sentences:  There were plans in the 1990s for a Mass Rapid Transit line to be extended towards Pulau Ubin and Pulau Tekong thus cutting across the harbour.The building of bridges or tunnels to link mainland Singapore to these islands were also considered so as to make these islands more accessible, in view of future plans to build light industries and high density housing on both islands, however due to environmental concerns and other complications the plan was shelved.There were also proposals to build a third causeway between Singapore and Malaysia with one of the suggestions being the bridge be built over the southern end of the harbour, linking Changi, Singapore and Pengerang, Malaysia, however Singapore had rejected the proposals in favour of the Kuala Lumpur–Singapore high-speed rail project and this led to the proposal being scrapped by 2016.