Santiago Metro, Chile
Santiago Metro (Metro de Santiago) is one of the largest and most advanced underground railway networks in Latin America. It currently has six lines, with a further one under construction, plus 118 stations, running across almost 120 km and carrying around 2.5 million passengers every day.
In 2015, Pandrol secured a fastening systems contract for the construction of lines 3 and 6, which was supported by the delivery of resilient systems for vibration mitigation and low maintenance catenary for the tunnel sections.
Santiago is one of the locations in the world that experiences earthquakes on a regular basis – in the last 12 months alone there have been 67 earthquakes in Santiago. As a result, the project required a fastening solution that allowed for potential future adjustment of the track of up to +30 mm vertical adjustment. In addition, Santiago Metro required a fastening solution for 50 km of track, a lightweight baseplate and under-track rubber mat for noise and vibration mitigation.
To respond to these challenging requirements, Pandrol developed a new composite plastic baseplate. This baseplate had to be designed that could be embedded into fresh concrete or by wet pour methods. This would be more cost effective than traditional castings and would be easier to handle and install on the track. The solution was to develop the SEE-SD, a rail fastening system which provides adequate resilience (stiffness) to attenuate to the concrete slab and enables large vertical adjustments to the rail position. The innovative air evacuation system prevents trapped air entering underneath the baseplate. The SEE-SD plastic baseplate has a special feature of vents and channels that optimise insertion into concrete and ensures excellent resistance to lateral forces. It also provides a lightweight solution for handling/installation and can be pre-assembled to further simplify installation operations.
Once the system was developed, rigorous tests were carried out by our R&D team to demonstrate to the customer that the solution could meet both performance and cost requirements. The project required technical validation of the system, including a complete and fully tested assessment of the recommended solution.
The innovative SEE-SD rail fastening is designed to give a typical vertical dynamic stiffness of around 60 MN/m. It offers a wide range of pad stiffness levels, making it suitable for meeting noise and vibration mitigation requirements on this project. It also meets all requirements of the latest updates of EN 13146 and EN 13481-5:2012 standards, for category B (metro applications). The SEE-SD system maximises the use of common components, for example, an anchoring solution designing to facilitate installation and future maintenance operations. In addition, its performance relating to electrical insulation complies with EN 13146-5:2012.
The SEE-SD was designed for use with the SD clip, with its screwed design that optimises track construction costs and provides very high technical performance. SD stands for ‘safely driven’ which relates to the controlled clip guidance from the ‘parked’ to the ‘in-service’ position.
SD insulated blocks are designed to offer lateral adjustment of the track gauge in increments of 1.25 mm. The method to adjust the gauge is managed simply by adapting the insulated block combination. The baseplates used in the SEE-SD design are made from glass fibre reinforced polyamide material in order to provide maximum resistance to lateral loads. The baseplate is not ‘laid’ on the concrete but ‘anchored’ and integrated into the slab. There is consequently no risk of slippage. The stress level in the screws is significantly reduced even on tight curves, as a result of the anchoring system, which is based on the use of two screws.
To compliment the SEE-SD system, Pandrol also supplied the QTrack® embedded rail system for the depot areas and to meet with vibration minimisation requirements, Pandrol supplied its Floating Slab Mats (FSM), which are continuous resilient mats used for the isolation of train-generated vibrations in concrete slabs. These FSMs are manufactured from high quality resin-bonded rubber to achieve vibration attenuation, with a low resonance frequency.
Electrification was a major part of the Santiago Metro project too, which was completed in 2017. Santiago Metro required 60 km of Rigid Catenary for this project, for which we designed and manufactured the whole system. This was supplied mainly for use within tunnels. Pandrol’s rigid catenary system was specified as it offers low maintenance, high performance and enhanced safety.
The project involved providing technical support and training to the contractor installing the system. This included on-site training and members of the Pandrol technical team were present at the installation to ensure the process ran as smoothly as possible.
Metro de Santiago has invested in rail fastenings which mitigate the impact of frequent earthquake activity, whilst ensuring their long term performance and resilience. An 8.8 magnitude earthquake shook the southern part of Chile back in 2010 but the majority of the Metro survived well. More recently in April 2017, an earthquake of magnitude 7.1 reached Santiago after starting around the Chilean coast, whilst the metro remained largely unaffected.
It is common practice that in earthquake zones around the world, once an earthquake is detected, trains are immediately stopped, after which operation is continued at reduced speeds or is suspended, depending on the strength of the shock. When a solution is in place like the SEE-SD which allows for large vertical adjustment, it gives metro systems far greater resilience which ensures the return to normal operation can take place much more quickly.