Visibility splays

cjdew

I was wondering if anyone knew the answer to the following? I can't ask highways as they'll immediately go to a high site visit fee and i think that i know the answer.

We have been asked to provide a visibility splay map for a driveway exit from our property.

I can see that a 60mph road has approx 160metres splay requirement... But the actual road is a thin country lane which has 1 car an hour... It's length isn't even 160metres so how can I show visibility splay when the road isn't that long. 🤔

Anyone have experience in this?

Woodstok2000

Does this help:

https://assets.publishing.service.gov.uk/media/5a7e0035ed915d74e6223743/pdfmanforstreets.pdf

Can you show a map or diagram of the layout?

Section62

https://forums.moneysavingexpert.com/discussion/6672184/visibility-splays

One method is to project the kerbline of the road so it is long enough to achieve the required 'y' distance… in other words imagine the road continues in a straight line far enough to get to 'y'.

But if the road is short due to there being junctions so that traffic could never reach the speed limit then it may be acceptable to work with a lower design speed - only the highway authority can give you an answer whether this would be acceptable.

The road only having 1 car per hour isn't relevant though…. that one car could be travelling at 60mph (or more). There's an argument that speeds on lightly-trafficked roads may be higher than those which are busy.

cjdew

https://forums.moneysavingexpert.com/discussion/comment/82031966#Comment_82031966

Thank you, will have a good read of this

cjdew

The road is short as on one side it gets to around 70metres and then curves sharp round to continue.

The other way it continues for 70 metres to a junction.

The road itself is single track, 3 houses and very bendy with no straight lines. The visibility isn't there beyond metres as the road physically isn't built like that. Victorian track farm lane basically.

cjdew

https://forums.moneysavingexpert.com/discussion/comment/82031990#Comment_82031990

I tried to quote you but it didn't work, i wrote response above

IOWJJBTM2025

https://forums.moneysavingexpert.com/discussion/6672184/visibility-splays

Yes - have done this a few years ago. Get a map of your address and print it out.

Then pretend that you are on your driveway in your car and show the distance that you can actually see. In my case there was only a low wall at the side of the drive and no hedges so I could see clearly both ways.

If you have a 6ft fence and the road has large hedges then you cannot see very far and this is what the planners will be concerned about.

Simply draw on the map the lines that you can see without any obstruction.

magicmoneyportaloo

If you are trying to measure distance on a map you can right click on Google Maps, and select 'Measure distance'.

cjdew

https://forums.moneysavingexpert.com/discussion/comment/82032028#Comment_82032028

So just went as far as you could see in both directions, and ultimately if there's not enough road then there's no thing to actually "look out for" road wise.

Section62

https://forums.moneysavingexpert.com/discussion/comment/82032727#Comment_82032727

The 'y' distance is more complicated than how far the driver pulling out of the driveway can see. The distance relates to the potential speed of approaching traffic and the amount of time taken for both drivers to identify the hazard, make a decision, and (if necessary) to stop safely before a collision.

Although you can't 'see' around a corner, the fact the road exists beyond the corner means oncoming traffic can be travelling fast. The 'y' distance is also assessed using the edge of the carriageway, but allows that on a curved road the driver and parts of the oncoming vehicle will potentially be inter-visible sooner than the part of the vehicle closest to the kerb. In other words, for a driveway or junction on the inside of a bend parts of the vehicle nearest the centre of the road will be visible at a distance further away than the furthest point you can see at the edge of the carriageway.

What IOWJJBTM2025 is describing is a method of showing how far you can see. What the planners are usually interested in - on behalf of the highway authority - is whether there are any obstructions preventing the required sightline being achieved. Depending what exactly you've been asked to produce, the response you might get back is that you don't have the required sightline and the application (if you've made one) is going to be refused on those grounds. It would be worth clarifying what they want to see before submitting your plan.

cjdew

https://forums.moneysavingexpert.com/discussion/comment/82032763#Comment_82032763

I've been given this:

Visibility splays should be measured 2.4 metres back from the edge of the metalled carriageway at the

centre of the junction (X-dimension) and drawn to the nearside edge of the carriageway, in both

directions, without encroaching third-party land (Y-dimension). Nothing above the height of 0.6 metres

should be positioned within the visibility splays. The provided visibility drawing provided does not

appear to show this, although it is not entirely clear.