We’re all familiar with maximum speed limits, but how about a minimum? Starting today, August 1, the Malaysian Institute of Road Safety Research (MIROS) – together with the Malaysian Highway Authority (LLM), PLUS and SKVE – is running a proof-of-concept (POC) trial for minimum advisory speed limits on selected highway stretches, under the banner Had Laju Nasihat Minimum.
The idea is simple: each lane gets a recommended minimum speed, displayed on signboards, and drivers are encouraged to travel at least at that pace for the lane they’re in – unless conditions don’t allow it, such as in heavy rain or congested traffic. In other words, if you want to cruise slowly, keep left; the further right you go, the faster you’re expected to flow.
Note the word “advisory” – this is a trial of guidance signage, not a new enforceable speed floor. MIROS lists five objectives for the exercise:
- Preventing lane monopolising (lane hogging)
- Reducing the speed difference between vehicles
- Increasing traffic capacity and flow
- Reducing the risk of dangerous lane changes
- Improving overall road safety
The POC runs at three pilot locations:
- PLUS E1 (northbound): Tanjung Malim-Behrang
- SKVE E26: Ayer Hitam toll plaza-Bandar Saujana Putra
- PLUS E2 (northbound): Bandar Ainsdale-Nilai
Through the trial, drivers on these stretches are encouraged to:
- Use the lane that matches the advisory minimum speed shown on the signboards
- Avoid overtaking from the left
- Give way to vehicles that wish to overtake
- Maintain a safe following distance
“Jangan jadi punca trafik terganggu” – don’t be the cause of disrupted traffic – is how MIROS put it in its announcement, and that framing is the whole point of this exercise.
Why slow driving in the wrong lane is dangerous
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It sounds counter-intuitive, but driving slowly on a highway – in the wrong lane – doesn’t make anyone safer. Road safety research has long shown that the danger on highways isn’t absolute speed alone, but speed variance: the bigger the difference between the fastest and slowest vehicles sharing the same stretch, the higher the crash risk. A car doing 70 km/h in the right lane of a 110 km/h highway is a moving obstacle that every single vehicle behind it must react to.
The research on this goes back decades. The classic reference is the “Solomon curve” – US researcher David Solomon’s 1964 study of around 10,000 crash-involved drivers, which plotted crash involvement against deviation from the average traffic speed and found a U-shape: drivers travelling near the mean speed had the lowest crash rates, with risk rising for those going faster and, in his data, rising even more steeply for those going slower. Later work tempered the slow side of that curve – a 1970s reanalysis showed many of Solomon’s “slow” crashes involved vehicles slowing to turn rather than cruising slowly – but a 1968 follow-up by Julie Cirillo found the same U-shaped pattern on American Interstate highways, where turning traffic isn’t a factor. Economist Charles Lave’s oft-quoted 1985 finding distilled it further: fatality rates tracked speed variance, not average speed. Modern reviews land on a balanced position – higher absolute speeds raise crash risk, and so do large speed differences between vehicles on the same carriageway, because differentials force the braking, lane-changing and undertaking manoeuvres where crashes happen.
And how do they react? Each following driver has to brake, then change lanes – often to the left, into the blind spot-riddled space lane hogs force them into – then accelerate past and merge back. Every one of those manoeuvres is an opportunity for a misjudgement, and the more cars that have to perform them, the more opportunities stack up. The lane hog experiences none of this drama; they simply motor on, oblivious, while generating risk for everybody else. We’ve seen where this leads – a slow car drifting into the fast lane caused a rear-end collision in one widely-shared local incident.
There’s a traffic-flow cost too. Braking waves propagate backwards through dense traffic – the “phantom jam” effect, famously demonstrated in a 2008 Japanese experiment in which drivers asked to simply maintain a constant speed around a circular track spontaneously produced stop-and-go shockwaves. One slow vehicle in the overtaking lane can likewise congest a highway for kilometres behind it. That’s why “increasing capacity and flow” sits alongside safety in MIROS’ objectives: lane discipline isn’t just about courtesy, it’s about how many vehicles a highway can safely carry.
It’s worth remembering that lane hogging is already an offence in Malaysia, carrying a fine of up to RM2,000 – the middle and right lanes are legally for overtaking, with the left lane the default cruising lane. Heavy vehicles are separately banned from the right lane on highways. What the MIROS trial adds is the other half of the equation: not just “don’t camp in the fast lane”, but “if you are in it, keep up”.
To be clear, this isn’t a licence to speed – the advisory minimums sit below the posted maximums, and the guidance explicitly excuses heavy rain and congestion. It’s about matching your speed to your lane, so that traffic sorts itself by pace: slower traffic left, faster traffic right, everyone predictable.
If the POC delivers the goods, minimum advisory speed signage could conceivably spread to more highways. In the meantime, whichever road you’re on: keep left unless overtaking, let faster traffic through, and don’t be the reason a hundred drivers behind you have to make a lane change they didn’t need to make.
What do you think of minimum speed limits on our highways – long overdue, or hard to enforce? And be honest: does your cruising lane match your cruising speed? Share your thoughts in the comments.
