Cycleway separators are designed to keep motor traffic out of the cycleway, however, it will be necessary to allow motor vehicles across the cycleway at certain midblock locations, mainly driveways – it should not be difficult to identify where to provide motor vehicle permeability.
In such locations, consider whether to provide:
A gap in the separator (with appropriate painted markings to delineate the conflict zone)
A mountable separator – desirable where higher volumes of vehicles, especially involving heavy vehicles or drivers unfamiliar to the site, are present, as this helps to limit speeds at which vehicles cross the cycleway
The gap width in continuous separators should be limited to providing for the required design vehicle at a slow turning speed (typically no more than 4-5 m gap for single private accesses).
Spacing of intermittent separators ( eg posts) should be sufficiently frequent to discourage access by adjacent moving or parked vehicles (typically at least two separators per parking bay or no more than 5 m apart).
Cyclists will also need access to and from the cycleway at midblock locations to begin and end their trip, or transition to a different road.
Ensure that gaps for cyclist permeability are provided:
Where there is a side road opposite the cycleway
Where there is a major destination (park, school, workplace, shopping centre etc) opposite the cycleway
Where there is a midblock crossing provision
At regular intervals along the midblock ( eg every 50-100 m) for general access to / from residential properties or potential cycling destinations (note, this can often be provided via driveways, unless the cycleway is adjacent to a large property, eg a park or school).
The size of the gap in the separator to provide cyclist permeability will depend on the width of the separator – cyclists should be able to turn in and out of the cycleway at a comfortable speed, without awkward negotiation.
A gap in the separator intended only for cycle permeability should not be wide enough to allow motor vehicles to pass through (ie no more than 1.6 m minimum clear gap perpendicular to the vehicle direction
Where there are footpaths, pedestrians will also need to cross the cycleway separator.
Generally, the gaps provided for cyclist permeability will also suffice for pedestrian permeability, although a footpath kerb cut-down may also be needed.
In strategic locations (eg opposite side roads and midblock crossings) ensure the gaps (and any ramps) are suitable for pedestrians with mobility impairments, and design according to the Pedestrian Planning and Design Guide.
Installing a separated cycleway may also affect the flow of stormwater.
Verify stormwater flow during detailed design.
Where crossfall falls to the outer cycleway edge, ensure there are small, frequent gaps built into, or between, the separators to accommodate stormwater flow.
Alternatively, provide additional storm water sumps on the road side of the separators.
Height affects ability of users to mount (ie drive or cycling up and over) it (and therefore permeability), and cyclists’ perception of safety.
Consider the following principles:
The lower the device, the less it is a deterrent for motor vehicle drivers to drive over it, even if it is not intended to be mountable.
Some devices may appear mountable but cause damage to vehicles.
There may be operational reasons why it is desirable that some vehicles can straddle the separator (eg waste collection, street sweeping).
It is important to consider the conspicuity of lower devices, from the point of view of cyclists, pedestrian and motorists, so that none of these users unintentionally collide with the separator. Occasional higher separators may be required to direct attention to the lower separator to be avoided.
If devices are too low, pedestrians may not notice them and trip up.
On the roadway side, devices (that are not intended to be mountable) should be at least 80 mm high.
Based on experience with the Ilam Road cycleway, Christchurch City Council uses 85 mm high devices.
Auckland Transport generally uses 150 mm high separators (their standard kerb height)
On the cycleway side, cyclists will shy away from separators above pedal height (about 50 mm); to mitigate this, either:
Consider a bevelled edge (eg on a concrete island) - see section on cycling shy space
Or, increase the width of the cycleway to allow for shy space next to a higher separator (eg kerb, planter box)
Where pedestrians travel next to the cycleway, or may choose to cross it, separators should be more than 60 mm high to ensure they are (Norgate, 2012(external link))
Where it is intended to provide for pedestrians crossing the separator, an accessible crossing point should be provided, designed according to the Pedestrian Planning and Design Guide.
Vertical delineator posts, either stand-alone or at the ends of lower separators, should be sufficiently high to be noticed by motorists, ie typically at least 800-900 mm high from the road surface. Note that delineators higher than 900 mm high may conflict with cycle handlebars if not separated laterally.
Vertical delineators might not be suitable where it is expected that maintenance vehicles eg rubbish collection) need to straddle the separator.
The profile of the road and cycleway cross-section may result in there being a substantial difference in level either side of the separator.
In this case, and especially where a wide, low separator (eg island) is used, careful consideration of the height requirements for users on either side should be made.
Where pedestrians are likely to stand on the separator, its surface should be reasonably horizontal. This may result in the separator having different heights above the ground on either side.
As well as the height of the device, the slope of its sides affects the ability of motor vehicles to drive over it, cyclists to ride over it, and pedestrians to walk / roll over it; these three users have different requirements and should preferably be provided for at different locations.
Mountable devices that enable vehicles to cross into the cycleway should also encourage slow speeds whilst doing so.
A 1V:1H slope is suitable where only motor vehicles (ie not cyclists or pedestrians) need to cross.
A cyclist’s ability to ride over a device depends on the angle at which they approach it:
A 1V:2H slope may be appropriate for cyclists to mount the separator at large or perpendicular angles only (but is not desirable).
A 1V:3-4H slope should be used where cyclists need to mount the separator at shallow angles.
A 1V:3-4H slope should also be used to separate a cycle path from a cycle path where there is a difference in level. This minimises the trip hazard for pedestrians and will also be suitable for pedestrians with prams and be negotiable by wheelchairs provided the height difference is modest.
Where it is intended that cyclists will cross the separator (eg at a driveway, or marked access point), ensure the separator edge does not include a significant lip, as it may be difficult to mount from a shallow angle, and can also be hard to see (meaning cyclists may unintentionally glance it at a shallow angle and lose control). As a result:
a bevelled kerb is preferred over a kerb with a vertical lip in the figure below
a lip no greater than 20 mm with rounded edge may be acceptable
Mountable devices will generally not be suitable for wheelchair access: a ramp or flush surface should be provided where it is intended for pedestrians to cross a separator.
Where motor traffic crosses the cycleway, it is important that drivers and cyclists can see each other. The type of separator used may affect the inter-visibility between cyclists and other traffic; for example, a row of parked cars restricts inter-visibility much more than small, intermittent devices such as bollards.
If a row of is higher than driver eye height (1.1 m above the ground), their length and spacing near driveways and intersections should be reviewed, to ensure adequate sight lines are provided.
The side of the separator adjacent to the cycleway should be designed for cyclists’ comfort. Separators higher than pedal height (about 50 mm) cause a ‘shy space’ – ie. cyclists will give the edge of the separator a wider berth. To mitigate this, either:
Allow an extra 250 mm of path width next to a separator 50–600 mm high (the upper limit chosen to be lower than riding arm height).
Allow an extra 450 mm of path width for separators higher than 600 mm.
Use a 1V:1H slope (or flatter) on the kerb face to avoid pedal strike.
This criterion is superseded by any requirements for the device to be mountable by users (see Mountable kerb detail), wherever cyclists should be able to ride over the separator.
A wider horizontal buffer between cycleway users and adjacent users (moving traffic, parked cars, pedestrians) increases the level of comfort and safety (perceived and actual) for cyclists (and pedestrians, where they are involved). People accessing and egressing from parked vehicles may require a wide enough separator to comfortably organise themselves (consider especially those with prams, dependent children, or mobility devices).
Wider separators also provide space for infrastructure / amenities such as signage, traffic signal poles, light poles, parking meters, rubbish and recycling bins, trees, seating etc. The following list outlines recommended separator widths:
Between a cycleway and active traffic lane:
Provide a 1.0 m horizontal buffer (0.5 m normal) between a cycleway and adjacent traffic lane.
Consider the effects increased separation (and the devices used) may have on inter-visibility at driveways, etc.
Consider the effects of passing traffic on higher speed roads.
Narrower separators (ie <0.5 m) may be considered where space is at a premium (eg intersections, temporary treatments).
Between a cycleway and parking lane:
Provide a 1.0 m (0.85 m tolerable minimum, 0.7 m absolute minimum) between the cycleway and adjacent parked vehicles.
Devices need to be visible to road users, during both day and night, so that everyone is aware of the presence of the separators and cycleway. Cycleway designers may sometimes feel in conflict with urban design objectives, which can favour styles that are less conspicuous.
Ensure devices are suitably conspicuous, including under conditions of limited visibility (dark, rain).
This might involve the use of reflective paint, reflectors, or vertical elements such as flexi-posts or planter boxes.
Be wary of low-height separators or lips that may create a trip hazard if not noticed.
Where separator devices are adjacent to road markings, it is usually desirable that they have matching or complementary colours, eg white delineator posts within an area of white diagonal hatching, however they should have some differentiating colour element on them to avoid camouflage at the right angle.
Yellow or orange separator devices may be viewed as ‘temporary’ (and less care taken to avoid them); therefore, it may be advisable to use other colours for permanent separators.
Work with urban designers to ensure that devices are noticeable, yet attractive – eg consider use of colour, planting, etc.
Separation devices will be struck on occasions by motor vehicles, either while driving or manouevring. It is important to choose a product that suits the expected type and frequency of impact – these will depend on the traffic volumes, traffic speed, traffic lane widths, road curvature, visibility and propensity of drivers to try to enter the cycleway (eg in locations where demand for on-street parking exceeds capacity).
New Zealand experience so far has yielded the following observations:
The method of attaching the separator to the road is important. Many pre-fabricated products are designed to be dyna-bolted to concrete roads (as in the northern United States and Canada). The solution often suggested for NZ roads is to use longer bolts that go into the substrate, however:
This may not be as effective, and devices subjected to frequent or heavy impact may be ripped out of the ground, also causing damage to the pavement surface.
It may be adequate on roads with asphaltic concrete (AC) surfaces, depending on the thickness of the AC layer (eg roads that have been resealed multiple times without the previous layers being milled down).
Simply using an adhesive product (eg glue or grout) between the separator and the road surface will not be sufficiently strong, unless for temporary treatments.
A concrete footing can be installed for bolting down devices.
Concrete separators that are cast in-situ should be ‘keyed in’ to the carriageway – ie the separator extends below the carriageway surface. The extra time it takes to dig up the road surface and re-form it later will be offset by the savings in maintenance and repairs during the cycleway’s lifetime.
Concrete products should be suitably reinforced. Those that are pre-fabricated can also be pre-stressed for added durability.
Resin products are expected to be more durable than rubber products.
Areas likely to face the most damage are inside corners of curves, near driveways/accessways, and at the start and end of separators. Consider additional highlighting in these areas or setting back further where possible.
It is important to regularly and routinely clear debris from separated cycleways.
Points to consider are:
If a cycleway is less than 2.6 m wide, special sweeping equipment may be required eg figure below used in Palmerston North City.
This may require an upfront purchase, that would make it easier to sweep other narrow cycleways installed in the future.
If the road controlling authority outsources its road maintenance, the maintenance contract should be updated to include requirements of sweeping a narrow separated cycleway, before the cycleway is opened.
Design cycleways to be wide enough to be used by conventional street sweepers
Design cycleways with low separators that can be straddled by street sweepers (may depend on sweeper vehicles used)
It may be intended that separators are permanent fixtures, or they may only have a temporary function. Maintenance works may also occasionally necessitate temporary removal of separators.
Cast-in-place concrete islands and kerbs are generally permanent solutions, but other separators that are bolted or glued to the ground can also be considered permanent solutions, as long as their materials and fixtures are suitably durable.
A “temporary” separator is intended as an interim solution and will have a relatively short design life at a specific site. Temporary separators are not necessarily disposable; some types of separators may be able to be transferred to other sites and used multiple times, for a variety of purposes. Temporary devices could be installed, for example, to be in place for 2-5 years until a major road upgrade is conducted and permanent separated cycleways are installed, or they could be part of a trial to illustrate to the public what separated cycleways might look like at a site.
The effects of removing the separation device on the road surface should also be considered. In general, any device that requires significant road reconstruction after its removal should not be considered as a viable temporary option. In some site-specific cases, however, if road reconstruction is planned to coincide with the removal of the interim cycleway, this could be considered, especially if the separation device itself could be reused.
Thus, depending on the site and project requirements, most of the separators presented in the separator type chart (except for cast-in-place concrete options) could be considered temporary. In addition, other products could be used, for example the temporary fencing from Shanghai, shown below, which uses connectable units with heavy metal bases that don’t need to be attached to the road surface.
Consider whether the cycleway is being retrofitted to the existing carriageway, or whether there will be significant changes to the carriageway (or even a new carriageway being formed completely). Devices that are attached to the road surface may be more appropriate for retrofit projects, whereas cast-in-place options require the road to be dug up, and so are more suited to projects where significant construction is taking place.
Temporary traffic management during installation is an expensive project component, and disturbances to traffic flow and parking opportunities during construction can induce public opposition to cycleways in general. Therefore, on busy roads or where parking demand is high, ready-made products that quickly attach to the road surface may be preferable to cast in-situ products, due to the amount of time and space required for construction.
If it is necessary to close a cycleway for maintenance (either to the cycleway, or related to the road environment in general), consider how the cycleway traffic will be provided for. In most cases where a separated cycleway exists, it would not be suitable to expect the target audience for this facility to simply join the motor traffic on the carriageway, unless traffic volumes are low and traffic operating speeds were significantly reduced. It may be necessary to temporary remove some traffic lanes, parking, or other space like flush medians to accommodate a relocated cycleway. In some cases, a temporary shared footpath may be appropriate.
Have generic traffic management plans in place in case a cycleway needs to be closed for maintenance. A key aspect of the plan should be to prescribe the type of temporary separation that will be provided (or appropriate speed management for temporarily shared roadways or paths). This could include the use of temporary posts or barriers to provide a physical separator.