CIVILS, CONSTRUCTION & STATIONS
Tower cranes and railways
The Construction Plant-hire Association has launched a new guide for contractors using cranes on or near railways. Adam Hewitt reports.
T
he latest in the ‘safety publication series’ by the Construction Plant-hire Association
(CPA) has just been published, aimed at giving clarity on the issue of oversailing of Network Rail infrastructures by tower cranes.
This presents “inherent risks”, the CPA says, to Network Rail operations, personnel and the travelling public, so oversailing is not normally approved, except in unavoidable circumstances or constrained sites.
The ‘Requirements for Tower Cranes alongside Railways Controlled by Network Rail’ good practice guidelines explain that lifting operations, by their very nature, involve risk.
The CPA said: “The starting point for the reduction of risk should always begin with consideration of the need to carry out lifting operations, or whether other, less hazardous, techniques can be used.”
Tower cranes
Tower cranes present particularly high risks when they are being erected, climbed, used, maintained and dismantled because they are temporary structures. “It goes without saying that if the crane or its load falls onto the track a catastrophic accident may well result. It is therefore essential that best practice is followed to eliminate or reduce this risk,” the CPA explains.
It urges contractors to consult Network Rail at the earliest stage of planning works whenever it is necessary to carry out lifting operations over or adjacent to a live railway, Network Rail infrastructure or public railway areas. Its own experts can then determine the precise level of safety measures required, including the need, potentially, for possessions and isolations.
Obviously, these cannot be expected to happen just like that: a long lead time is required.
Preventing collapse near railway assets
Network Rail says it must be consulted by the crane user “in all circumstances where the tower crane and its load can collapse within 4m of a railway asset or property boundary”. The guidance also requires such cranes to be positioned behind buildings or similar obstacles, preventing a fall directly onto the railway.
The guidance adds: “No part of any crane jib shall oversail the Network Rail operational boundaries under any circumstances, even in out-of-service conditions, unless specific permission is given by Network Rail. This may require the selection of a luffing jib crane.”
There is a hierarchy in place whereby the contractor must first attempt ‘elimination of risk by position’ (notifying Network Rail is not mandatory if a crane collapse would not be within 4m of an operational railway boundary or railway property). If this is impossible, it must ensure the ‘reduction of the risk of collapse by restraint’ (tying to an adjacent structure, or shielding). If this, too, is impossible, the requirement is the ‘reduction of the risk of collapse by configuration, including down rating’.
Down rating cuts the rated capacity to 75% of the manufacturer’s specification, for example: “A 280m-tonne saddle jib crane with a 50m-long jib erected on 2.3m tower sections in a C wind region with a 25-year return wind period has a maximum rated capacity of 12,000kg and a maximum capacity at the end of the jib of 5,600kg. When erected close to the railway these values must be reduced to 75%
All ‘lifts’ must be in a direction away from the railway, so that in the event of a collapse, the crane and load cannot fall within 4m of the operational railway boundary.
Other subjects covered in the guidance include ‘guying’, where mast guys must be used (two are required, to provide redundancy), or a second mast – if this is approved and agreed with the crane contractor.
Inspections must be carried out before a crane gets to the site, so faulty or worn parts can be identified and replaced. The guidance explains: “It is considerably easier and less costly to replace components and carry out lubrication and adjustments in a depot, than when the crane has been erected on site.
“Work on an erected tower crane always involves work at height and presents difficulty in handling heavy components.”
The guidance provides diagrams to illustrate how collapse distance can be calculated with different types of crane, and whether the load is slung horizontally or vertically.
This guidance – produced with the assistance of the Tower Crane Interest Group, CPA and Network Rail – is recommended to all contractors, cranes hirers and operators, and can be downloaded for free from the CPA website.
FOR MORE INFORMATION
The guide is at: W:
www.cpa.uk.net/tower-crane-interest- group-tcig-publications/
rail technology magazine Aug/Sep 14 | 37
i.e. 9,000kg and 4,200kg.” Planning and preparation
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