Bridge Deck Deformation Sensor for Vehicle Weight Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle weighing systems, particularly for heavy goods vehicles, face uncertainties due to factors like suspension movements, speed, and load transfers, leading to imprecise measurements and high costs, especially when integrated into bridge structures, which are also prone to damage and wear.
Innovation Solution
A method that uses sensors to measure the overall deformation of a bridge deck as a vehicle passes, calculating the vehicle's weight by integrating deformation values over time and comparing them to a pre-established scale calibrated with vehicles of known weights, avoiding the need to sum axle weights and reducing sensitivity to uncertainties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are placed very close to the bridge's rolling surface to measure axle weights, then measurement sensitivity is improved, but the device becomes expensive and sensitive to road surface wear and damage
Solution Approach 1:
The patent extracts the measurement function from the road surface level and relocates it to the bridge superstructure level. Sensors are mounted on the bridge deck or girders to measure global deformation caused by vehicle passage, rather than placing sensors at the rolling surface to measure local axle loads. This extraction eliminates the need for road surface integration while maintaining measurement capability through global structural response monitoring.
Solution Approach 2:
The patent merges the function of multiple axle weight measurements into a single global weight measurement. Instead of using multiple sensors to measure each axle separately and summing the results (which accumulates uncertainty and increases complexity), the system uses a single sensor to measure the total deformation caused by the entire vehicle, directly providing the gross weight without needing to resolve individual axle contributions.
2Loss of information
If multiple sensors are used to measure each axle weight separately, then detailed weight distribution information is obtained, but measurement uncertainty accumulates and device complexity increases
Solution Approach 1:
The patent merges multiple measurement functions into a single measurement. The single sensor captures the cumulative effect of all axles on the bridge structure, providing direct total weight information. This merging approach eliminates the accumulation of measurement uncertainties that would occur with multiple separate axle measurements, while still enabling gross weight determination without needing to resolve individual axle weight distributions.
3Reliability
If sensors are integrated into the bridge construction, then structural monitoring is improved, but the system becomes sensitive to bridge wear and aging
Solution Approach 1:
The patent applies local quality by selecting specific locations on the bridge superstructure where deformation is most indicative of vehicle weight while being least affected by wear. Sensors are positioned on girders or deck elements that experience measurable deformation from vehicle loading but are not directly exposed to traffic wear, environmental degradation, or corrosion that affects the rolling surface and lower structural elements.
4Device complexity
If a simple measurement method is used, then device complexity is reduced, but measurement precision and reliability deteriorate
Solution Approach 1:
The patent replaces complex mechanical measurement systems with a simplified sensor-based system. Instead of using multiple load cells or force sensors to directly measure axle forces, the system uses a single deformation sensor (such as a strain gauge or displacement sensor) to measure the bridge structure's response to vehicle loading. This substitution of the measurement principle simplifies the device while maintaining or improving precision through the use of calibrated deformation-weight relationships.
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
This method provides a simple, reliable, and precise measurement of vehicle weight by utilizing global deformation data, minimizing the impact of uncertainties and bridge wear, while also allowing for bridge monitoring and aging assessment.
Implementation Method 1
obtain values indicative of a parameter of the overall deformation of the deck at successive times of the passage of the vehicle
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
A chronogram is obtained of a parameter indicative of the deformation of the deck (4) of a span (8) of the bridge (1) when a vehicle passes over it. A gross integral is obtained by integrating, in time, the value of the parameter during the time interval during which the deck is deformed by the vehicle. The time difference between the above-mentioned chronogram and a similar chronogram obtained by deformation sensors placed on an adjacent span (8a) provides information on the speed of the vehicle (7). A measurement of the total weight of the vehicle is obtained by multiplying the gross integral by the speed of the vehicle, in order to obtain a normed integral that is compared with a comparative scale previously obtained by calibration with vehicles of known weight.