This post is part 2 of a new “how-to-series” that illustrates how easy it is for users to start analyzing their traffic signal network once signing up for INRIX Signal Analytics and selecting the signalized intersections and corridors they would like to get insights for.

Getting Started with the Intersections Module:

The Intersections Module presents a map and list view of all of signalized intersections within your network.  Use this module to click, discover, and rank the performance of signalized intersections within the network. You can color these intersections to look at overall LOS (Level of Service) values or the % change in LOS values for 3 key performance measures: Average Control Delay per Vehicle, Percent Arrivals on Green, and Split Failures.

 

Selecting Which Intersections to Track in Signal Analytics:

Before getting intersection insights in your network, you’ll need to specify which intersections you’d like to get information for. To select the intersections that you’d like to track in Signal Analytics, simply click on the “Admin” gear icon on the left-hand panel then switch to “Signals”. A map visualizes all your currently available intersections, and the right-hand panel provides some high-levels stats on the current status of all requested/provisioned intersections.

To add a new intersection to track, click on individual intersections or draw a polygon to add to your selection. You can also hold the Alt/Option key and click an unrepresented intersection to request data for that area. Remember to click the grey “Save Selection State” in the bottom right to save all changes to your intersections.

Add Intersections

 

Visualizing Key Performance Metrics on Map:

Once you’ve selected intersections to track in Signal Analytics, you can now get insights for them. To visualize performance measure LOS metrics in the map view, start by selecting a time range to analyze using the Time Range Display filter.

3-Filter Time Range

You have the option to analyze a specific day (Daily), a specific week (Weekly), or specific month (Monthly). Additionally, you can analyze different Day Parts by selecting either 24 Hours, AM Peak, Midday, PM Peak, or Overnight.

The Map Display filter lets you select which performance measure to visualize any of the 3 performance measures mentioned above.

4-Map Display

Under the Map Display filter, select the LOS Values option to see a visual representation of LOS on the map. Green represents better-performing intersections, while red represents worse-performing intersections.

Select the Change in LOS map display filter to get a similar visual representation but specifically for the percentage change in the level of service for the performance measure that you are analyzing.

Click the circular icon in the lower left of the map to view the legend which explains the ranges for the colors depending on which performance measure you are looking at.

Visualizing Average Control Delay Per Vehicle on Map:

Under the Map Display filter, select LOS Values and Avg. Control Delay/Vehicle to visualize control delay LOS values. The Average Control Delay Per Vehicle metric describes operational conditions within a traffic stream, defined as:

A ≤10 Free Flow

B >10 – 20 Stable Flow (slight delays)

C >20 – 35 Stable flow (acceptable delays)

D >35 – 55 Approaching unstable flow (tolerable delay, occasionally wait through more than one signal cycle before proceeding)

E >55 – 80 Unstable flow (intolerable delay)

F >80 Forced flow (congested and queues fail to clear)

To visualize the percentage change in average control delay per vehicle select Change in LOS and Avg. Control Delay/Vehicle under the Map Display filter,

5-Visualize Change in LOS

This feature shows the number of levels an intersection has changed in LOS compared to a historic 4-week average. Green represents an improvement, while a red represents a degradation.

Use this feature to quickly pinpoint intersections that might be affected by seasonal changes, malfunctioning equipment or other outside forces.

Visualizing Percent Arrival on Green on Map:

6-Visualizing Percentage on Green in Map

Under the Map Display filter, select LOS Values and Percent on Green to visualize Percent Arrival on Green LOS values. The Percent Arrival on Green metric describes operational conditions at an intersection, specifically progression, defined as

A >90% arrival on green (near perfect)

B >75 – 90% arrival on green

C >55 – 75% arrival on green

D >35 – 55% arrival on green

E >20 – 35% arrival on green

F ≤ 20% arrival on green (very poor)

To visualize the percentage change in Percent Arrival on Green LOS change select Change in LOS and Percent on Green under the Map Display filter.

This feature shows the number of levels an intersection has changed in LOS compared to a historic 4-week average. Green represents an improvement, while a red represents a degradation.

Visualizing Split Failures:

A Split Failure occurs where a green signal time fails to meet the vehicle volume demand and a driver is forced to stop more than once at a traffic signal.

To visualize this in Signal Analytics, under the Map Display filter, select LOS Values and Split Failures to visualize split failure LOS values. The Split Failure metric describes operational conditions at an intersection, based on the percentage of observed vehicles experiencing a split failure, defined as:

A ≤1% less than 1% of observed vehicles experienced a split failure

B >1-5%

C >5-15%

D >15-30%

E >30-50%

F >50% over half of the observed vehicles experienced a split failure

To visualize the percentage change in Split Failure LOS change select Change in LOS and Split Failures under the Map Display filter.

This feature shows the number of levels an intersection has changed in LOS compared to a historic 4-week average. Green represents an improvement, while a red represents a degradation.

9-Visualizing Split Failure Changes

 

Visualizing List View of Performance Metrics:

The Map View provides an easy way to quickly visualize how intersections on your network are performing but the List View makes it easy to rank and prioritize intersections that might need improvement.

10-Visualizing List View of Performance Metrics

You can easily toggle List View on by clicking list icon in the bottom-middle of the dashboard. You can sort intersections by metric, area, or other details

Visualizing Hybrid Map/List View of Performance Metrics:

The Hybrid View provides the best of both worlds and let’s you visualize colorized performance metrics on the map and sort intersections in the list view at the same time.

11-Visualizing Hybrid Map:List View of Performance Metrics

To toggle Hybrid View on simply click the Hybrid View icon on the bottom-middle of the dashboard.

Getting More Details About An Intersection:

The Map and List views of the Intersection Module provide a great holistic view of your entire network but you’ll need to dig into the details about a particular intersection’s performance to really understand how to fix issues. To do this, simply click on any intersection that you want more insights on from

To visualize the percentage change in average control delay per vehicle select Change in LOS and Avg. Control Delay/Vehicle under the Map Display filter,

If you want more detail into an individual intersection you can zoom in to that intersection and select the intersection you are interested in.

Intersection Diagram & Trajectory Plots

The Intersection Diagram which provides metrics at both the movement and the approach level. If you are interested in more details about a given movement or approach, you can click that movement or approach and you will see count stats and time stats for each movement or approach at an intersection

Another major feature to the Signal Analytics product was the addition of trajectory plots. Foundational to the field of transportation engineering, these figures allow engineers to investigate specific periods and gain insights about how individual vehicles are experiencing an intersection. They can be used to identify progression issues, highlight times when split failures may be occurring, and visualize traffic flow for reports and presentations.

12-Intersection Diagrams

 

Summary

Both of these tools provide you a way to summarize and dig deep into intersection and corridor problems that you may have and really provide valuable insights to help you make data-driven decisions to solve transportation engineering problems.

If you want to learn more about Signal Analytics and our growing list of enhancements join our upcoming  free webinar on February 26th, 2025 called “Optimizing Traffic Signals at Scale”.

Want a personalized Signal Analytics demo? Request a virtual demo  or reach out to Signals@INRIX.com if you have specific questions.

Be sure to check back for the next post in this series which will show you how to analyze the reliability and performance of user-defined corridors at various times of the day using the Corridors Module.