Fiber Optic Traffic Sensors in Road Trenches
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Solution Overview
Problem
Current traffic monitoring systems lack the ability to accurately and robustly measure multiple traffic parameters, such as vehicle speed, weight, and classification, under various environmental conditions, while being cost-effective and requiring minimal maintenance.
Innovation Solution
A fiber optic-based traffic monitoring system using fiber Bragg grating sensors embedded in the pavement, which are immune to electromagnetic interference and capable of self-calibration, allowing for the simultaneous measurement of multiple parameters with high spatial resolution and dynamic range, and can detect lane-changing events and imbalanced loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiber optic sensors are installed in trenches along roads for traffic monitoring, then measurement precision and reliability of traffic parameters are improved, but device complexity and installation difficulty increase
Solution Approach 1:
The optical cable is divided into multiple sections with optical sensors distributed at different locations along its length. Each sensor segment can independently measure traffic parameters at its specific position, allowing the system to achieve high measurement precision across multiple points simultaneously while keeping each individual sensor component relatively simple
Solution Approach 2:
The fiber optic cable serves multiple functions simultaneously: it acts as both the transmission medium for optical signals and the sensing element through integrated FBG sensors. This multi-functionality reduces the need for separate sensing components, thereby decreasing device complexity while maintaining high measurement precision for multiple traffic parameters
2Productivity
If multiple optical sensors are multiplexed along a single optical cable, then productivity and coverage of traffic monitoring are improved, but device complexity increases
Solution Approach 1:
Multiple optical sensors are merged into a single optical cable through multiplexing techniques, where several FBG sensors are embedded along the length of one cable. This combining approach enables simultaneous monitoring of multiple traffic parameters at different locations, significantly improving productivity and coverage while managing device complexity through integrated design
Solution Approach 2:
The system transitions from single-point monitoring to distributed monitoring along the spatial dimension of the optical cable. By arranging FBG sensors at different positions along the cable's length, the system achieves multi-point measurement capability in one dimension, thereby improving productivity without requiring proportional increases in system complexity
3Measurement precision
If fiber Bragg grating sensors are used to detect wavelength changes, then measurement precision of traffic parameters is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The system replaces traditional mechanical or electrical sensing methods with optical FBG sensors that detect traffic parameters through wavelength changes. This substitution eliminates the need for complex mechanical linkages or electrical connections in harsh road environments, improving measurement precision while reducing the difficulty of detection through immune-to-interference optical measurement
4Reliability
If optical cables are installed in road trenches, then reliability and robustness of traffic monitoring are improved, but ease of manufacture and installation worsens
Solution Approach 1:
The optical cable with FBG sensors is prepared and configured outside the road structure before installation. The sensors are pre-positioned at specific locations along the cable, and the cable is tested and calibrated in advance. This preliminary preparation simplifies the actual road installation process while ensuring the reliability and proper functioning of the monitoring system
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
The system provides accurate and reliable monitoring of traffic parameters, reducing maintenance needs and enabling better traffic management and pavement maintenance, while being cost-effective for large-scale deployment.
Implementation Method 1
A FBG sensor is formed by a periodic modulation of the refractive index along a finite length (typically a few mm) of the core of an optical fiber. This pattern reflects a wavelength, called the Bragg wavelength, determined by the periodicity of the refractive index profile.
Implementation Method 2
A FBG sensor is formed by a periodic modulation of the refractive index along a finite length (typically a few mm) of the core of an optical fiber.
Implementation Method 3
The Bragg wavelength is sensitive to external stimulus (strain and/or temperature, etc.) that changes the periodicity of the grating and/or the index of refraction of the fiber.
Implementation Method 4
The Bragg wavelength is sensitive to external stimulus (strain and/or temperature, etc.) that changes the periodicity of the grating and/or the index of refraction of the fiber.
Data Source
AI summary
One or more spacers for installing an optical cable are disposed in a trench that extends along an axis. The optical cable includes one or more optical sensors. Each spacer includes a base configured to rest in a bottom of the trench. A first arm extends from the base. The first arm is adjacent to a first wall of the trench. An opposing second arm extends from the base. The second arm is adjacent to an opposing second wall of the trench. The optical cable is configured to extend along the axis.