For the first time in the station’s history, the platforms at Glasgow Central station are being completely refurbished. The Glasgow Central Station Platform Renewals project aims to improve all existing platform structures, excluding platforms 12 and 13, to ensure that they are able to meet the requirements of a 50 year design life.
Network Rail’s original plan was to carry out simple concrete repairs to the existing deck and concrete copes along with the complete resurfacing of all of the platforms. Carillion made an alternative proposal for the complete replacement of the structural slab including the copes, thereby providing a DDA, step and clearance compliant platform and enhancing the design life of the new works.
This will be achieved through the construction of entirely new decks for platforms 1 to 11, 14 and 15 – platforms 12 and 13 were only recently constructed (as reported in issue 68, June 2010). The existing masonry platform walls are to remain in place with minimal alteration, but the concrete decks and steel joists are being replaced by reinforced concrete slabs. New copes and tactile strips will be installed throughout.
An in-situ concrete screed will be poured to bind everything together and form a base for a polyurethane non-slip resin which will provide a compliant, anti-slip surface. Train tanking points on platforms 1, 2 and 9 to11 will be relocated and their number increased if required to better suit the needs of station staff.
Start at platform 1
Work commenced on site during August 2011. The sequence in which the platforms would be taken out of service, and for how long, was agreed after thorough consultation with the train operators. The first platform to be rebuilt would be number 1, followed by 2, 12, 11, 3, 4, 15 and 13. This seemingly illogical sequence, but one that is necessary for the smooth running of train operations, would continue with 14, 10, 9, 8, 7 and 6. The final piece of work, platform 5, is due to be handed back on 22 March 2014.
Carillion’s approach required some innovative thinking with regards to programming and methodology to complete the project in this sequence. Work commenced on Sunday 17 October 2011 and the programme to complete the first two platforms was tight, with eight weeks allotted for platform 1 and nine for platform 2 including the two weeks shut down around the Christmas period. Due to their overall length and geometry, these first two platforms were considered by the project team to be the ones that would be the most difficult to complete.
The method of working is relatively straightforward. Carillion started by erecting hoardings to protect the worksite. A free- standing type is being used as this provides flexibility for erection, maintenance, dismantling and reuse as the project progressed through the station.
The existing concrete deck is then marked up into slabs which are cut in-situ into two tonne units by operatives from Corecut Ltd. This cutting work is carried out using a diamond road saw with a blade diameter of up to 750mm to cut through the deck which varies in thickness between 250mm and 350mm. On platform 1 alone there was approximately 1500 linear metres of concrete to be cut.
As the cutting is carried out in a live station environment, acoustic barriers are placed along the length of the hoarding to dampen the noise levels. Carillion also carries out extensive noise monitoring to ensure that the cutting operations do not unduly affect passengers on other platforms or the station concourse.
Upon completion of the cutting operation, four holes are cored through the slab for lifting eyes.
The train now arriving…
At this point, an engineering train of ‘pike’ wagons is brought into the platform road. These wagons have a steel body and floor construction with drop down side doors and a 30 tonne capacity which makes them ideal for moving the platform slabs. The slabs are lifted off the platform walls and loaded into the pike wagons using a 10 tonne tracked crane, a Maeda LC785 supplied by Blackwood plant hire. This zero-tailswing crane was chosen due to its small footprint, making it ideal for working in restricted areas such as these platforms.
After all the old platform slabs had been loaded, the wall head is cut to the correct level for the precast concrete slabs that will be installed to form the new platform structure. Due to the site constraints, this has become a labour-intensive operation and, to maintain health and safety standards, Carillion monitors the HAV (hand arm vibration) exposure of its operatives using a Reactec System supplied by Speedy Hire. This ensures that no occupational health issues arise from using vibrating tools.
Once the wall head has been prepared to the correct level, a second set of wagons arrives, fully loaded with the new precast slabs. Every new slab is different, each one designed for a particular part of the platform,
so a detailed delivery plan had to be devised. Slabs are delivered by the manufacturer, Creagh Concrete of Toomebridge, Northern Ireland, to PD Stirling’s rail yard at Mossend. Here the slabs are loaded into each pike wagon in the order in which they will be installed. Following arrival at site, the new slabs are unloaded using the same Maeda crane.
Once the slabs are in place, the copes and tactiles are installed to ensure programme continuity. The copes are manufactured by architectural masonry specialist Sterling Precast, and the tactile tiles by Charcon.
Finally, the concrete screed is poured to form the body of the new platform. Working in a live station, this is another logistical challenge which involves pumping 80m3 of C50 concrete onto the platform from an adjacent site.
When the concrete has cured sufficiently, the final platform surface is applied. This is a polyurethane resin which provides both the colour contrast finish and the required slip resistance. The Uradeck BC system from Nufins was chosen for this particular application.
The project is now about halfway through. Work is taking place on platform 13 and, so far, every platform has been handed back on time and Carillion has recorded over one year without a lost time incident.
In a challenging high profile environment, this project has been an excellent example of what can be achieved through innovative thinking and collaborative working between main contractor Carillion, station owner Network Rail and the Glasgow Central station management.