Could drivers become too reliant on new speed warnings and limiters?

Legislation kicks in on Sunday, but it doesn’t mean that your car will automatically slow down

Speed limit assist systems are mandatory on all new cars from Sunday, July 7th. Image: Mercedes
Speed limit assist systems are mandatory on all new cars from Sunday July 7th. Image: Mercedes

New EU legislation which kicks in this week is aimed at getting drivers to slow down, potentially eliminating as many as 30 per cent of all crashes, with the possibility of saving 140,000 lives across the Continent every year.

The new legislation, which comes in to force on Sunday July 7th, makes the fitting of an active speed limit warning or limiter mandatory for all vehicles sold in the EU or Northern Ireland. Britain is currently opting out from mirroring the legislation but the fact is that pretty well all cars sold there will be fitted with these systems anyway. These Intelligent Speed Assistance (ISA) systems, are designed to assist drivers with reminders of the local speed limit.

Those reminders can come in four separate or complementary forms, the most basic of which – and the one which will be fitted to most cars – is a visual warning flashing on the dashboard combined with an audible tone to alert you to the fact that you’ve just exceeded the local speed limit. That limit is monitored by a combination of a camera mounted in the windscreen which reads local signs, as well as a GPS location set-up which is fed with regular information as to the speed limits in a given area.

There is also the option for “haptic” feedback, such as the throttle pedal of the car either resisting being pushed or vibrating, or the engine or electric motor power cutting out. The system won’t actively change the speed at which the car is being driven unless you have cruise control engaged, and your car is fitted with a system which automatically ties the cruise control speed to the speed limiter; not all do.

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It has been reported in some media outlets that specialise in manufactured PC-gone-mad outrage that, as of Sunday, all cars will automatically hold you to the speed limit, but that’s not the case. The legislation only affects cars sold from Sunday onwards (although most cars have had such systems fitted anyway since 2022) and the effect of such systems is a reminder and a warning, not an active intervention in how the car is being driven. Any warnings can be overridden by simply pressing on the accelerator.

A potentially more important question is whether or not such systems are actually an effective solution. Clearly, excess speed is a factor in serious crashes, hence the EU’s estimate that 30 per cent of all car crashes could be avoided with the fitting of speed limiters. But the technology has no nuance. It cannot differentiate between someone cruising along at 2km/h over the posted limit and someone driving 50km/h over the posted limit.

That latter driver is in any case far more likely to simply ignore any warnings. Equally, the systems don’t allow for the over-reading of speedometers – all car speed readings are allowed, by legislation, to overestimate the speed of a car (but never to underestimate it) to allow for changes in wheel speed versus vehicle speed. The difference between the figure on your dashboard and your car’s speed across the ground can be as much as 5km/h.

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The European Automobile Manufacturers’ Association (ACEA), the umbrella organisation that represents Europe’s car makers at governmental and EU level, has previously cautioned against over-reliance on active speed limiters. “In practice, ISA systems still show too many false warnings due to incorrect or outdated speed-limit information,” it said. “For example, because road signs are not harmonised across Europe. Digital maps are also not fully populated with speed limit information for all roads, and data are not always updated. Moreover, camera-based systems cannot anticipate all scenarios, such as when traffic signs are covered up.”

Consumer organisation Which? has also cautioned against over-reliance on such systems. “We’ve found ISA to be unreliable on many of the cars we’ve tested. For example, we’ve had multiple instances where a car has registered the speed limit as being 80mph in 30mph zones,” it said.

That last assertion chimes with the experience of The Irish Times’ Motors team, who have frequently come across speed warning systems that tell us that it’s fine to do 80km/h down a narrow village street while moments later on a three-lane motorway the same system is insisting that the speed limit is 30km/h, not the 120km/h that it actually is.

The European Commission has responded to such concerns by pointing out that the limiters are not God, they’re just there to help. “The driver is always responsible for adhering to the relevant traffic rules and the ISA system is a best-effort driver assistance system to alert the driver, whenever possible and appropriate.”

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That said, there’s also a concern that the systems themselves cause drivers to rely on them too much, rather than actively thinking about what’s really safe in the moment. Gemma Briggs, from the Open University, along with Helen Wells and Leanne Savigar from Keele University, wrote in The Conversation: “Clearly, drivers are not great at respecting speed limits, so it may seem like a good idea to aim to take the choice of whether to speed or not out of our hands.

“To make something ‘techno-fixable’, though, you need to reduce complex driving behaviour to dichotomies of ‘safe’ and ‘dangerous’. Technology needs to be told which behaviour triggers which response in simple, binary terms as it cannot (yet) handle ifs and buts and context.

“But the risk is that this may encourage us to believe that 50km/h, for example, is inherently safe, even when 30km/h, or even less, might have been the safer choice. This is something we would like to explore further in our research.

“Likewise, tech that warns a driver if they are showing signs of drowsiness or intoxication, and parks their car for them if they don’t respond correctly, could actually encourage drivers to think that they can drive when unfit because the car will step in and save them. Technology can be marketed as improving safety, but safety requires understanding – not dichotomies.”

Neil Briscoe

Neil Briscoe

Neil Briscoe, a contributor to The Irish Times, specialises in motoring