Understanding the impact of external devices on driver speeds

Goal

Identify the impact of physical radars on driver behaviour using the Path Analysis tool. We’ll learn this by completing the Blacktown use case.

Context

After installing two VMS speed radars, Blacktown City Council found some vehicles were exceeding 50km/h on a residential street. They wanted to investigate driver behaviours before and after the VMS speed radars were installed. Specifically, the council wanted to understand average and 85th percentile speeds.

Do

Let’s re-create this use case. You can follow along with the video to make your analysis or download this .ciot file.

Download this file and upload it to the Road Intelligence platform to complete this module. If you don't remember how to upload a ciot file, see the instructions here.

Further Links

• Impact of VMS Speed Radars on Driver Behaviour

00:00

Let's use the Road Intelligence platform to understand the impact of physical speed radars on driver behaviour.

We'll pretend we're part of the Blacktown Council in Australia. We've installed some VMS speed radars and identified some vehicles exceed 60km/h. Keep in mind, the speed limit is 50km/h. To validate this, we want aggregated speeds to compare how drivers behave before and during the VMS installation.

00:23

To start the study first we'll select the Path Analysis tool. Then we'll search for Turner Street Blacktown where the VMS speed radars were.

Next we'll put in date ranges for before and during the installation. For the before date range we'll go to 2024. Select the 1st of October up to the 25th of October.

Then we'll create another date range for the period during. We'll go back to 2024. Select the 11th of November to the 26th of November.

01:14

For the path selection, we know that radars were approximately here and here. So we'll draw a path that exceeds a bit before and after those points, going east.

01:25

Now we can click the Analyse button. You can also upload the CIOT file which you can download from the lesson notes.Now that the results are loaded, we'll go through the platform to see how driver behaviour changed before and during the speed radar installation.

01:44

The questions we'll ask ourselves are, was there speeding before the radars were installed? What happened to the 85th percentile and average speeds when the radars were installed? And what was braking behavior like before and during the installation?

01:57

So what vehicle speeding before the installation? To find out what opened the Results Panel and select the date before the installation, the path along Turner Street and car as the vehicle type. We'll scroll down to the Speed Analysis section because we want to look at speeding.

02:12

We'll look at the 85th percentile option and choose the Chainage graph. When we hover over the graph, we can see speeds were mostly at or above 55km/h, except for two dips. Knowing the speed limit here is 50km/h, this shows there was speeding on Turner Street before the radars were installed.

02:29

Next we want to know what happened when the radar was installed. We'll scroll back up, select both date ranges, then we'll go back to the Speed Analysis section, leaving the 85th percentile option selected. We'll momentarily hide the before date range by going to the top of the graph and clicking the date tag.

02:46

On the 85th percentile graph, we can see speeds are still over the 50km/h speed limit. If we hover over the graph, we can see as vehicles pass the first sign, 85th percentile speeds are at 52km/h. Then there is a drastic drop in speed as they approach the second VMS sign. The graph here shows approximately an 8km/h drop to 48km/h.

03:10

You can also turn on the other date range to see the difference. Now if we change the 85th percentile tab to average, we can see that speeds before the radars, shown by the dark pink line, were consistently higher than the during period, but were mostly under the 50km/h limit.

03:26

Interestingly, during the period with the radars, as shown by the light pink line, we can see this bell curve where vehicles increase in speed after the first radar and then decrease in speed on approach to the second. This shows that the VMS radars were successful in reducing speed.

03:41

Next, we'll analyse the braking behaviour before and during the installation. We'll scroll down to the G-forces section. Click on the Braking tab. Then we'll select the Average tab. And we'll look at both ranges at the same time.

We can see before the radars were installed, there was minimal braking behaviour along the path. When we compare this to the period with the radars, we can see vehicles are braking more frequently and harsher where the second radar is.

04:11

And that's it. Through the study, we found speeding by looking at the 85th percentile speed, speeds decreased when the radars were installed, and drivers would start braking when approaching the radars.

04:21

Now you can apply these skills to your own studies or try following along with this video. Just know that the platform is constantly updating its dataset, so results may vary, but the steps are generally the same. We'll see you in the next in-practice lesson.