Very good Observation...
Pamban Bridge is need as it is Old Bridge for more than 100 Years Now it's time to Build New Bridge for safety reason...
As far as Electricity concern... Govmnt also Working on Green Energy instead of Coal Generated Electricity Hence Solar power capacity increase day- by-day
There are so many section where less than 4 Pair of train but...
more... this section used fir freight traffic after Electrification