Sequentially Yielding Cable System for Highway Safety
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Solution Overview
Problem
Existing roadside safety cabling systems rely on vertical posts that can bend and break under impact, allowing vehicles to penetrate into dangerous areas.
Innovation Solution
An energy absorbing safety cabling system with sequentially yielding cables of different modulus of elasticity, spaced further apart than traditional systems, to absorb energy and increase contact time, reducing the reliance on vertical posts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If vertical posts are used to support safety cables, then the barrier structure is simple and easy to install, but the posts bend and break under impact force allowing vehicle penetration
Solution Approach 1:
The patent changes the physical parameters of the cable system by using cables with different modulus of elasticity values. Lower cables have higher modulus (stiffer) while upper cables have lower modulus (more flexible). This parameter variation allows the system to absorb impact energy through controlled elastic deformation of multiple cables at different rates, preventing post failure while maintaining barrier strength.
Solution Approach 2:
The safety barrier system combines multiple cables with different material properties (different modulus of elasticity) into a composite structure. This composite cable system provides both strength and energy absorption capabilities, replacing the reliance on individual vertical posts while maintaining structural integrity during impact events.
2Reliability
If vertical post spacing is reduced to increase barrier strength, then the barrier becomes more reliable, but the cost and installation complexity increase
Solution Approach 1:
The patent optimizes the spacing parameters between vertical posts by using a standardized distance (e.g., 30 feet) combined with the multi-cable energy absorption mechanism. This parameter optimization achieves reliable barrier strength without requiring excessive post density, thereby reducing installation complexity and cost while maintaining safety effectiveness.
3Strength
If cable tension is increased to improve barrier strength, then the barrier can stop vehicles more effectively, but the risk of exceeding cable elasticity and causing failure increases
Solution Approach 1:
The patent carefully controls the tension parameter applied to each cable during installation, ensuring that pre-tension forces are set below the elastic limit of each cable. This parameter control allows the cables to undergo controlled elastic deformation during impact, absorbing vehicle kinetic energy through elastic potential energy storage and release, while preventing permanent deformation or cable failure.
Solution Approach 2:
The system prepares the cable structure in advance by installing multiple cables with specific tension levels and elasticity characteristics. This pre-configured elastic cushioning system is ready to absorb impact energy through controlled deformation, protecting against vehicle penetration while avoiding cable failure during the actual impact event.
4Loss of energy
If the number of cables is increased to improve energy absorption, then the barrier becomes more effective, but the installation time and material cost increase
Solution Approach 1:
The patent optimizes the cable quantity parameter by using a specific number of cables (e.g., four cables per vertical post assembly) with different modulus of elasticity values. This optimized configuration provides sufficient impact energy absorption capacity while avoiding excessive material usage and installation complexity, achieving a balance between safety effectiveness and installation productivity.
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 effectively absorbs energy from impacting vehicles, increasing the contact time and reducing the force on the cables, thereby preventing vehicles from entering dangerous areas.
Implementation Method 1
cables with different modulus of elasticity... different spring/elasticity rates are used... The cable on the lowest horizontal position yields first... sequentially yielding cables
Data Source
AI summary
An energy absorbing cabling system is provided to be used in place of existing cabling systems that run parallel to highways as an upgrade for safety. The system comprises a sequentially yielding cabling system that allows for increased contact time (hold time) between cables and vehicles that have lost control, thereby preventing such vehicles from breaking the cabling system and entering into dangerous areas.