Good road surfaces often seem to be ruined by sinking manhole surrounds which then accelerates due to the pounding of wheels.
What is the cause?
Is it the brickwork of the chamber that is sub-standard and is crumbling?
Is it the foundations that are sinking - if so then what are the implications for the drain or pipework?
Is it that the cover does not spread the weight over a large enough area?
Is it poor workmanship or is there a lack of a proper standard when these are constructed?
Do they all have brickwork these days? I seem to see large corrugated plastic tubes where roads are being built, maybe that's just gulleys rather than manholes ...
Anyone know why these services have to be under the *road* as opposed to under the pavement or verge?
Who knows but I note that increasingly they are now made of bloody plastic as the travellers are nicking the metal ones. Brian
Well, I would hate to think of so many inspection covers on footways, a recipe for broken hips.
Brian
That is the modern way. They are SUPPOSED to have well supported concrete collars around them.
Having seen a road remade down to the foundations, I think the problem is way the surrounds are fitted. The hole is coved by a temporary steel plate and the surface is laid over everything. Then the nice new surface is dug out, the surround dropped in and the gaps made good. So there is always bit around the cover that is not part of the main surface and that's where the frost and salt and everything get in.
It's due to the bigger/heavier trucks allowed by EUSSR legislation a good few years back. Harmonisation.
Basically its expediency over care and attention I think. Brian
Over the years our government has often found it convenient to blame the EU for something it wanted to do anyway, but had to overcome criticism from some pressure group or other. Quite often, the EU directive in question was written at British instigation in the first place. But don't let me stop you blaming the EU for things.
Well they wont be able to have that excuse anymore will they?
Another plus for Brexit.
No, he'll blame the Muslims then.
44 tonne HGVs and a huge increase in the number of 2+ tonne 4x4s, and 30 million cars on the road has all combined to do the damage.
I see quite a few Romanian or Bulgarian HGV's where the tractor unit only has a single rear axle, and is obviously heavily loaded on that axle, and the diameter of the driving wheel/tyres seems to be smaller than most other HGVs. These must impose a far more significant loading on everything the vehicle passes over.
Many years ago (back when HGVs were limited to 32 tonnes), a TV programme (I am pretty sure it waS Tomorrows World) did a test. The results then showed that 1 badly loaded HGV did as much damage to the road as 125,000 cars passing.
I am pretty sure that increasing the limits for HGVs and the massive increase in their numbers is the cause of most of the road damage.
The rate of damage would be vastly reduced though if all road repairs were carried out to a proper standard, instead of quick, cheap and shoddy repairs.
SteveW
It takes 28 days for concrete and mortar to achieve its full strength. Under the manhole outer ring is usually a course of engineering bricks (because the road level has increased over the years as more layers of tarmac was added). This is what fails.
It would cause massive traffic disruption if a reset manhole cover was cordened off for that period. hence any repair is almost guaranteed to fail sooner rather than later.
Collapsed manhole cover just down the road from where I am.
99% of road damage is by trucks. The problem got worse with GPS sending them down country roads.
Re multiple axles, the damage happenswhen the third axle hits the bump/depression. The entrie weight carried by the axle group is carried momentarily by the oneaxle.
You wouldn't think there were manhole covers on the motorway would you? Back when I was young they were running traffic on the hard shoulder between five and four on the M6. As I drove down there I noticed a manhole cover that was lifting from the surface. I called the police and they had to close one of the lanes while someone fixed it. The hard shoulders were not designed to carry traffic.
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