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      Traffic Delay Data

      A summary of Urban SDK's Traffic Delay Data specification.

      Traffic_Delay

      1.0 Introduction

      Traffic Delay data metrics are collected from vehicle navigation devices for every hour of day and quantify vehicle travel time along a segment of road.  The raw data is processed to calculate the following metrics:

      • Free Flow Travel Time

      • Average Travel Time

      • Travel Time Index (TTI)

      • Planning Time Index (PTI)

      • Buffer Time Index (BTI)

      2.0 Methodology

      Data Collection

      Urban SDK gathers raw Traffic Delay data from vehicle navigation chips that are provided in 15-minute intervals. As vehicle navigation chips emit a location ping, it is tagged to the nearest road link over which the vehicle is travelling. This data is collected for every hour and every day throughout the year allowing a sample of trip speed observations to be collected on every public roadway within your community.

      ⚠️NOTE: On rare occasions where the number of trips travelling along a road is exceptionally low, the provided value will be null.  These are typically in rural areas, and during times of the day where there is little to no traffic volume (i.e. if there are no trips to observe, there will be no speed observations to report).

      Data Processing

      The raw data collected by Urban SDK can be very large and difficult to work with for the purposes of traffic analysis. The amount of data collected in a major city for a single day would be too big to manage or analyze with conventional data analysis tools like Excel or Access, never mind trying to analyze an entire year's worth of data! For this reason, Urban SDK aggregates the data to hourly intervals and processes Traffic Delay metrics in a format that can easily be queried, analyzed, and downloaded without requiring any complex database storage on your network.

      Free Flow Travel Time

      Free Flow Travel Time quantifies the time it takes for a vehicle to travel along a road segment under ideal conditions, with no traffic congestion or delays.  It is calculated based on a rolling monthly average of raw speed observations. It is provided as a value in seconds.

      1. Free Flow Speed is the average of the provided raw data observations on weekdays across the previous 20 weekdays prior to the given day analyzed. The Free-Flow speed is based on the observations within the following periods of day: 1- Overnight (12 am - 3:59 am), 2 - Early Morning (4 am - 6:59 am), and 7 - Evening (7 pm - 11:59 pm).
      2. Free Flow Travel Time: is calculated by dividing the road segment length by the Free Flow Speed.

      Free Flow Travel Time = (Road Segment Length) / (Free Flow Speed)

      Average Travel Time

      Average Travel Time quantifies the mean length of time necessary for a vehicle to travel along a segment of road. It is provided as a value in seconds.

      1. Average Speed is the average of the provided raw data observations for the given hour, or period analyzed.
      2. Average Travel Time is calculated by dividing the road segment length by the Average Speed.

      Average Travel Time = (Road Segment Length) / (Average Speed)

      Travel Time Index (TTI)

      Travel Time Index quantifies the average additional time required for a trip during peak times compared to the time it takes during Free Flow conditions. It is provided as an Index.

      1. Travel Time Index is calculated by dividing the Average Travel Time by the Free Flow Travel Time for the given hour, or period analyzed.

      Travel Time Index (TTI) = (Average Travel Time) / (Free Flow Travel Time)

      NOTE: TTI is constrained to be ≥1.00.

      Planning Time Index (PTI)

      Planning Time Index quantifies the total time needed for on-time arrival in 95% of all trips. It is provided as an Index.

      1. 5th Percentile Speed is calculated based on a rolling monthly average of raw data observation. It is the average of the 2 slowest individual raw hourly average speed values across the previous 20 weekdays prior to the given day. This should equate ~40 data points.
      2. 95th Percentile Travel Time is calculated by dividing the road segment length by the 5th Percentile Speed.
      3. Planning Time Index is calculated by adding the Travel Time Index + the Buffer Time Index for the given hour or period of day.

      95th Percentile Travel Time = (Road Segment Length) / (5th Percentile Speed)

      Planning Time Index (PTI) = Travel Time Index (TTI) + Buffer Time Index (BI)

      Buffer Time Index (BTI)

      Buffer Time Index quantifies the extra buffer time (or time cushion) that travelers should consider along with the average travel time to ensure on-time arrival 95% of the time. Expressed as a multiplier for the extra time required.

      1. Buffer Time Index is calculated by subtracting the Average Travel Time from the 95th Percentile Travel Time and dividing the difference by the Free Flow Travel Time.

      Buffer Time Index (BTI) = (95th Percentile Travel Time - Average Travel Time) / Free Flow Travel Time

      ⚠️NOTE: BI is constrained to be ≥0.00.

      3.0 Data Specification

      Metadata Fields

      Metadata fields that are provided for all data are detailed in Urban SDK's Linear Referencing System (LRS) specification.

      Data Fields

      The following table is the format in which downloaded Traffic Delay data will be provided:

      Field Type Description
      year integer The year associated with the provided data.
      month integer The month associated with the provided data as an integer between 1 and 12.
      period integer

      The period of day associated with the provided data as an integer between 1 and 7:

      1. Overnight: 12 am - 3:59 am
      2. Early Morning: 4 am - 6:59 am
      3. AM Peak: 7 am - 9:59 am
      4. Midday: 10 am - 12:59 pm
      5. Early Afternoon: 1 pm - 3:59 pm
      6. PM Peak: 4 pm - 6:59 pm
      7. Evening: 7 pm - 11:59 pm
      hour integer The hour of day associated with the provided data as an integer between 1 and 24.
      data_value string

      Identifies which data is provided:

      • Average Travel Time (in seconds); or
      • Free Flow Travel Time (in seconds); or
      • Travel Time Index (ratio); or
      • Planning Time Index (ratio); or
      • Buffer Time Index (ratio)
      speed_category integer

      Estimated based on road functional class and observed average speeds (in mph); it is intended to provide an estimate of what a reasonable speed limit would be on a road, within +/- 5mph.
      monday numeric

      The calculated value for Mondays within the selected period.
      tuesday numeric

      The calculated value for Tuesdays within the selected period.
      wednesday numeric

      The calculated value for Wednesdays within the selected period.
      thursday numeric

      The calculated value for Thursdays within the selected period.
      friday numeric

      The calculated value for Fridays within the selected period.
      saturday numeric

      The calculated value for Saturdays within the selected period.
      sunday numeric

      The calculated value for Sundays within the selected period.
      weekdays numeric

      The calculated value for Weekdays within the selected period.
      weekends numeric

      The calculated value for Weekend days within the selected period.
      weekly numeric

      The calculated value for a typical week within the selected period.

      💡Tip: For convenience, data is disaggregated by Month, Period of Day, Hour of Day, by Day of Week, Weekday/Weekends, as well as Weekly values to make it easy for customers to see and compare the differences in Traffic Congestion at a scale suitable for each customer's unique analysis needs.