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Signal Performance Metrics

This is part 2 of 4 in our blog series on Traffic Insights. This post covers Signal Performance Metrics. Stay tuned for more!

In part one of this series, we covered the evolution of data-driven traffic operations. We looked at the obstacles many cities face in implementing modern systems. And we didn’t forget to cover the benefits:

1. Better payback from infrastructure investments and 2. Better served citizens.

Both are driven mainly by the traffic insights available from Spectrum.

These insights fall into three main categories: Signal Performance Metrics (the subject of this blog post), Arterial Performance Metrics, and Maintenance and Infrastructure (which we will cover in future posts).

Design, Tune and Troubleshoot with SPMs

Signal Performance Metrics (SPMs) are a set of measurements and visualizations that help traffic teams design, tune, and troubleshoot traffic intersections. They are part of Miovision Spectrum, a turnkey solution for remote traffic signal optimization.

Spectrum provides the entire range of solutions needed to collect, monitor, and understand traffic signals. This includes a managed cellular connection and tools for signal monitoring, video streaming, maintenance alerts, and traffic data insights.

Spectrum’s analytical tools and reports generate actionable information from the raw traffic intersection data. SPMs provide intersection-level reporting of key metrics like:

  • Vehicle volumes
  • Wait times
  • Problem detection

Do These Questions Ring True?

If you recognize the questions below, your team is a good candidate to test these solutions.

SPMs help traffic agencies answer the most basic questions like:

  • Are my traffic signals working?
  • What kind of traffic volumes are we seeing?

But also deeper-level questions like:

  • Do we have an appropriate allocation of green time between movements?
  • Are we meeting our goals on vehicle wait times at rush hour?

How Are SPMs Generated?

Spectrum captures event data from the traffic controller, detectors, and other cabinet devices. This data includes signal state, pre-emption, and detector actuations. This is generated from stop-bar and upstream count detectors and pedestrian call button actuations.

Spectrum’s cabinet hardware is able to generate this data even from cabinets housing older traffic controllers. These typically do not produce high resolution reporting. The raw data is securely stored in Spectrum’s cloud where analysis is performed to extract meaningful information and actionable insights.

screen-shot-2016-11-14-at-9-45-34-am

What are the Infrastructure Requirements for Signal Performance Measures?

Although Spectrum Traffic Insights can be useful in an intersection with no detection, the set of available analytics expands with additional detector infrastructure.

With no detectors, Spectrum SPMs include:

  • Red/Green Allocation: The proportion of green time allocated to each approach and movement.
  • Pre-emption Summary: Reports of pre-emption events, durations, and triggers, including railroad crossings or emergency vehicle pre-empts.

With stop-bar detection data, Spectrum SPMs include:

  • Red and Green Occupancy Ratio: Gauges the demand for the various phases based on the ratio of time that vehicles are present in the associated movements. This allows for tuning of split times between phases.
  • Purdue Split Failure: Industry-standard metric that charts the frequency of split failure occurrences, an incident where green signal time fails to meet the vehicle volume demand.
  • Simple Delay: Simplified approach delay measures the time between detector activation during red singals and movement service at start of green signals. Simple delay approximates the overall delay experienced by intersection users.

With advanced upstream detection, Spectrum SPMs include:

  • Arrival Volumes: Counts of total vehicle traffic through an intersection from each approach.
  • Arrivals-on-Red vs. Arrival-on-Green: Counts of total vehicle volume arriving during red or green, giving a rough sign of progression quality for the given movement.
  • Purdue Coordination Diagram: A graphical representation of individual vehicle arrivals relative to cycle time (red, yellow and green), highlighting arrival characteristics, and platoon progression quality.
  • Average Delay: The length of time vehicles are delayed at a congested intersection.

What do SPM Dashboards and Reports Look Like?

We’ve included three screen grabs for dashboards that are generated by Spectrum.

The UX is designed to 1. Be as simple as possible for a big data set and 2. Show performance patterns over time.

Check these out!

Approach Volume: chart showing the volumes for the chosen day compared to the previous 12-week weekday average and variability bands.

approach-volume-pg11

Arrivals on Red/Green over a 12-week period showing the average volume of traffic arriving at the intersection during the red or green phases at different times of the day.

arrivals-on-red-pg11

Occupancy Ratio chart showing the stop bar occupancy ratio during red, green, and the first 5 seconds of subsequent red (ROR5) for each cycle of a selected movement.

occupancy-ratio-pg12-1

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Feeling informed? Part three of this blog series will appear in two weeks. It will cover Miovision Traffic Insights for Arterial Performance Metrics.

National Traffic Signal Report Card 2012 from the NTOC – Part Two

In the previous blog article, National Traffic Signal Report Card 2012 from the NTOC – Part One, we reviewed previous results of NTOC Report Cards and this year’s results including two of the five criteria that attribute to the overall grade.

This week’s blog article will focus on the importance of signal operations as well as the remaining three criteria that contributed to the NTOC Report Card.

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Miovision Introduces Traffic Data On Demand

Miovision is a leading provider of traffic data collection technology, specifically through our Scout video collection units (VCU). The Scout provides traffic engineers with the ability to easily collect traffic data by deploying these portable, non-intrusive units to record traffic movements within an intersection which are processed using our proprietary video analytics software.

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Proven Safety Countermeasures – Part 2

Last week’s blog, we reviewed the first 5 proven safety countermeasures which were established by the Federal Highway Administration (FHWA) in January 2012. This week, we’ll review the remaining four proven safety countermeasures which focus on using a data driven approach to improve road safety and reducing fatalities on American highways.

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National Work Zone Awareness Week

From April 23-27, the USA Federal Highway Administration celebrates National Work Zone Awareness Week along with State Departments of Transportation (DOT) and other government agencies. It is the 11th annual event which aims to bring national attention to motorist and worker safety as well as mobility issues in work zones.

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Miovision at Intertraffic Amsterdam

Last week, Miovision attended Intertraffic Amsterdam which is one of the top international events for infrastructure, traffic management, safety and parking. It was held from March 27-30 at the Amsterdam RAI Convention Center. It is one of Europe’s most attractive and innovative conference and exhibition centers and hosts more than 1000 international conferences, tradeshows, meetings, presentations and other gatherings.

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Top 5 Reasons to Automate Your Spring Counts

Spring is officially upon us and transportation professionals are in the midst of kicking off the traffic count season. Last week’s blog, Top 3 Traffic Data Projects to Start Off Your Spring Count Season, focused on maximizing your traffic data collection efforts amongst three transportation projects.

This week, we’ll focus on why many transportation professionals are now automating their traffic studies. The start of a new year provides a great time to step up your traffic data collection efforts and leave the manual counters in the dust.

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Top 3 Traffic Data Projects to Start Off Your Spring Count Season

With the days being longer and the first day of spring having arrived yesterday, traffic engineers are ramping up to begin the spring count season.  The spring is a great time to plan your traffic data collection and project objectives for the remainder of the year. Planning ahead will help provide efficiencies in traffic data collection equipment deployment, traffic study turnaround time and resource availability.

In this week’s blog, Miovision reviews the Top 3 Traffic Data Projects to Start Off Your Spring Count Season. These top three traffic data collection projects will provide resource efficiencies– the equipment can be used across these three projects. The traffic data collected is also relatable and can be used for various other projects.

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Urban Congestion Impacts and Improvements

The US Federal Highway Administration (FHWA) released their annual Urban Congestion Trends for 2010, which shows an increase in congestion and traffic levels overall within US urban cities. Twenty cities are measured annually and the latest report shows an 18 minute increase in daily delays from 4:20 to 4:38. Congestion levels have been steadily increasing since 2008 when levels dropped due to the downturn in the economy. However, they haven’t reached the levels previously seen prior to the recession in 2007.

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