Gravel driveway - transverse ridge / hump

[CraigT]

Hi. I've got a badly broken up driveway consisting of tarmac & concrete sections. The tarmac on my drive continues down a shared drive to the road.
I intend to remove the old coverings & replace by gravel following the guide on this site (ie 180mm compacted to 150mm Type1 as sub-base & approx 35mm of gravel - depending on the gravel size that I get).
The only real issue that I have is that the drive is on a bit of a slope (away from the house & meeting with the continuing tarmac). The edges will all be bordered by upstands, but I need to try to prevent as much gravel as possible 'running away' down the drive & onto the tarmac.
It looks like the Transverse Ridge (or hump) will be my best option & I like the look of the stone sett example shown in the guide.

What is the best way of constructing the stone set hump? The width of my drive at the transition is about 3.5m. I'm hoping to get a 'clean' transition cut onto the tarmac using a grinder to cut the existing tarmac. I see from the guide that a width of 10 sett stones is used. Is the hump formed with a based material or concrete first & then the setts cemented on top? Is it an idea to run the level of the hump on the gravel side to a lower height in order to give as much of a 'wall' as possible?

Any advice would be much appreciated!

[DNgroundworks]

Ive done quite a few stone "sett humps" on gravel driveways in the past.

I made a template out of 3/4 inch ply to the shape of the "hump" as in the shape of an orange segment. I then placed these either side, trapped them in with 3/4 steel pins, ran a string over the top of the ply and across to the other side and laid my setts and dipped the MOT to the string.

Just make sure you have 100 - 150mm of concrete underneath, i also leanmix the joints to approx 40mm below finish pointing height and compact the leanmix with the blunt end of my cold chisel. Makes it easier to point and its really strong.

Yes id have the gravel finish height 40mm lower (ish) than your setts, so you bump over the setts rather than having the gravel flush and dragging it over the setts....the gravel makes a mess of the pointing.

I dont know if that how cookie would do it lol but it worked ok for me.

[CraigT]

Ive done quite a few stone "sett humps" on gravel driveways in the past.

I made a template out of 3/4 inch ply to the shape of the "hump" as in the shape of an orange segment. I then placed these either side, trapped them in with 3/4 steel pins, ran a string over the top of the ply and across to the other side and laid my setts and dipped the MOT to the string.

Just make sure you have 100 - 150mm of concrete underneath, i also leanmix the joints to approx 40mm below finish pointing height and compact the leanmix with the blunt end of my cold chisel. Makes it easier to point and its really strong.

Yes id have the gravel finish height 40mm lower (ish) than your setts, so you bump over the setts rather than having the gravel flush and dragging it over the setts....the gravel makes a mess of the pointing.

I dont know if that how cookie would do it lol but it worked ok for me.

Hi, thanks for the advice & sorry for the delay in replying... I had a mini-digger hired yesterday to breakup & clear the old conrete & tarmac. It's the first time I've had a go with one & what fun!!!
It was only a 1 1/2 tonne digger, so I had a hammer attachment as well & it made pretty short work of the whole thing (I'm sure it would have been quicker still in the hands of a profesional!).

Anyway, your explanation of how to make the hump makes sense. Can I just confirm what you mean with regards the preparation under the setts. Do I grade the subbase into a hump & then place the concrete following the hump profile over this. If that's correct I guess that the concrete can't be too wet or it will just flow down the hump before it cures?

[DNgroundworks]

Yea you can grade the hardcore to your strings and pull the profiles out afterwards, tbh it wouldnt make much difference if you had say 150mm of concrete in the middle and 100mm of concrete at the edges of your hump, either or really.

Semi dry mix for your concrete, just put enough concrete down to lay one row of setts at a time.

[CraigT]

Yea you can grade the hardcore to your strings and pull the profiles out afterwards, tbh it wouldnt make much difference if you had say 150mm of concrete in the middle and 100mm of concrete at the edges of your hump, either or really.

Semi dry mix for your concrete, just put enough concrete down to lay one row of setts at a time.

Brilliant - thanks for the advice. There's lots of preparation to do first, but hopefully I'll be up to getting this done over the next few weeks.