Overloading and aging equipment are just excuses dished out by smrt. Japan has packed trains and is much older than our system. They have more natural disaster than us. Why is it that they have no problem of frequent disruption?
Japan design and build the system. Their staff know how the system works and how to maintain. Sg buy the system. The staff take over the system with little idea of the critical parts and maintenance. Worst is that they go through motion during maintenance with no one picking up and accumulating the know how. The system will continue to fail. Even if they replace the management with one who is really good, it will take years to remove the dead woods and train good maintenance staff. With emphasis on cost saving, how many good staff can they find?
for a fully electric system, much of the problems are related to, of course, the electrical system. there are trains running on dc current and trains running on ac current. with voltage spikes which happen frequently or sporadically in any aging system depending on the quality, amount and frequency of maintenance ac-equipped trains are easier to repair as typically blown fuses can be cheaply and quickly replaced. not so for a dc-equipped train. thyristors will need to be replaced, and they are not readily available as spares or cheap to stock up. due to shortages, trains will remain in the yard in longer durations waiting for parts to arrive.
the other problem is the signaling system which relies on the electrical power system. the component with lowest mtbf is typically the power amplifier, and it can cause chain reaction failures to trains either being overpowered or underpowered. it will need power control and a secondary failure detection mechanism. the longer term issues of insulators getting caked with dust, soot and residue which have conductive properties can easily be fixed with regular and more frequent inspection and maintenance, especially in the tropics. the hot, humid, rainy climate and accompanying corrosive index that sinkie transit systems operate in demand a more stringent approach to maintenance, repair, and replacement. that they operate relatively well in overall stats on the equatorial belt should not be taken for granted (name me another equivalent transit system on the equator that operates with better kpi and i will concede), yet they no doubt require constant improvements and upgrades to keep up.