Britain's Highway Code says a car at 30 mph stops in 23 metres: 9 metres while the driver reacts and 14 while the brakes work. It does not say what kind of driver that is, but the arithmetic does. 30 mph is 13.4 metres a second, so 9 metres of thinking distance means 0.67 seconds, and every row of the UK table from 20 to 70 mph works out to the same 0.67 seconds and to braking of about 6.5 metres per second per second. That is our back-calculation; the table itself gives no basis. Its 0.67 seconds is a shade quicker than a review of reaction-time studies found even for alert drivers, who take about 0.70 to 0.75 seconds to get a foot onto the pedal when they know a brake signal is coming (Green, 2000, which we read in abstract).
That is why stopping distance charts disagree at the same speed. Each one assumes a different driver and different brakes, and the assumptions can be read off its own numbers. Singapore's current Basic Theory of Driving handbook, last updated on 2 January 2026, prints a chart whose rows imply a reaction of about one second and gentler braking than Britain's. The friction figures are not in either document, and nothing here is advice on how to drive.
School-zone speeds
Singapore's school zones have a 40 km/h limit from 1 January 2026. At that speed the handbook's chart (para 138) gives 20 metres, 10 of reacting and 10 of braking, and above it braking is the larger share in every row. In Britain's table the two are level at 20 mph, about 32 km/h, and braking is already the larger share at 30 mph.
Our stopping distance calculator gives a different answer at the same speed, because its default reaction is 1.5 seconds, the figure Green gives for a surprise such as an object moving suddenly into the road. At 40 km/h on a dry road it gives 25 metres, 17 of them thinking and 8 braking, and thinking stays the larger share until about 79 km/h. The common line that at town speeds most of the stop is reaction time is true only if the driver is slow to react. With the reaction times the Singapore and UK charts assume, braking has caught up by 40 km/h.
Town speeds
Singapore's default speed limit is 50 km/h, and at 50 km/h there are two versions of the chart a learner in the region might meet. Singapore's current handbook gives 15 + 20 = 35 metres. An earlier Singapore edition, the Traffic Police's 2024 riding booklet for motorcyclists, and Malaysia's driver curriculum manual (the KPP, third edition, August 2021) all give 14 + 18 = 32 metres. The two versions differ by up to three metres in any row.
The Malaysian copy we read, hosted by a driving institute because the manual on JPJ's own site loads as a flipbook we could not extract, has a misprint in that row: braking is printed as 28 metres while the total is still 32 and the bar is drawn to about 32. 28 would also be more than the 27 metres printed for 60 km/h.
The riding booklet has a second inconsistency. Its text says "the average rider takes 3/4 of a second to react", but its own table's 28 metres of reaction at 100 km/h works out to about one second. At three-quarters of a second the figure would be 21 metres.
Expressway speeds
At 90 km/h, Malaysia's national speed limit, the spread is widest:
- Britain's table: 73 metres at 60 mph, which is 96.6 km/h, so a slightly higher speed.
- Our calculator at its 1.5-second default, dry road: 80 metres.
- The table Malaysia shares with the older Singapore editions: 93 metres.
- Singapore's current chart: 25 + 70 = 95 metres.
- US road-design values: 154 metres.
Worked backwards from its rows at 70 km/h and above, Singapore's chart assumes braking of about 4.5 to 4.7 metres per second per second, roughly 70% of the rate in Britain's table, on top of the slower reaction. The US figure is a different kind of number. It is not a table drivers learn but the value engineers use to lay out sight lines on roads, and the US Federal Highway Administration describes its 2.5-second reaction as meant "to exceed the 90th percentile of reaction time for all drivers". Its braking rate of 11.2 feet per second per second, 3.41 in metric, is one that about 90% of drivers exceed, by the same account. The 154 metres is our arithmetic from those two values.
Following-distance rules are a separate question, because the car in front is braking too. Singapore's handbook now teaches a "three-second" rule, "previously two-second rule", for all vehicles at any speed (para 136); at 90 km/h three seconds is 75 metres. Britain's Highway Code asks for at least two seconds on high-speed roads, and Malaysia's KPP two seconds, with four suggested in bad weather or on slippery or sandy roads. China's traffic regulations (Art. 80) set a distance instead: at least 100 metres above 100 km/h and never less than 50 metres below it. Singapore's statutory Highway Code, a different document from the UK one, still asks for at least one car length for every 16 km/h, which with a 4-metre car is about 0.9 seconds of travel.
Wet-road speeds
Singapore gets rain on an average of 171 days a year, according to its Meteorological Service. The handbook says a wet road makes the stopping distance "about twice the distance of that on a dry road" (para 184), and Britain's Highway Code says wet stopping distances "will be at least double".
Our calculator gives a smaller ratio. It uses round friction figures of 0.75 for dry asphalt and 0.50 for wet, which we could not trace to a published engineering table, and with those the braking part grows by half while the reaction part does not change at all. The whole stop grows by 14% at 30 km/h and 27% at 90 km/h: 101 metres wet against 80 dry. To double Britain's 70 mph figure with the table's own 0.67 seconds, wet braking would have to fall to about 2.9 metres per second per second, below the calculator's figure for gravel. The handbooks' "double" reads best as a rule meant to be remembered and kept to, and our ratio as what one set of friction figures produces. Neither is a measurement of any particular car on any particular road.
Every speed
Whatever chart you start from, every extra second of reaction adds the speed in km/h divided by 3.6, in metres: 14 metres at 50 km/h, 25 at 90, 31 at 110. On Singapore's 90 km/h row that turns 95 metres into 120.
Green's review puts a rough size on that second. Expectation alone roughly doubles reaction time: about 0.7 seconds for a driver waiting for a signal, about 1.25 for a lead car's brake lights, about 1.5 for a sudden surprise. Singapore's handbook adds tiredness and alcohol to the things that lengthen it (para 139). A driver who is expecting the stop covers the thinking part of it in roughly half the distance of one who is not, and no table can tell which of those drivers will be at the wheel.
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