Construction started in 1986, part of a wider push to unblock the region's infrastructure and its economy. More than 500 people worked on the project, and many of them did not commute to it — they relocated, moving into quarters built on the construction site and living beside the work for the duration.

The hardest problem was the middle of the channel, where the piers had to go and the water was deepest. The solution was to build steel sheeting out into the river, seal it, and pump the enclosed section dry so crews could work on the exposed bed. Into that dry pocket went P300 concrete for the central pillars — a Vietnamese grade specification, poured to a standard set for a bridge that would have to carry the whole country's traffic on one deck. Then the sheeting came out and the river came back.

The finished structure runs 630.5 metres over thirteen spans, and it is not one bridge so much as four techniques stitched together. A prestressed reinforced concrete T-beam carries the leading span. Steel truss girders take the main channel, the deep-water stretch where the pumped-out cofferdam had stood. Two simple beams of 53 metres each and three continuous girder spans make up the rest.

It opened to traffic on 19 May 1990, the anniversary of Hồ Chí Minh's birth. When it opened it was the second-longest bridge in Vietnam, and the first permanent crossing of the Cả River in the region's history. Nghệ An and Hà Tĩnh, which had been fifteen minutes and an indefinite wait apart, were suddenly one drive.

The bridge's importance became clearest when it stopped working. Between 2009 and 2010 a series of serious motor accidents raised real concerns about the structure's integrity, and engineers began closing it without warning to run structural tests. Each closure backed up traffic into the thousands of vehicles.

There is a bleak logic to that. A bridge that nobody misses is a bridge nobody needed. Twenty years after opening, Bến Thủy was carrying so much of Vietnam's north-south freight that taking it out of service for an afternoon produced queues visible from the air. The jams were not an argument against the bridge; they were the strongest possible argument for a second one. In 2010 the government announced exactly that.

Bến Thủy Bridge 2 opened in September 2012, a box girder structure 996 metres long, built alongside its predecessor to take the through traffic off it. National Route 1 now runs across the newer bridge, bypassing Vinh, and the 1990 span has become part of the old road — local journeys, commuters between the two banks, the kind of traffic it was originally sized for.

It got its first major overhaul in 2014, closing for three months. That is a striking number: twenty-four years of continuous service before the first significant repair, on a bridge that had absorbed far more load than anyone specified in 1986. What began as the fix for a three-ferry bottleneck now works as the local alternative to the road that replaced it — a demotion that is really a kind of retirement, and better earned than most.