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Webinar recording is available in the ITS Australia Portal.
ITS Australia's ITS Tech Talk series is transport technology 101. Each episode will serve as an introduction to one key part of the ITS industry . . . this is episode 3.
This talk will give a brief overview of the standards and underlying technologies of electronic road signs and focus on the considerations that must be taken when manufacturing them. We’ll also take a brief look at the future of electronic signs and where we might be heading with operator to driver communications. Register for this, and all of our upcoming ITS Tech Talks, through the ITS Australia Portal.
All technical information in this talk will be presented in an easily digestible way with a non-technical audience in mind. Anyone who deals with electronic road signs on any level should be able to learn something during this talk.
Dr Mahmood Hikmet Head of Research and Development / Ohmio and HMI Technologies Head of Research and Development / Ohmio and HMI Technologies
Dr Mahmood Hikmet is the Head of Research and Development at Ohmio and HMI Technologies and is tasked with overseeing and synchronising R&D activity for the autonomous vehicle program and all other areas of research. As a science communicator, Mahmood’s focus is on bringing across technical information to non-technical stakeholders. Throughout his career Mahmood has been closely involved with the direct development of IoT infrastructure for intelligent transportation and mobility. Most recently, Mahmood oversaw the development of the first 5G connected autonomous shuttle in the world in conjunction with Spark as well as the delivery of the largest 3d printed autonomous vehicle in the world, the Ohmio LIFT, to Christchurch Airport.
Mahmood holds a PhD in Electronic and Electrical Engineering and a Bachelor of Engineering (Hons) in Computer Systems Engineering from the University of Auckland.
Get in touch with HMI Technologies.
Yes! Flip dots can be used for outdoor applications if they’re rated for it. Flip dots are a fantastic option when signs don’t need to change often as power is only used when a message is changed. There are also “dots” that come in larger sizes (more like blocks, really). However, more moving parts than a regular sign means that the Mean Time Between Failures for this sort of technology might be shorter than a sign using a technology such as LEDs or e-Ink. It is a mature technology but without a large demand so you may be limited with the number of suppliers that still manufacture them. While the stand-by power is very small, the driving current is comparatively large. To reduce the power, they are usually flipped in a staggered manner (rather than all together). This might not be acceptable for the road authority from the power usage perspective, or the latency between sending a message and having it be displayed by the sign.
Adopting global standards for technology is almost always a good idea. It is a great way to not only leverage off the expertise of global experts, but it allows for a wider market for acquisition. Developing your own national standard for a technology such as variable message signs creates a barrier to entry for competition. Specifications which reference global standards or which augment global standards is where attention should be focused to create custom solutions which are fit for purpose.
EN12966 does not tell you how to build a VMS. Instead, it creates a variety of classes and specifications which are a common language that the industry can use to discuss solutions. There is little to be gained, in my opinion, of having an Australian definition for the colour Green as opposed to simply using the one put forward by EN12966. It also just means that we’re not redoing the work that someone else is already doing. We can help contribute to these efforts through bodies like CEN and ISO rather than competing. We can set our standards to be mirror standards of current European or global standards if we need to bring them in our jurisdictions.
Keep in mind, however, that complying to a standard does not necessarily mean you get a good or better product that works for the application you have in mind. Especially if the standard specifies a range of parameter sets to choose from. The buyer needs to very carefully (and probably with technical help) select the correct mix of requirements. If this is not done correctly, you will most likely end up with a product that is expensive and does not perform as required.
Before I answer this question, there’s sometimes confusion in the use of the term “full colour”. As I understand it, its used to refer to signs which utilise colour-mixing of Red Green and Blue to achieve different colours. You will almost always need more than one LED (except in the cases of Red and Blue) to achieve the other EN12966 colours. The alternative to these is a discrete colour sign, where each colour that you want to use will have a different LED dedicated to it. These are usually Red, Green, White, and Yellow (Blue isn’t used very often in road signs). You would only need one LED to display the colour that you’re looking for, but you can only display these colours.
This is a frequently discussed issue in some jurisdictions. Matrix signs are created when what can be displayed on them is variable. The requirements for text are a much lower density than the requirements for graphics. Further, the use of full colour (RGB) over discrete colours only gives you the advantage of displaying images (such as photos) and nothing else (assuming, a road authority never chooses the colour pink, for example, for text). A sign with discrete colours (only displays a pre-defined set of colours such as Red, Green, White, Yellow) will allow for almost all traffic signs to be displayed effectively as we don’t tend to use other colours in these signs, and we keep them relatively simple and flat rather than using gradients and pictures so that they are more immediately recognisable by road users. An answer to a question like “what can be done to make better use of full colour full matrix signs” would largely be up to the transport authority. Using them as advertising billboards, for example, might be a controversial option to further make use of a sign. Pushing traffic safety campaigns when the sign is not giving information could be a good use, as well as generally positive messaging wishing people well could provide some value. I, personally, have yet to see any authority display an actual image as part of regular operation on a full colour (RGB) sign – they have only used them to display pictograms and text which a discrete colour sign could. The popularity of full colour signs could be based in FOMO (Fear Of Missing Out) on the full colour feature which may be used in the future rather than in a business case for current needs.
There is a reason that pictograms have come into fashion especially in a more globalised world. They convey a message very simply to speakers of all languages. One of the main features of pictograms is simplicity. If you check pictogram based instructions, colour is almost never used as it increases complexity. In terms of colour signs; just because we can does not mean that it is a better option.
With regards to smartphones replacing VMS in the future, I would suspect not. You cannot make the assumption that a road user has a smart phone on them, which means that if you were to display a critical message to road users, it should be accessible by *all* road users. We assume, for example, that all road users are reasonably well-sighted and make that a pre-requisite for obtaining a license. That’s why we’re able to use purely visual methods of communication. I would expect that we would see connected vehicles before we see smartphones completely replace VMS’s. However, seeing as the age of the fleet is roughly 14 years in NZ and Australia, we would also need to retrofit all vehicles with this connected capability before we can consider completely replacing a variable message sign in the future. It’ll happen eventually, but not soon (in my opinion).
Expanding on my answer to the previous question, it is one thing to have some vehicles on the road with the ability for connectivity, it is another thing entirely for *all* vehicles to be connected. This creates a bit of a problem for critical V2X applications as this transitionary period will require any critical application to be accessible by both connected and non-connected vehicles.
Now to the topic of wireless communication technology – it is unclear where the industry is going. DSRC was created specifically for vehicles but we’re yet to see that adopted widely, and with the problems, of course, of different jurisdictions adopting different frequencies. 5G is a candidate for (almost) peer to peer communication which could enable connected environments. The advantage of 5G is that, unlike DSRC, the business case for it spans many different industries and business cases – which means that it will happen regardless of whether or not vehicular communication is at the forefront of thought for a jurisdiction. I would say that DSRC is a possibility but 5G is an inevitability.
Before I answer this question, there’s sometimes confusion in the use of the term “full colour”. As I understand it, its used to refer to signs which utilise colour-mixing of Red Green and Blue to achieve different colours. You will almost always need more than one LED (except in the cases of Red and Blue) to achieve the other EN12966 colours. The alternative to these is a discrete colour sign, where each colour that you want to use will have a different LED dedicated to it. These are usually Red, Green, White, and Yellow (Blue isn’t used very often in road signs). You would only need one LED to display the colour that you’re looking for, but you can only display these colours.
If the same level of quality of service needs to be maintained, then full colour signs will definitely be more expensive.
One of the many reasons is that colour purity would need to be trimmed every so often to ensure that the required colours are actually in the correct part of the colour space. This is because as LEDs age, their brightness begins to degrade. This is not a problem for discrete colour signs as they will only appear dimmer and can be built with this degradation in mind so that in 10 years’ time, the degraded brightness will still be acceptable. With full colour (or signs that require colour-mixing), the intensity of each LED will impact how the colours mix with each other, and as the sign ages, each colour LED will age at a different rate. This means that the sign may display different colours – with serious risk for White, Green, Yellow and Orange – as time goes on. If you replace a single “module” within the sign as it fails, that module will appear more vibrant and very different to the rest of the sign as it will have new LED’s contrasted to the rest of the sign’s degraded LEDs. Burn-in is also a factor if the same message or image is displayed for a long time.
The only advantage it gives you is the ability to display real images (such as photos). I would argue that the current pixel pitch that we utilise (around 20mm) would not make for very clear representations of photos compared to an electronic billboard or a video display that you see at a stadium, for example (which are now usually using pixel pitches of 10mm or less). We would need a higher density in order to show *good* quality images, while pictograms like road signs can look acceptable on the current resolutions we are seeing in Australia and New Zealand. If you are looking for cost savings, I would avoid colour-mixing. If you need colour for pictograms, use a discrete-colour sign. If and only if you see yourself needing to display images, then a colour sign makes more sense than the alternatives. It definitely would not be more cost effective, though. More parts and complexity will almost always result in a higher cost.
This can be solved pretty simply with a current limiting resistor on the input line. For greater efficiency, a pre-charge circuit can be used to limit current while the circuit capacitors are uncharged and then fall to an unlimited mode when a reasonable charge has been reached. This question stresses again the importance for clear specifications. The manufacture and design of any product to a specification lies in the specification itself. Anything not specified will be left to the discretion of the manufacturer who will usually be under pressure to reduce costs where possible.
It’s definitely possible to create machine readable signs – it is just a question of which machines we are talking about specifically here. This is something that can definitely be part of the final design of a sign – it just needs to be specified. When creating a tender, state that the sign should be readable by cameras within a given framerate. The onus is then placed on the manufacturer to create a machine readable sign. The current signs on the road are not machine readable (or only incidentally so) because when specified, they were only specified to be readable by humans.
Coming to this question from the V2X side, we would more likely see augmentations to current infrastructure to communicate over RF as opposed to communicating over a visual medium such as LED’s on a sign. This means that as time goes on, and the vehicle fleet becomes more connected, the need for visual road signs would disappear. A way that we can pave the way for this future is to implement a V2X channel on supplied signs from now. That would mean that the infrastructure is ready for V2X communication. So rather than retrofitting current technology it would be better to implement a parallel technology for the time being in order to switch over completely in the future.
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