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Kerbs and phased lights keep cars and bikes apart

Left hook collisions — where a motor vehicle turning left hits a cyclist — were involved in nine of London’s fourteen cycling deaths in 2013. Now the borough of Camden is to get what's believed to be London’s first intersection specifically designed to make a left hook collision impossible.

Known as Cobden Junction, the intersection of Crowndale Road, Eversholt Road and Camden High Street is currently a mess of traffic lights and one-way streets with no provision for cycling. Or, in other words, a typical London intersection.

The dreaded left hook
The dreaded left hook

A proposal from Camden Cyclists — the local branch of the London Cycling Campaign — would replace the current junction with one that uses kerbs between lanes and cycle-specific lights to eliminate the chance of a left hook. Yesterday, the borough’s cabinet member for sustainability, transport and planning, Phil Jones, approved the plan.

According to Camden Cyclists coordinator Jean Dollimore, that means the modification will definitely go ahead. "Officers plan to start in July and complete by the end of 2014-5 financial year," she told road.cc.

Camden Cyclists had criticised an earlier proposal for the junction as “exposing cyclists going straight ahead to unacceptable left hook risks.”

The group’s proposal will allow cyclists to move off from the junction ahead of motor traffic, so they are able to cross the junction before a separate traffic lights phase turns green for drivers.

Here's how it would work for a crossroads — a T-junction is similar, but simpler:


Lights for cycles and for cars going straight ahead are green. Cars turning left are held by a red signal.


Turning cars have a green light while both cycles and cars going straight ahead wait at red lights.

The design was based on an idea described independently by Rik Andrew and Paul James.

Ms Dollimore said that Cobden junction is a good place to start with a prototype implementation of a protected junction. 

She said: "It is made up of a pair of T-junctions and the design would be much less complex than for a cross roads  as there are many fewer potential conflicts from the choice of ways in and ways out — maybe 2 x 2 instead of 3 x 3.

"At Cobden there would be several serious risks of 'left hook' without this design. Also the passage through the part between Eversholt Street and Camden High Street is tricky without a way of safely protecting cyclists."

Camden Cyclists had originally proposed a contraflow cycle lane on Crowndale Road to provide a better west-east route through the area, but that was turned down because of concerns over conflicts with busses.

On Camden Cyclists’ website, Ms Dollimore wrote: “Since we had been very critical about safety for cycling through the junction, we had further discussions with Camden officers and eventually had to decide between safety and permeability.

“Since safety must come first and also the contraflow was unlikely to be agreed, we asked Camden to implement a 'cycle segregated junction' – one that eliminates the possibility of left hooks.

“The officers' report is now on Camden Council's website and the papers include a drawing for a pair of cycle segregated junctions on Crowndale Road – one at Eversholt Street and the other at Hampstead Road.

“At each junction left turning motors are held on red while cyclists and straight-ahead motors get a green. Then when the left turning motors get a green signal, the cyclists and straight-ahead motors get a red.

“In the drawing below you can see the kerbs separating the cyclists and the left turning motors  and another kerb between left turning and straight ahead motors. The kerbs are needed for the different signals.”


Cobden Junction with kerb-separated cycling lanes to prevent left hooks. Click for much larger image.

Cycling provision on London’s streets is guided by Transport for London’s London Cycling Design Standardswhich are currently undergoing a revision process.

Ms Dollimore said: “Camden is being quite innovative in doing this because TfL haven't yet issued their LCDS version 2 which promises to describe designs for this type of junction.”

Note: an earlier version of this story claimed this was the UK's first such junction. It has been brought to our attention that Cambridge previously had a separated left-turn junction on Hills Road.

Our official grumpy Northerner, John has been riding bikes for over 30 years since discovering as an uncoordinated teen that a sport could be fun if it didn't require you to catch a ball or get in the way of a hulking prop forward.

Road touring was followed by mountain biking and a career racing in the mud that was as brief as it was unsuccessful.

Somewhere along the line came the discovery that he could string a few words together, followed by the even more remarkable discovery that people were mug enough to pay for this rather than expecting him to do an honest day's work. He's pretty certain he's worked for even more bike publications than Mat Brett.

The inevitable 30-something MAMIL transition saw him shift to skinny tyres and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.