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Cycling by Design

Road Narrowings

7.25 General Design Aspects:

7.26 The incorporation of horizontal deflections within the carriageway can help to reduce traffic speeds, discourage unsafe overtaking manoeuvres and facilitate pedestrian and cyclist crossing movements. The main features used, either combined or on their own are (Refer to Figure 7.2):-

(i) Central Islands : Comprises an island within the carriageway with or without a crossing facility.

(ii) Pinchpoints : Comprises build outs constructed opposite each other on both sides of the carriageway.

(iii) Chicanes : Comprises build outs staggered on alternate sides of the carriageway.

7.27 Impact on Cyclists:

7.28 When used in conjunction with other forms of traffic calming, road narrowing can be an effective method of reducing traffic speeds. However, cyclists may feel at risk due to the reduction in carriageway width available because:-

(i) If no alternative cycle facilities exist cyclists may find themselves closer to motorised vehicles, especially HGVs; and

(ii) Motorists may continue to pass cyclists within the narrowed area.

7.29 Recommendations:

7.30 Cycle Bypass : Where adequate space is available and there is no serious conflict with the needs of pedestrians a cycle bypass should be provided. The following design guides are recommended:-

(i) The bypass should be 1.0-1.5m wide;

(ii) The bypass should preferably be straight. If a curve is necessary then it should allow for easy manoeuvre by the cyclist;

(iii) The cyclist should be guided towards the bypass by way of a cycle lane, which should start in advance of the point at which the carriageway begins to narrow;

(iv) Access to the bypass should be kept clear of parked vehicles;

(v) The bypass should remain at the same level as the main carriageway (rather than rising to footway level for a short length);

(vi) Cyclists should have easy access back onto the main carriageway, preferably designed so that they are not required to give way on rejoining the main traffic flow or such that they conflict with other road users (Refer to Chapter 5, Figure 5.9); and

(vii) Where there are a series of narrowings along a route a bypass in the form of a continuous cycle track away from the carriageway, may be provided if space permits.

7.31 Cycle lanes : If there is insufficient width for the provision of a cycle bypass then a cycle lane should be provided.

7.32 Provision of a cycle lane through a narrowing provides greater separation between the cyclists and overtaking vehicles and may act as an additional speed reduction measure.

7.33 If a cycle lane through a narrowing leaves less than 3m for the main carriageway area then it should be expected that up to 20% of motor vehicles would encroach within the lane. This level of encroachment may increase within areas of high HGV and bus content.

7.34 Cycle lanes should be introduced in advance of the point at which the carriageway begins to narrow and should preferably be at least 1.5m wide. If a cycle lane is being introduced along the whole length of a route which includes narrowings then it is recommended that the cycle lane width is not reduced in the vicinity of the narrowing. If this cannot be avoided then the cycle lane should be narrowed gradually and well in advance of the point at which the carriageway narrowing occurs.

7.35 Unsegregated Use : Where the 85^th percentile speed of traffic has been reduced below 30kph cyclists and motorists should be able to share the traffic calmed carriageway safely. Therefore, no specific cycle facilities should be required. However each case should be treated individually as local circumstances may necessitate additional measures.

Figure 7.2: Road Narrowings

Rumble Devices and Surface Treatment:

7.36 General Design Aspects:

7.37 Rumble Strips : Rumble strips generally incorporate a series of parallel lines of coarse chippings, granite setts or thermoplastic material laid transversely across a carriageway. They are intended to alert drivers both audibly and dynamically about the need for extra care and attention.

7.38 Surface Treatments : Surface treatments often incorporate the use of contrasting colours to provide an additional visual warning. Although not generally intended as speed control measures, rumble strips and surface treatments may be used to give warning to drivers that they are either in, or about to enter, an area where speed should be tempered.

7.39 Impact on Cyclists:

7.40 The main concern to cyclists is that:-

(i) The rumble strips may provide an uneven surface area over which it is both uncomfortable and dangerous to ride, particularly at speed (e.g. downhill);

(ii) The surface treatments may produce areas of low skid resistance; and

(iii) The transition from one form of surfacing to another may result in an abrupt change in level and loss of control.

7.41 Recommendations:

7.42 The following treatments are recommended to ensure that rumble strip and surface treatments do not have a detrimental impact on cyclists’ safety:-

(i) Provide a gap between the edge of the rumble strip and kerb of Desirable Minimum width 1.0m, Absolute Minimum width 0.75m. (Where a high level of parking is envisaged it may be necessary to locate the gap away from the edge of the road);

(ii) Surface treatment should not risk cyclists’ safety or cause undue discomfort; and

(iii) Surface should be to DMRB skid resistance standards.

Environmental Road Closures

7.43 General Design Aspects:

7.44 The closure or partial closure of minor roads at one end can be an effective traffic calming measure.

7.45 Minor Road Closure: A typical layout for a minor road closure is shown on Figure 7.3. The design of the closure should take into account the needs of emergency access, pedestrian access and the local environment. A TRO with cyclist exemption will be necessary to prohibit motor vehicles.

7.46 False One-way Streets: A typical layout is shown on Figure 7.4. False one-way streets restrict motor vehicle access from one direction into an otherwise two-way road. A TRO with cyclist exemption will be required. The jug handle feature with a central island should be considered when the vehicle flow on the main road is > 6000vpd. Where vehicle flows are < 6000vpd refer to Chapter 5, Figure 5.5.

7.47 Impact on Cyclists:

7.48 Closure or partial closure of a road may result in increased traffic flows on other roads within the local network to the detriment of the cyclist. However, this impact may be negligible compared to the positive benefit to the cyclist of being able to use a lightly trafficked route on the cyclist’s actual desire line. The creation of a false one-way street is recommended as the preferred method of allowing cyclists to travel ‘contra-flow’. (Refer to Chapter 5).

7.49 Recommendations:

7.50 In order to ensure that the cyclist is safely accommodated within a minor road closure the following actions are recommended:-

(i) Cyclists should be made exempt within the TRO’s.

(ii) The minimum cycle gaps should be:

Desirable Minimum 1.5m

Absolute Minimum 1.0m.

(iii) Build outs may be required to prevent vehicles blocking cycle access/exit points.

(iv) The closure should enhance the environmental amenity of the area through appropriate treatments including benefits for other groups.

Figure 7.3: Minor Road Closure

Figure 7.4: False One-way Street

Traffic Management

7.51 General:

7.52 Traffic management has traditionally been used by Roads and Planning Authorities as a tool through which road capacity may be maximised. However its use as a means of optimising the road network for the benefit of all road users is becoming more common and, in particular, offers substantial improvement opportunities for cyclists. It is recommended that in all traffic management schemes, the opportunities to positively assist cyclists, in terms of convenience and safety, should be fully assessed. The implementation of the Cycle Audit Procedures introduced in Chapter 14 is viewed as an important aspect in this respect for trunk roads.

7.53 Typical Applications:

7.54 The following traffic management techniques may be used to assist cyclists:-

(i) Urban Traffic Control Systems, designed to recognise cyclists and accord them priority as appropriate;

(ii) Contra-flow cycle lanes and two-way streets for cyclists;

(iii) Exempting cyclists from road closures;

(iv) Exempting cyclists from banned turns and TROs that restrict access;

(v) Combined bus/cycle priority measures;

(vi) On-street parking restrictions;

(vii) Advance Stop Lines for cyclists at traffic signals;

(viii) Bypasses for cyclists at traffic signals;

(ix) Junction/Crossing treatments in accordance with Chapter 6.

(x) Adjustment of lane markings to provide additional road space for cyclists.

7.55 Prior to promotion and implementation Police, Emergency Services and any other potentially affected parties should be fully consulted, including local representatives and cycling interest groups such as Sustrans, CTC and Spokes.

COMMENTS : CHAPTER 7

Cycling by Design’s prime objective is to draw together and rationalise existing cycling design guidelines into a single comprehensive, coherent reference document that may be used as a source of sound technical advice. In order to achieve this objective it is imperative that Cycling by Design is developed through consultation. Please provide any comments or suggested amendments you may wish to put forward with respect to the preceding chapter.

Comments/Proposed Amendments:

Please send your comments to:

The Scottish Executive Development Department,

Standards Traffic & Environment,

Area 2-E,

Victoria Quay,

Edinburgh EH6 6QQ.

On or before 31^st December 2000.

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