolphins use to see, but instead of sound, it uses safe, invisible beams of light.

LiDAR sensors shoot out millions of laser pulses every second to scan the intersection. When these pulses hit an object, they bounce back to the sensor. By measuring how long it takes for the light to return, the system creates a precise, 3-dimensional map of the intersection in real-time. While some sensors, known as spinning LiDAR, rotate to capture a 360-degree view, others are "solid-state" and stare in a fixed direction without moving.

How is LiDAR Different from Cameras or Radar?

You might wonder why we need LiDAR if we already have cameras and radar at many intersections. Each technology sees the world differently:

Cameras (Video Detection): These are like human eyes. They see color and details, but they can struggle when it is dark, foggy, or if the sun is shining directly into the lens. They also see a flat 2D image, which can make it hard to tell exactly how far away something is.
Radar: This uses radio waves to detect motion. It is great at tracking fast-moving cars and working in bad weather, but it is not as good at detecting the precise shape of an object. It might have trouble telling the difference between a small car and a group of pedestrians.
LiDAR: This offers the best of both worlds. It creates a perfect 3D shape of objects, so it can easily tell the difference between a truck, a cyclist, and a person walking. It works perfectly in the dark and does not get blinded by the sun. Also, because it only sees 3D shapes and not actual video, it protects your privacy by not recording faces or license plates.

How Utah Uses LiDAR to Keep You Safe

We are testing and installing LiDAR at several intersections, such as 5900 South & State Street and Redwood Road & 2100 South. Here is how this technology is helping vulnerable road users right now:

1. Passive Pedestrian Detection

Have you ever worried the "Walk" signal would run out before you finished crossing the street? LiDAR solves this. It can "see" that you are still in the crosswalk even if the timer is running out. If it detects a slower walker, it can automatically talk to the traffic signal computer and extend the crossing time by up to five seconds to let you finish safely. Though you won't see the number on the countdown timer increase, the traffic light will hold back conflicting traffic while you finish your crossing.

2. Smarter Flashing Yellow Arrows

You have likely seen the flashing yellow arrow that allows cars to turn left when there is a break in traffic. Sometimes, a driver might be looking at oncoming cars and miss seeing a pedestrian crossing the street on their left. LiDAR adds a safety layer here. If the system detects a pedestrian in the crosswalk, it can delay or turn off the flashing yellow arrow, keeping the cars stopped until the pedestrian is out of the danger zone.

3. Connected Vehicle Safety

In the future, cars will be able to "talk" to traffic signals. We are currently testing systems where the LiDAR detects a pedestrian on the corner and broadcasts a message to nearby connected cars, warning the drivers that someone is about to cross the street.

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