ISA has been around for nearly a decade but have evolved over time, so fixing on a definition of exactly what an ISA is can be a challenge. In essence, an ISA system is a combination of a forward-facing camera that can recognise speed limit signs and is integrated with mapping data so the car should know what speed limit applies to its location (in case the camera misses a sign, or the sign is blocked by a hedge). The system can provide speed limit information to the driver, and it can also ease up on the accelerator to gently bring the car down to the speed limit.

Car manufacturers have been offering ISA as an option on new cars since about 2015, finessing the technology on each new model, and ISA has been mandatory on all new cars sold in Europe since 2022. Note that although fitting an ISA is mandatory in Europe, the driver can choose to switch it off if they want to.

While there have been critics of ISA in the past, including quite a bit of contradicting information in the media, it is my belief that drivers are now beginning to realise and appreciate the many benefits driving with ISA can bring.

Because my professional life is devoted to improving road safety, I naturally start with that as ISAs greatest benefit. ISA is part of the bundle of vehicle technologies included in the 2015 update to the European General Safety Regulations [1]. When the UK Government consulted in 2022 on adoption of these vehicle technologies [2], many respondents recognised that the maximum benefit of the regulations could only be achieved if all the technologies were included.

Professor Oliver Carston at Leeds University calculated that Great Britain could see up to 12% reduction in injury accidents due to ISA, depending on exact system in use and the road type [3]. That equates to thousands of people walking away from road collisions unharmed or with lesser injuries, and many more avoiding collisions altogether.

Vulnerable road users are protected by the combination of technologies in the General Safety Regulations and by ISA in particular

Considering the road transport system holistically, any evolution that makes roads safer and keeps the traffic flowing is highly desirable. Vulnerable road users (and most of us walk or wheel at some time or another) are especially protected by the combination of technologies in the General Safety Regulations, and by ISA in particular.

I personally choose to keep my ISA turned on in my car all the time. It stops me getting speeding fines. It saves me money on my fuel bill, which is always very welcome. But, best of all, it provides an extra set of eyes, which I find particularly helpful when I’m navigating new places, or the roads are busy. ISA gives me head space and that makes me a better driver. On a motorway, I use ISA in conjunction with cruise control, and have been pleasantly surprised by how much less tired I am after a long journey when using this system.

Critics of ISA sometimes complain about nanny state interference, but I don’t see it that way. You can always turn it off or override it, so how is that interfering in your choice of how you drive? Speed is a crucial element of safe driving. Everyone becomes a better driver with ISA helping them (it’s called an assistance system for that reason), which means fewer collisions, less time stuck in traffic, and more time to spend on tasks that aren't travel-related.

Critics also complain that the technology is imperfect, but so is every human driver. In the rare event an ISA system malfunctions, you will get a warning. How inconvenient is it to simply override it or turn it off? In my car, it’s a tap of the accelerator or a touch of a button. I can’t fault the ease of use.

Sometimes the mapping data can take a while to update when a speed limit has changed, but it is still helping me out the vast majority of the time. But, as we move towards a more digitised road system, this will improve. However, this is less a technology problem, and more of a policy issue. Government and vehicle original equipment manufacturers (OEMs) have a way to go to ensure that digital traffic orders will automatically and cooperatively update in-car systems when speed limits change. However, the inclusion of plans to digitise traffic regulation orders in the Automated Vehicles (AV) Bill, recently announced in the 2023 King’s Speech, may mean that such improvements in ISA mapping data are nearer than we think [4]. There is a general vision for a future vehicle parc that is supported by high-quality digital twins of the road network: then ISA will work perfectly.

That’s all in the future, however. For now, ISA needs cameras to read the road and see actual speed repeater signs. I believe that ISA would be more popular if it could be helped along a bit. Local authorities could cut hedges and make sure speed signs are clearly visible, or by having variable message signs (VMS) broadcast simple alerts to oncoming vehicles of a temporary speed restriction. These things cost money, but all cost-benefit calculations come out in favour of the investment.

You can tell I’m a big fan of ISA. It’s a liberating technology; it provides genuine freedom for everyone to travel safely – by car, by bike, or on foot. But like any new technology there is a hype cycle and adoption curve. The greatest benefits will be achieved with the greatest number of users, in the same way that mandatory seatbelts and a prohibition on drunk driving delivered significant reductions in casualties once everyone got behind them.

Europe has been enjoying the increasing benefits of ISA since 2022. Here in the UK, we are still waiting for a decision from Government on adopting the full set of measures within the General Safety Regulations. It’s complex, requiring new Type Approval Regulations and a new legal framework. On the bright side, whilst OEMs are not obliged to sell cars with ISA in Great Britain, it is in their commercial interests to do so. They get a higher score in Euro NCAP ratings, which boosts sales. So, we are seeing increasing choice of new vehicles with ISA included. Fleet managers, always at the cutting edge when it comes to introducing new things to make life better for drivers, are doing a great job of prioritising the purchase of vehicles with ISA and helping to educate drivers on its effective use.

There are motorists who want driving to be an “experience”. They are opposed to ISA systems, fearing a curtailment of “fun”. I ask them: why are you driving in the first place? Having my ISA always on, for me, means a helping hand for me, so I arrive fresher, I don’t have to worry about getting a speeding ticket, and I know my fuel consumption will be better, which saves me money every journey. But above all, it doesn’t fundamentally change the way I drive; I accelerate, and I brake when I want to. With ISA I’m still in complete control.

Turn your ISA on and try it – you might enjoy it as much as I do.

Dr David Hynd, chief scientist at TRL, wrote this blog for Road Safety Week 2023. Sign up now to join the national conversation about speed.

References Down arrow icon to open accordion
  1. The General Safety Regulation (GSR - Regulation (EC) No 661/2009) and the Pedestrian Safety Regulation (PSR - Regulation (EC) No 78/2009). The GSR specifies the type-approval requirements for the general safety of motor vehicles, their trailers, and systems, components and separate technical units; the PSR sets out the type-approval requirements for motor vehicles with regard to the protection of pedestrians and other vulnerable road users. All vehicles sold in the European Union must comply with the regulations.
  2. GSR consultation report – recognising that the majority of respondents agree that maximum benefit can only be achieved if GSR adopted in full Future of transport regulatory review: modernising vehicle standards - GOV.UK (
  3. Carsten O, Lai F, Chorlton K, Goodman P, Carslaw D and Hess S (2008). Speed limit adherence and its effect on road safety and climate change: Final report. University of Leeds. isa-report.pdf (
  4. Automated Vehicles (AV) Draft Bill, Pat 6, Clause 93 “Provision of information about traffic regulation measures” will require local authorities to send the legal traffic regulation orders they make (e.g., to set speed limits, close roads and designate parking bays) to a central digital publication platform.

Dr David Hynd, Chief scientist, TRL

David has more than 20 years of experience working in vehicle safety and is Chief Scientist for Safety and Investigations. He originally specialised in biomechanics and injury prevention, injury risk, and the development of test procedures for secondary safety performance. More recently, David’s work has focused on the safety of automated vehicles and other new modes of transport, working with TRL’s Smart Mobility Living Laboratory in London.

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