The climate group Insulate Britain is holding its tenth day of protest in the past three weeks.
The organization said around 30 of its activists had blocked roundabouts at junction 3 of the M4 near Heathrow Airport in west London and junction 1 of the M1 at Brent Cross in north London.
Drivers stuck in long traffic jams honk in frustration.
Insulate Britain said protesters include eight people who were released from police custody Thursday after blocking the M25 at Junction 30 in Essex and others arrested earlier this week.
It has pledged to continue its actions until the government makes “a strong statement suggesting that it will isolate all 29 million leaky houses in the UK by 2030”.
The group said in a statement: “It is incomprehensible that the government continues to delay home insulation measures when we urgently need to cut our carbon emissions, eradicate energy poverty and help hard-working families with their rising energy bills.
“Also, the industry is crying out for the government to show leadership and get behind a national retrofit strategy. Come on, Boris: keep working. “
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