However the worry was short-lived and, after being inspected by specialists, the viaduct was deemed safe and only in need of small repairs, which would take place overnight and did not jeopardise its safety.
Early reports queried whether the flyover was at risk of collapsing, although those concerns were quickly dispelled by authorities.
Early on, radio station TSF reported municipal police had said there was a risk that parts might fall off the viaduct due to a problem with one of its expansion joints.
This problem was apparently pointed out to authorities by a local, which resulted in traffic in and around the area being diverted.
However, it wasn’t long before the issue had been checked out and traffic slowly returned to normal, first trains, then road traffic.
Speaking at around 11am on Wednesday morning, Lisbon Councillor, Manuel Salgado gave pubic assurance that the overpass “is not at risk of collapsing” but was in need of repairs.
The loosened joint is believed to have been caused after a lorry ran into the pillar.
The councillor recalled that the viaduct in question was inspected on 13 February this year and showed no signs of problems, and had also had restoration work carried out on it in 2005.