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Random query, but there is a huge building site over the railway from us and every night they leave the cranes with the booms pointing up in the air - why is this? Wind resistance would be increased in the line of the boom, so can't be that.
Only reason I could think of us less tempting for urban climbers who might want to walk along the boom at night...
They probably don't have space to lower the booms down. A vertical boom takes up a lot less space.
Why not leave them horizontal?
So they can look at the stars and dream of being space rockets. Machines can have dreams too
[url= https://live.staticflickr.com/65535/49912117136_a2e25b6f19_z.jp g" target="_blank">https://live.staticflickr.com/65535/49912117136_a2e25b6f19_z.jp g"/> [/img][/url][url= https://flic.kr/p/2j3yDvJ ]Untitled[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
So they can look at the stars and dream of being space rockets. Machines can have dreams too
Thanks!
I knew STW would have the answer....
Why not leave them horizontal?
A horizontal boom has a greater footprint, if you put the crane down it will take up space, which may interfere with vehicle movements and other work on the site. You might not be using the crane all day and then would have to start it up to raise the boom to clear an area.
Easier to just leave it stood up.
Edit - Tower cranes not mobile.
Apparently they are allowed to turn with the wind as it reduces the force exerted on the structure, so you don't want your boom horizontal with structures near by, in case it hits them.
You mean it has a luffing jib?
(I'm now an expert due to huge building site across the road with 6 cranes.)
So they can look at the stars and dream of being space rockets. Machines can have dreams too
Simply beautiful.
Some modern cranes are designed to weathervane in high winds. Keeping the boom up reduces the radius of the weathervane.
Also, leaving the boom up reduces the impact on effective crane radius for other cranes working in the site.
You mean it has a luffing jib?
No need to swear...
Luffing cranes can be fitted with Zoning devices to electronically limit against over sailing important or dangerous structures adjacent to site. This can include schools, public area's or main highways and they are usually mandatory next to railway and electrical installations..
I guess that's why they chose them being next to a Railway....
it's so all the skydivers can look up at them wistfully and wonder if there is _just_ enough height to BASE jump from it.
Look out for people wearing magic backpacks
It's combination of the need for zoning due to the railway, and free slew while left unattended. The zoning prevents the operator from swinging the boom over the railway, but has to be turned off to allow the crane to swing in the wind. The wind pressure on the crane is much greater if the boom is side on, and a gale force wind could overload the mast. Tower cranes have a max operating wind speed (where the jib can be in any orientation) and a max out of service wind speed for which the jib must be free to slew in line with the wind.
Wonderful. If Strava could get this sort of content they would have no problems raising cash
As Greybeard says Network Rail don't like anything overhanging the track, more-so if there's high voltage cables above the rails.
Always thought it was to relieve the pressure on the hydraulic system, but its not, reason being, the larger cranes arrive on site bare of counter balance weights on the rear, to save weight when travelling, on arrival they're placed in position,and weights added ,stabiliser legs extended etc, this also creates a space round the crane that will be kept clear of obstructions, for lifts, and it saves space on site not to have huge jib sticking out the front, and also saves the time extending the jib for the job
So they can look at the stars and dream of being space rockets. Machines can have dreams too
Wins the internet for the month, if not the year!
As above - simply beautiful. And wistful.
You mean it has a luffing jib?
Surely boom?
the jib for the job
This sentence pleases me.
There's a hire depot near me and they always leave the cages extended. Maybe something to do with hydraulics?
Anyway, always puts me in mind of some prehistoric scene. 😊
Keeping the basket of a MEWP up keeps the numpties out of it at night.
It's a luffing jib crane, it goes into free soon at night / when not in use so that it points down wind to reduce wind load and the boom is raised, so it covers the least footptintbon the ground and doesn't potential oversail any adjacent properties.
As others have said - luffing jib. Oversailing Network Rail assets (the boundary fence) is a big deal and requires a very detailed lift plan, form 2 & 3 etc..it takes many months to get approval. Network Rail rightly instist on restricting the cranes capacity (typically around 75%) of the maximum lifting capacity, and applying a factor of safety to the crane capacity.
Tower cranes tend to stop working at 18mph winds...and when lightening starts!!! they're massive lightening conductors (with isolated cabs).
Tower cranes tend to stop working at 18mph winds…and when lightening starts!!! they’re massive lightening conductors (with isolated cabs).
The expression ‘no shit, Sherlock’, springs lightly to mind at this point! 😁