The PubNub Train

A few years ago I participated in a team competition to build a proof-of-concept tunnel management system for the engineering firm Costain. The system was intended initially to be used in a multi-billion pound project to upgrade London’s electrical infrastructure, with the aim of improving both the safety and productivity of the workforce.

For certain engineering projects, Costain use large tunnel boring machines (TBMs) to create underground tunnels. Services such as the London Underground, drainage/sewage systems or in this instance electrical infrastructure, could not be done without these tunnels.

The video below explains more about the London electrical infrastructure project and has some footage of the tunnels:

During the tunnelling process, lots of waste material needs to exit the tunnel whilst supplies and infrastructure need to be sent in. As the tunnels may be several kilometres long, locomotives are installed to traverse them.

We were asked primarily to design and implement a new system that would allow staff to track the locations of both trains and personnel in the tunnels, in real-time, with a graphical tunnel representation. Tracking the trains wasn’t possible with GPS as the engineering work takes place deep underground and a LPS (local positioning system) wasn’t cost-effective due to the temporary nature of their construction projects. The winning design conceived the use of RFID loops placed at 100m intervals and RFID tags to identify trains and staff.

Recently, whilst reflecting on this project, I considered how the management system might have been made better with modern real-time communication technologies and concluded that broadcasting information in real-time (whether it be locomotive location data or safety alerts), would have improved the system greatly. I therefore decided to make a simplified model demonstrating how this aspect of the system could work using PubNub.

Why PubNub? First, is its ease of use. Within just a few minutes it’s possible to start publishing messages and the worries of scaling and managing infrastructure are non-existent. Secondly, it’s free up to 1 million transactions and is very affordable beyond this allowance. For many people, the cost of PubNub will actually be less than hosting a comparable multi-cluster architecture on AWS. Finally, it’s fast. With data centres distributed globally PubNub boasts a <250ms latency worldwide.

For this demonstration I wanted to build a model of one of these tunnels and track the position of a locomotive around it. I didn’t have any tunnels or RFID loops to hand but I did have a few spare electronic buttons, a Raspberry Pi and a toy train.

This project consists of two parts:

A brief video demonstrating the project:

The following simple circuit diagram shows how I connected the buttons for train detection to my Raspberry Pi:

For reference here is the Raspberry Pi GPIO pin diagram:

PubNub’s efficiencies have proven to me that it would be a far better solution to the client-server API model originally proposed by my team several years ago. By avoiding HTTP, PubNub avoids the need for headers and avoids constantly open and close connections. By reducing network traffic and decreasing communication time the whole system becomes more efficient and safer.

As the system grows it will need to support multiple engineering projects, multiple geographical locations, numerous trains and will also need to track the movements of staff, vehicles and cargo. With this in mind, it’s clear to see that a scalable solution is required and an efficient system will be extremely beneficial.

Finally there is the consideration of safety. Almost all engineering projects pose safety risks to those working on them. Most of the Costain tunnels for example consist of a single bidirectional track which means that, without proper management, two trains travelling in opposite directions could collide. In addition, trains could break down, staff could enter an active section of the tunnel or an incident in one section of a tunnel could pose a safety risk to unaware staff in another. Having a system that can instantly broadcast alerts/safety warnings across many devices is invaluable in these scenarios. The faster information can be delivered, the faster it can be acted on.

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