How did the building of the Tay and Firth bridges come about?

Two great estuaries lie north of Edinburgh: the Firth of Forth and the Firth of Tay.

The Firth of Forth begins at the ancient town of Stirling and runs 50 miles to the east, where it emerges into the North Sea. Edinburgh is situated on the southern bank at the mouth of the estuary, 30 miles east of Stirling. Eleven miles west of Edinburgh, at Queensferry, the firth narrows down to about a mile in width, but the water is still between 40 and 60 feet deep depending on the tide.

The Firth of Tay lies about 25 miles to the north of the Forth: it begins at Perth and runs east for about 25 miles until it too meets the sea. At this point, near Dundee, the Tay is 1.5 miles wide and is up to 80 feet deep.

The two Firths have always been a major barrier to communications from and to Edinburgh. A passenger who wanted to go from Edinburgh to Dundee and perhaps on to Aberdeen, had to travel the long way round through Stirling and Perth, adding about 60 miles to their journey.

Alternatively, the passenger had to endure two ferry crossings, across the Forth from Granton to Burntisland and then across the Tay from Tayport to Broughty Ferry. The fastest boat train of the day left Waverley station at Edinburgh at 6.25 a.m. and was timed to arrive at Dundee at 9.37 a.m., a journey time of 3 hours 12 minutes for a distance of only 46 miles - at an average speed of only 14 mph! In bad weather, the ferries might not run at all; if they did the hapless passengers would probably arrive cold and sea-sick.