Road surfacing  - difficult conditions - Difficulties finding surface methods

[Farther Common]

We have a 200m stretch of ancient lane to surface. It has traditionally been covered with local flint and chalk although the subsoil is greensand and erodes easily.

The road is steep down hill and in a hollow - made by centuries of previous use. Most incomers want to slap tarmac in - low maintenance and solves run off problems - but it is in a wood with an ancient monument and we want to keep it looking a little rural...

We have been looking at the drainage first -

In heavy rain, water really moves fast down the slope and rips out anything that has been put in. Flint and chalk lasts 5 years at very best. We are thinking of increasing the crest height - but it is unclear what to use at the sides as gullies. It is difficult to take water off because the lane it is largely in a hollow.

The surface - I would like to use recycled materials and be as sympathetic to the monument, woodland and fauna as possible.

We have been considering getting the surface cut to a flat bed and putting in a crested surface of planings.

I am concerned though that this will not survive run-off and will end up in the fields at the bottom of the slope like a previous expensive gravel effort run by some newly arrived Londoners who 'knew it all' and are now running the local council! (thanks Councillor and Mrs Pattie.....and where's our cash !!!)

What are the options other than hot tarmac? Could we use some heated planings with a different top rolled in, or gravel asphalt?

Any ideas welcome...


Ian Brodrick

[84-1093879891]

As with many questions which are basically "What's the best surfacing for my job...?", I'm at a disadvantage because I can't actually see the site. However, with projects of this type, where some regard for the aesthetics in a rural area is just as important as the long-term performance, the first 'solution' that jumps to ind is to use a self-binding gravel of some sort.

If you look at the page dealing with SBGs, you'll see that there are a wide variety availabel and they tend to be region specific. The SBG we use in NW England is not the same as that used most commonly in, say, Cornwall or NE Scotland.

So, you need to speak with local contractors and/or suppliers and see what it is that's used in your area. Alternatively, take a look at the Breedon Gravel, which is made available nationally and is widely regarded as one of, if not the, best SBGs in the country.

Careful construction, relying on a new sib-base layer, with a cambered profile, edge gullies to each side of the lane, and then the SBG surface dressing, would be adequate to resist the problem you have with scour, but again, I can't see the site so I can't be sure. If scour was a serious problem, then some form of bound surfacing might be a better option, but take a look at the SBG page, see what you think, and then if you feel it's not quite what you're looking for, post back and I'll talk you through the alternatives.

[danensis]

Another option is to have a central channel rather than try to put a drain down each side. This has the advantage that there is less of a line between the road and the verge. On country lanes it also stops that "grass growing in the middle and taking your sump off" problem.

[ABILITY]

A client of ours had their farm drive done with two strips of concrete, over a good base, to take the tyres. Local gravel was rolled into the top before final setting.

Whilst it sounds a bit of a crude method it look good once the grass and surrounding vegetaion was allowed to grow over the edges. Thus it looked like the old farm track but with out the potholes, puddles and loose surface.

[Farther Common]

Dear Tony Mc C

Thanks for that - SBG seem a very good surface. However here, I think the steepness and run-off would take too much away top and deposit it in the field below.

Can you run me throught the other possibilities. ABILITY's solution is very intersting (thanks !) how would that be built? - in particular foundations in soft sand soil?

Danensis' centre drain would need a concave road surface?

Thanks for the ideas - very helpful


Ian Brodrick

[84-1093879891]

The basics of creating an exposed aggregate concrete are explained on a page on the main website.

For this sort of project, you'd need a 100-150mm deep 'slab' of concrete on a prepared sub-base of 100-200mm of appropriate sub-base material. You could incorporate a membrane to reduce excavation and sub-base requirements, but without seeing the site, it's impossible (or unprofessional, at least) to give a full spec.

This is a popular solution in some parts of the south-west of Eng-er-land as it's relatively cheap and can be done with ease by cack-handed labourers, so the farmers love it!

[Farther Common]

What about gravel ashphalt - can that be made into a rural looking surface? How does it compare cost wise?


Ian

[Tony McC]

What do you mean by 'gravel asphalt'?

Do you mean a bitumen-bound surface dressing of gravel or do you mean road planings? ???



Edited By Tony McC on 1097267872

[Farther Common]

Hi Tony

I understood it was possible to make a different dressing with a local stone bound with bitumen and use that in the same way as tarmac - but that it wears toa better finish?

Are there any other options we should be thinking about?


Ian

[Tony McC]

These surface dressings are typically applied to existing road surfaces as a way of repairing minor cracks and potholes, improving the overall strength and durability of the surface, re-texturing what may have become a polished surface, making it look a whole lot better, and extending the serviceable life by several years.

The key thing is that it is done to an existing surface: there has to be a bitmac road there to which the surface dressing can be applied. So: starting from scratch, surface dressing is more expensive than a plain bitmac pavement. However, if the appearance is more important than the cost, then it could be a viable option.



Edited By Tony McC on 1097411911

[Farther Common]

Hi again

Thanks for that..... very clear.

Last nights deluges took away most of the remaining surface so we had better get on and so something!

More quesitons to follow


Ian