6-minute read

Rally co-driver app: what a co-driver does, and how Turini does it

In a rally, the co-driver reads the road to the driver before it comes into view. Here is how crews write those notes, how they call them on a stage, and how Turini does the same job from map data on any road.

What does a rally co-driver do?

The co-driver sits in the passenger seat and reads the stage to the driver, corner by corner, over the intercom. The driver can only see as far as the next crest or the next line of trees. The notes describe what comes after that: which way the next corner goes, how sharp it is, whether it tightens, and what is waiting over the rise.

Between stages the co-driver also runs the clock: time cards, the schedule and getting to each control on time. But on the stage the job is the notes, and nothing else.

How are pace notes made?

Crews write their own notes on the recce, in the days before the rally. They drive each stage in a road car at a limited speed, usually twice.

On the first pass the driver describes each corner as they see it, direction and a number for how sharp it is, plus anything that matters: a crest, a corner that tightens, a rock on the inside. The co-driver writes it down in shorthand and adds the distance to the next corner from the trip meter.

On the second pass the co-driver reads the notes back and the driver corrects them. A corner that felt like a 4 the first time becomes a 3 tightens. Crews also add warnings such as “caution” or “don’t cut” where a mistake would be costly.

The notes belong to the driver. They describe how that driver sees the road, so two crews rarely have the same notes for the same stage. Some drivers even run the scale the other way round, with 6 as the tightest.

How does a co-driver call the notes on a stage?

On the stage the co-driver reads from the book while keeping track of where the car is: by the trip meter, by landmarks they noted on the recce, and by feel. Lose your place and the notes become dangerous, so good co-drivers check constantly.

Each call has to come early enough for the driver to act on it, but not so early that it gets mixed up with the corner before. Corners close together are linked with “into”, so the driver hears them as one piece. The voice stays steady. The driver should hear the road in it, not the co-driver’s nerves.

Why timing matters more than the words

A perfect note at the wrong moment is no use. Too early and the driver is still busy with the last corner. Too late and there is no room to brake.

That is why a co-driver times calls to the car’s speed, not to a distance. At 50 km/h, 100 metres takes about seven seconds. At 120 km/h it takes three. A sat nav’s “in 200 metres” works for turns at a junction, but for corners the gap that matters is seconds.

Can an app be your rally co-driver?

Turini does the co-driver’s job without a recce. Where a crew drives the road to learn it, Turini reads it from OpenStreetMap and elevation data:

• The shape of the road gives each corner its direction and a grade from 1 to 6. Hairpins and square corners get their own names.
• Comparing the start and the end of a corner tells it whether the corner tightens or opens, and whether it is long.
• Elevation data shows crests and dips.
• Map tags add bridges, tunnels, narrows, gravel, cobbles, roundabouts, level crossings, and speed cameras in countries where that is legal.

On the drive, Turini calls each note about 4.5 seconds before you reach it, worked out from your speed and how you take the corners, and earlier for hairpins and hard braking. You can move the calls earlier or later. The notes are saved on the phone before you set off, so it keeps calling with no signal and the screen off. With no route at all, Free Roam follows the road you are on.

It speaks the same language a crew uses, or simply Easy, Medium and Hard if you prefer. If the words are new to you, start with how to read pace notes.

What an app co-driver can’t know

Turini reads the map, not the road. It can’t see wet leaves, ice, gravel washed onto a bend, a tractor round the corner or a closed lane. It doesn’t know how much grip your tyres have today.

The map can also be out of date. A road rebuilt last year may still have its old shape in OpenStreetMap, elevation data can miss a small crest, and surface changes are only called where the map has them. A crew that drove the recce knows things no map does. Turini gives you a description of the road ahead, not a guarantee.

Always drive within the law, the conditions and what you can see. Turini tells you what the map says; the road is what counts.

Rally co-driver app: common questions

Read next: pace notes on Android Auto and how to find twisty roads near you.