Cycleway Effective Width

The Bee Gees asked, “How deep is your love?”, Patti Page “How Much is that doggy in the window?” and I ask, “How wide is that cycleway?” We were never provided with answers to the first two of those big questions, but I will endeavour to do so for the latter.

So, riddle me this; When is a cycleway narrower than it is wide? It might seem obvious but you’ll no doubt know that you cannot ride on every centimetre of tarmac across the cycleway in front of you.

The “Effective width” refers to the usable width of a cycle path and this is determined by various features that we typically see alongside the route. In a lot of instances, the useable width is significantly less than the absolute width.

Watch this video of a ride from the Roundhouse building of Derby College (The other DCG in town) heading towards the riverside gardens and see if you can spot anything that reduces the usable width of the cycleway.

So, what features did you see?

Walls and Fences

Clattering your handlebars against railings, clipping high kerbs with your pedals and riding right up against a wall could leave you with grazed knuckles, bruised elbows, bloodied knees and broken toes. In addition to the extra width required to accommodate handlebars, our natural instinct is to give some wiggle room between bars and wall or “kerb shyness” to use a highway term.

Lighting columns and signposts

Since lighting columns and signposts are typically higher than handlebar height, the rider must give them the same wide berth as they would for walls and fences.

It’s particularly frustrating that lighting columns are positioned immediately adjacent to cycleways when there is usually plenty of space further away in the verge.

Vegetation

Trees and bushes, if left unmanaged, can encroach the cycleway from the sides and above. Nobody wants a mouthful of leaves so we duck and dive around vegetation when we should be concentrating on the way ahead. Overhanging branches also impede vision ahead – This image doesn’t really do justice on the hinderance this branch causes but it’s definitely due an early morning visit with a pair of loppers.

Sight lines

Only superheroes can see round corners so people on bikes invariably take a wider berth when negotiating blind corners or even slow down to a crawl.

Here we see a vertical wall hampering the view around a tight radius which is compounded by the overhanging vegetation.

Passing under Holmes bridge as well as being a popular hangout it’s also where you’re most likely to have a head on collision with a pedestrian or another cyclist such is the poor sighting around both sides of the underpass. And whether it’s rained recently or not there are always those two puddles at each end to add further peril to your journey!

Puddles

Speaking of puddles, hollows in the tarmac surface collect water, leaves and other debris. The rider is naturally cautious of riding through puddles, not only to protect their designer trousers from splashes, but the puddle could be hiding a deeper hole or built-up silt may result in loss of traction. It is therefore perfectly valid that the presence of puddles reduces the effective width of a cycleway.

Manholes and gully grates

Manhole covers are typically made of cast iron. Some effort is made to provide an anti-slip surface but on the whole, they’re designed for car tyres and not higher-pressure thin bike tyres. Overtime, cast iron gets polished with the passage of traffic. Gully grates potentially are a hazard but can generally be ridden over, provided the openings run transverse to the direction of travel. All in all, as a rider I tend to avoid passing over them or making sudden movements if riding on them.

Cycle lane alignment and geometry:

Sharp right-angled bends cannot be negotiated on a bicycle without making a wider sweeping turn – The bridge over the Mill Fleam is a prime example where it’s often difficult for two riders to pass.

Pedestrian guard railing compounds the already restrictive alignments found on many crossing islands. It can often be impossible for users of tandems or adaptive cycles to negotiate the route which requires twisting and turning through a narrow passage.

Street Furniture

A helpful pointer sign, somewhere to dispose of one’s rubbish or a place to rest those weary legs are all items of street furniture. But an overabundance and poor thought on their positioning has resulted in the term street clutter being coined. While there wasn’t a lot to note on the ride in the video, it is a common annoyance that is encountered on a ride. Lighting columns, telecoms cabinets, bins, bollards, pedestrian guard rails and advertising boards are strewn across cycleways with little thought to the users of said paths.

Parked cars:

Although not seen in the video, which was traffic-free, the presence of cars parked along a route will narrow the effective width two-fold. Firstly we don’t want our handlebars scuffing peoples’ pride and joy and secondly you never know when someone might fling open their razor-edge car doors. Avoiding the door zone is something novice riders may learn the hard way, so leave a healthy buffer or build one in if you’re an infrastructure designer.

So why is a reduced effective width something to be concerned about?

• Inhibits passing other users safely
• Slows down journeys by preventing riders from travelling at a consistent speed.
• Braking and then accelerating back up a normal riding pace expends a lot of energy
• Riders on adaptive bicycles, trikes, hand cycles etc may not be able to physically pass other path users.
• Riders’ attention is on the surface rather than on other cycleway users and hazards.

What can be done to improve the effective width?

Good design is the key. New roads aren’t designed with obstacles in so why should cycleways be any different?

• Good drainage to prevent build up for debris, ice and prevent surface degradation.
• Position lighting columns and street furniture at least 500mm from the cycleway
• Set manholes and cabinets into the verge or use covers that are flush with the surface.
• Design an alignment that is smooth and flowing.
• Use high-splay kerbs as they are more forgiving than traditional road kerbs.
• Where cycleways are designed adjacent to parked cars, a 500mm minimum buffer is required – (Although car doors open further than this)
• Manage vegetation high and low that encroaches within a metre of a cycleway.

Requirements document. CD 195 “Designing for cycle traffic” and “Guidance and good practice document for cycle infrastructure LTN 1/20” acknowledges that effective widths are not always possible to achieve due to existing physical constraints but along virtually all of the route in the video, the effective width was always compromised.

The figure below is from CD 195 and it illustrates the required allowance for each edge constraint when designing new cycleway infrastructure. In the same standard it notes that the required allowances for gullies (and manholes) shall be the width of the gully grate or manhole cover.

In effect for an existing route where there are sign posts, railings or walls on both sides of the cycleway, the width of the path is reduced by a whole metre! That’s a lot of wasted tarmac that will never see a bike tyre on it.

Closing remarks

Riding a bike is more than about balance – With only a small contact patch between the tyres and the surface deciding where you put your front wheel in a smooth and timely manner is the difference between sliding into the verge or staying up right. Good cycleway design and implementation means there should be less focus on the front wheel and more on the views and other people around you.

What looks ok on an engineering drawing may not be used in the manner the designer intended. That’s why it’s vital that cycleway designers are themselves regular users of routes. On high-quality user-designed infrastructure you don’t have to be hyper focussed on the surface and people’s commutes or rides to the shops become less stressful.