E-scooter speed muddle

From 4 July, the use of electric scooters will become legal in Great Britain, albeit on a limited trial basis. The use of privately owned e-scooters will remain illegal, and e-scooters will not be permitted on pavements. E-scooter design speeds will be limited to 15.5 miles per hour.

The rather odd maximum design speed of 15.5 mph is presumably an attempt to accommodate the use of e-scooters already in use in other countries, many of which have a maximum design speed of 25 km/h (15.53 mph). Unfortunately, when converting the km/h value to mph for the relevant legislation, the value was rounded down to the nearest 0.1 mph instead of it being rounded up. The legislation therefore seems to prohibit the use of the very e-scooters that it was probably intended to permit.

The maximum speed was decided after consultation, where respondents were asked to reason whether 12.5 mph or 15.5 mph should be the maximum design speed allowed. Again, these seemingly odd values are approximations of 20 km/h and 25 km/h. Wouldn’t it have been more sensible just to use metric values throughout?


12 thoughts on “E-scooter speed muddle”

  1. I’m sure the manufacturers are not going to redesign the scooters for a English version of 24.9 km/h. The legislation may state 15.5 but it will be treated like the pub pint, where the legislation claims a pint is 568 point blah blah millilitres, but turns a blind eye when beer and ale is poured into a 570 mL glass.


  2. As well as proposing speed limits of 20 km/h or 25 km/h, the regulations specify a “mass not exceeding 35 kilograms” and a “maximum motor power of 350 Watts”.

    Shame about the upper-case W, but at least they do not refer to horsepower!


  3. @Daniel Jackson
    Operating an electric scooter that has a maximum design speed that exceeds the regulations by 0.1 km/h might sound trivial, but if I was running a company with a fleet of e-scooters for hire, I would be very worried if there was any doubt about whether my vehicles complied with regulations or not. At the very least, failure to comply with regulations can void insurance policies.


  4. m,

    Fortunately, when it comes to speeding, there is an allowed tolerance for over-speeding. No one is pulled over or gets cited for going 0.1 km/h over the limit. If the limit is 70 km/h, then going over 75 km/h will attract attention. Going over 80 km/h, depending on the jurisdiction may get you a visit to a court.

    The reason 15.5 miles was chosen is it is a somewhat comfortable number to imperial users. 15.53 or 15.6 would bring about complaints from imperial lovers who would know the spirit of the law was catering to the metric system and not imperial. 15.5 may be close enough to 25 km/h to be seen as the same, but to an imperial lover it is hoped that no one will catch on that 15.5 is a dumbing down from 25 km/h but was intended to be an imperial based speed. The “true” speed to them being 15, and the extra 0.5 a buffer.


  5. Ramsden,

    The watt being the SI unit of power has been a part of non-SI unit collections for electrical applications only for some time, the horsepower for mechanical applications. Unlike SI, Imperial and EEU (Evil Empire Units) seem to create multiple units for different flavours of a physical attribute whereas SI has only one unit for each attribute. Thus, whereas the watt is suitable for all uses of power in SI, in imperial and EEU, electrical is watts, mechanical is horsepower, thermal is BTU/h, etc.

    However, in this case where you would expect the mechanical power of the motor to be in horsepower, England, being a part of the EU for some time has seen its engineering industry drop the horsepower for electrical motors and use the watt rating throughout. IEC motors, which I’m sure are used in England and will continue to do so in the future measure their input and output solely in watts. Thus the scooter mechanical output power being stated in watts.

    If the motor was run by a source other than electricity, such as petroleum based fuels, you might not have been so lucky.


  6. @Daniel Jackson
    I think you have misread the article. It is about the legal definition of an electric scooter in relation to various newly amended legislation. Speeding is not the issue.

    The statutory instrument includes the following:

    “electric scooter” means a vehicle which—

    (a) is fitted with an electric motor with a maximum continuous power rating not exceeding 500 watts;
    (b) is not fitted with pedals that are capable of propelling the vehicle;
    (c) has two wheels, one front and one rear, aligned along the direction of travel;
    (d) is designed to carry no more than one person;
    (e) has a maximum weight, excluding the driver, not exceeding 55 kgs;
    (f) has a maximum design speed not exceeding 15.5 miles per hour;
    (g) has a means of directional control through the use of handlebars which are mechanically linked to the steered wheel;
    (h) has a means of controlling the speed through hand controls; and
    (i) has a power control that defaults to the ‘off’ position;

    If any of the above requirements are not met, then, for the purposes of the affected legislation, the vehicle is not an electric scooter. It would be an unregulated vehicle.

    An e-scooter with a maximum design speed of 25 km/h (15.53 mph) fails the requirement in paragraph (f), in the same way as a vehicle with a weight of 55.1 kg would fail the requirement in paragraph (e).


  7. Well m, that presents a problem for England. Technically, then every scooter will just have to be out of compliance with the law. Of course it would be simple to fix the problem and that is to amend part f to read as 25 km/h (~15.5 mi/h). I’m sure the difference between 24.9 and 25 km/h will just have to be ignored.

    How, would you as a designer redesign the scooter to have a maximum speed of 24.9 km/h? How much extra would you charge extra for a scooter that is technically different from the rest of the world?

    Something tells me though that the difference between 24.9 and 25 km/h speed will not be challenged and the same scooter as sold world-wide will be the same scooter sold in England. No one is going to be that pedantic and just accept that 15.5 is the same as 25 km/h and move on.


  8. In addition to the errors already noted, the phrase “has a maximum weight, excluding the driver, not exceeding 55 kgs;” [Section 2(3)(b)(e)] has two errors – the word “weight” should read “mass” and “kgs” should read “kg”.

    As regards the maximum design speed being 15.5 mph rather than 15.54 mph, the ultimate test is whether or not the courts will uphold such a complaint. The question is who would ultimately ask the courts to rule on this particular point? The only scenario that I can see is one in which a motorist badly injures a scooter-rider and in order to reduce his damages [through his insurance company] argues that the rider was on an illegal machine and as such is only entitled to minimal damages.


  9. This odd situation is a consequence of the decision taken in 1970 by the UK Department of Transport (now the DfT) not to join the rest of the UK economy in adopting metric measures but to continue using the mile, yard, foot and inch for road traffic signs. Today, this set of four units is found on the roads of no other country in the world – even the USA does not use yards on its highway signs.
    Let’s hope we don’t have to wait another 50 years until the DfT acknowledges its mistake and puts it right.


  10. As time moves on from E-scooters to self drive E-cars!
    I have noticed that in various clips of self drive cars, they are generally from USA or Germany.
    I can see an almighty collision course coming here on this one also. Not only will “we” have to specially modify them to learn to drive on the left (a number of other countries do, Japan for one),”we” also have to teach them to read (presumably) road signs in both Imperial and metric, and convert speeds between the two.
    This is unless they have a system totally independent from any current human interfaces, and still they will need to know the laws in whatever units they are calibrated in, likely mph if USA, or more common and likely km/h.
    For sure they will be as complicated as trying to get our trains to use one …two … three systems as on cross-rail!


  11. Brian,

    Driver-less cars don’t read road signs. They have a GPS system that gives them their position and they use the GPS system to navigate to their desired location. The GPS is metric. The speed limits are sent to the car as part of the GPS system. They would also be in metric. Unlike humans, cars aren’t limited to whole numbers.

    A driver-less car won’t have a steering wheel and can be signaled via the GPS as to what side of the road to drive on. There won’t be a need for any modifications to the vehicle. It will be universal.


  12. @Brian, Daniel

    I am not totally convinced that driverless cars would work entirely off their GPS systems. GPS is a one-way system – the car reading the satellite signals signals to see where it is in terms of lat/long coordinates and then accessing its own database to see what is at that lat/long position. There is of course no problem in designing the database such that when it is read, the vehicle “knows” what type of road it is on – left/right, dual/single etc. What is a problem is knowing the speed limit on smart [sic] motorways where speed limits can change at a moments notice while it might take a number of years for the cars database to be updated. Combining these two we have problems on the UK/Ireland border and also on the US/Canadian border where speed limits change from mph to km/h


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