The call came ahead of a protest ride in memory of Dr Marta Krawiec, the paediatrician killed by a left-turning HGV near Holborn station last month as she cycled to work at St Thomas’ hospital.
More than 7,000 people have signed a London Cycling Campaign petition demanding rapid action to prevent further deaths at the capital’s most lethal junctions.
The LCC estimates there are more than 100 junctions that present a substantial risk to cyclists. It said many recent upgrades had only been partial solutions.
Dr Krawiec, 41, was the eighth cyclist to be killed at Holborn since 2008 – and the fourth at the junction of Theobalds Road and Southampton Row.
Transport for London awarded Camden council almost £9.5m two years ago to remove the Holborn gyratory and introduce protected cycle lanes but nothing has happened, partly because of the pandemic.
Simon Munk, campaigns manager at the LCC, said the introduction of temporary barriers and pavements to encourage cycling and walking during the first wave of the pandemic showed safety measures could be introduced speedily.
The LCC says the so-called “London boulevard” - the east-west stretch linking Old Street and Holborn - is a priority for action because of its heavy cycle use and numerous dangerous intersections.
The protest ride will set off from Barbican at 6pm. Flowers will be laid at Holborn, followed by speeches in Russell Square.
Pointing to recent changes to Bank junction and to Bishopsgate, Mr Munk said: “We have seen TfL and other boroughs start to work with temporary materials, which can be done without spending millions.
“The last thing we want to do is go back to the old, slow way of working. Doing this work in temporary materials is feasible.”
In 2017, Mayor Sadiq Khan pledged action at 73 dangerous junctions. According to the LCC, changes demanded by a coroner following the HGV death of cyclist Lucia Ciccioli at Lavender Hill only make one leg of the junction safer.
Similarly, changes at Battersea Bridge following the death of jogger Jack Ryan in January this year introduced a pedestrian crossing but there was no added protection for cyclists.
Mr Munk said: “Over and over we see junctions like the one that Dr Krawiec was killed at, known for years to be dangerous, lethal even, left untreated.
“The mayor’s ‘Vision Zero’ of a London free of serious and fatal collisions 20 years from now is meaningless without comprehensive action on dangerous junctions.
“The mayor and boroughs must act faster, be bolder and dismantle the systemic barriers stopping us making roads safe for all.”
TfL said that TfL work had been completed at 43 junctions so far as part of the safer junctions programme, including Rotherhithe roundabout, Highbury Corner and Charlie Brown’s roundabout.
It said Camden council was “urgently leading on proposals for short, medium and long term improvements” to the Theobalds Road and Southampton Row junction.
Will Norman, London’s walking and cycling commissioner, said: “We are now urgently working to support Camden to deliver short-term measures to reduce road danger in Holborn, as well as investigating longer-term proposals to improve cycling safety in the area.”