A group campaigning for fathers' rights has warned that a series of protests on bridges is "just the start" of a nationwide campaign of civil disruption.
The protesters are campaigning for better access to their children
Several members of Fathers 4 Justice climbed bridges and gantries in Bristol, London and Newcastle on Monday, causing widespread traffic disruption.
Bristol's Clifton Suspension Bridge remained closed to traffic on Monday night, after three protesters dressed as cartoon super-heroes remained on it.
One protester also remained on a gantry above the westbound
carriageway of the A13 in east London, although the road stayed open.
Four other protesters were arrested in London after climbing gantries across the M4 and A40 and at the Blackwall Tunnel.
In the Bristol protest, four men dressed as Batman, Superman, Spiderman and Robin unveiled banners reading: "Fathers 4 Justice Fighting for your
right to see your kids."
By Monday night, one of the protesters had left the bridge but the other three pledged to sit tight despite bad weather.
Spokesman Jeff Skinner said: "It's cold and it's wet but we are staying put
and are not giving up. We will be here for the foreseeable future."
Mr Skinner said the men wanted to raise awareness of the "unfair" system of child access.
"All motorists have been denied access to the Suspension Bridge... as all our members are denied access to their children," he said.
An Avon and Somerset police spokesman said: "All efforts are being made to peacefully resolve the
situation as quickly as possible, though there is no indication of when the
protest will end."
In London, one man was arrested after protesting on a gantry above the A40 in west London,
while another two were arrested after they protested on a gantry above the
entrance to the Blackwall Tunnel in east London, which was shut northbound for a time as a result.
The fourth was arrested after protesting on a gantry above an elevated section
of the M4.
The westbound carriageway of the A13 near Prince Regents Lane, where the fifth protester remains, was reopened after having been closed for some time during the day.
Fathers 4 Justice said it was planning to disrupt roads, railways and courts in a campaign of "widespread civil disobedience".
Spokesman Matt O'Connor said his members were ready to go to jail in their campaign of peaceful protest.