Complex sentence: A report published by SBT in 1987 looked at details for a subsea tunnel to the mainland, and was the first official document to use the "Triangle Link" term, although this had previously been used by the press.
Split into simpler sentences: A report published by SBT in 1987 looked at details for a subsea tunnel to the mainland. It was the first official document to use the "Triangle Link" term, although this had previously been used by the press.