Intelligent Traffic Signal Control: How Do Industrial Switche Ensure Millisecond-Level Synchronous Transmission of Instructions?
In a traffic signal control renovation project at a crossroads in Hangzhou, engineers faced a "war against time": traditional switches failed to handle the millisecond-level synchronization requirements of traffic lights at multiple intersections, resulting in a 40% increase in average vehicle waiting time and a 35% decrease in intersection traffic efficiency during morning rush hours. This scenario reflects the core pain point of intelligent transportation construction—how to ensure real-time, accurate, and synchronous transmission of signal control instructions in scenarios where traffic flow changes dynamically by the second?
When the green light at an intersection ends 100 milliseconds early, it may trigger a chain reaction: sudden braking by vehicles behind increases the risk of rear-end collisions by 23%; if the light changes 100 milliseconds late, it may cause the congestion length in the opposite lane to increase by 15 meters. Research by Beijing Jiaotong University shows that for every 100-millisecond increase in signal synchronization error, intersection traffic efficiency decreases by 5%-8%. At hub intersections with daily traffic volumes exceeding 100,000 vehicles, this efficiency loss may translate into economic losses of tens of thousands of yuan per hour.
Protocol Fragmentation: The coexistence of protocols such as Modbus, Profinet, and EtherCAT requires additional protocol conversion for communication between devices, increasing latency by 50-200 milliseconds.
Network Jitter: Commercial switches can experience data packet transmission delay fluctuations of ±50 milliseconds in electromagnetic interference environments, failing to meet deterministic transmission requirements.
Single Point of Failure: In traditional star topologies, a failure at the central node can paralyze the entire regional signal system, with recovery times lasting several minutes.
A project leader for an intelligent transportation project revealed, "Our biggest concern is 'invisible latency'—a seemingly normal network may suddenly experience millisecond-level jitter under extreme conditions such as heavy rain or high temperatures, which traditional monitoring tools cannot capture at all." This uncertainty is becoming a key bottleneck restricting the large-scale implementation of intelligent transportation.
The USR-ISG series of industrial switches adopt dual-core high-precision clock sources to achieve nanosecond-level time synchronization through the IEEE 1588v2 protocol. Its internal clock module has the following characteristics:
Temperature Compensation: Clock drift is controlled within ±50 ns/day across a wide temperature range of -40°C to 85°C.
Timekeeping Capability: It can maintain microsecond-level synchronization accuracy for up to 24 hours after losing GPS signals.
Redundancy Design: Dual clock modules serve as backups for each other, with a fault switching time of <10 μs.
In a smart tunnel project in Shenzhen, USR-ISG switches successfully achieved microsecond-level synchronization of 16 sets of traffic lights in a 200-meter-long tunnel, reducing the standard deviation of vehicle passage time from 0.32 seconds to 0.08 seconds.
To address protocol fragmentation, USR-ISG has developed a five-layer protocol parsing engine:
Physical Layer: Supports 12 types of interfaces including RS485, CAN, and optical fiber, compatible with the full range of IEEE 802.3 standards.
Data Link Layer: Automatically recognizes industrial bus protocols such as EtherCAT and Profinet.
Network Layer: Achieves protocol-independent forwarding through SRv6 technology, with protocol conversion delays of <50 μs.
Transport Layer: Supports QoS priority marking to ensure priority transmission of control instructions.
Application Layer: Establishes a standardized data model for transparent conversion from Modbus to Profinet.
In a smart intersection renovation in Chengdu, this technology improved the collaborative efficiency of multi-brand devices by 40% and reduced the debugging cycle from 2 weeks to 3 days.
USR-ISG adopts the ERPS ring network protocol to achieve telecom-grade self-healing in the event of link failures:
Fault Detection: Achieves link state awareness within 50 milliseconds through OAM mechanisms.
Path Switching: Primary and backup path switching time is <20 milliseconds, with business interruption of <50 milliseconds.
Traffic Optimization: Supports multi-protocol redundancy such as STP/RSTP/MSTP to automatically avoid congested links.
In a smart transportation project in a new district of Nanjing, this technology achieved a network availability of 99.999%, reducing annual fault time from 8 hours to 5 minutes.
Wide Temperature Design: Operates within a temperature range of -40°C to 85°C and passes -55°C low-temperature startup tests.
Electromagnetic Compatibility: Passes IEC 61000-4-6 level tests and operates stably under electromagnetic field strengths of 10 V/m.
Protection Rating: IP67 protection rating, capable of withstanding 6000 V lightning surge impacts.
In a road renovation project around the Harbin Ice and Snow World, USR-ISG operated fault-free for 18 consecutive months at -35°C, with a data transmission integrity rate of 99.999%.
Digital Twin: Achieves real-time mapping of device status through the UYou Cloud platform, with a fault prediction accuracy rate of 92%.
AI Diagnosis: Built-in machine learning algorithms can automatically identify 12 types of typical network anomalies.
Remote Configuration: Supports the SNMP v3 protocol for batch parameter distribution to devices across regions.
In a smart transportation operation and maintenance project in Guangzhou, this system improved operation and maintenance efficiency by 3 times and reduced fault location time by 80%.
Urban Main Roads: Achieves synchronous control of traffic lights at multiple intersections through 16-port full Gigabit switches.
Smart Tunnels: Adopts a hybrid design of optical and electrical ports to solve signal attenuation issues in long-distance transmission.
Bus Priority Systems: Ensures real-time transmission of bus signal priority instructions through VLAN isolation technology.
Vehicle-Road Coordination: Supports 5G+TSN integrated networking to meet the low-latency requirements of autonomous driving.
Heat Dissipation Design: Avoid products without fans but with overly small heat dissipation holes, which may cause internal temperatures to exceed standards.
Power Protection: Confirm whether they have reverse connection protection and overvoltage/overcurrent protection to prevent equipment damage from power abnormalities.
Interface Lifespan: Industrial-grade RJ45 interfaces should have a plugging and unplugging lifespan of ≥500 times, while ordinary commercial products only have around 100 times.
Protocol Support List: Require manufacturers to provide detailed protocol compatibility test reports.
Conversion Delay Testing: Test the actual delay of protocol conversion in simulated environments.
Firmware Upgrades: Confirm whether they support remote firmware upgrades to address future new protocol requirements.
Ring Network Protocol: Prioritize products that support the ERPS protocol, whose self-healing time is 200 times faster than STP.
Power Redundancy: Dual power inputs should have automatic switching functionality with a switching time of <10 ms.
Link Redundancy: Confirm whether they support link aggregation to increase bandwidth on critical paths.
With the popularization of TSN standards such as IEEE 802.1Qbv, industrial switches are evolving from "ensuring synchronization" to "defining synchronization":
Time-Aware Shaping: Achieves nanosecond-level traffic scheduling through gating lists.
Frame Preemption: Allows high-priority frames to interrupt low-priority frame transmission, ensuring zero waiting for control instructions.
Stream Reservation Protocol: Reserves dedicated bandwidth for critical services to avoid network congestion.
USR's newly launched TSN switches already possess these forward-looking capabilities: in tests at a smart factory in Suzhou, they reduced multi-axis coordinated control delays from 5 ms to 50 μs, providing network infrastructure guarantees for future scenarios such as vehicle-road coordination and autonomous driving.
On the track of intelligent transportation, millisecond-level synchronous transmission of instructions is no longer a technical option but a survival necessity. USR-ISG industrial switch have built a foundation for "deterministic networks" in traffic signal control through three core technologies: hardware-level time synchronization, intelligent protocol conversion, and self-healing network topologies. When engineers no longer worry about network latency and traffic managers can precisely control the switching timing of each traffic light, the "last mile" bottleneck of intelligent transportation will finally be broken.
