That is correct - "trunk" as in body, so the main roads are trunk roads. The vans spread rock salt (which we call grit), hence called gritters! We Scots always get confused in the states when offered grits for breakfast .... Sadly it does mean you have to look after your car in winter, as that salt does wonders for chassis rust - you have to keep the car clean!

It's a salt/sand mix, since the sand (grit) provides extra grip.

If it's really cold (I assume this can happen in Scotland) it would just be grit.

(I'm not sure why "gritter" would be difficult to work out. "Grit" is a normal English word: bits of grit in the cabbage, 100 grit sandpaper.)

UK rock salt grit comes from here: https://www.saltassociation.co.uk/education/make-salt/rock-s...

The UK's biggest rock salt mine is in Winsford in Cheshire https://en.wikipedia.org/wiki/Salt_in_Cheshire https://en.wikipedia.org/wiki/Winsford#Rock_salt

Additionally part of the mine is now used as a deep secure store for files from the health service.

Mainly rock salt but doesnt work in extreme cold as the ice freezes with the rock salt in it. Ruins the vehicle chassis in the European country's which salt their roads but it keeps the Car industry going, not to mention pollutes water courses and crops.

And my favorite: in northern Scandinavia we try to be careful with salt because reindeer find it tasty...

"Main road" is actually considerably more general than trunk road in the Great Britain. The roads in GB are ordered hierarchically starting with motorways (although these have restrictions, ie. motorvehicles only), through trunk roads, primary, secondary, all the way down to byway.

It is important for navigation in GB. When you want to go somewhere you are supposed to use trunk roads to navigate to the first town/city on the trunk network beyond where you are going. The signs are coloured to indicate you are on the trunk network. Then as you approach your actual destination you will begin to see it signposted on the local non-trunk roads, at which point you leave the trunk roads.

This has been mostly forgotten in this age of GPS navigation, though, and many signs are in a poor state of repair or badly occluded by trees or shrubbery.

> you are supposed to use trunk roads to navigate to the first town/city on the trunk network beyond where you are going

Yes, this is why it is very useful to know, when navigating out of a UK town / city, the next big town / city beyond your actual destination. If you get on the correct main road, you will usually find signs to your actual destination as you get closer to it. Knowing the main road numbers (A35, etc) as opposed to their names is also really useful as is is the numbers that will be used on the signposts.

So kinda like riding a metro train, where the lines are named after the final destination.

Yes, although the London underground uses a slightly different convention. The lines have names like Northern, Central etc, and most are linear. The line level signage at a station usually directs you to an eastbound / westbound / northbound or southbound platform. The direction and destination of a specific train is indicated by the furthest stop in each direction (which can vary depending on whether the line bifurcates, or a train isn't going all the way to the end).

For example, you'd think about going westbound on the Piccadilly line if you wanted to get to Heathrow from Central London

Eastbound, no? Since Heathrow is West of the center?

Since Heathrow is to the West of the centre, you go westbound to get to it, from the centre.

Sorry, yes, I'm an idiot.

I'm from the UK and was unaware of this method (trunk road to town/city after destination).

Is there somewhere I can read about this in more detail?

Thanks!

Here is a list of primary destinations.

They are separated by region. So for example if you are in Cambridge (EAST region) you follow signs for EAST MIDLANDS. Once you are in that region, you will start seeing signs for the primary destinations in the region.

https://assets.publishing.service.gov.uk/government/uploads/...

It's really just standard manual map based navigation. A dying art these days. I haven't seen many shrubbery related problems, we still have the best signage in the world (that I've seen) and it's perfectly possible to use sign based navigation without any GPS. You however may need to ask directions for the last couple of miles in rural areas.

It used to be documented in the usage section at the beginning of road atlases.