The on-going development of driverless cars is seldom out of the headlines. There are questions about the reliability of the software which will drive the cars and who will be liable should there be an accident.
Our own family car displays the current speed limit on the dashboard, having read this from the last speed limit sign that it passed, so it appears that the developers of driverless car are working on using AI (artificial intelligence) to interpret the input from the cameras on the cars. This make sense, after all, if one were to rely on maps etc, one could not react to changes in speed limit displayed on intelligent motorways.
Once the software to control driverless cars has matured, it will be necessary for various countries to “marry” up systems from various countries so that the owner of a driverless car can use it to visit other countries. This “marrying up” involves not only the technical aspects of the software associated with the cars, but also the legislation surrounding the use of the vehicle in countries other than the country where it was registered. Three of the most prominent issues facing Britain when Continental drivers bringing their driverless cars to the UK (and when British drivers taking their driverless cars to the Continent) are:
- Driving on the left or the right.
- Rules pertaining to priority at junctions.
- Possible conflict caused by switching between metric and imperial units.
Although the first two will probably pose bigger problems than those caused by switching units, it is the latter that is of concern to the editors of Metric Views.
A Look at the Railways
Before looking at the problems associated with changes between mph and km/h on the roads, it might be instructive to recap what is happening on the railways. Over the years, the various railway companies in Europe developed a multitude of signalling systems which hindered international railway travel as locomotives often had to be changed at the borders. In December 1989, European Transport Ministers decided that a standardised Train Control System for Europe’s railways should be developed to reduce the way in which the various state railways’ disparate signalling systems hindered cross-border traffic. The resultant system is known as the European Rail Traffic Management System (ERTMS), with the European Train Control System (ETCS) as its signalling component.
ETCS is now being rolled out across much of Europe. Unsurprisingly ETCS uses metric units. At the time of writing, it is operational in the UK on the Cambrian Line (where it was first trialled), parts of Crossrail and the Thameslink line and is being rolled out on the East Coast Mainline and will also be used on HS2. By the end of next decade, the bulk of the British railway network should be using ETCS.
What is ETCS? ETCS is a digital based system that does away with line-side signalling equipment. As a result, the train driver relies on the instruments in front of him rather than those on the ground. In this way he is more like an airline pilot than the driver of a car. Trains pick up information telling them about the state of signals that are ahead of them, how fast they are allowed to travel etc from boxes (called Eurobalises) that are mounted on the track. In order to allow for its roll-out, ETCS can operate at one of three levels – at Level 1, it merely replaces existing controls in the cab often replicating lineside equipment, while at Levels 2 and 3 it calculates the train’s exact position and shows all information inside the cab without reference to lineside equipment.
The use of mph was of particular concern to British users, especially when a train would be operating at Level 1 and the driver had to follow lineside speed restrictions given in mph and then the train moved into a Level 2 area where the driver would receive instruction in km/h via his display. The solution was that ETCS would use metric units throughout, but the British variant would display target and actual speeds in mph when operating a Level 1. As the trains enter a Level 2 area, the display will change to a km/h display, with the speedometer graduations changing such that the indicator needle was in the same position regardless of units displayed.
Lessons from the Railways
The biggest difference between the development of the driverless car and the development of ETCS is that on a railway system, railway management has complete control over the system including the vehicles using the track. This is not the case for driverless cars. It is commonplace for drivers to take their cars to foreign countries – I am sure that many MV readers have taken their cars to France, Spain or Belgium on a ferry or on Eurotunnel. Furthermore, one does not need to stop when motoring between Dublin (speed limits in km/h) and Belfast (speed limits in mph) except to pay a toll. If one is using a driverless car, it follows that one should be able to use one’s car anywhere in Europe where driverless cars are permitted.
The first lesson that can be learnt from ETCS is that in order to minimise the risk of problems when changing units of measure, the UK agreed to phase in the use of metric units as and when needed.
Another interesting aspect that could be learnt from the railways is that if one uses an analogue speedometer with a digital backdrop (whether the needle is genuine or digital) the positions of the mph or km/h graduations can be set such that if the backdrop is flipped between mph and km/h (or vice-versa) the needle will not change position unless the speed actually changes.
What problems could happen?
One of the sayings in software engineering is “Bugs congregate on the borders and breed in the corners.” In the case of the driverless car, one such border is the metric/imperial dividing line.
In theory, it should be possible to program the AI module of the driverless car to operate in any country – on start-up the car would use GPS to check which country it is in and then use the instructions for that country.
Should a country decide to change its regulations there could well be a problem – for example, the maximum speed limit might be increased or decreased, which, in the United Kingdom could be done without changing any road signs. This would necessitate an update to the configuration tables in every car in Europe. Such changes would obviously have to be kept to a minimum and if the UK decided to change over to the metric system once driverless cars were commonplace, the logistics of managing the change are such that while the change-over is taking place, the use of driverless cars could be banned. In the Republic of Ireland, such a change was done over one weekend.
It is impracticable for speed limits to be transmitted to driverless cars in real time – they change quite frequently on “intelligent motorways” and again communicating these changes to drivers would poses problems. The obvious way is for the cars to rely on their on-board cameras to read the speed limits in the same way that human drivers read the road signs.
In practice, one could expect AI upgrades to be installed in driverless cars at regular intervals. In theory, each new release should be thoroughly tested before release, but in practice, corners are often cut and this is where bugs are able to enter the system. The more complicated the “rules” pertaining to the software changes, the more likely it is that subtle bugs could enter the system. One such scenario is where a Continental-based car manufacturer regards mph as an “add-on” and does not adequately test the associated software. Such an error might only be discovered when the owner decides to visit the UK. The obvious way around this situation is to remove the relevant restriction altogether and for the UK to adopt km/h in anticipation of the introduction of driverless cars.
Similar situations could arise with misinterpretation of height and width limit signs.
What should be done?
What should be done to forestall the problems that I have highlighted above? The obvious solution (and one obviously favoured by MV) is to speed up the conversion of road signs to metric units. However, the editors of the Daily Express and the Daily Mail are likely to have fits should a wholesale change be announced without a sound technical reason behind it. There will be calls for “Betrayal of BREXIT” and the like. The solution is therefore for the Government to clear the path for a change-over in a low-profile manner so that should a change-over be necessary, it can be done once it becomes obvious and with a minimum of upheaval.
It is suggested that the Government takes steps to ensure that all height, width and length signs are upgraded as soon as possible to show both metric and imperial units as per the 2016 version of the TSRGD which only mandates dual units once signs reach the end of their useful lives. Thereafter it should become mandatory for the display of vehicle heights in the driver’s cab to be in metric units. With all this in place, it should be possible to safely align vehicle height, width and weight signs with those on the Continent at short notice.
As regards speed limit signs, the Government can make a few small changes in legislation to mitigate the impact of a conversion to km/h should it be technically necessary to do so. The one change that could be made is a requirement that the user of any new motor vehicle that is sold in the United Kingdom should be able to change all the units on the dashboard from imperial units to metric units and vice-versa without outside assistance. Moreover, the metric dashboard should be no different to its continental equivalent.
I believe that if these changes are done to satisfy a technical need rather than a political need, there will be little resistance from the general public. It should be noted in passing that I have made no reference to the display of distances on road signs.
References
https://www.modernrailways.com/article/digital-signalling-and-control
https://railengineer.co.uk/etcs-more-deliberations
Metric Views 
Super post! Let’s hope the changeover to metric can happen as suggested!
Ezra aka punditgi@
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An interesting article. Surely there are officials/public servants in the UK’s Dept. for Transport that understand all this technical stuff. A problem is their failure to convince MPs and members of the House of Lords that completion of metrication is essential.
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An interesting article. But it would be much simpler if the UK followed the same units of measurement as the countries amongst which it sits and to which it is connected by land border, tunnel and ferry. It is all very well having a display which automatically flips when one passes into the imperial UK (the only country in Europe which still uses these outdated units of measurement) but to me it makes much more sense for the driver to be able to actually know what units he or she is looking at and what the figures mean. I visited the UK recently with a metric-only, continental-registered vehicle. On a dual carriageway, the figure 70 in a circle suddenly appeared on my dashboard where the local speed limit normally shows. I am used to it showing 50, 80, 100 (km/h) but I had never seen 70 before. I thought it must have flipped by itself to mph but from my recollection the speed limit on those roads was lower and 70 mph is the motorway speed limit. Plus the figure 70 didn’t tally with the needle which was showing a higher figure in km/h. I later leant that 70 mph is indeed the speed limit on that road but even as a seasoned cross-Channel driver I was confused. Britain really needs to upgrade the roads. The main beneficiaries would be the British themselves who would be able to apply the knowledge of measurement they had learnt at school and not have to adapt to the old-fashioned measurements which are used on the roads (and only on the roads).
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@metricviewer. Although the technical gurus in the Department of Transport might understand this stuff, my understanding is that the real pressure comes from industry and outside sources, often backed up by opinions of academics whose job is to keep up to date with changing technologies.
As an example, the UK was one of the last, if not the last country to ditch pounds shillings (£sd) and pence in favour of a decimal currency – decimalisation being announced in the mid 1960’s just as the computer industry was beginning to make an impact in business. I believe that this was not a coincidence – computers had bult-in processes for handling decimal number, but processes for handling £sd were having to be written from scratch for every application. To put this into perspective, how you add up a column of transactions expressed in £sd using SXCEL? The same has happened with merication, except that Joe the Voter has not had to adapt in the same was as he had to adapt to a decimal currency. However, with driverless cars, as I explained in the lead article, things could well be difference.
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Definitely another excellent reason to complete the change over ASAP.
Sadly you might think there is a reversal of the work done prior to 2016 as I’ve noted several new cars sold in the UK have analogue speedometers marked in only MPH (this is from a glance rather than a proper look). You could be excused for thinking that motor manufacturers are pinching pennies wherever they can at our expense.
Where some may have a digital display alongside this many are now digital only which means you have to make the choice. On my own car I have the instruments set to metric so I can read off things like fuel consumption and range in metric but can still see MPH on the analogue dial (don’t forget to change back to imperial for your MOT, getting the certificate corrected after the fact is a real pain!!!)
My motorcycle though, which is the same year is digital only… which means I have to suffer the pain of MPG on the fuel consumption screen; I can tollerate MPH as thats whats on the road signs, but anything else… grrr! At least switching that is easy which is useful as I’m off to France next weekend.
Another thought though – these displays generally have 3 settings; metric, imperial and US. Why can’t we have a fourth that retains MPH for speeds but lets us see fuel consumption using metric units. It’s been decades since you’ve been able to buy petrol in gallons here and even some of the more stubborn among us agree that measuring in gallons is absurd!
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Metric, Imperial, and US displays? Ugh! Makes me shudder that the USA is so far behind the curve. 😦
Ezra aka punditgi
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Ezra said: “Metric, Imperial, and US displays?”
That is what as known as an accident waiting to happen. Question is, who is at fault when it does?
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“It is impracticable for speed limits to be transmitted to driverless cars in real time – they change quite frequently on ‘intelligent motorways’ and again communicating these changes to drivers would poses problems. The obvious way is for the cars to rely on their on-board cameras to read the speed limits in the same way that human drivers read the road signs.”
That sounds straightforward enough. And it probably is in most countries, including the USA, where the number on a speed limit sign means, “This is the speed limit from this point forward until you see a sign indicating something else.”
If only things were so simple in the UK. Here we don’t even sign a speed limit on a motorway if the maximum 70 mph applies. So the car needs a way to detect that a motorway is being joined, otherwise it will just retain the speed limit applicable to the road just left. Repeaters are not allowed where the speed limit is 30 mph, unless there are no lamp posts. (So again, the car needs a good “memory”, even if it has been parked for a period.) However, where a 30 mph speed limit is to be applied to a road subject to motorway regulations, repeaters are not only allowed but required (Hendon, A1(M) and M1 link roads). Incidentally, the residential road where I live has no lamp posts or repeater signs. Does this mean the speed limit is 60? I could show you plenty of examples where the signed speed limit actually increases as one enters a roundabout or goes from a main road to a narrow, winding, country lane.
I pity motorists from abroad trying to understand our crazy and complicated way of indicating speed limits – in fact I wonder if our own people understand them fully. All this is a result of sticking plaster upon sticking plaster and more sticking plaster. Since the 1930s, when speed limits were introduced, it has just been a case of progressive modification of existing rules.
We are in dire need of complete review of our speed limits and their implementation. This review should of course include metrication. At present we see lack of any plan, strategy or foresight, while certain factions in various parts of the UK go it alone with their 20 mph limits under the pretext of accident reduction. If we expect driverless cars to blend in with driven cars we need a plan of action on speed limits. I don’t see one.
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One thought for the engineers of the future might be to incorporate a QR code or similar into speed limit signs indicating the speed limit, you would have an international standard that all motor manufacturers would agree on so that they would all be in metric regardless of which country they are in, which avoids the possibility of a sign being mis-read because of it being in the wrong unit.
Include security and check digits in the code so they can’t be tampered with – though what you do in the case of a sign that the vehicle can’t read needs to be agreed; there was a news story earlier this week where it had been proven thar you could use a light source to confuse the sensors to that the speed limit couldn’t be read by the AI. W
e all know as drivers that there are even times when a human can’t see a sign so the AI would need to have rules in place to know what to do in the case of a mis-read sign. Perhaps authorities will have little choice but to have an on-line database of current speed limits that cars would have to update on a regular basis (or perhaps be disabled until updates) to ensure that problems don’t occur.
Every time you come up with a new solution another potential problem pops up and complicates things. This is why it will be a while before I get close to trusting something non-human to drive anything on the roads!
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