No one was injured in the collision, which happened at around 6am when the trains were being reconnected in the railway yard.
But an area of around 600 metres from the scene of the accident was cordoned off on Tuesday morning, and several buildings were evacuated, including a school and a nursery school.
Trains were also prevented from passing the scene of the accident, Sävenäs marshalling yard, which affected traffic to and from Gothenburg to Stockholm, Alingsås and Skövde.
In the afternoon, traffic had resumed, but knock-on delays were to be expected.
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One train car was carrying ethylene oxide – which is a toxic and flammable gas – and another hydrogen peroxide, which is a corrosive substance, and fire services initially warned of a “very high” risk of explosion.
But by 11am it had been established that the train cars were not leaking.
Shortly after 3pm, the cordoned-off area had been reduced to around 100 metres, but people in the area were still encouraged to be careful and keep up-to-date with health and safety announcements in the area.