How Sensors Monitor Bridges to Keep Us Safe

February 22, 2021

Vital to our infrastructure, bridges require regular maintenance to ensure safety for the cars, trucks, rail cars and people regularly traversing them. Many bridges are 50 years or older, with citizens traveling across structurally deficient bridges every day.

“Structural health monitoring of bridges clarifies which repairs need to be prioritized,” says IEEE Senior Member Clint Andrews. “The deferred maintenance backlog has become so severe that it is easy to just throw up your hands and invest opportunistically in repairs, but the proper way is to prioritize based on the timely status information.”

Technologists are utilizing sensors and other smart technologies to monitor and protect our bridges and from irreparable damage to the infrastructure or the people involved if a structure collapsed.

While sensors are being used to detect early warnings of a catastrophic structural failure, they are also gathering important data about necessary structural repairs after a natural weather event like an earthquake or hurricane.

“In terms of civil management, the wireless sensors are commonly used to monitor and report the physical condition of bridges, such as the slip-factor and humidity,” says IEEE Member Yidong Li. “Estimating traffic on different road segments would provide very useful information for further analysis and decisions that would be taken or generated by the system.”

Gathering this type of data is also helpful for city management, providing the public with real-time traffic conditions.

“Information generated from this system could be integrated with SMS-based services that alert users about congestion, automatic traffic light timers, geographic information systems and analysis tools that help to manage traffic and plan extensions to transportation networks,” says Li. “The technology will enhance the efficiency of traffic circulation, minimize risks and time to take corrective actions both on design and management levels.”

Sensors are also used for emergency rescue situations in remote areas. “If there’s an emergency condition on the roadside and emergency services can’t be reached nearby due to a lot of traffic, in this scenario, emergency vehicles can be triggered automatically through the connection of nearby wireless sensors sharing location details of the spot to those services,” explains IEEE Senior Member Aiyappan Pillai.

How Do Sensors Protect Bridges?

A wireless sensor device, also known as a wireless sensor node, has a sensing unit connected to a processing unit, a communication unit and a power unit. The sensor will also have storage memory.

“The sensing unit may include one or many sensors for data acquisition of any physical phenomena of interest, such as temperature, humidity, strain and acceleration. There is also a signal conditioning unit, which incorporates an analog-to-digital converter (ADC) unit for converting the analog signals,” says Li. “The processing unit is the main controller of the node. It is responsible for managing the wireless sensor node operations, including sensing and wireless communication. It generally consists of an on-board computer (i.e. a microcontroller unit) with processing and data storage capabilities.”

“When we monitor bridges, we apply a large number of sensor nodes to formulate a wireless sensors network (WSN) and the sensors formulate data acquisition subsystems,” Li adds.

Li explains there are two types of data acquisition subsystems a WSN can acquire:

1. Control and Data Analysis Subsystems

The control and data subsystem collects and processes the data, then takes appropriate sets of predetermined actions to solve or to prevent traffic problems.

2. Communication Subsystems

The communication subsystem enables the communication between wireless sensor nodes by way of wireless links. These links depend on the transmission media and can be in the form of radiofrequency (RF), optical, acoustic or magneto-inductive links.

Sensors are not the only way technology is being utilized to keep our infrastructure safe. Pillai says edge computing, 5G, IoT, AI and machine learning in combination with other cutting-edge technologies are providing ground-breaking infrastructure advancements to citizens in many countries.