- The Joint Teams formed by the Land Transport Authority (LTA) with the two public transport operators (PTOs) SMRT and SBS Transit (SBST) in 2012 have been closely monitoring service delays above five minutes as well as train withdrawals as two key indicators of train reliability.
Measuring Service Delays and Train Withdrawals
- Service delays on the trains occur from time to time. However, such delays have significant impact on commuters, especially during peak hours. By monitoring the occurrence of all service delays lasting above five minutes, LTA can better assess the level of rail reliability, and put in place targeted measures to address the specific faults.
- When trains are withdrawn from service, passengers have to wait for the next train and their journeys get delayed. The reduction in capacity, especially during the crowded peak hours, adversely impacts the rest of the network and leads to a build-up of commuters who are unable to get onto the first train. Subsequent scheduled train trips are also affected. Therefore, withdrawal rates for trains on each rail line are also closely monitored by the LTA Joint Teams with SMRT and SBST.
- Notwithstanding the spike in the number of incidents in the first two months of 2014, there has been progress in reliability improvements over the last two years.
Service delays lasting beyond five minutes have fallen since 2011.
- Averaged across the North-South East-West Lines (NSEWL), the North East Line (NEL) and the Circle Line (CCL), service delays above five minutes have come down by 20%, from 1.49 delays for every 100,000 train-km in 2012 to 1.18 in 2013. This works out to 311 service delays for the whole of 2013, or an average of less than one service delay a day, out of more than 2,500 daily train trips operated in total across the entire MRT network. The rate of occurrence for service delays above 10 minutes remains generally low, at 0.14 per 100,000 train-km operated for all rail lines in 2013, compared with 0.19 for 2012.
Train withdrawal rates have steadily fallen since peak in 2011/12.
- For each of the three rail lines, train withdrawal rates have fallen by 25% or more in 2013, compared to 2012. For the NSEWL, train withdrawal rates was 2.2 occurences per 100,000 train-km in 2013, compared to 3.3 occurences in 2012, bringing it back to 2010 levels. The LTA-SMRT Joint Team will work towards its target of 1.8 train withdrawals per 100,000 train-km (or about 18% improvement) for the NSEWL in 2014. As a medium term target, the Joint Team aims to restore withdrawal rates for the NSEWL to 2008 levels of 1.5 per 100,000 train-km by 2016.
- For CCL, withdrawals have improved to 0.9 occurences per 100,000 train-km in 2013. While the NEL maintained its performance in 2013 with 0.5 withdrawals per 100,000 train-km, the LTA-SBST Joint Team aims to further improve service reliability as the NEL overhead power system components are replaced with more corrosive-resistant materials. Please refer to Chart 1.
Enhancing Train Reliability
- The Joint Teams’ “find and fix” approach to rectify specific system problems, LTA’s tightened regulatory standards, and PTOs’ additional investments in repair and maintenance have helped to address some of the issues affecting our older rail lines. To further improve reliability, LTA and the PTOs will move to a new “predict and prevent” maintenance approach.
First, we will adopt new whole-life asset management frameworks.
- Management of railway assets is especially challenging because of the large scale of our MRT network and its diversity of assets with unique characteristics. Therefore, it is critical for the PTOs to be able to monitor the conditions of rail equipment over their life-cycles, detect possible areas of declining performance early, and put in place measures to address these areas to sustain a high level of service reliability, even as the system ages.
- As an owner of rail assets in our MRT network, the LTA has embarked on the process of establishing an asset management framework based on the PAS 55 (or its equivalent ISO 55000) international guidelines for whole-life asset management. The framework will specify clear enablers, such as strategic organisational planning, taking into account actual day-to-day work and asset realities, to ensure sound and high quality asset management.
- The PTOs also play a pivotal role since they are fully responsible for the daily operation and maintenance of the rail assets. Both the London Underground and the Hong Kong MTR have adopted such frameworks and are already accredited with PAS 55. SMRT has committed to adopting the whole-life asset management approach and LTA is working with SBST to do the same, for both PTOs to achieve timely accreditation of PAS 55 or its equivalent ISO 55000 in their asset management process.
Next, we will step up condition monitoring.
- To ensure accurate and timely knowledge about the conditions of all rail assets, LTA is developing a central data repository for asset failure reports and maintenance records. Apart from its regulatory audits, LTA will also review asset health and performances with the PTOs on a regular basis, to engender a shift in maintenance culture where possible areas of concern are surfaced early based on monitored trends, and where measures are put in place to arrest such trends before faults develop.
- The PTOs will develop more extensive real-time condition monitoring to allow for timely detection of faults or likely faults. For instance, SBST will be investing in technology that provide early indications of performance issues on the ageing NEL rail system. It will progressively introduce real-time condition monitoring technology for the NEL overhead power system in 2015, in addition to conducting component condition analysis through yearly sampling and stepping up its inspection frequency.
- SMRT has already put in place new technology, such as the Automated Current Collector Devices (CCD) Detection System, the Wheel Impact Load Detection (WILD) System and the Linear Variable Differential Transformer (LVDT) System, to monitor condition trends and detect faults early so that engineers can quickly rectify them. Over the course of this year, SMRT will be installing these condition monitoring equipment on more trains and along more stretches of the NSEWL network.
Finally, we will continue to upgrade the network for greater resilience.
- Having identified specific aspects of our rail systems that may be more susceptible to faults, upgrading works have been planned to remove these vulnerabilities and prevent service disruptions. Since last year, LTA and SMRT have started to replace the ageing timber sleepers on the NSEWL with concrete sleepers for faster and smoother train rides. This year, replacement works of the NSEWL’s third rail system will commence, while SMRT will also push ahead to upgrade its older trains on the NSEWL to further improve the overall reliability of train services. Together with capacity-enhancing measures such as the signalling system upgrade for the NSEWL to run trains more frequently, commuters will experience improved services when these projects are completed from 2016 onwards.
- LTA and SBST have also started replacing components of the NEL overhead power system with materials more suitable for the NEL tunnel environment. This will arrest the occurrence of stress corrosion cracking in these components, which resulted in a number of major disruptions on the NEL over the last two years. The replacement works are expected to be completed by end-2015.
Reliable Train Services Remain Our Priority
In 2014, we will continue to place emphasis on effective maintenance to further reduce service delays and train withdrawals. At the same time, we are embarking on a comprehensive shift to a preventive maintenance and asset management approach with the PTOs. We expect to see even greater improvements on the ground, as these measures are progressively rolled out over the next two years.
 The Downtown Line (DTL) is not included as it started revenue service on 22 December 2013.
 In 2013, about 1,500 train trips are operated each day on the NSEWL, about 500 on the NEL and about 650 on the CCL.
 The British Standard Institution’s internationally-recognised Publicly Available Specifications (PAS) for the optimised management of physical assets.
 A depression of the third rail on the NSL was detected in December 2013 by one such live monitoring device, which allowed SMRT to respond immediately and divert train services to another track. Even though travel time along that short stretch became slightly longer, train services were able to carry on while the depression was rectified by the engineers.