Design manual
Design Manual for Urban Roads and Streets
The design of roads and streets within urban speed limits.
Department of Transport, Tourism and Sport and Department of Housing, Planning and Local Government · 2019 (version 1.1) · 165 pages
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- 79May 2019 (Version 1.1) Lighting Good quality lighting promotes a safer environment by ensuring inter-visibility between users. Poorly illuminated carriageways and cycle lanes can also make it difficult for users to identify potential hazards. The quality of lighting will also have a major impact on perceptions of security. If lighting levels are not sufficient, a place may not be perceived as safe, particularly for pedestrians and cyclists. This may discourage people from walking and cycling, particularly in the winter months when days are shorter, and undermine the viability of public transport. The standards used for lighting within Ireland are generally taken from British Standard Code of Practice for the Design of Road Lighting (BS 5489). Whilst these documents should be referred to in regard to technical details, there are broader design considerations in regard to type of lighting used and the position and design of lighting columns. Lighting should be designed to ensure that both the vehicular carriageway and pedestrian/cycle path are sufficiently illuminated. On roads and streets within urban areas white light sources should be used, such as metal halide, white SON, Cosmopolis and LEDs. Where orange (SOX) or softer honey (SON) coloured lights are currently used, they should be replaced with white light as part of any upgrade (see Figure 4.21). With regard to the height of lighting columns: • Heights should be sensitive to the scale of the adjacent built environment. • In city, town and village streets, a lantern mounting height in excess of 8 metres is unlikely to be required. • On Local streets, and in areas of heritage significance, mounting heights should be no greater than 6 metres. • Where higher numbers of pedestrians are active, such as in Centres, consideration should be given to supplementing the traffic route lighting installation with a lower intensity pedestrian lighting lanterns mounted at a lower height on the same columns (see Figure 4.22). Figure 4.21: Examples of differing types of lighting and their effectiveness in terms of safety and placemaking. POOR (Orange SOX) BETTER (White SON) BEST (Metal Halide)
- Design Manual for Urban Roads and Streets80 Lighting installations should be generally located within a verge (see Section 4.3.1 Footways, Verges and Strips) and/or within build-outs that separate bays of on-street parking (see Section 4.4.9 On-street Parking and Loading). Where no verge is available, lighting should be located at the back of footways, to minimise any disruption to pedestrian movement provided: • They are positioned, where possible to coincide with property party lines to avoid obstructing entrances or windows. • They are not located in close proximity to properties where they may compromise security. On narrow streets or streets with narrow footways, consideration should be given to using wall-mounted lanterns Lanterns should be selected and positioned so as to avoid creating obtrusive light spill on windows, particularly in the case of upstairs residential properties. Internal or external baffle plates can be fitted to lanterns to minimise nuisance light spill. Lights should also be positioned away from trees, which in time may grow to envelop the lanterns or cast shadows which will render the lighting less effective. To reduce street clutter designers should consider combining lighting with other installations (see Section 4.2.4 Signage and Line Marking and as per Figure 4.22). Traffic signal heads, small signs, bus stop signs etc. can be mounted on lighting columns with a degree of co-operation and co-ordination between the relevant authorities and service providers. CCTV columns, which need to be more rigid than lighting columns, can also accommodate lighting and other functions. Ancillary lighting equipment, such as electrical supply pillars, should also be located with a view to minimising their impact on the streetscape, while not creating an obstruction or hazard to pedestrians. Metering cabinets in particular, which may be up to 1.5 metres high, should be located against walls, as unobtrusively as possible, while bearing in mind that they must be accessible for maintenance and meter reading. Figure 4.22: Example of a light installation that is designed with both the pedestrian and the vehicle in mind and also incorporates signals for a pedestrian crossing (image source: Camden Streetscape Manual).
- 81May 2019 (Version 1.1) 4.2.6 Materials and Finishes The use of materials and finishes is one of the most defining elements of a street, particularly where it is used to define the levels of segregation and integration within a street. The material palette can define space, calm traffic and improve legibility, reducing the need for barriers, signage and line marking in favour of texture and colour. Materials can be used to enhance the value of place and produce more attractive and cost-effective streets. When choosing surface materials, designers should: • Use robust surfaces (such as natural stone, concrete block paving or imprinted asphalt) extensively throughout Centres and around Focal Points to highlight the importance of place, calm traffic and alert drivers of higher levels of pedestrian activity (see Figure 4.23). • Use robust surfaces and/or changes in colour around Gateways and Transitional Zones to alert drivers of changing driving conditions (see Section 3.3.4 Wayfinding). • Choose items from a limited palette to promote visual cohesion (see Section 5.2.1 Policy and Plans). Figure 4.23: O’Connell Street, Dublin. The high place status, intensity of activity and low design speed (30 Km/h) is highlighted by high quality and robust materials, such as granite paving. • Apply a hierarchical approach to the application of materials. Altering the palette according to the street hierarchy and/or importance of place will assist in way finding. • Use of contrasting materials and textures to inform pedestrians of changes to the function of space (i.e. to demarcate verges, footway, strips, cycle paths and driveways) and in particular to guide the visually impaired (see Section 4.3.4 Pedestrianised and Shared Surfaces). The layout and colour of tactile paving used to assist the visually impaired in navigating the pedestrian environment should ensure that a consistent logic is applied. This includes the cumulative impact of tactiles with other material choices. For example, the use of strong red or yellow tactile paving may not be appropriate to avoid visual clutter associated with too many surface types or colours. In such instances an approach which balances the need for visual contrast (to aid the visually impaired) whilst promoting visual cohesion is preferable (see Figure 4.24). Further guidance on the use of tactile paving may also be taken from Section 13.3 of the Traffic Management Guidelines (2003) and the UK Guidance on the use of Tactile Paving Surfaces (2005).
- Design Manual for Urban Roads and Streets82HIG H E R D E N S I T YH I G H E R A C T I V I T YH I G H E R A M E N I T Y HIG H E R D E N S I T Y H I G H E R A C T I V I T Y H I G H E R A M E N I T Y HIGHER HIGHEST HIGHHIGH HIGH HIGHER HIGHER STANDARD STANDARD Figure 4.25: Diagram illustrating a hierarchical and cost-effective approach to the specification of materials on streets. Designers may have concerns in regard to the initial costs associated with using higher specification materials and their ongoing maintenance. The use of higher quality materials has wide economic benefits. For example, in relation to shopping streets, research in the UK has shown that streets finished with better quality materials result in better market prices, better rents and better retail sales.17 Capital costs should also be measured against savings that result from a reduction in the need for barriers, signage, line marking and longer term costs related to durability and maintenance. Further guidance may be obtained from Advice Note 2 - Materials and Specifications and the Natural Stone Surfacing - Good Practice Guide (SCOTS Guide) (2004) . The quality of materials may also be selected to ensure that more robust and higher quality materials are used where they are most needed and appreciated. Figure 4.25 from the Adamstown Street Design Guide (2010) provides an overview of how the standard of materials may be applied with regard to amenity, density and activity. When applied systematically it directs the designers to use the highest specifications of materials in the Centres and along streets which are the most active, such as Arterial and Link streets. It will also direct the use of higher specification materials to the vicinity of Focal Points. Good results may also be achieved on lower budgets, provided material selection has the desired effect of supporting other measures aimed at calming traffic and defining place (see Figure 4.26). 17 Refer to Paved with Gold (2007). Figure 4.24: Example form Drogheda, Co. Louth, of red tactile paving at a zebra crossing which has been toned down to balance the degree of contrast with higher specification materials. Figure 4.26: Fade Street, Dublin City Centre. To reduce the overall cost of work in remodelling the street, lower budget materials such as HRA with coloured aggregate chips and epoxy resin bound surfaces were used on the carriageway and footpath, respectively.
- 83May 2019 (Version 1.1) 4.2.7 Planting Planting is generally located in areas such as medians, verges, build-outs and privacy strips. Landscaping is traditionally used to add value to places though visual enhancement. There are many approaches that can be taken with regard to planting, for example: • Within Centres a greater emphasis may be placed on using ‘harder’ landscape elements that define them as urban, allow greater freedom of movement and are able to withstand higher level of pedestrian traffic (see Figure 4.27). • In Neighbourhoods and Suburbs a greater emphasis may be placed on the use of planted materials to promote ‘softer’ landscape elements and a greener ‘living’ character (see Figure 4.28). Other key considerations include the ongoing maintenance and size of street trees/planting at maturity. Quality and maintenance should be viewed in a similar regard to the application of materials and finishes (as per Figure 4.27) with a hierarchical approach that promotes the use of higher quality planting within Centres and along streets which are the most active, such as Arterial and Link Streets, and around Focal Points. Figure 4.27: Example from Dundalk of an area with higher activity, the use of planted materials will be more sparsely and selectively applied in favour of more robust and durable materials. Figure 4.28: Example of a residential character, a rich palette of planted materials will enhance green qualities.
- Design Manual for Urban Roads and Streets84 Designers should also consider the size of trees, shrubs and other landscape elements at full maturity. In general designers should avoid planting that will grow to obstruct movement and surveillance. There are exceptions to this, for example overgrown medians can help reinforce narrower carriageways and tall shrubs may deflect sightlines reducing forward visibility. Streets also support an important drainage function within built-up areas. The shift toward sustainable forms of development has seen the emergence of Sustainable Urban Drainage (SUDs) systems. SUDs consist of a range of measures that emulate a natural drainage process to reduce the concentration of pollutants and reduce the rate and volume of urban run-off into natural water systems (and thus the pollutants it carries). The incorporation of SUDs elements into the fabric of the street itself can also serve to increase legibility and add value to place (see Figure 4.29). Further advise with regard to the use of SUDs may be found in the Greater Dublin Strategic Drainage Study (2005). Figure 4.29: Examples of Sustainable Urban Drainage incorporated into a street in the form of a small ‘swale’ (top) and larger linear basin (bottom). These treatments not only assist in containing urban surface water run-off but also contribute to the sense of place by adding a unique feature.
- 85May 2019 (Version 1.1) 4.2.8 Historic Contexts Additional design considerations must be taken into account in areas of historic significance that are highly sensitive to interventions. Historic features help reinforce an areas character/place value and may also play a role in managing speeds (see Figure 4.30). The most appropriate course of action should be to minimise any level of intervention to existing historical features. Elements of street furniture associated with the historic use of the street should be identified and protected, where appropriate (see Figure 4.31). Significant historic features may also include the street surface itself (as per Figure 4.30)18 and any features set into it such as coalhole covers, weighbridges, pavement lights, cellar doors etc. An ‘assessment of significance’ should be prepared when dealing with interventions within historic core areas. This is seen as addressing/acknowledging essential elements of the historic urban environment which may have architectural, historical and technical significance. For example when dealing with an established street layout and associated materials a distinction is drawn between three levels of significance: 1. Undisturbed areas of existing historic streets, which have the highest value and bear witness to the skill of historic craftsman; 2. Areas where streets have been altered or reconfigured using the original design/ material; 3. Reinstated street areas re-using salvaged material from other places. The mechanism for the protection of historic areas is based on statutory protection. If an area lies within an Architectural Conservation Area (ACA) or forms part of the setting of a protected structure (or a number of protected structures), development policies will be set out in the relevant County/City Development Plan, as well as active planning control.19 18 Refer to Paving: the Conservation of Historic Ground Surfaces. Forthcoming in 2013. Department of Arts, Heritage and the Gaeltacht.’ 19 Refer also to the Architectural Heritage Protection Guidelines for Planning Authorities (2011). Figure 4.30: The stone sett paved carriageways of Temple Bar, Dublin, are of historical significance, enhance the areas value as a cultural corner and calm traffic by creating a sense of shared space. Figure 4.31: An example of a historic water fountain in Newcastle, Co. Dublin. Such features are integral of local identity and should be retained.
- Design Manual for Urban Roads and Streets86 Figure 4.32: Illustration of the area generally thought of as the footpath. This area should be viewed and designed as three areas of activity. Strip Footway Verge Figure 4.33: Example from Castlebar, Co. Mayo, where the verge acts a designated space for street furniture, lighting facilities and planting of trees, keeping the footway clear of obstacles. 4.3 Pedestrian and Cyclist Environment 4.3.1 Footways, Verges and Strips A strong sense of enclosure and active street edges contribute to a pedestrians/cyclists sense of security and comfort by creating streets that are overlooked, animated and sheltered from inclement weather conditions. Studies have found that providing wider and better quality walking facilities can lead to an increase in walking.20 Well designed footpaths are free of obstacles and wide enough to allow pedestrians to pass each other in comfort. For this purpose the footpath is divided into three areas (see Figure 4.32): • Footway: this is the main area along which people walk. • Verges: These provide a buffer between pedestrians and the vehicle carriageway and provide space for street furniture and street trees as well as overflow space for pedestrian movement (see Figure 4.33). • Strips: These spaces, provided directly to the front of a building, may be occupied by activities generally associated with retail/commercial uses such as stalls or outdoor seating. Strips may be incorporated into the private space of a dwelling (as per Figure 4.13). 20 Refer to Section 5.1 of the UK Manual for Streets 2 (2010). Footways Minimum footway widths are based on the space needed for two wheelchairs to pass each other (1.8m). In densely populated areas and along busier streets, additional width must be provided to allow people to pass each other in larger groups. In this regard: • The width of footways should increase from Suburbs (lower activity), to Neighbourhood (moderate activity) and to Centres (higher activity) and as development densities increase. • The width of footways should increase according to function from Local (lower activity), Link (moderate activity), to Arterial streets (moderate to higher activity) as connectivity levels increase. • The footway should be maintained at a consistent width between junctions and should not be narrowed to accommodate turning vehicles. Figure 4.34 illustrates the space needed for pedestrians to comfortably pass each other with reference to the anticipated levels of activity within a street. These standards should be used to formulate the minimum footway widths.
- 87May 2019 (Version 1.1) Figure 4.34: Diagram showing the amount of space needed for pedestrians to pass each other with regard to pedestrian activity levels. PEDESTRIAN ACTIVITY AND FOOTWAY WIDTH Minimum space for two people to pass comfortably. Areas of low pedestrian activity 1.8m Desirable space for two people to pass comfortably. Areas of low to moderate pedestrian activity 2.5m Minimum space for small groups to pass comfortably. Areas of moderate to high pedestrian activity 3.0m Minimum space for larger groups to pass comfortably. Areas of high pedestrian activity 4.0m In areas of particularly high pedestrian activity, such as shopping streets or close to major nodes (such as a train station) more complex modelling may be needed to determine footway widths. In such cases designers may refer to the UK Pedestrian Comfort Guidance for London (2010) for further guidance in regard to footpath widths based on the volume of pedestrians per hour (provided these do not fall below the thresholds in Figure 4.34). This guidance may also be of particular assistance in assessing pedestrian comfort levels on existing footways. In a retrofit situation increasing footpath widths should be a priority for designers and where appropriate, accommodated by narrowing vehicular carriageways (see Section 4.4.1 Carriageway Widths). Increases in width should also be considered as part of a package of facilities, including the provision of cycle lane/tracks, on-street parking and other street facilities (including street trees). Designers should also ensure that the design of vehicle crossovers clearly indicate that pedestrians and cyclists have priority over vehicles. There should be no change in level to the pedestrian footway and no use of asphalt (which would incorrectly indicate vehicular priority across a footpath). Large or busy driveways (i.e. access to large car parks) may, however, be demarcated by a change in surface materials, such as contrasting paving and/or coloured concrete (see Figure 4.35). Designers should also refer to Section 5.4 - Entrances and Driveways of the National Cycle Manual (2011) for further design guidance where cycle tracks are present. Verges The need and size of the verge will largely be dependent on the function of the street and the presence of on-street parking. In general: • On Arterial and Link streets with no onstreet parking a verge of 1.5-2m should be provided as a buffer and to facilitate the planting of large street trees and items of street furniture.
- Design Manual for Urban Roads and Streets88 • There is no minimum requirement for verges on Local Streets, but designers may need to provide space to prevent any encroachment of street furniture into the footway. • Where on-street parking is provided, a verge (and change in kerb line) may be needed on approaches to junctions to enforce the visibility splays (see Section 4.4.5 Visibility Splays). In such cases the width of the verge will generally correspond to the width of car parking spaces. • A verge should be provided where cycle tracks are located adjacent to parking spaces (see Section 4.3.5 Cycle Facilities) • A verge (minimum of 0.3m) should be provided in areas of perpendicular parking where vehicles may overhang the footway (see Figure 4.36) Figure 4.36: An example where a narrow verge is provided to ensure that vehicle overhangs do not intrude on the footway. Figure 4.35: Example from Dublin where pedestrian priority across driveways is indicated by maintaining footway levels and surface treatments. Strips Strips may be provided as a designated zone that further animates the street and, in the case of a residential property, provide a buffer between the footway and the private residence. With regard to areas of commercial activity: • Where outdoor seating is provided the minimum width of a strip should be 1.2m. • Outdoor seating may also be provided within a verge area, where the footway runs between the shop front and seating area. • There is no recommended maximum size of a strip, but the design team should consider the impact of larger setbacks on the sense of enclosure of the street if a large area is proposed. • A designated strip may also be considered within Centres on shopping streets to provide additional space for window shopping. For residential areas designers should refer to Section 4.2.3 Active Street Edges, with regard to the width of privacy strips.
Source Department of Transport, Tourism and Sport and Department of Housing, Planning and Local Government: Design Manual for Urban Roads and Streets (2019 (version 1.1)) · Licence the publisher's termsText read from the publisher’s PDF; tables, maps and drawings do not survive as text, and page numbers are the PDF’s (its first page is 1). Check the original before relying on a passage.