Average Traffic Speed Calculation Using Probe Data
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Solution Overview
Problem
Existing methods for determining average traffic speed over longer path segments are inaccurate due to limitations in calculating harmonic mean speed, which can result in zero average speeds when encountering vehicles with zero velocity measurements.
Innovation Solution
A method using a processor to calculate total distance and total time traveled by navigation devices over a path segment, incorporating instantaneous velocities, geographic locations, and timestamps, which allows for accurate average traffic speed determination even with zero speed measurements by excluding them from calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If harmonic mean method is used to calculate average traffic speed, then the calculation is simple and provides space mean speed, but the result becomes zero when encountering vehicles with zero velocity measurements and is inaccurate over longer path segments
Solution Approach 1:
The patent changes the calculation parameters from instantaneous velocities to travel time and distance metrics. Instead of using velocity data that can be zero, the system calculates the time each vehicle takes to traverse the path segment and the distance covered, then derives average speed from these non-zero parameters. This transformation eliminates the zero-velocity problem while maintaining calculation feasibility.
Solution Approach 2:
The patent extracts the problematic velocity measurements from the calculation and replaces them with travel time and distance data. By removing the instantaneous velocity parameter that causes zero results and substituting it with temporal and spatial traversal data, the system achieves accurate average speed calculation without the harmonic mean's limitations.
2Measurement precision
If measurements are taken at a single location or over short distance, then harmonic mean provides accurate space mean speed, but it cannot provide accurate results over lengthier path segments
Solution Approach 1:
The patent transitions from spatial sampling at a single location to temporal-spatial tracking over the entire path segment. Instead of measuring velocity at one point, the system tracks vehicles throughout their traversal of the path segment, collecting time and position data across the full length. This dimensional expansion from point measurement to segment-wide tracking enables accurate average speed calculation over longer distances.
Solution Approach 2:
The patent performs preliminary tracking of vehicle position and time data throughout the entire path segment traversal before calculating the average speed. By collecting comprehensive traversal data in advance and then deriving the average speed from total time and distance, the system ensures accurate results over lengthier path segments without relying on instantaneous velocity measurements.
Data Source
AI summary
Navigation devices, services, and methods are provided for determining an average traffic speed for a path segment using probe data from a plurality of navigation devices. The method for determining an average traffic speed may include retrieving probe data from a plurality of navigation devices, each navigation device traveling over at least a portion of a defined path segment for at least a portion of a defined time interval, wherein the probe data for each navigation device comprises an instantaneous velocity of the navigation device. The method may further include calculating a total distance traveled and a total time traveled by the plurality of navigation devices over the path segment and within the time interval using the instantaneous velocities from the retrieved probe data. The average traffic speed may then be determined based on the calculated total distance traveled and total time traveled.