Sand and Gravel on Thailand's Coastal Roads

The commonest way a visitor comes off a scooter in Thailand is not a collision. It is a patch of sand on a bend, on a dry sunny day, at a modest speed, five minutes from the beach. The front wheel goes, the bike is down before the rider has understood what happened, and the holiday continues with a dressing on one arm and a leg and an argument with a rental shop.

It is also almost entirely avoidable, because sand collects in predictable places and behaves in a predictable way.

• Where it collectsThe outside of bends, junction exits, beach accesses
• Worst combinationSand plus lean angle plus front brake
• The techniqueUpright, straight, no inputs, ride through

Why the sand is there

Beach traffic. Every vehicle that leaves a beach car park carries sand out on its tyres and drops it on the road. The heaviest deposits are at the exits of beach accesses and at the junction where the beach road meets a main road — because that is where vehicles slow, turn and shed. It accumulates into a visible drift at the edge and a thinner, much less visible film across the turning line.

Wind. On roads running behind a beach, wind blows dry sand onto the carriageway continuously, building along the windward edge and drifting across in ripples. This is why a road can be clean in the morning and have a sand patch across it by mid-afternoon, and why the same corner can be fine one day and treacherous the next.

Runoff. Rain washes sand, grit and soil off unsurfaced verges, building sites and cut slopes, and deposits it in a fan wherever the water slows down: the low point of a dip, the inside of a bend where the camber sheds water, and anywhere a side track meets the road — the same mechanism described in riding a motorbike in tropical rain. And trucks carrying sand, gravel and soil shed it continuously, particularly when they turn, so a building site on a coastal road produces a permanent hazard for as long as the build lasts.

Where to expect it, precisely

Seeing it

Sand on tarmac is a colour change and a texture change, and both are easy to miss because you are looking at the traffic rather than the road. Train yourself to look at the surface through the bend before you commit to the bend.

• A lighter patch on dark asphalt. Obvious in flat light, much harder to see in bright midday sun or through a scratched visor.
• A matt area where the rest of the road has a slight shine. Sand kills the reflection.
• Ripples or a fan shape. Wind-blown sand ripples; water-borne grit fans from a point.
• A clean line where traffic runs. Two swept wheel tracks through a sandy area is where the grip is. Ride the clean line.
• Dust hanging in the air behind a vehicle that has just gone through.

Why it puts you down

A layer of sand or loose grit behaves like ball bearings between the tyre and the road, and available grip drops enormously. That matters only if you are asking the tyre for grip at the time — and there are exactly two ways you do that: leaning, and braking.

Leaning is the killer. A tyre at a lean angle relies entirely on side grip; take that away for a fraction of a second and the front wheel slides out from under you with no warning and no time to correct. Braking on sand is more forgiving — the wheel locks, you feel it, and you can release — but braking while leaning combines both and is the worst thing you can do.

The technique

If you can go round it, check what is behind and beside you first, then take a line that keeps you on clean tarmac — often the wheel track other traffic has swept, which may not be where you would normally ride. Adjust early and smoothly, while the bike is still upright and travelling straight.

If you cannot, three rules in this order:

1. Get the bike upright. Do your straightening before you reach the sand. A vertical bike on sand is stable; a leaning one is not.
2. Off the brakes, off the throttle. Neutral. Let the bike coast across at whatever speed it is doing.
3. Relax your arms and let the bars move. The front wheel will wander and the bike will feel vague. That is normal. Fighting it with stiff arms converts a wobble into a steering input, and a steering input on sand is a crash. Grip the bike with your knees, loosen your hands, look at the clean road beyond the patch and ride to it.

If the front does go, there is very little to be done in the moment — a front-end slide on sand is over faster than a reaction. What you can control is what you were wearing. A low-speed slide produces exactly the injuries described in road rash and exhaust burns: abrasion to hands, forearms, hips, knees and feet, plus a burn where a bare calf meets a hot exhaust. Gloves and shoes turn most of that into nothing, and riding a scooter in flip-flops explains why the footwear question is not trivial.

Where this bites hardest

Islands and beach roads, unsurprisingly. Phuket combines beach accesses with steep hills and heavy traffic. Koh Phangan has a well-earned reputation for scooter injuries, and the combination of sand, gradient and riders who have been drinking is why. Koh Samui's ring road, Koh Tao's steep concrete tracks, Krabi and Ao Nang, the Khao Lak coast road and the eastern seaboard around Rayong all present the same pattern. Riding onto the sand itself, incidentally, almost always ends with the bike on its side: a rental scooter has narrow road tyres and will dig in, so walk it if you must get it onto soft ground — and expect the shop to look closely for salt corrosion afterwards, a point covered in what happens if you drop a rented scooter.

It is not exclusively coastal. Every point here applies to grit washed onto a mountain bend, which is why mountain roads and hairpin bends covers the same technique from the other direction, and to the loose chippings left behind by surface dressing anywhere in the country.

Frequently asked questions