Shared lanes

Traffic lane widths - providing for cycling

For roads where no formal cycle facilities are provided and cyclists share the road with general traffic, provision should be made for cyclists based on the volume of cycle and motor vehicle traffic such that the lanes are either:

• wide enough for cyclists to ride adjacent to other vehicles (see wide kerbside lanes);
  Wide kerbside lanes
  or
• narrow enough that cyclists and other vehicles must travel in single file (see narrow urban road traffic lanes).
  Narrow urban road traffic lanes

In-between widths, where there are no suitable alternative cycle facilities available, should be avoided as these can result in drivers or cyclists attempting to pass each other when it is not safe to do so.

Note that Austroads allows an absolute minimum shared lane width of 3.7m; this is not recommended in NZ as the NZ recommended minimum is 4.0m.

Wide kerbside lanes

On urban roads, the width of wide kerbside lanes is a function of the speed limit and whether there is on-street parking present. Table 8‑6 provides desirable widths and acceptable ranges for mixed traffic roads where no formal cycle facilities are provided and cyclists can share the roads with general traffic.

Table 8‑6: Urban wide shared lane dimensions

Table 8‑6 notes:

1. The speed limit is used unless 85^th percentile speeds are significantly higher.
2. Interpolation for different road speeds is acceptable.
3. The lower width is the absolute minimum width and should only be used in low speed environments (85th percentile speed of 40km/h and below) and when it is not possible to achieve a wider kerbside lane.
4. If a greater width than identified here is available, consideration should be given to providing a cycle lane. If lanes are too wide, car drivers may attempt to travel two abreast.
5. This is the lane width clear of the parking lane.

On rural roads, wide lanes and narrow shoulders are less beneficial to cyclists than conventional width traffic lanes with wider shoulders. Therefore, on rural roads, wide shoulders are the preferred treatment (as opposed to wide lanes) if cycle lanes or cycle paths cannot be provided.

Narrow urban road traffic lanes

Narrow traffic lanes require cyclists and motorists to travel in single file – sharing the lane. Only a small proportion of cyclists will be comfortable with this form of provision, which requires a cyclist to ‘take the lane’. Sharrows may also be marked to indicate that a cyclist can share and position itself within a traffic lane with other vehicles.

Sharrows

For situations where this occurs, the following conditions should be met:

• lane width is 3.0m or narrower;
• traffic operates at slow speeds (30km/h or less);
• the traffic volumes are low (less than 3,000vpd);
• the traffic lane is not directly adjacent to a high turnover parking lane;
• the treatment is over short lengths, approximately one or two blocks, longer distances may evoke driver impatience as most cyclists will be travelling at speeds of around 20km/h; and
• the road is not a bus route.

Where buses will be present, or could be in the future, specific design will be required because 3.0m lane widths are unlikely to be suitable for two-way bus traffic. Caution is also required if a combination of narrow facilities (eg traffic lanes and parking bays) is proposed across a road cross-section due to the risk of the minimum dimension facilities resulting in encroachment of moving vehicles across the centre-line.

Sharrows

General

A ‘sharrow’ is a cycle marking that indicates a cyclist can share and position themselves within a traffic lane with other vehicles. These markings are now legally allowed to be marked on New Zealand roads; refer to TCD manual Part 4 for information on sharrows at intersections.

Current guidance (Best Practice Guidance Note - Flow Transportation Specialists, February 2016) on sharrows states that:

There are a number of themes that can be identified with regard to where sharrow markings are most appropriate to implement. The primary characteristics for the potential implementation of sharrow markings on a route are:

• low vehicle volumes
• low vehicle speeds
• the operational characteristics of the carriageway, including the available width, terrain and vehicle composition.

Sharrow markings have also been successfully trialled in city centres with lower posted speed limits (posted 30km/h).  While vehicle volumes can be moderately high (for example, less than 8,000AADT) through city and town centres, a slower posted speed limit, for example 30km/h, may result in a road environment suitable for sharrow markings. This is because cyclists can more easily travel at the same speed as vehicles in areas with lower operating speed. This in turn means that cyclists may feel more confident to ‘own the lane'.

Markings

The markings comprise a reflectorised white cycle symbol along with two reflectorised white chevron markings. The layout and minimum dimensions are illustrated in Figure 8‑9. A coloured surface marking to act as backing for the marking in apple green colour or similar may also be installed.

Figure 8‑9: Sharrow symbol (Refer TCD Rule – Schedule 2: M2-3B)

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Location

Refer to Figure 8‑10 for road marking layout plans and Table 8‑7 and Table 8‑8 for dimensions.

Figure 8‑10

Table 8‑7

Table 8‑8

Lateral positioning of sharrows where parking is not permitted:

• The centre of each sharrow should be positioned on the centre or slightly to the left of the centre of the useable traffic lane with each sharrow remaining clear of the marked road centre-line or imaginary line that is the centre of the trafficable width of the road where no centre-line is marked.
• For roads with widths less than 8m, on which sharrows are proposed, consideration should be given to marking no-stopping lines to prevent parking where it may otherwise occur. However, if parking demand is high, the road may not be suitable for sharrows.
• Where on street parking is not provided, the distance from the edge of seal to the centre of each sharrow should be no less than 1.4m.

The centre of a sharrow is defined as the longitudinal centre-line of the sharrow.

Lateral positioning of sharrows where parallel parking is permitted:

• The width between the outer edge of the marked carpark (or the roadside edge of parked vehicles where carparks are not marked) and the centre of each sharrow should be no less than 1.4m.
• Where kerb extensions project into the roadway where there is otherwise on-street parallel parking, each sharrow should be centrally placed in the usable traffic lane.
• If a road does not have a marked centre-line (or other treatment to define the centre of the road), then each sharrow should be positioned clear of the vehicle door-opening zone and placed entirely ‘within the lane’ to the left of an imaginary centre-line.
• Where marked or unmarked on–street parallel parking is provided, the preferred minimum width between the kerb and the centre of each sharrow is 3.5m.

Table 8‑7: Distance from kerb to centre of sharrow (parallel parking)

 Figure 8‑10: Sharrow marking layout plans

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Lateral positioning of sharrows where angle parking is permitted:

• There is generally no need for sharrows in a lane over 3.8m wide.
• It may be difficult for adequate width to be available for the constrained situations where sharrows are being considered alongside angle parking.
• Where sharrows are provided alongside angle parking, the clearance between the angle parking and the nearest edge of the sharrow should be as described in Table 8‑8.

Table 8‑8: Preferred clearance between angle parking and edge of sharrow

Frequency of placement:

• should be marked along the roadway every 30m to 70m; and
• placed more frequently where enhanced guidance is needed (eg where there is a need to provide connectivity between tow cycle lanes) and on roads with higher volumes.