When did Singapore gain a mainland rail connection?

Were railway lines connecting Singapore with mainland Asia available during this period?

Singapore had an earlier island railway, and the Johor-Singapore Causeway added the mainland rail connection in the late 1920s.

A viewer asks whether Singapore was connected by rail to mainland Asia during the base debate. The answer distinguishes the island's earlier railway from the later cross-strait connection. The Johor-Singapore Causeway carried the railway link and was completed in the late 1920s. This transport infrastructure connected the naval base and port to Malaya, rather than leaving Singapore as an isolated island installation.