shared path joining between roads

Doing Permeable Wrong

Poorly integrated incremental additions continue to be the method of choice in Melbourne with the opening of a permeable passage on an already popular bicycle route. It is notable in that where permeable routes typically connect straight through with good visibility, this example takes a dead end road straight into a cross street.

Where cyclists previously jumped kerbs and squeezed between parked cars a suspiciously adequate bidirectional shared path is installed but the dropped kerbs were hastily grafted to the existing segmented road surface with a veneer of tarmac, making the overly tight turn to/from the road quite challenging.

shared path terminates into narrow road

From this view the poor sight lines can be seen and the routinely parked vehicles narrowing the useable lane width to 6m (20 feet) for bidirectional traffic which includes heavy articulated trucks. Within days of opening cars had already been seen using this convenient connection, and the number of obvious tire tracks indicated it was quite popular. One day between the morning and evening commute these appeared in the path:

bollards added in middle of shared path

No warnings, just some new posts right in the middle of the unlit path which I collided into in the dark while exiting the road and concentrating on the traffic around me.

We can refer to the Australian guides on design of these “Terminal Treatments”:

it would be inappropriate to locate terminals at or near curves, within a distance of less than 5 m of kerb ramps or within a manoeuvring zone of cyclists

Check, check, and check, all criteria simultaneously failed by placing the bollards so close to the kerb that cyclists are still leaning over through the turn off the road. Bollards should also:

Be painted in a contrasting colour (white or yellow) and be fitted with quality reflective tape on horizontal and vertical elements to ensure it is visible from all directions

Here we have white on white, that most contrasting of known combinations and the reflective tape can be added later. The entire structure should:

Be illuminated in accordance with AS/NZS1158, or with the lighting requirements of this guide, as appropriate

But no illumination here. And finally:

a minimum opening width of 1.4m is appropriate to encourage slower speeds

As the other guidance has been ignored so it should be fine to add more hazards to the design with a 1320mm (4 feet 3 inches) opening. And this is where the people responsible for the infrastructure again fail to understand that bicycles are not statically stable like a car. When turning corners a bicycle leans over and widens its swept volume considerably. The design guides specify a minimum radius curve of no less than 10m (33 feet) which in this alignment is not possible to achieve. Instead, keeping to the left of the road before turning into this path would yield a radius of curvature of less than 4m (13 feet).

From this we can calculate the angle a cyclist would be leaning at to maintain just 15km/h (9 mph) through such a curve, and overlay it onto the design:

bicycles and car trying to fit between bollards

Placing an upright cyclist to the extreme right to show both oncoming users, and the point about which a cyclist would rotate when leaning into the corner less than 100mm (4 inches) of clearance are present on either side of a typical bicycle to allow for the rough surface or any other obstacles. Clearly there is not enough room for bidirectional traffic and should any problem occur making an emergency stop across following vehicles is sure to end in disaster.

For comparison an average Australian car is placed behind bollards with an 1800mm (6 feet) gap, bizarrely the design guides recommend a width of 1400mm (4 feet 7 inches) or 1600mm (5 feet 3 inches) to enhance safety, despite that the vast majority of vehicles would be completely prevented from entering with a much wider spacing. As seen before, the safety of motor vehicles shall never be compromised, but pedestrians and bicycles are fair game.


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