Climate campaign group Insulate Britain is holding its 10th day of protests in the past three weeks.
The organization said around 30 activists blocked roundabouts at junction 3 of the M4 near Heathrow airport, west London, and junction 1 of the M1 in Brent Cross, North London.
Drivers stuck in traffic honked their horns in frustration as long lines formed.
Isulate Britain said the protesters included eight people released from custody Thursday after blocking the M25 at Junction 30 in Essex, and others who were arrested earlier this week.
He pledged to continue his actions until the government makes “a meaningful statement that it will isolate all of the 29 million leaking British homes by 2030”.
The group said in a statement: “It is incomprehensible that the government continues to delay action on home insulation when we urgently need to reduce our carbon emissions, end fuel poverty and help working families. hard with their growing energy bills.
“In addition, the industry is asking the government to show leadership and support a national modernization strategy. Come on Boris: keep up the work.
The government obtained an injunction last week, which means anyone blocking the M25 could face contempt of court, with a maximum penalty of two years in prison or an unlimited fine.
Insulate Britain admitted its actions this week violated the injunction.
Sir Stephen House, Deputy Commissioner of the Metropolitan Police, told the London Assembly Police and Crime Committee on Thursday that he feared the police would be under so much pressure to quickly eliminate the protests that ” officers put their lives in danger ”.
“The most recent one I saw had officers running between articulated trucks moving on the main roadway of the M25,” he said.
“We can’t do that. We cannot put people’s lives in danger. The lives of my officers in danger and in fact that of the demonstrators in danger. We have to pay attention to it first. But we were very quick to move these people and arrest them. “
He added: “They started on the suspenders, which is bad enough, but now we have moved to the main carriageways of the M25, which is absolute madness. “