How to use fiber optic infrastructure to improve smart city governance

About the use of distributed acoustic sensingOptical fiberA report on improving infrastructure for smart city governance, sharing applications such as traffic monitoring, threat detection, and fault location detection.

Distributed acoustic sensing is built on critical optical fiber infrastructure, which can improve urban management and protect essential infrastructure.

Optical fiber is the foundation of modern cities, enabling data transmission between citizens and businesses. Data drives our lives, but the speed that optical fiber can provide exceeds one gigabyte per second. Fotech has deployed its Distributed Acoustic Sensor (DAS) devices for various applications ranging from traffic management and threat detection to fault location.

As smart cities become increasingly complex, cities and businesses need more refined data, making the use of information from optical fiber networks a clear solution.

DAS upgrades traditional optical fiber cables to include thousands of vibration sensors, similar to placing numerous microphones around pipelines, roads, or buildings. Lasers emit thousands of pulses per second along the cable. A small portion is reflected, and any disturbances are absorbed by the sensors. Each disturbance has its own characteristics, and advanced algorithms in this technology can inform operators about what happened, exactly where it occurred, and when.

Laid alongside the road and equipped with DAS technologyOptical cablecan pick up the movement of vehicles, determine the size of vehicles using the road, calculate the formation and type of congestion, assess the state of infrastructure, and identify unexpected work.

With these technological means, management authorities can improve travel times and air quality through congestion management methods, alerting to potential road bottlenecks that could lead to accidents, obtaining information about infrastructure usage, and protecting pipelines and cables from damage.

This special report will explore three applications of Fotech DAS technology, but this is just a representation of its potential.

1. Traffic Monitoring

Existing traffic tracking technologies have their drawbacks. Endpoint sensors and cameras are fixed and have limited fields of view, while onboard sensors tracking location data cannot provide sufficient detail. Floating point data can provide average waiting times at intersections, but the latency in data transmission is insufficient to change traffic lights to improve vehicle flow.

However, DAS connected to roadside optical cables can continuously track vehicles traveling on several kilometers of road. This capability means it can detect where traffic congestion begins and ends, change traffic lights to alleviate congestion, and warn drivers of queues in advance.

Fotech collaborated with the Spanish infrastructure and engineering company COMSA to determine how DAS manages traffic on roundabout sections and whether it helps change the sequence of traffic lights to improve congestion. DAS trials were conducted on a five-kilometer-long road passing through open countryside, light industrial areas, and the Catalan town of La Bisbal d’Empordà, with optical fiber inserted in micro-trenches alongside the road and then below the sidewalk in the town. The test aimed to thoroughly assess the functionality of DAS for traffic management systems and determine its sensitivity limits.

During the day, Fotech and COMSA measured normal traffic flow at specific points along the route using a combination of DAS and GoPro cameras (for inspecting findings). They also measured the movement of pedestrians, cyclists, and the vibrations of the old stone bridge along the route. At night, a 500-meter-long road between two roundabouts was closed for a series of tests. These tests included tracking different braking and acceleration methods and running simulated traffic queues. Each parameter was changed one by one to understand how much the sensors could measure.

Data analysis is still ongoing, but it is clear that DAS can track vehicle movements in both directions without interruption across the entire road and provide sufficient information for complex traffic management systems. In addition to identifying traffic bottlenecks, queue lengths, and growth rates, the technology can also determine the size of vehicles and their speed. Fotech continues to evaluate the data to identify more applications.

At the same time, it has begun collaborating with traffic management companies to establish a fully integrated solution that can control traffic lights and optimize traffic flow through the road network. Another benefit of the system is that reduced traffic congestion leads to lower emissions and improved air quality. The solution is expected to undergo practical testing in the coming months.

2. Threat Detection

In addition to tunnels for power companies, telecom operators, and pipeline suppliers, cities also have a complex network of underground pipelines and cables. Third parties may be unaware of their existence, while malicious actors may wish to deliberately damage them, or the infrastructure may be so valuable that criminals or terrorists are interested. In any case, infrastructure can be compromised through access holes or excavation.

In this case, Fotech's DAS technology can be used to detect activity near underground areas,Optical fiberwhich is part of underground cables or installed near pipelines or tunnels. Artificial intelligence is used to identify each unique signature of every activity, and alerts are triggered when any relevant event occurs. The security teams of infrastructure providers are notified of what happened and its exact location within minutes or even seconds.

The technology can also be integrated into other systems, such as allowing cameras to automatically turn towards activities or automatically deploying drones for deterrence. These upgraded security systems enable staff to remotely assess violations before needing to access an area in person.

Criminals have become increasingly sophisticated in their methods of digging into underground pipelines, often excavating tunnels far from the infrastructure. They use increasingly complex techniques to evade existing security measures. An example of DAS technology protecting valuable liquids is in India, where criminals dug a tunnel from a building 20 meters away from an underground pipeline to carry out criminal activities.

However, Fotech's technology identified various attempts to compromise pipelines by detecting sporadic and subtle digging activities over several nights. The pipeline leak detection system locates leak points within a 500-meter range, but by integrating it with Fotech's own technology, accuracy can be reduced to 10 meters.

Another example is in South America, where Fotech technicians picked up unexpected signals in the rainforest. Pipelines are prone to theft, but the remote location of the area and the lack of notification for planned work made it difficult for pipeline operators to believe they were facing a threat. However, at Fotech's insistence, due to vibrations coinciding with human activity, Fotech indicated that the site needed to be checked, and operators discovered a seismic team drilling holes and dangerously placing explosives near the pipeline to support their own exploration work.

These examples illustrate how DAS forms the foundation of a broader system, where technology can detect activities, and the provider's own security processes can determine whether its infrastructure has been compromised.

3. Fault Location Detection

The advantages of DAS in detecting threats to critical infrastructure can also be transferred to fault detection. In many cases, critical infrastructure is located in remote areas, whether deep underground or underwater. Cables in such areas may be damaged due to unexpected water or ground movement. Due to their location, the risks of excavation can be severe and may lead to fires or electrocution fatalities.

Finding faults can be time-consuming and may involve discovering issues by delivering discharge 'strikes' to the cable, further damaging the infrastructure. This method requires engineers to spend significant time at various locations to find where arcing occurs on the cable. In many cases, this infrastructure is crucial, so downtime needs to be minimized.

An example of how DAS helps operators identify remote infrastructure faults is when an offshore cable operator detects issues with the export cable of an offshore wind farm. Subsea cables face particularly harsh environments. Undersea currents can erode protective seabed layers. Exposed cables may then drift or vibrate, initially causing damage but potentially leading to breakage.

Fotech's Helios DAS solution is used to determine the precise location of faults along the cable. The anchor chain moves from the cable to the seabed offset but is located near a fault. Vibrations are then extracted by DAS and associated with GPS. Due to the precise nature of this data, divers are able to determine the overall fault location and begin 'listening' to the cable to generate sound signals. This signal further refines the location of the fault, allowing engineers to remove only 3.5 meters of cable. Because Helios DAS can pinpoint the exact location of the problem, a single joint can be used to repair the cable without needing additional cables.

Another advantage of Helios DAS compared to traditional fault finding and repair methods is speed. In this case, after the cable repair, the weather immediately worsened. If traditional repair methods were used, the work on the cable would have to be postponed for a month, resulting in the company losing millions of pounds in productivity.

Evolution of DAS

These are the current deployment applications of the technology, but its potential will only grow as smart cities become increasingly complex. Fotech is currently exploring how machine learning can extract more data from DAS data. It hopes to understand how to best deploy DAS systems across the city. Collaborations with telecom companies are underway to access their fiber infrastructure and help them further monetize their networks. The advantages of DAS are expected to lead to further deployment of fiber in areas where sensing will bring new services.

As cities develop and become truly smart, DAS will play a key role in supporting value-added services. While short-term benefits include traffic management, cities will rethink their public transport networks in light of the coronavirus pandemic, making traffic management increasingly important. In the medium term, cities can explore how weather or public events impact urban areas.

Looking ahead, DAS can predict the effects of building new infrastructure in cities, or be crucial for decisions such as introducing congestion charges.

Data is at the center of our lives. It connects us, builds relationships, and drives business growth and innovation. Fiber is the foundation, and DAS demonstrates how fiber can further develop to help operate traffic networks, protect critical infrastructure, and change the way cities operate.