A KEANE EYE: Working on different levels

Brisbane is the prime example in Australia at present, largely because of the number of current and proposed tunnelling projects in the city. While it is politic to say that this is because of the high sustained growth levels in southeast Queensland, it is also fair to say that no other option is left because there were long periods of time when little substantial infrastructure was built.I suspect that eventually the busway network in Brisbane will be regarded as one of the modern engineering marvels of Australia, and a significant part of this is because of the courage to grade separate the busway in and close to the city, starting with an underground bus station in the city.The current first stage of the Northern Busway being built by Abigroup will be remarkable in having a long section of elevated road crossing a train line and the Inner City Bypass, crossing major roads close to the main hospital complex in Brisbane, having an elevated bus station at the hospital and linking with the Inner Northern Busway that exits the city without mixing with general traffic. A 20-minute saving in peak hour is very impressive.The section in front of the hospital will be cantilevered over an existing footpath, will not interfere with hospital access or general road traffic, and will be built around existing infrastructure and a heritage wall. This is a difficult and expensive project, but its benefits in allowing buses to quickly enter and exit the city regardless of the time of day will be felt for decades to come.I suspect that other cities will have to bite the bullet to improve public transport in the city. A good rail system works well along the spines that it services, but there is still a big role for buses in servicing areas that cannot viably be covered by rail. Their effectiveness is limited by mixing with general traffic, and dedicated bus lanes are often a mickey mouse solution.All that aside, it brought to mind the large number of concrete beams being lifted in Australia, and how some of these lifts become quite difficult because of the weight of the beams, the difficulty of access for cranes and transport, or the need to minimise disruption to traffic.This got me thinking about whether sometimes these jobs can become unnecessarily difficult and expensive. Australia now has a good population of large cranes, but the difficult lifts can require multiple large cranes to be used because of the weight of the load and the radius of the lift. The width of a bridge for a major highway or freeway can also require multiple set-up positions for the cranes. These cranes need to be able to pick up a beam from a position accessible to transport, and then slew to a position to place the beams, and this can necessitate one crane passing to another during the course of the lift.It has struck me that the piers of these bridges are substantial structures capable of taking the weight of the beams and the traffic that travels above them. There are various heavy lift skate and gantry systems around the world, and it occurred to me that it could be feasible to mount a simple track and trolley system on the piers to transfer beams along a pier to the installation position.If such a system incorporated a capability to micro-adjust the position of the beam, for example with small jacks, it should simplify the positioning of the beam over the bearings.It would also mean that beams could be lifted onto the piers from one position, regardless of final resting place, and that the crane would be freed up for rigging to the next beam much earlier than if it had to hold the beam until it was settled on the bearing. Is there someone out there who thinks the idea is a possibility, or alternatively is prepared to tell me I’m mad?

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