Validación según teoría de respuesta al ítem

Cyclists can share the traffic lane with motor vehicles. The roads included in this section are generally arterial or collector type roads, or roads through town centre environments but not roads that have been specifically designated as ‘neighbourhood greenways’ (which are covered in Section 5.6). The sharing can either be when the cyclist and motor vehicles travel side by side in a wide traffic lane (wide kerbside lane) or when motor vehicles follow the cyclist in a narrow traffic lane (with the possibility for overtaking when there is no oncoming traffic) which is known as ‘vehicular cycling’.

The difference between a wide kerbside lane and narrow traffic lane in the context of shared traffic lanes is shown clearly in Figure 5.3, noting that this diagram is from a country where vehicles travel on the right- hand side of the road and where ‘sharrow’ markings are used. Sharrows have recently been trialled in NZ and could be a useful marking for shared lanes, however they are not yet a legal traffic control device (Bunting 2013).

Table 5.2 Cycle Lane Gap

Guidance

A summary of existing guidance for wide kerbside lanes is shown in Table 5.3.

There is currently no guidance in Austroads or the NZ Supplement regarding narrow traffic lanes. Transport for London specified that narrow lane widths for cycling should be less than 3.5m and that lane widths between 3.5 and 4.0m should be avoided. The NZ industry training (Wilke and Fowler 2015) recommends that narrow lanes where intended to be shared by cyclists and motor vehicles should only be considered under the following conditions:

 The traffic lane is no more than 3.0m wide,

 Traffic must operate at slow speeds (30km/h or less),

The ability to use narrow lanes also depends on other factors, such as the traffic composition – on a route with buses or heavy vehicles it may be necessary to provide wide lanes.

It should be noted that even with the right conditions it may be off-putting for inexperienced cyclists to share a 3.0m wide traffic lane, particularly if the lane is directly adjacent to a high turnover parking lane. The important aspect of sharing the lane is that traffic lanes widths of between 3.0m and 4.2m should be avoided. These widths result in an unsafe arrangement where cyclists are ‘squeezed’ by traffic overtaking within the same lane when there is insufficient width for this to occur safely.

Figure 5.3

Diagram showing difference between two types of shared traffic lanes

Our Ref: Issue Date: 59

National NZ Local Guidance International

Width Austroads GTR3 (Table 4.20)

 Posted speed limit, 60km/h

 Desirable Minimum: 4.2m

 Acceptable Range: 3.7m-4.5m

 Posted speed limit, 80km/h

 Desirable Minimum: 4.5m

 Acceptable Range: 4.3m-5.0m

 If kerbside parking is significant in the off-peak period: Minimum width is 4.0m

MOTSAM Part 2 (2.10.02 a)

 Lanes where cyclists share with motorised traffic should ideally be between 4.1 m and 4.5 m wide

NZ Supplement (Table 4.4)

Without Parking

 50km/h Speed Limit:

 Desirable Minimum Width: 4.2m

 Acceptable Range: 4.0m-4.5m

 70km/h Speed Limit:

 Desirable Minimum Width: 4.5m

 Acceptable Range: 4.2m-5.0m With Parking

 50km/h Speed Limit:

 Desirable Minimum Width: 4.5m

 Acceptable Range: 4.3m-4.8m

 70km/h Speed Limit:

 Desirable Minimum Width: 4.8m

 Acceptable Range: 4.5m-5.3m

Nelson Land Development Manual (Table 4.14)

On classified roads, desired widths are:

 Speed ≤ 50km/h:  Parking: 4.5m  No parking: 4.2m  Speed = 70km/h:  Parking: 4.8m  No Parking: 4.5m ATCOP (Table 40) Minimum Widths

 Speed Limit/85th _{Percentile Speed 50km/h:}

 Parking (not all times): 4.2m

 No parking: 4.2m

 Speed Limit/85th _{Percentile Speed 70km/h:}

 Parking (not all times): 4.8m

 No Parking: 4.5m

 The minimum lane width may be reduced by 0.2m at “pinch points” over a short distance

 Where greater width is available than identified here, consider a cycle lane.

ATCOP (Page 359)

 Wide kerbside lanes should not have kerb extensions that leave inadequate room for cycling

VicRoads Traffic Engineering Manual (5.4.2)

 Ideally 4.2m wide

 Maximum width of 4.5m

 When lanes are used for parking for park of day: lanes should be 4.0m-4.2m

Transport for London

 At least 4.0m wide

VicRoads Traffic Engineering Manual (5.4.2)

 No special line markings are required

Discussion

No relevant research on shared traffic lanes has been identified.

Guidance of the desirable width of wide kerbside lanes is consistent across national, local and

international guidance, except for the 3.7m minimum of the acceptable range offered by Austroads which is not considered best practice. There is no national guidance for narrow traffic lanes beyond the industry training.

It is likely that most of this can then be included in the TCD Manual chapter ‘Between Intersections’.

Gap Identification

The gap identification for shared traffic lanes can be seen in Table 5.4.

Gap Type Comments

Wide traffic lanes -

Austroads acceptable minimum not considered best practice. Guidance is not

considered best practice

In Austroads the acceptable minimum width for a wide shared traffic lane is 3.7m. In NZ this is considered within the unsafe zone of 3m to 4.2m. This is taught in the industry training so should be reflected in the national guidance.

No narrow lane

guidance

Lack of guidance Narrow lanes may need some supporting measures to ensure that drivers and cyclists are clear on the ‘sharing of the lane’. National guidance on this is required as there are more instances of this approach being taken.

5.5 Bus/Cycle Lanes