Opened in 1879, Glasgow Central is Scotland’s busiest railway station, with around 34 million people passing through the station every year.
A recent renovation of the transportation hub, instigated by Network Rail, included a new public address system featuring the largest installation of Tannoy Qflex loudspeakers to date.
The cavernous nature of the building, along with expansive reflective floor surfaces, sandstone walls and a glass roof, resulted in lengthy reverberations times that caused serious intelligibility issues.
To handle the extensive audio upgrade, Network Rail and main contractor Babcock brought in respected UK-based sound and communications company TG Baker, who had worked with them on previous rail network projects to great success.
After careful consideration and design testing, TG Baker elected to proceed with the optimal solution comprising of QFlex, Tannoy’s award-winning digital beam steering loudspeaker range.
“Glasgow Central is a famous Victorian structure that is protected by The National Trust for Scotland, which in itself presented a whole set of architectural limitations,” explains Brian Andrew, who heads up the Railway Division for TG Baker. “As well as that, the station had a problem with intelligibility of announcements, as the reverberation time was in the region of 6 seconds.
“Deploying conventional speakers would have meant a low direct to reverberant ratio, adversely impacting on intelligibility. With such a harsh acoustic environment and protected architecture, acoustic treatment of the space would have proven to be prohibitively expensive, so in the end the whole project required a cutting-edge technology solution, and digital beam steering was the perfect answer.
“In most cases digital beam steering technology is the only effective way of achieving the required levels of speech intelligibility in large reverberant spaces.”
Network Rail and Babcock were looking at a number of loudspeaker technology options when TG Baker put forward proposals using Tannoy’s QFlex digitally steerable, multi- channel, array speaker system.
QFlex is revolutionary in that it is the only digitally steerable array with full range steering capability. At higher frequencies, in order to achieve effective steering and avoid aliasing you need densely spaced transducers; Qflex is able to steer highly focused beams of acoustic energy to beyond 12 kHz.
Even SPL coverage is maintained across the entire listening plane due to its ability to create an asymmetrical pattern thanks to its patented steering algorithm. But as well as these aspects, there were other reasons why QFlex was an ideal solution for a project as challenging as Glasgow Central, as Andrew points out.
“Apart from a significant cost saving to the customer, another good reason for using QFlex over some of the alternative steerable options on the market is that most other products have a fixed mounting height,” Andrew continues. “But in Glasgow Central, the National Trust for Scotland dictated the height of the speakers, where they were to be positioned, and also the colors of them.
“Tannoy was able to offer combinations of different custom colours in order to blend with the surroundings and mimic what was there before, and the adaptability of QFlex meant they could be mounted where required, without compromising on coverage.”
This adaptability comes from QFlex’s unique ability to steer coherent beams up to +/- 70 degrees, allowing the devices to be located much higher up in a space, above the ‘listening plane’, than would normally be possible.
Tannoy has also developed a number of additional features and options specifically aimed at the PA/VA and mass notification markets to provide unrivaled flexibility and capability in even the most demanding applications. In addition, QFlex now benefits from redundant input capabilities (both analog and digital), the capability to monitor pilot tone, and has also been weatherized, making it even better suited for large scale transport hub applications such as Glasgow Central.
For all of these reasons, Network Rail elected to proceed with the solution proposed by TG Baker.
The installation includes 29 QFlex 48s, eight QFlex 32s and ten QFlex 16s, all in varying customized colors to match the existing architectural scheme.
Comprehensive system overview and diagnostics is provided courtesy of six Sentinel SM1 system monitors, which sit on the VNET network and ensure system-wide integrity and provide alerts in the event of any fault condition, eliminating the need for a PC to be constantly connected to the network. This is essential to the system’s compliance as a mass-notification and emergency paging system, providing reporting solution that meets and exceeds all worldwide legislative and safety standards.
The end result for the client and commuters is crystal clear intelligibility on all announcements.
“The biggest benefit to the end user is that people can actually hear what is being said! As soon as we switched it on, everyone involved remarked on the notable difference in terms of intelligibility,” explains Andrews. “Also, another aspect is that the announcements are now automatic; mirroring what is on the information screens in the station.
“That is all done by a PC that we have networked into the system. Network Rail can override it in case of emergency, and QFlex is able to step up and cope with all of the eventualities.”
“As with any project of this scale, there were a lot of challenges to be faced and overcome,” said Andrew in conclusion. “It has been an accelerated process to get it to where it is now. We worked with Tannoy and really pushed the boundaries of the VNet network, and throughout the project we have had hands on support from Tannoy engineers and staff in order to make the project such a resounding success.”
Summing up the project, Graham Hendry, Head of Tannoy’s new Applications Engineering and Training (AET) group, stated: “The new system at Glasgow Central underline’s Tannoy’s agility as a manufacturer and supplier. As a company, we worked closely alongside TG Baker to make sure that QFlex was able to do all that was asked of it. In some cases we added some job specific features along the way.
“Ultimately we delivered a product that was fully capable of integrating with the existing infrastructure with ease, not to mention stand up to the environmental challenges of a busy rail terminal.”