NEWSFLASH: SBS Transit and SMRT will offer commuters free use of all bus services calling at designated bus stops and interchanges in close proximity to stations, in the event of an extended MRT service disruption.
This was a result of the Land Transport Authority working closely with both operators to improve incident management measures and it was announced in a joint statement on Tuesday afternoon.
Both transport operators have also agreed that fares on these free bus services will be borne by the operator of the disrupted MRT line.
Citation: http://www.straitstimes.com/BreakingNews/Singapore/Story/STIStory_769006.html
Unlike Japanese megalopolis, Singapore has no competing railways. So, alternative transportation would be bus service.
In Japanese megalopolis, if a railway has to suspend its operation due to an accident, parallel railways are supposed free service only for those who have commuter tickets of the former railway. When we take bus service in Singapore as parallel railways in Japan, the measure is reasonable.