A protest over the road death of a 13-year-old boy left motorists stranded in near-freezing conditions for almost five hours.
Demonstrators blocked the A127 near Basildon, Essex, from around 9.45pm by parking cars across two lanes of the busy route into London.
The group staged the protest close to where a teenage boy was knocked down and killed on Monday.
Several of the group were pictured standing on top of a 4x4 daubed with slogans in white paint.
In photos posted online one of the cars had the message "We want a footbridge - How may more?" scrawled across its side.
However the handling of the protest by police caused anger among some of the motorists caught in the tailbacks.
Sarah_T_182 wrote on Twitter: "a127 still not moving! Been here since 10pm, it's freezing and no one is getting anywhere!"
Meanwhile obi_ben_n tweeted: "An hour and a half stuck still on the A127 whilst protesters wander up and down drinking beer. @EssexPoliceUK pull your finger out."
"No sleep tonight it is then..... #StuckOnRoad #A127" said endersusf.
Those stuck in the jam said they were only permitted to U-turn after around four hours at a standstill.
An Essex Police spokeswoman said they worked hard to "achieve a resolution as quickly and safely as possible" and several diversions were put in place.
Officers were called to the scene at around 9.45pm on Tuesday where they found a "large number of people and vehicles" had blocked the highway.
A helicopter was eventually scrambled to monitor the crowd and both carriageways on the London to Southend arterial road were closed until around 2.45am on Wednesday.
The force earlier said a 31-year-old driver of a BMW car involved in the incident at around 8pm on Monday was arrested and bailed pending further inquiries.