Real-Time Traffic Data Transmission Over IP
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Solution Overview
Problem
Existing traffic control systems face significant time delays in transmitting data from field devices to control centers, with delays ranging from 30 to 60 seconds, which is inadequate for real-time data streams like signal group statuses, due to the reliance on non-deterministic timing and batch-based data collection methods.
Innovation Solution
Implementing Real-Time Protocol (RTP) and Real-Time Streaming Protocol (RTSP) over IP connections, where the traffic control center initiates a data stream using RTSP and traffic data is transmitted in real-time using RTP, with buffering to manage connection issues and ensure data integrity, aligning with the Open Communication Interface for Road Traffic Control Systems (OCIT) standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If batch-based data collection methods are used with TCP/IP protocol, then system simplicity is maintained, but data transmission latency increases to 30-60 seconds
Solution Approach 1:
The patent changes the timing parameter from batch-based (30-60 second intervals) to event-driven real-time transmission. When specific traffic events occur (e.g., signal changes, detector activations), the system immediately transmits data packets with timestamps, reducing latency to under 2 seconds while maintaining TCP/IP protocol simplicity
Solution Approach 2:
The system transitions from static batch collection to dynamic event-triggered transmission. The field devices continuously monitor for traffic events and automatically initiate data transmission when events occur, creating a responsive system that adapts to actual traffic conditions rather than following fixed schedules
2Reliability
If data is transmitted only when specific events occur, then bandwidth usage is reduced, but deterministic timing cannot be achieved
Solution Approach 1:
The control center provides feedback by sending data collection requests to field devices. The field devices respond by transmitting relevant traffic data with timestamps, creating a closed-loop system that ensures deterministic timing through coordinated request-response cycles while maintaining efficient bandwidth utilization
Solution Approach 2:
The system establishes predetermined data collection schedules and event thresholds in advance. When events meet these pre-set criteria, data transmission is automatically triggered, ensuring deterministic timing without requiring continuous high-volume data transmission
3Speed
If field devices buffer data locally before transmission, then network load is reduced, but transmission delay increases to match block collection intervals
Solution Approach 1:
The system uses periodic data collection requests from the control center combined with event-triggered transmissions from field devices. This hybrid approach maintains local buffering for efficiency while ensuring data is transmitted within predetermined time intervals (under 2 seconds), balancing network load reduction with timely data delivery
Data Source
Figure 1
AI summary
Method for transmitting traffic data from a traffic field device to a traffic control center, wherein the traffic field device transmits the traffic data in real time in a data stream to the traffic control center via an IP connection.