Manhole cover loading (skip lorry)

NickK · 31 Jul 2020 at 20:49

We have two manhole covers to a shared car park - one a BS497 class c and the other a BS497 class b.

The skip driver pointed them out to be check as the skip lorry is 9.8t and the 8 yard skip will be about 8t of sand. 18t in total.

Manhole cover class C is 25t and Class B is 12.5t.

The skip truck has four wheels so I assume the load of 17t is spread over the wheels (at least 17t over two rear wheels) - question is if one wheel goes over the manhole cover, is it at risk of breaking?

NoobCannon · 31 Jul 2020 at 21:09

Maybe

DXP55 · 31 Jul 2020 at 21:24

Just put a builders plank over them.

ik9000 · 1 Aug 2020 at 00:06

your assumption that the weight is on two wheels is more realistic. Last time I looked at axle loads most of the weight was on the rear two for similar kinds of vehicles. logic would say the cover rating is its working capacity so hopefully you'd be ok, but you would want to check that. Can you get a copy of BS497 on l'interwebs?

NickK · 1 Aug 2020 at 06:28

ik9000 said:
your assumption that the weight is on two wheels is more realistic. Last time I looked at axle loads most of the weight was on the rear two for similar kinds of vehicles. logic would say the cover rating is its working capacity so hopefully you'd be ok, but you would want to check that. Can you get a copy of BS497 on l'interwebs?

Even with the now defunct BS497 they want to charge £90 for it!

I was thinking of something like this: https://safefence.co.uk/road-plate.html such as a 19mm trench cover could then be used to spread the load. Even a 20mm thick 1x1 meter plate would spread the load (the manhole is 600mm diameter circle). £150 inc VAT.

HSS and most places seem to hire them too: https://www.balloohire.com/product/equipment-hire/road-plate so a hire for the week sounds good. However I suspect that they don't position them as it's likely to be heavy.. it would be good if they can simply hoist off the truck and position.

ik9000 · 1 Aug 2020 at 21:49

cough , the internet is your friend. https://wenku.baidu.com/view/d6520b3e0912a21614792933

NickK · 2 Aug 2020 at 12:57

ik9000 said:
cough , the internet is your friend. https://wenku.baidu.com/view/d6520b3e0912a21614792933

Yup you still need to pay for a VIP pass to access..

However it does provide a requirements in the free abstract - so B is 150kN and C is 10kN which seems the complete opposite to other works.. So with 1.0-1.1kN per ton/tonne means that's 150 tons over 1 m2. Given a tyre is a small area.. that's probably the same states in the original post.

DB_SamX · 2 Aug 2020 at 17:03

The C250 rated cover "should be fine" but it wouldn't hurt to put a roadplate on both. The B125 I would definitely protect as it's mainly aimed at car loads.

NickK · 2 Aug 2020 at 17:11

DB_SamX said:
The C250 rated cover "should be fine" but it wouldn't hurt to put a roadplate on both. The B125 I would definitely protect as it's mainly aimed at car loads.

It's old standard and not the Cnnn standard..

I found this which gives a really useful comparison: https://www.jdpipes.co.uk/knowledge/manhole-covers/bsen124-explained.html

Group 1 For use in pedestrian areas where vehicles have no access A15 15kN (1.5 tonnes) Grade C
Group 2 For use in car parks & pedestrian areas where infrequent vehicle access is likely (incl. driveways) B125 125kN (12.5 tonnes) Grade B
Group 3 For access covers & gully gratings in areas of slow moving, heavy traffic; also for gully gratings in certain carriageway areas (see full definition above) C250 250kN (25 tonnes) Grade A
Group 4 For use in carriageways of roads, hard shoulders and parking areas D400 400kN (40 tonnes) Grade A

So for BS497 the grade C is only 1.5 tonnes and the grade B is 12.5 tonnes. So for a 18t skip lorry with 9t per wheel.. the B is ok but the C is a problem.

The road plate is 450kg.. so that is the next issue.. will talk to the hire places tomorrow and see what they can deliver and position.

jpaul · 2 Aug 2020 at 17:27

if the man-holes are touch and go, wouldn't you also be concerned about integrity of concrete shrouding on the pipes beneath ?

we have a large buried bricked cess-pit with a couple of manhole covers, on our shared land ... owner of adjacent property had the nerve to have a skip deliverd / filled adjacent to those covers, and created some massive divets in earth above it, from hydraulic lorry supports recovering it ... original builder thinks it's ok

DB_SamX · 2 Aug 2020 at 17:42

NickK said:
It's old standard and not the Cnnn standard..

I found this which gives a really useful comparison: https://www.jdpipes.co.uk/knowledge/manhole-covers/bsen124-explained.html

So for BS497 the grade C is only 1.5 tonnes and the grade B is 12.5 tonnes. So for a 18t skip lorry with 9t per wheel.. the B is ok but the C is a problem.

The road plate is 450kg.. so that is the next issue.. will talk to the hire places tomorrow and see what they can deliver and position.

Good point. I didn't pay attention to the older code of your covers. Thanks for correcting me.

NickK · 2 Aug 2020 at 18:09

jpaul said:
if the man-holes are touch and go, wouldn't you also be concerned about integrity of concrete shrouding on the pipes beneath ?

we have a large buried bricked cess-pit with a couple of manhole covers, on our shared land ... owner of adjacent property had the nerve to have a skip deliverd / filled adjacent to those covers, and created some massive divets in earth above it, from hydraulic lorry supports recovering it ... original builder thinks it's ok

There's 3m between the two - so the guy could drive down the road more on my side (the grade C) then I think with the plate spreading the load I think we'll be ok. A sheet would provide some support (2.4x1.2m 2cm thick). These are 1/2 way down the drive, so the truck will be moving at that point but I take your point and may lift the grade C with the neighbours permission to see the direction of the pipes they could drive right on my side of the property line and it should be ok.