Traffic Signal Controller Evacuation Mode Preemption
Solution Overview
Problem
Current traffic control preemption systems do not effectively allow transit vehicles to preempt traffic signals during emergency situations or large events, limiting their ability to efficiently move large volumes of people, and lack flexibility in prioritizing vehicle preemption based on specific events or directions.
Innovation Solution
A system that allows transit vehicles to preempt traffic signals by configuring traffic signal controllers to operate in an 'evacuation mode' where they can change a non-green phase to green, similar to emergency vehicles, and prioritizes preemption requests based on vehicle identifiers, directions, and scheduled events, using a central management system to manage and configure preemption controllers at intersections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transit vehicles are allowed to preempt traffic signals during normal operation, then transit efficiency is improved, but emergency vehicle priority is compromised
Solution Approach 1:
The system dynamically adjusts preemption permissions based on operational mode. During normal operation, only emergency vehicles can preempt signals. During evacuation mode, transit vehicles gain preemption capability. This dynamic adjustment resolves the contradiction by allowing different vehicles to have different priorities at different times.
Solution Approach 2:
The system changes the parameter of preemption eligibility based on operational mode. In normal mode, transit vehicles are excluded from preemption. In evacuation mode, the system changes this parameter to include transit vehicles, thereby resolving the conflict between transit efficiency and emergency priority through parameter modification.
2Speed
If traffic signal preemption is restricted to emergency vehicles only, then emergency response time is optimized, but transit vehicle mobility during events is limited
Solution Approach 1:
The system transitions from a static preemption rule to a dynamic one based on operational mode. During normal operations, only emergency vehicles can preempt signals, optimizing response time. During evacuation mode, the system dynamically allows transit vehicles to preempt as well, improving mobility when needed.
Solution Approach 2:
The system segments preemption rights by operational mode. Normal operation mode reserves preemption for emergency vehicles only. Evacuation mode creates a separate state where both emergency and transit vehicles can preempt. This segmentation allows optimized emergency response during normal times while enabling improved transit mobility during events.
3Adaptability or versatility
If preemption controllers are configured with multiple modes, then system flexibility is improved, but controller complexity increases
Solution Approach 1:
The preemption controller is designed with multi-functionality to handle both normal operation mode and evacuation mode. This universal design allows a single controller to adapt to different operational requirements without needing separate controllers for each mode, thereby improving flexibility while managing complexity through integrated design.
4Productivity
If transit vehicles can extend green phases during normal operation, then traffic flow efficiency is improved, but intersection safety is reduced
Solution Approach 1:
The system dynamically enables or disables green phase extension based on operational mode. During normal operation, green extension is disabled to maintain intersection safety. During evacuation mode, it is enabled to improve traffic flow efficiency. This dynamic control allows the system to optimize for different priorities at different times.
Solution Approach 2:
The system changes the parameter of green phase extension eligibility based on operational mode. In normal mode, transit vehicles cannot extend green phases, maintaining safety. In evacuation mode, this parameter changes to allow extension, improving efficiency when needed while sacrificing safety considerations of normal operation.
Data Source
AI summary
Controlling a traffic signal phase at one or more intersections. A control system at an intersection is configured to operate in one of a first mode or a second mode. While operating the controller in the first mode, in response to a transit priority signal received by the control system from a vehicle assigned transit priority, a green phase of the traffic signal is extended in favor of the vehicle assigned transit priority. While operating the control system in the second mode, in response to a transit priority signal received by the control system from the vehicle assigned transit priority, a current non-green phase of the traffic signal is preempted to a green phase in favor of the vehicle assigned transit priority.