I. Why is “tunnel‑in + tunnel‑out” coordination necessary for highway safety monitoring?

In highway safety management, tunnels and vehicle overheating are two critically important risk factors.

Tunnels are relatively enclosed spaces; once a vehicle catches fire, cargo ignites, hazardous materials experience abnormal temperature rises, or a smoke‑and‑fire incident occurs, risks spread rapidly, evacuation becomes extremely challenging, and the window for effective response is very short. While conventional video surveillance can capture images, under conditions such as heavy smoke, glare, low illumination, or interference from vehicle high beams, standard visible‑light cameras often suffer from delayed detection and assessment.

Overheating of vehicles outside tunnels must not be overlooked. Heavy‑load trucks, vehicles transporting hazardous materials, abnormal brake system performance after long downhill stretches, excessive tire temperature rise, and unusual engine compartment heating can all pose risks before entering tunnels, bridges, toll stations, or service areas. Waiting until a vehicle smokes, stalls, or catches fire before taking action is already a reactive approach.

Therefore, thermal‑imaging monitoring on expressways should not be limited to standalone devices; instead, it should adopt an integrated solution that combines “in‑tunnel video‑based temperature measurement with out‑of‑tunnel vehicle over‑temperature early warning.” Within the tunnel, the system handles spatial safety monitoring and fire‑related over‑temperature alerts, while outside the tunnel it conducts temperature screening of vehicles prior to their entry into critical areas and enables proactive interception.

II. Inside the Tunnel: The Role of the TX9800 Dual-Optical Fusion Temperature Measurement System

The SSK/NW-TX9800 is a dual‑sensor thermal imaging device designed for demanding, harsh environments such as tunnels, transportation systems, power infrastructure, and fire‑monitoring applications. Equipped with high‑performance visible‑light and infrared thermal imaging sensors, it enables real‑time fusion of thermal and visible imagery. Infrared thermal imaging captures the location and temperature of heat sources, while visible‑light imaging provides high‑resolution details of targets; the system can automatically adjust the weighting of the visible‑light and thermal channels based on ambient illumination.

In tunnel scenarios, this design offers three direct benefits:

First, thermal imaging is responsible for detecting abnormal temperatures.
Vehicles, cargo compartments, tires, engine compartments, ignition sources, or high-temperature areas—when abnormal temperature rises occur, thermal imaging can more easily highlight the location of the heat source.

Second, visible light is responsible for enhancing on-site details.
Inside the tunnel, it is necessary to clearly discern vehicle shapes, road positioning, lane conditions, and the surrounding environment; visible-light imagery provides more intuitive contextual information.

Third, the integration of dual-light imaging enhances diagnostic efficiency.
When viewed in thermal imaging alone, details are insufficient; when viewed in visible light alone, temperature information is lacking. With dual‑spectrum fusion, operators can simultaneously see the target’s outline, environmental details, and temperature anomalies on a single display, making it ideally suited for tunnel safety monitoring.

III. Temperature Measurement and Intelligent Analysis Capabilities of the TX9800

The TX9800 is not just an ordinary dual‑spectrum camera; it is a tunnel‑specific monitoring device equipped with temperature measurement and intelligent analytics capabilities. The device supports 273 preset temperature‑measurement scenarios and allows users to define 21 temperature‑measurement rules, including point‑based, area‑based, and line‑based measurements. Temperature ranges are divided into a high‑gain mode (−20°C to 150°C) and a low‑gain mode (0°C to 550°C), with a temperature‑measurement accuracy of ±2°C or ±2% of the reading, whichever is greater.

This type of capability is well-suited to a variety of monitoring requirements within tunnels:

First is localized over-temperature monitoring of vehicles.
It can monitor thermal anomalies in critical vehicle areas, the cargo compartment, the vehicle body surface, and near the tires.

Second, early fire warning.
Compared with waiting until open flames or thick smoke appear before triggering an alarm, thermal imaging temperature measurement can detect abnormal temperature rises much earlier.

Third, regional temperature management.
Temperature measurement ranges and alarm thresholds can be configured for key areas using rules based on points, lines, and bounding boxes.

Fourth, video intelligent analysis.
The TX9800 supports VCA rules such as line-crossing, intrusion, area entry, and area exit, with up to 10 scenes and 8 rules per scene, making it suitable for assisting in event monitoring within tunnels.

IV. Why Tunnel Monitoring Cannot Rely Solely on Conventional Video Surveillance

Conventional video surveillance has significant limitations in tunnels.

First, it is easily affected by high beams.
Inside tunnels, vehicle headlights are very bright, causing ordinary cameras to suffer from glare, light spots, and washed-out images.

Second, fire smoke can impair visible-light imagery.
Once smoke appears at an accident scene, conventional video footage struggles to accurately identify temperature anomalies.

Third, it can only display images and cannot directly measure temperature.
Whether a vehicle is overheating, whether the cargo compartment is abnormally hot, or whether there are high‑temperature spots on the ground or on equipment—these conditions are difficult to detect in advance using visible light alone.

Traditional video‑based event analysis systems rely on video imagery; when the images are unclear or visibility inside tunnels is poor, it becomes difficult to generate accurate detection results. Meanwhile, tunnel fire and explosion risks demand earlier warning, earlier detection, and earlier response.

Therefore, within tunnels, a comprehensive monitoring approach combining visible light, thermal imaging, fused temperature measurement, and intelligent analysis is more suitable.

V. Outside the Tunnel: The Function of the Vehicle Overtemperature Warning System

The core of the vehicle temperature‑screening system outside tunnels is to conduct non‑contact temperature screening of vehicles before they enter key areas such as tunnels, bridges, toll stations, long downhill sections, and service areas.

The vehicle over‑temperature early‑warning and monitoring system can be deployed in scenarios such as highways, national roads, bridges, tunnels, and toll stations. By integrating a front‑end temperature‑sensing and data‑acquisition module, a license‑plate recognition system, LED message boards, an audio broadcasting system, fiber‑optic transmission, industrial Ethernet switches, and a backend management platform, the system enables vehicle over‑temperature alerts and comprehensive data management.

A typical workflow can be summarized as follows:

The vehicle enters the monitoring point.
The license plate recognition camera captures license plate and vehicle information.
Infrared thermal imaging temperature measurement equipment acquires a thermal map of the vehicle.
The system determines whether areas such as the tires, brakes, engine compartment, and cargo box are overheating.
Once the temperature exceeds the threshold, the platform triggers an alarm.
LED message boards and broadcast systems alert vehicles or on-site personnel.
The backend logs license plate numbers, images, heatmaps, timestamps, locations, and alarm information.

This approach enables the shift from “post-incident response” to “early warning during the abnormal temperature-rise phase.”

VI. Why Should Tunnel Exterior Temperature Measurement Be Integrated with License Plate Recognition?

If vehicle over-temperature warnings are based solely on temperature readings without associating them with vehicle identities, their managerial value will be diminished. In highway scenarios, where vehicles pass continuously, it is essential to link temperature data with vehicle information.

The front-end temperature‑measurement and data‑collection system of the intelligent transportation solution integrates infrared non-contact thermometry with thermal radiation thermometry, and is further equipped with an infrared laser‑array‑based license‑plate and vehicle‑type recognition system to capture basic vehicle information. The system also supports image and photo capture, records and retrieves license‑plate‑related data, and automatically generates logs based on fields such as date and time, facilitating subsequent queries and data export.

This means the system does not merely trigger an alarm; instead, it can establish a complete data chain:

Which vehicle is overheating?
When will it be approved?
At which monitoring site did it occur?
Where is the over-temperature zone?
Whether to trigger the information board or broadcast;
Whether follow-up handling and post-event review are required.

VII. The Practical Value of Integrated Tunnel-External Coordination

To unlock the full value of thermal‑imaging monitoring on expressways, it is essential not merely to deploy equipment at a single location, but to establish a closed-loop system encompassing pre‑tunnel screening, in‑tunnel monitoring, post‑tunnel verification, and centralized backend management.

Vehicle temperature screening outside tunnels is responsible for proactively identifying risks associated with the vehicles themselves.
Dual-spectrum thermal imaging within the tunnel is responsible for monitoring fire sources, abnormal temperature rises in vehicles, and on-site incidents.
The backend platform handles alarm logging, historical queries, statistical analysis, and access control.
LED information boards, public address systems, and on-site response personnel are responsible for guiding and managing the situation following an alarm.

The vehicle over‑temperature warning system can generate over‑temperature data by road segment, vehicle type, and time period, providing management authorities with targeted monitoring data on flammable and explosive hazards along specific routes. This enables the implementation of cooling ponds or emergency detour lanes tailored to seasonal conditions and route characteristics, thereby furnishing a robust analytical foundation for safe highway operations.

VIII. Recommendations for System Development

When developing a thermal‑imaging monitoring system for expressways, the following approach can be adopted:

First, inside the tunnel, the focus is on integrated temperature measurement.
Select devices that support visible light, infrared thermal imaging, dual-spectrum fusion, picture-in-picture, temperature measurement rules, intelligent analytics, and network connectivity.

Second, outside the tunnel, the focus is on vehicle temperature screening and early warning.
Temperature-measurement stations are deployed at locations such as tunnel entrances, bridge approaches, toll plazas, the bottom of long downhill grades, and service-area entrances.

Third, the license plate and vehicle information must be linked.
The vehicle over-temperature warning system shall centrally record license plate recognition data, vehicle heat maps, abnormal temperature readings, alarm timestamps, and monitoring locations.

Fourth, prioritize coordinated reminders.
Upon triggering an over-temperature alarm, the system shall automatically activate the LED information display board, the public address system, the backend platform, and on-site response personnel.

Fifth, prioritize data analysis.
The system shall support historical record management, alarm query, report generation and statistical analysis, image storage, and access control.

Sixth, consider the integration of existing systems.

The system can leverage the existing fiber-optic network of the video surveillance infrastructure and integrate with the legacy video surveillance system and the information display board system.

Summary

The highway thermal‑imaging monitoring and video‑fusion temperature‑measurement solution goes beyond simply installing a few thermal cameras; it establishes a comprehensive closed loop centered on in‑tunnel safety monitoring and out‑of‑tunnel vehicle over‑temperature alerts. The SSK/NW‑TX9800 is ideally suited for dual‑spectrum fusion temperature measurement and fire‑related over‑temperature warning inside tunnels, while the external vehicle temperature‑measurement system enables non‑contact temperature screening before vehicles enter critical zones. Together, these systems help highway management authorities shift risk mitigation from post‑incident response to proactive early warning at the stage of abnormal temperature rise.

Corresponding Device Orientation (Important)

For different application scenarios, common corresponding device orientations include:

• Solution for Road Vehicle Overtemperature Warning System

https://www.settall.com/news_details/10.html

• Tunnel-Specific Dual-Optical Fusion Temperature Measurement System: SSK/NW-TX9800

https://www.settall.com/products_details/SSK/NW-TX9800.html