Rail Technology | Case Study
Streamlining the automation process
The use of rugged portable memory tokens has helped to streamline the automation process on Sheffield’s Stagecoach Supertram service, as Michael Barrett explains
T
he Stagecoach Supertram in Sheffield, South Yorkshire gradually opened in phases between 1994 and 1995. Now thanks to intelligent use of portable memory, which enables a greater level of automation the service has been able, through the use of rugged memory tokens, to streamline the automation process.
Memory tokens with a serial interface help these trams to accurately navigate the busy streets of Sheffield. For the past three years, the technical team at Orion Projects the company responsible for the upgrade of the Supertram Vehicle Identification System, has been using Datakey Electronics’ Electrically Erasable Programmable Read-Only Memory (EEPROM) devices supplied by Nexus. The Stagecoach Supertram serves the city of Sheffield with three light rail routes, covering a total of 29km. The tram network links five park and ride sites with the city centre and provides easy access to the mainline rail station, shopping areas including Meadowhall, both of Sheffield’s universities, the Cathedral, the city’s sports arenas and a wide variety of entertainment venues. The Supertram plays a key part in the
city’s infrastructure and as half of the system is located on streets running with mixed traffic, so the Orion team tasked with upgrading the tram to track
26 May 2013
communication system had to address a variety of challenges in successfully delivering the project.
The VIS system manages the routes, signalling, stops and priority levels for the tram, helping it to integrate seamlessly with urban traffic. Because accurate communications are paramount for the efficient functioning of the tram, the team looked for a memory solution that would provide flexibility, as well as safe and rugged data storage. Datakey Electronics’ serial interface token was chosen to store configuration data. This configuration data is uploaded onto the token by the Orion team and then plugged in at trackside boxes. “In order for the trams to safely and
efficiently negotiate Sheffield’s traffic, we needed a robust memory product that would still be flexible enough to allow multiple data uploads” explained Roger Burridge, Director at Orion Projects. The memory token will ultimately be used to store configuration data at 59 trackside locations. This data is used for controlling trackside traffic controllers points and signals and because each location is unique, individual controls need to be used for each token employed.
A set of inductive loops lie hidden
underneath the tracks and act as a sensor for the tram, providing continuously
Components in Electronics
updated status concerning tram location to the trackside equipment and the Operational Control Centre. The trackside hardware reads the information stored on the memory token and based on the signals it receives from the loops, sets the appropriate output information. The tokens contain a variety of possible responses called up from data tables and the right option is chosen for individual locations.
“The tokens supplied by Nexus are used to determine the operation of relay outputs which help direct traffic controllers and trackside control equipment. Traffic controllers are located at every major junction and their aim is to effectively control traffic lights and vehicle priorities. The data table stored on the token is used by the trackside equipment to signal the traffic controller so that trams get priority in mixed traffic, alongside cars and buses” Burridge explains.
This technique allows a tram to cross the network of tracks in Sheffield and ensure it does so as quickly as possible - thanks to the priority arrangement input into the traffic signal. According to Burridge “In the past we have used fixed embedded memory to manage tram configuration table, but that presented us with flexibility issues. The benefit of using the Datakey Electronics’ tokens is that they are removable and most importantly, very robust. Having a token that you can literally plug and play has significantly streamlined tram communications. This means that when required, a new memory token can be programmed at headquarters and then a trackside engineer can just plug it in after removing
the old one. Furthermore, the tokens are reliable and easy to reconfigure – they can be used time and time again. The fact that they are reprogrammable helps keep the costs down as well.” Reliable receptacles that help read the information uploaded onto the token are perhaps the most critical aspects of the system.
Nexus offers a range of field-proven
mating receptacles from Datakey Electronics’ for each data-carrier system and distributes the full range of Datakey Electronics’ memory systems. They are available with SPI, I”C, Microwire, USB and SD Interfaces. Memory capacities range from 1Kbit to 64GByte allowing easy customisation that fits particular application requirements. These products are ideally suited for data-logging, parameter and configuration upload, data storage and access control. “Since we started working with Nexus and Datakey Electronics’ products three years ago we have experienced more streamlined and effective communications. We cannot afford systems failures and tram traffic disruptions, so only a reliable device that can be easily tailored, would do” concluded Burridge. In recent years, the Sheffield Supertram has become an emblem for its native city, just like the iconic cathedral or the university campuses. Much like these two institutions, the tram has become an integral part of urban life, sustaining crucial activities.
Nexus |
www.nexus.com
Michael Barrett is operations and engineering director at Nexus
www.cieonline.co.uk
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