Making yourself heard in transport projects

Installing audio in transportation venues is as tricky as it is vital. Paul Milligan explores how to get the sound right where you want it.

Of all the permanent effects caused by the pandemic we’ve seen across the many verticals the AV sector covers, the growth of Microsoft Teams in the corporate world for example, the transport sector is the one segment that has simply returned exactly to how things were before. It’s a simple case of “if it ain’t broke, don’t fix it”.

That’s not to say innovation isn’t happening with the AV supply into airports and train stations, it is, but it is happening on the audio side, rather than on the displays side, and that’s what this article will concentrate on. We will also look at why transport clients behave differently to other sectors. Transport clients have very individualistic and specialist needs, which means that you don’t get too many AV companies providing design and installation for say the transport sector and the corporate market, it tends to be ‘we do transport and that’s it’.

If you have a transport client, when should you expect them to refresh technology, is it three years? Five years? Or more like ten or even fifteen years? “It’s one of the most conservative and slowest markets in our field, much slower than sports or entertainment,” says Dirk Noy, general manager, Europe, for acoustic consultancy WSDG. It’s the nature of the industry to be cautious but there are genuine reasons for their caution he adds. “You cannot just close a train station for three weeks, if you want to change something, you have to think it through very carefully. You don’t want to do that every few years.”

With railways there generally tends to be a lot of hoops to jump through with regards to safety and compliance says Jonathan Hoskin, business development manager for the OEM and major projects team at Ampetronic. Those managing new technology on board transport vehicles are looking a long way ahead he adds: “They generally tend to compensate for that long decision making process by looking years in advance for when technology will become available, because the last thing they want is a train they’re specifying for five to ten years’ time to turn up onto the rails and have obsolete technology on board.”

A public address system can last more than 15 years, depending on the quality of the equipment and its maintenance says Luc Richard from AREP, a subsidiary of SNCF that carries out design studies for new train stations and the extension/renovation of existing ones in France. The decision process is slow because there are so many parties involved adds Edo Dijkstra, CEO of integrator TVV Sound Project. Anything being suggested will have to pass through the site owner, and potentially another company who operates the venue, who will pass it through its engineers and IT team to ok, it will also have to get the ok from architects too. “Before the final speaker is installed it’s always half a year to one year between the order and the finalising of the project,” says Dijkstra.

The adherence to a range of standards also slows down the decision process says Eric Grandmougin, marketing director, Arbane Group, which includes brands Active Audio and APG, often seen in European transport projects. “It’s very long to change the technology because standards and are very important in this kind of market and to change the standards so it takes time, especially in Europe because the standards are not only French but European as well.”

The sheer size of many transport projects means that very few are alike, does it really involve a custom design every time? “Every station is different, with added complexity when some are listed as historic monuments,” says Richard. “The broadcasting systems are studied in detail to meet the specific requirements and constraints of each station: acoustic conditions, presence of sales agents in the sound area, separation of call zones, etc. Architectural integration of the loudspeakers in the sound area may also require the development of customised systems.”

There is so much individual work to be done on each transport project says Dijkstra that’s it’s just not possible to re-use designs from previous jobs. “Because so many things are different in most airports and train stations, we are always customising the system. We put everything in 3D, we do sound checks, we listen to the reverb times and put this all this information in the system that’s making the calculation. It’s what the Germans call fingerspitzengefühl, you have the experiments to know exactly what the speaker will do and will not do, because you know it’s one of the most difficult environments.”

The redundancy of audio systems in transport projects is the most important aspect of any installation. With the public’s safety at stake, the systems installed must keep working, even in the event of an IT or power failure. So how can the AV industry help build in redundancy within audio systems? We always try to use equipment that has failure detection says Noy. “That way we get a message when the system is not working, you cannot do that with a regular loudspeaker, you will never know whether its working or not.”

The choice of equipment is vital because it has to have a certain complexity level to make redundancy work correctly. The PA system is the means of broadcasting the evacuation alarm in the event of fire, so it must be operational at all times explains Richard, and a good way to do this is to have it powered by the station's back-up power supply, which continues to power the system if the normal power supply fails. “They can also be equipped with backup amplifiers, which automatically take over in the event of amp fault or downtime. Automatic monitoring applied to the central systems and loudspeaker networks means that maintenance staff can be informed of any faults without delay.”

WSDG builds redundancy into some projects by installing an analogue network (of speakers) parallel to the digital network says Noy, “There are some products out there that can accept both inputs - digital and analogue. If the digital fails it switches over to the analogue.” You can also protect the audio by adjusting how the speakers are wired says Grandmougin, “In transport projects you don’t wire the loudspeaker with the one closest to it, you wire the third speaker with the first and the fifth with the third and the second with the fourth, so if there is a failure in the line you still have a signal. The audio quality will be less, but you can still have sound if a problem is happening.”

Infrastructure is always a topic that comes up in discussion on any transport project. Given its elderly age sometimes, can the infrastructure in place be a stumbling block to installing
the right audio? It’s often creaky and old but well maintained says Noy. “It has to be well maintained because they have such a low tolerance for failures.”

Another major hurdle to overcome in railway stations and airports is the architecture, which can vary wildly in shape and style. What problems can it cause installers, and how can they be overcome? The main problem is ceiling height says Grandmougin. “At the beginning of the last century you needed to have very high ceilings in train stations because of the fumes generated by the machinery.” The second problem is concrete he adds. “You need to have it in railway stations and in metros because it is a very strong material, able to deal with lots
of people, but it produces bad acoustics.” 

There are normally two issues with the architecture says Grandmougin, it’s either old buildings with structural issues or very nice buildings you can’t modify. “In that case you have
to adapt the directivity of the loudspeaker. Using column loudspeakers for instance to increase the intelligibility even if the acoustics are poor. This mainly concerns train stations and sometimes metro stations. In airports, it’s different because the acoustics of an airport, generally speaking are fine. An architect or acoustician can put absorption in the ceiling or the walls to allow more possibilities for quality sound in the space.” With older buildings there are often strict rules in place says Dijkstra, “It’s definitely more complex because every time we make a decision, we have to take into account the (architectural) design and we are simply not allowed to do what we want.”

You also have the added problem says Noy that many architects hate to see loudspeakers. “Thankfully we are seeing more transport buildings being made out of wood so that makes it a little easier for us because you can easily treat wood to be an absorber, you can’t treat glass to be an absorber.”

You have two possibilities to cover a difficult acoustic environment says Grandmougin. “The first one is to limit the number of loudspeakers to reduce the interaction between the loudspeakers and in that case it’s best to have column loudspeakers because you control the directivity and you only put sound where you need to have sound. The second possibility is to install several ceiling or pendant speakers very close to the public, to reduce the level generated by each loudspeaker. The second solution can be interesting but it’s not a cost effective solution, because by limiting the number of loudspeakers you limit the cost of wiring, which is the biggest cost of a project.”

As mentioned above, detailed acoustic modelling is vital in transport projects. “Computer models enable us to work with architects to study the position of the loudspeakers with a view to meeting acoustic objectives, particularly intelligibility,” says Richard. We would never go to a station, install it and then give it to try and hope that it works says Dijkstra. “It’s a case of making software simulations and putting real possibilities such as trains and other people in the simulation. What are the materials they are using? We also look at the dimensions and the shapes from the walls and ceilings. This calculation is not done in one day or one week, it takes a really long time but when it is finalised we then go and start the installation.” 

Finally we come to the issue of noise, or rather how to deal with lots of it. As airports and train stations get busier that increases the overall noise levels, which can seriously affect intelligibility. “More trains close to other trains means more noise, so you have to have higher levels (of sound) to compete with that,” says Noy. “The second problem is that more people now have hearing loss, which makes it really important to invest more planning time, money, and equipment into having high speech intelligibility. As noise gets louder, which is bad for intelligibility, it gets worse for everyone.” One solution is to control the directivity in a vertical angle but also in a horizontal angle explains Grandmougin. In a recent transport project in Leuven in Belgium, the Arbane Group and TVV Sound achieved this not by using column loudspeakers but huge vertical sound bars. “The idea is to reduce the directivity and only to focus the sound on the railway platform, to prevent (sound) disturbances from one platform to each other, but also to the local neighbourhood.”




Directivity can be a key product in transport locations because we can send the sound where it needs to be. “We’re using directional beam steering to get high speech intelligibility because we have a large space and you don’t want to excite the entire space. You really want to reduce reflections from the surfaces, so you have to have a very tailored sound beam because you know exactly where the people are, they’re on the platform, they're not on the rail tracks or on the ceiling,” says Noy.

Another way to cut down on unwanted noise is to deliver sound directly to people’s own devices. Ampetronic has the Auracast and Auri systems, which offers the opportunity to potentially reduce some noise by delivering audio directly to mobile phones. “It also potentially gives us the opportunity to deliver lots of different channels of audio, so potentially there's the option for multiple language streams, which may remove some of the confusion from a space. Also if you’re sat in a specific lounge there might be something that is specific for that space that could be delivered directly to people’s devices, which again gives us the opportunity to remove some of that audio,” says Hoskin.

Transport projects are clearly not for the uninitiated, or the fainthearted. It is difficult work, fraught with problems not of your own making, with hurdle after hurdle to jump over before a project is completed. Luckily for the rest of us, there are people out there in our industry who are committed to making the aural experience of visiting an airport or train station a much more pleasurable experience than it has ever been in the past.

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