On more modern cranes, built in the last ten years, there’s probably a programmable logic control system built in, even if it isn’t available to the customer. It wouldn’t be much of an issue to add a blackbox (datalogger) to that.
On older cranes, which used contactors [big electrical relays used to switch motors, etc] it will be more expensive and problematic. You could be looking, at a guess, at several thousand pounds, although if a datalogger manufacturer sees this as an opportunity to mass produce retrofitting kits, costs could come down.
It’s fine to say, let’s have a blackbox, but you need to set a standard to say which of maybe 40 functions are monitored, and this will effect costs again.
It’s a valid point to say dataloggers wouldn’t have helped to prevent either of the recent accidents in New York, or with the subsequent investigation: one seems to have been due to a tie collar getting caught on something while it was being lifted, and the other due to a bad weld on a slewing ring support. Datalogging helps to show if a crane has been overloaded, how often, and what the operator was doing before the incident.
Any blackbox designed to be used in accident investgations would need to be very robust to withstand a collapse, and that would add further costs. Some systems upload data over a mobile modem, but you then have the problem of sifting through large volumes of data.
Dataloggers have some benefits, but they’re not a panacea. Human factors such as training, and commercial pressures that may affect maintenance standards, are a more important issue.
Tagging is feasible, using RF tags, for example. There are now models that can be scanned through metal, and if people used these, tracking might work. Barcodes aren’t robust enough though.
In theory, lifetime tracking is a great idea, but it has to be robust and universal: fleet owners don’t want to have to have a Liebherr system, a Comedil system, and a Manitowoc system.
The big problem, of course, is what do you do with the existing equipment? Tower cranes are built to last, and you’d need to implement this on all of the old tower sections that are out there.
At the end of the day, there’s no substitute for good maintenance and thorough examination, and that’s what the CPA has focussed on with its most recent best practice guide.
There is a danger, if you pack too much technology into cranes, that it gives a false sense of security. What the industry really needs is to start tackling is the people issues.
Tim Watson, tower crane safety consultant and adviser to the CPA Tower Crane interest group
