Are “sinusoidal” speed bumps the way to reduce traffic speed, or should West Hampstead’s Sumatra Road become one-way?

Last year we had cycle permeability, 20mph zones, and debates over “table humps” to slow traffic. As 2013 hoves into view, Camden is launching a consultation on how to reduce traffic speeds on Sumatra Road by converting the existing speed cushions into sinusoidal road humps.

A speed cushion

Sinusoidal speed bump

Ok, lets get it out of the way: sinusoidal definitely sounds like a medical condition. In fact, a sinusoidal road hump has a less severe profile than old-style speed bumps but apparently is also effective at reducing speeds.

The speed limit on Sumatra Road was reduced to 20mph last year. A raised junction was also built at the junction with Glenbrook Road. During the consultation for this, some residents told Camden they felt the existing speed cushions were not bringing car speeds down enough, and the idea of turning Sumatra into a one-way street was mooted.

Indeed, I was cc’d on a chain of e-mail correspondence between one Sumatra resident and the council. The first mail, from Septmeber 2012, was trying to cultivate support for making Sumatra Road one-way to control speeding traffic.

“There is a children’s playground on our road and the number of speeding cars and large lorries is a danger to children and families that live on this residential street,” went the argument. “There is also only room for one car on Sumatra Road and traffic often builds up as cars refuse to reverse to let others through.”

The resident reckoned that a one-way sign placed at one end of the road would be a “cheap and common sense solution to this problem of public safety.”

Back in October I received a similar mail from another local.

“As someone who drives around [Sumatra Rd and surrounding streets] a couple of times a week they’re certainly narrow and it’s difficult to see round the corners because of all the parked cars. I think if there was a way to make them one-way it would be more useful than a 20mph limit, but I guess that’s also more expensive.”

Camden’s response to the one-way idea:

“In general it is against our policy to introduce one way streets as these often lead to increased speeds as vehicles do not have to deal with any opposing traffic and hence can speed up.

Making the road one way could potentially increase the volume of traffic as more drivers would find it an attractive option given they would not face any opposing traffic. In addition, traffic would potentially be displaced to nearby streets as they would not be allowed to use Sumatra Road in one direction.”

The change in type of speed bump is partly a reaction to these complaints. The road accident data shows that in the three years to the end of February 2012,there were six accidents along Sumatra Road, of which two resulted in serious injuries.

The proposal is therefore to convert the speed cushions into these sinusoidal road humps along the full length of Sumatra Road.

There’s also a plan to convert an existing 15 metre shared use parking bay into a 15 metre pay & display only parking bay outside the Solent Road Health Centre. This follows a request from the clinic to provide short-term parking facilities for visitors. The proposed pay and display parking will operate Mon–Fri 08:30–18:30 and would mean permit holders will not able to park in these three spaces during these hours.

If agreed, all this will happen in early 2013 and will be funded by TfL.

To give Camden your views, complete this questionnaire and return it by 25th January 2013 to: London Borough of Camden, Culture and Environment Directorate, Transport Strategy Service, FREEPOST RLZH–UEYC–ACZZ, Argyle Street, London, WC1H 8EQ. Or send a separate response to each question to (you must include your postal address though).