Tay Bridge disaster warned of their unreliability, and declined to estimate conditions at Dundee from readings taken elsewhere. One modern interpretation of available information suggests winds were gusting to . Usage of the bridge was restricted to one train at a time by a signalling block system using a baton as a token. At 7:13 p.m. a train from the south (consisting of a 4-4-0 locomotive, its tender, five passenger carriages, and a luggage van (brake van) slowed to pick up the baton from the signal cabin at the south end of the bridge, then headed out onto the bridge, picking up speed.
Tay Bridge disaster had a good view of most of the bridge from his house in Newport-on-Tay but other buildings blocked his view of the southern high girders. He had seen the train move onto the bridge; then in the northern high girders, before the train could have reached them, he saw "two columns of spray illuminated with the light, first one flash and then another" and could no longer see the lights on the bridge – the only inference he could draw was that the lit "columns" of spray – slanting from north to south at about 75 degrees – were areas