Driving the Eryri mountain passes: what to check first
Llanberis Pass, Pen-y-Pass, the Ogwen valley and the Horseshoe Pass are some of the finest driving roads in Britain. They are also the places where a marginal battery or a worn tyre stops being an inconvenience and becomes a problem.
A breakdown up here is not like a breakdown in town
On the A55 you are minutes from a junction. On the passes, several things stack against you at once.
- There is often nowhere to pull off. Long sections are single carriageway with a stone wall on one side and a drop on the other. Stopping frequently means blocking the road.
- Recovery takes longer. A recovery vehicle has the same narrow, steep, twisting road to climb that you did, and it may have to reverse a long way to turn.
- Mobile signal is unreliable in the valleys. Steep sides block it. You may need to walk to get a bar, which is not something to discover after dark.
- The weather changes fast and is colder up top. Conditions at the summit can be nothing like the conditions at the bottom of the hill.
- It gets busy. On a fine weekend the car parks at Pen-y-Pass fill early and the passes carry a lot of traffic, much of it unfamiliar with the roads.
The five-minute check that matters most
- Tyres. Steep descents and tight bends put far more into a tyre than flat road does, and it is usually wet. Tread is your only contact with the road — see tread depth and the law. Check pressures cold.
- Battery. Cold reduces what a battery can deliver, and a marginal one that starts fine in Bangor may not restart in a car park at altitude on a damp afternoon. Try the battery health check.
- Brakes. You will use them hard on the way down. Any softness, grinding or pulling is a reason to postpone.
- Coolant and oil. A long climb in low gear is the hardest work an engine does all year.
- Fuel. Filling stations are sparse once you leave the coast, and a queue on a single-track road burns more than you expect.
Going down is harder than going up
Most trouble on these roads happens on the descent, and almost all of it comes from riding the brakes.
- Use a low gear going down and let the engine hold the car back. In an automatic, use the manual or low setting rather than leaving it to work it out.
- Brake firmly and briefly, then release, rather than resting on the pedal. Continuous braking overheats brakes and the pedal goes long just when you need it.
- Give way early on single-track sections. Passing places are for passing, not parking, and reversing uphill on a wet gradient is unpleasant.
- Expect walkers, cyclists and sheep around blind bends, particularly near the popular car parks.
- In an electric car, use regenerative braking on the descent. It saves the friction brakes and puts charge back in.
Breaking down on a mountain road
- Get the car as far off the road as the geography allows, and use a pull-in or passing place if one is close.
- Hazard lights on straight away. Sight lines are short and drivers arrive at bends with little warning.
- Think about which side you get out on. On a narrow road with a wall, the safe side may not be the usual one.
- Put a coat on before you need it. It is colder and windier than it looks, and you may be waiting a while.
- If you have no signal, note exactly where you are — the last village, junction or car park you passed — before walking to find a bar. A mapping app will usually give you a grid reference even without a data connection.
- On a blind bend, a warning triangle placed well back is more use here than on a dual carriageway, provided you can put it out safely on a low-speed road.
Tell someone your route before you set off if you are going out of season or late in the day. It costs nothing and it changes how quickly anyone starts looking.
Snow, ice and closures
The high passes can hold snow and ice when the coast is merely wet. Ice forms first in the shaded sections and on the bridges, and those are frequently the bends as well.
Gritting priorities go to the main trunk roads first, so a mountain road may not have been treated when the A55 has. If conditions are poor, the sensible route is often the long way round on the main road rather than the direct one over the top.
Check Traffic Wales before setting off in bad weather, and see our guide to winter driving in North Wales.
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Questions, answered
What should I check before driving the Eryri mountain passes?
Tyres first, because steep wet bends demand far more grip than flat roads. Then the battery, since cold reduces what it can deliver and these roads are colder and higher than the coast. Also check brakes, coolant, oil and fuel, as filling stations are sparse away from the main roads.
How do I drive down a steep mountain pass safely?
Select a low gear and let the engine hold the car back rather than riding the brakes. Brake firmly and briefly, then release, so the brakes can cool. Continuous braking overheats them and the pedal goes long exactly when you need it most. In an automatic, use the manual or low setting.
Is there mobile signal on the mountain passes in Eryri?
It is unreliable. Steep valley sides block signal in many places, so you may have to walk to get a bar. Note exactly where you are before you move, and tell someone your route before setting off, particularly out of season or late in the day.
Where can I stop if I break down on a single-track mountain road?
Use a pull-in or passing place if one is nearby, and otherwise get as far off the road as the geography allows. Put your hazard lights on immediately, because sight lines are short and drivers come round bends with little warning. Consider which side is safest to get out on.
Are the mountain passes gritted in winter?
Gritting priorities go to the main trunk roads first, so a mountain road may not have been treated when the A55 has. Ice forms first in shaded sections and on bridges, which are often the bends too. In poor conditions the longer route on the main road is usually the better choice.
Can a recovery vehicle reach me on a mountain pass?
Yes, but it takes longer. A recovery vehicle faces the same narrow, steep and twisting road you did, and may have to reverse some distance to turn. Giving an accurate location, including the direction you were travelling and the last place you recognised, makes a real difference.