I'm guessing that they vary in thickness. What is the average weight of a manhole cover? Any ideas on range of weights?

A quick google search shows results ranging from about 50 to 150 kilograms.

of coarse by 206x you could have troll municiple workers, requireing much bigger man holes...

Good thinking Method. That would especially be true of main streets and subway access tunnels.

Its possible that a combination of discrimination ("trolls aren't bright enough to fix things, only lift them") and the physical limitataions you mention would simply prevent the citry from hiring trolls for those jobs. I think this could be especially true if the work required retrofitting streets with bigger manholes.

Yeah, even today it is "legal" to practice discrimination if you have a valid reason (in the UK, at least). EG, no we are not hiring men to run the women's locker rooms; no we are not hiring a guy in a wheelchair to sell snacks at half time in the stands at the local football ground; etc. I think the key is how much the workplace would have to bend around the new hire. Putting in ramps for wheelchair access to a small office is one thing; reworking all the manholes on all the main streets in Seattle to accomodate trolls is another entirely.

I guess it depends. If you're going to tear the road up anyway down into the sewers, you may as well put in a troll-sized accessway. Especially what with some of the stuff that now lives down there, I imagine muncipal workers will be cured of racim VERY fast when they find that a troll municipal worker brandishing a wrench is all that's heroically standing between his own personal ass and devil rats or something.

If there's been enough damage to the roads and the underlying superstructure through the years that they have to redo the majority of the roads, you could well find Troll-sized manholes are now the norm. If not... Then it may sux to be a troll in the sewers.

I could believe in gradual retrofitting of manhole covers as streets needed replacing and would, if I were running the game, rule that about 50% of manhole covers were troll-modded.

On the other hand, I could see a troll squeezing through a normal sized manhole cover. He/She would fill all of it, but it could likely be done.

I doubt that. Going thru a normal manhole is inconvenient for guys now. Someone toll-sized would never fit.

When I followed the suggestion and googled it, I learned a few things.

Not all manhole covers are round. Round is the predominant shape because the manhole is round. The manhole is round because that shape provides the most stability (for holding back the surrounding rock, soil, etc.). To accommodate trolls perhaps they would make them ovals?

They weigh a lot because they need to be able to support the weight of the vehicles passing over them, and also stay in place when vehicles pass over them.

There is new technology being applied to the standard, old, cast iron or cast iron, concrete filled manhole covers. A Japanese company had a plastic and carbon fiber manhole cover. It came in 2 sizes that weighed about 1/7th the weight of a normal manhole cover. I think the weights were about 5 and 7 kgs. I do not know if they would stay in place on their own as a vehicle sped over them, but I suppose they could be latched or dogged in place.

[edit] My reason for asking was prompted by the levitate thread and thinking how levitating a manhole cover in front of a go ganger could really ruin his day. [/edit]

During your searches did you find that the reason their round is so they can't fall through the hole and kill someone working down there? That's what I always heard.

Um I wouldn't think that they would send people down into the sewers fo the sixthw orld unarmed.

Eh....

No I was talking about the cover itself falling through the hole. Something that heavy could easily kill somebody working down there.

A square, triangular, or rectangular cover could fall through it's own hole if you turned it right. Not so with a circular cover.

Oh, whoooops.

Not really mentioned, but makes sense.

They mentioned making them heavy to stay in place. They didn't mention a problem with the non-circular ones falling into the hole.

Might try googling that one yourself. They did show quite a few non-circular ones so if it is a problem... Now you have me curious.

Ok, I googled it again.

I did see some explanations of them being round so that they wouldn't fall in the manhole.

Most of the accidents involved hitting high manhole covers with vehicles, skateboards or people tripping over them as they walked. Sometimes the high manhole cover was hidden by a puddle of water.

There were several accidents involving people falling into open manholes. There were several instances of the open manholes being the result of stolen manhole covers, particularly in Shanghai. I guess that is called shanghaiing manhole covers.

No accounts of manhole covers falling and hitting workers, but I only went about 8 pages in.

I think manholes are really usually round simply because pipes are round, and manholes usually fit on the ends of big pipes sticking up to the ground. Pipes are round because it is a very strong shape for something underground and has minimum surface area vs cross section and is probably easiest to manufacture (don't have to worry about a little twisting, for example). The not falling into the hole thing is a handy side effect, but since square manhole covers are reasonably common it obviously isn't enough to make round compelling.

Manholes that open into square places (like junctions, air ducts, etc) are often square with hinges and recessed latches (which one can usually jimmy open with a screwdriver), sometimes padlocks.

Sewer systems are very infrequently upgraded, it is common for them to be 100 or more years old even in the US. It would never be worth it to retrofit such infrastructure simply so you could hire trolls to do maintenance work on them and probably not even worth it to build your new sewer accesses to be troll-ready. There are lots of people to fat to easily go down a manhole today and I don't think manholes are getting any bigger. Many manhole covers should be simply inaccessible to trolls, and the others should be very tight. Troll's should not be commonly employed in sewer system, or really any underground, maintinence simply because of thier size. Though lots of sewer maintenance involves digging up stuff, and they would be fine there.

The biggest reason they're predominately round? It's harder for them to fall in the hole if not correctly centred, and actually is belived impossible.

My workmates are full of crap facts.

Another reason for making them round is so it's easy to move around - just roll on it's side. It also makes it easier to put back - there's no special positioning to get it back into place (Unlike square or triangular) - just roll, and let fall into place.

Hmm... What would the armor ratings of a good thick manhole be?

I have to imagine even if awkward an inch or so of solid steel would stop a considerable variety of small arms fire.


-karma

It would, actually. Pretty much any non-APDS will be stopped cold by steel like that.

Well, it's not exactly armor-grade steel, but it would still probably stop anything short of the Barrett, or HMGs or Assault Cannons firing APDS/AV. Current 7.62x51mm (sporting rifle/MMG/light sniper rifle) armor piercing ammunition only penetrates about 12mm of armor steel at 90 degrees.