About 30 people from the Klimax climate action group formed a line across the road at 12.30pm on Saturday. The activists were reportedly keen not to break any laws and waited for the green light on the pedestrian crossing before shuffling over the road near Tegsbron bridge in the centre of the northern Swedish city.
The activists carried their message on banners and signs which argued for a reduction in car use, investment in public transport and to act now to save the environment.
Cars began to back up on the E4 bridge as the activists held up traffic. When the queues were at their longest the police diverted traffic over the alternative bridge, Kyrkbron. Police considered acting to remove the activists as car-drivers began to show their irritation but they dispersed by themselves with the minimum of fuss.
Sara Svensson at Klimax explained that the group's intention had been to generate interest in climate issues and not attack individuals.
"I think that it is working, people wake up and realise that they have to do something. As neither the media nor politicians are addressing the issue, we have to," Svensson told local newspaper Västerbottens Folkblad.
The town of Umeå has a long history of activism with vegan and animal rights movements particularly prominent in the town.