The Mumbai Trans Harbour Link (MTHL) which is the longest sea bridge in the country, will be inaugurated on Friday, January 12. Here’s the first look of India`s longest sea bridge Mumbai Trans Harbour Link the `Atal Setu`. The Mumbai Trans Harbour Link is constructed at a cost of around Rs 18,000 crore. The MTHL is a 6-lane sea link, with 16.50 kilometres of the stretch on the sea and 5.5 km on land. The Maharashtra cabinet had last week cleared a proposal to charge Rs 250 as toll amount for cars for using the Mumbai Trans Harbour Link (MTHL).