Build-Outs and Chicanes

Build-outs and chicanes are useful tools for local authorities intent on making streets calmer, safer, and more cycle-friendly.

From a cycling point of view they are of course not as good as physically-protected cycle tracks, but build-outs and chicanes can nevertheless be helpful – provided they come with cycle bypasses.

What are Build-Outs and Chicanes?

A build-out is a section of kerb built out into the carriageway on one side only to narrow the road, as pictured at the top of the page. A chicane uses two build-outs a short distance apart to create a wiggle in the road, and the stretch between the build-outs can be either single lane or two-way.

Here are a few interesting (well, it’s subjective of course) points on build-outs and chicanes, also known as horizontal deflections, from LTN 1/07 on traffic calming:

• drivers dislike them more than speed bumps (6.1.1)
• they only work to reduce a vehicle’s speed if there is opposing traffic (6.1.2)
• given 6.1.2 above, even vehicle flow is important if they are to work well; on residential streets with low flow or tidal flow, it’s unlikely that vehicles from opposite directions will meet at the narrowing (6.1.3)

As I mentioned above, build-outs and chicanes are only beneficial for cycling where there is a cycle bypass, as on Main Street Heslington.

Other types of narrowing include pinch points (road narrowed from both sides), pedestrian refuges, and traffic islands. These designs rarely have cycle bypasses, and in my experience they are dangerous to cyclists because drivers either attempt last-minute overtakes before the narrowing, or make dangerous close passes at the narrowing.

This fact is recognised by the guidance, which specifies widths to avoid in designing narrowings.

I doubt many local authorities pay attention to this guidance and avoid the proscribed widths.

Build-Outs and Cycling

A build-out can be connected to the kerb, or there can be a gap – which may be a drainage channel or a cycle lane. Sometimes it’s hard to tell what it’s meant to be!

I really like the three build-outs on Main Street Heslington. There’s enough traffic that you often do get two or three cars waiting at the build-out while you sail through the cycle bypass. The advantages are:

• it slows vehicles down
• drivers are less inclined to perform Must Get In Front overtakes, because they know they will have to stop again at the next build-out
• if a driver does overtake you at a build-out, they are physically forced to move right over to the other lane and give you lots of space

Are the Heslington build-outs perfect? No, not according to Cycle Infrastructure Design which says that the cycle lane should be at least 1.5m wide.

The Main Street cycle bypasses should be wider than they are, to allow for all types of cycle. I haven’t found that debris collects in them – maybe they are swept the old-fashioned way with a stiff-bristled broom?

Chicanes

Chicanes are in effect wiggles in the road. The tighter the turns, the greater the reduction in vehicle speeds (6.6.5 LTN 1/07). A DfT study showed average speed reductions of 12mph.

I’m surprised drivers don’t like them, as it’s an opportunity to pretend to be Lewis Hamilton – something 31.7% of those behind the wheel are keen to do nearly all the time.

A cycle bypass of the chicane should be provided.

LTN 1/07 says you might have to sweep a chicane’s cycle bypass with a broom.

A Badly-Designed Chicane

In my view the chicane on Bogs Lane, Harrogate, is badly designed for cycling.

There’s a gap between the build-out and the verge. Is it a cycle bypass? I don’t know.

If you did ride through the might-be-a-cycle-bypass, it would spit you out onto the main carriageway, into the path of any vehicle travelling in either direction. That makes it potentially dangerous.

Where Would You Put Build-Outs?

Build-outs and chicanes may be a niche and technical subject, but at the same time the details could be very important in creating a decent cycle network where you live.

If your local authority places build-outs like the Heslington ones on a suitable road, it could help existing cyclists feel safer, and encourage more people to get on bikes.

On the other hand, a council that uses dodgy chicanes like the Bogs Lane one isn’t doing anything helpful for cycling, and may be harming it in a small way.

Claro Road in Harrogate has a fairly even flow of traffic, much of it large commercial vehicles plying to and from the industrial estate at the northern end. To create protected cycle tracks, you would have to cut down mature trees – unlikely to be popular.

Claro Road would be a candidate for build-outs with cycle bypasses.

Are there any roads where you live that would benefit from build-outs?