Traffic Signal Preemption Prioritization Across Mixed Detection Mediums
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Solution Overview
Problem
Existing traffic control preemption systems are limited in their ability to recognize and prioritize preemption requests from different technologies, such as infrared light emitters and GPS-based systems, which can hinder mutual aid in emergency situations and require costly upgrades across entire municipalities and vehicle fleets.
Innovation Solution
A system that receives and prioritizes preemption requests from multiple sources, including light signals, radio signals, and network-coupled vehicles, using a processor to determine relative priorities and output requests for traffic signal phase changes, allowing for mixed detection methods and gradual technology upgrades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single preemption technology (e.g., infrared light emitters) is used across all vehicles and intersections, then system reliability is improved, but device complexity and upgrade costs increase significantly
Solution Approach 1:
The intersection controller is designed to accept and process preemption requests from multiple different technologies (infrared light emitters, GPS-based systems, and network-coupled vehicles) through a unified interface. This multi-functional capability allows the system to maintain reliability by supporting diverse vehicle types without requiring all vehicles to use the same technology, thereby reducing the complexity and cost of universal upgrades.
2Difficulty of detecting and measuring
If infrared light emitters are used for preemption detection, then detection range is improved, but interference from other light sources increases
Solution Approach 1:
The optical filter is configured with specific spectral characteristics that match the emission wavelength of the infrared light emitter. This localized filtering approach allows the detector to selectively receive signals within a narrow wavelength band, thereby maintaining long detection range while effectively rejecting interference from other light sources that operate at different wavelengths.
3Measurement precision
If GPS-based preemption systems are deployed, then location accuracy is improved, but system cost and complexity increase
Solution Approach 1:
A network interface serves as an intermediary that receives preemption requests from GPS-based vehicles and translates them into a standardized format that the intersection controller can process. This intermediary layer allows the system to benefit from GPS location accuracy without requiring every vehicle and intersection to be part of a complex dedicated GPS infrastructure, thereby reducing overall system complexity and cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables cost-effective upgrades and enhanced mutual aid by supporting multiple preemption technologies, improving emergency response times and transit efficiency without requiring uniform technology across all vehicles and intersections.
Implementation Method 1
A receiver, which includes a photodetector and associated electronics, is typically mounted on the mast arm located at the intersection and produces a series of voltage pulses, the number of which are proportional to the intensity of light pulses received from the emitter.
Implementation Method 2
an optical filter is used on the detector to restrict its sensitivity to light only in the near infrared (IR) spectrum
Data Source
AI summary
Approaches for prioritizing multiple candidates for preemption of a traffic signal phase at an intersection are disclosed. Light signals transmitted from light-signaling vehicles approaching an intersection encode priority codes using a first set of values. Radio signals from radio-signaling vehicles approaching the intersection encode priority codes using a second set of values. A set of preemption candidates is determined from the light and radio signals, as well as from network-based requests, and a respective relative priority of each preemption candidate based on the priority code of each preemption candidate is determined. A request output for preemption of the traffic signal phase for a preemption candidate having a highest priority.