DS.113 Traffic islands

Ver. Status Created by Date Approved by Date A Final D.Farnham/C.Agyei-Frempong 12.03.12 D.Waters 27.03.12 B Final D.Farnham 07.02.13 D.Waters 08.02.13 C Final G Lake 02.09.17 D Foden 07.08.19

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1 Introduction question carefully whether an island is truly necessary bearing in mind the various 1.1 Notes potential drawbacks discussed in Appendix a. This standard explains requirements A. They should also consider whether about the use and design of traffic crossing requirements for pedestrians of islands within the carriageway different abilities would not be better served (sometimes referred to as refuges) and at another location (existing or new) where longer reservations. This includes where islands would not be necessary. such features are proposed in association with controlled crossings. 2.2 Design requirements 1.2 Discussion 2.2.1 Pedestrian crossing facilities through islands a. See Appendix Afor a full background discussion. a. Where located within a controlled or uncontrolled pedestrian crossing then all 2 Common requirements for all types islands should include accessible of islands pedestrian routes through them unless a level 1 departure is agreed. Where NOTE: Further requirements that are specific provided in association with a toucan to different types of islands exist in section crossing these routes may also 2.2.. accommodate pedal cyclists. 2.1 Use requirements b. Except where ‘c’ applies, the routes a. Because of their potential adverse through islands for pedestrians in ‘a’ impact on pedal cyclists, islands should should include appropriate tactile surfaces not be introduced for traffic calming at the interface with the carriageway in purposes only. Other traffic calming accordance with standard DS.207. methods should be used instead. Islands should be used only to improve c. Where an island is provided in association ease of pedestrian crossing or (in limited with a ‘through’ crossing then no tactile circumstances) carry traffic control surfaces should be provided at the equipment. Any traffic calming effect interface between the route through the should be an ancillary and unintended island for pedestrians and the consequence of these other principle carriageway. functions. NOTE: This requirement exists in order to NOTE: Where islands are used to assist avoid confusing blind and partially sighted pedestrian crossing movements, the main users of ‘through’ crossings who may be beneficiaries will be more vulnerable confused by the presence of tactile paving pedestrians including those with visual or on the island and so stop rather than mobility difficulties. Except where traffic is completing their crossing movement as heavy and fast moving, other pedestrians intended. are likely cross where they choose. In order to avoid over use of islands, other sections 2.2.2 Width of islands of this standard establish threshold criteria NOTE: Greater widths than stated below beyond which introduction of islands will be may be required elsewhere in this and other acceptable (subject to design requirements standards for other reasons, including the being met). These criteria largely relate to need to accommodate street furniture. See the peak volumes of traffic experienced at a also section 2.2.2. location, residual carriageway width (after introduction of edge narrowing has been a. Where islands include tactile blister considered) and proximity to destinations paving then they should be a minimum of likely to be visited by significant numbers of 1.8m in width so that they can safely vulnerable pedestrians; but irrespective of accommodate a waiting pedestrian with a meeting any use criteria, designers should buggy.

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b. Where islands do not contain tactile b. 300mm or 450mm radius quadrant kerbs paving then they should be a minimum should be used to the ends of islands at of 0.6m in width. corners. Where islands include routes through them for pedestrians then the 2.2.3 Clearance between street furniture corners of the raised areas at the on island and carriageway interface with these should use square a. Where islands contain traffic signals (as kerb junctions between straight sections will likely be the case with signal of kerb and not quadrants. controlled crossing islands and most c. Kerbs at the ends of islands facing stand-alone crossing islands) then all approaching traffic should be 300mm apparatus associated with these (see wide in all instances. This includes island note) should be located on the island at build outs between parking bays at the a minimum 450mm horizontal distance carriageway edge and similar. The width from the edge of carriageway. The same of other edge kerbs should be as required distance should generally be kept for in the SSDM/SER/Surfacing Material other vertical items of street furniture, palette for the relevant SSDM/RP except where the feature is supported designation(s). by a “width restriction” traffic order or if NOTE: Where islands feature a staggered the furniture is adjacent to a cycle lane. crossing then careful consideration of However, a common sense approach bollards and street furniture is required. This should be taken and– subject to vehicle is in order to deter pedestrians from walking tracking assessment demonstrating straight across the island (without following reasonable clearance – lesser distances the stagger) whilst at the same time avoiding may be acceptable by agreement to a the creation of a trip hazard. Pedestrian level 1 departure. barrier railings are not generally used. NOTE: This includes traffic signal heads, d. See standard DS.603 about fixing of pedestrian demand call boxes and control kerbs and edge restraints. cabinets as well as any up right posts associated with these. When items are e. All areas of island pavements (e.g. both located on posts then the distance should be areas with and without pedestrian measured from the nearest edge of the item. facilities) should be treated as footway As signal head will normally overhang their pavements and surfaced to visually match posts this will generally be the edge of the the footways on the street. See standard signal head rather than that of the post. DS.130 for further information. However, where the normal footway surface course 2.2.4 Pavement design and overall form is flag or slab unit paving then, where the width of the island is less than 1200mm a. Islands should have a square or between the inner edge of the retaining rectangular plan form. Use of compound kerbs, that area may be surfaced with or radius kerb profiles will require small unit paving instead. agreement to a level 1 departure (see note) unless vehicle tracking f. For the purposes of standard DS.601, all demonstrates that a rectangular island is island pavements should be constructed unachievable. to a heavy overrun specification.

NOTE: Use of such details is generally to be avoided on visual grounds in urban areas and because of the sense of vehicle dominance they create. However, it is accepted that this may be unavoidable in some instances else preferable to setting back islands considerably to avoid extensive vehicle strike of kerbs.

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2.2.5 Location of trees and cycle stands traffic to bunch up into two lanes. This on islands may result in pedal cyclists being squeezed. As such, use of widths a. Trees and cycle stands may only be greater than 4.25m will require a level 1 located on extended central reservations. departure unless the island is at a Location on other types of islands will junction and vehicle tracking need agreement to a level 1 departure. demonstrates that lane widths have to Either way, they should be located on be greater than 4.25m. Except where a raised areas of the island. They should carriageway to the side of an island not be located within areas intended for would be for the use of pedal cyclists pedestrians. The following further only (see ‘c’) widths less than 4.0m will requirements should also be observed: need agreement to a level 1 departure i. Location of cycle stands on islands is (see note 2). subject to:  Provision of adequate width: The NOTE 1: See standard DS.102 about minimum width of the island widths where both a cycle lane and a should be sufficient to general traffic lane would pass together to accommodate the total use the same side of the island (traffic lane  envelope of the stand plus a 3m but  4.25m generally). further 500mm to either side of the NOTE 2: Use of widths < 4.0m will island from which cyclists may generally only be appropriate where other emerge. measures are provided in the vicinity of the  Highway visibility. See standard feature to substantially limit speeds and so DS.114 for further information. reduce possible intimidation of cyclists ii. Location of trees on islands is subject should motorists attempt to pass at the to: island. The possible effect that such  Provision of adequate clearance of measures might have in encouraging the carriageway over the inappropriate overtaking in advance of the carriageway for vehicles. See feature to avoid delay shall need to be standard DS.501 for further taken into account, as will the street clutter information. generated. Where proposed widths are <  Highway visibility. See standard 3.5m then the views of the emergency DS.114 for further information. services will generally also need to be taken into consideration. 2.2.6 Carriageway widths beside islands b. On 30mph streets, carriageway widths NOTE: Adequate carriageway widths beside beside islands should be 4.25m where islands are essential to ensure that pedal traffic moves in a single lane (though cyclists and motor cyclists are not squeezed or see note 1). Widths of 4.5m may be overly intimidated by motor vehicles should the agreed with a level 1 departure. This will latter try to overtake them whilst passing the be subject to approving officers being feature. However, note that provision of such satisfied that the nature of the widths will significantly reduce the speed arrangement would not lead to traffic reduction effect of islands. See also section forming into two lanes passing the 2.2.7.which will also impact upon comfort for feature (which might serve to squeeze these users. pedal cyclists). Except where a carriageway to the side of an island a. On 20mph streets, carriageway widths would be for the use of cyclists only (see beside islands should be 4.0-4.25m ‘c’), widths less than 4.25m will need (though see note 1). They should be agreement to a level 1 departure. 4.25m where buses or a significant NOTE 1: See standard DS.102 about widths number of commercial vehicles would where both a cycle lane and a general traffic pass. Whilst even greater widths are lane would pass together to the same side of preferable in such circumstances these the island. carry an increased risk of encouraging

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c. Where a cycle lane (or a prohibited ‘route designers should allow for tolerances for use by pedal cycles only’) exists to one accounting for opening of doors of parked side of a island and no other lane then vehicles and have regard to the likely carriageway widths should be as positioning of cyclists when passing the described in standard DS.102. island. In many instances cyclists are likely to position themselves closer to the edge of 2.2.7 Consideration of comfort for pedal carriageway than usual in passing islands cyclists when passing islands in order to avoid being squeezed by any a. Introduction of any island is subject to vehicle that may attempt to overtake them provision of satisfactory comfort in the alongside the feature. road layout for pedal cyclists - both when Introduction of ‘cycle symbol’ road passing a feature and in the vicinity of it. markings on the carriageway should also In addition to requirements related to be considered just in advance of the appropriate carriageway widths in section feature to alert other road users to the 2.2.6., designers should demonstrate potential for conflict with cyclists. regard to the need to avoid pedal cyclists being squeezed and intimidated by other 2.2.8 Visibility of pedestrians likely to road users both on the approach to and use islands for crossing purposes after the feature because of the need to negotiate around other obstructions in a. Where islands are provided it is likely these areas (see note 1). The that pedestrians will be attracted to use appropriateness of proposals in these them to help them cross the street – respects will be considered on a case regardless of whether crossing specific basis by approving officers (see facilities are provided within them. note 2 for general guidance). In the event Adequate visibility for approaching that it is not possible to agree acceptable road users of both the island and arrangements by consensus with nearside and far side areas of the designers then this should be raised as a footway from which pedestrians may Point Of Enquiry within an Audit Brief for a begin their crossing movements should Road Safety Audit (RSA). The proposals therefore be provided as per standard should be reviewed in light of the findings DS.114. of the Audit Report. Normally this will take place within a following Quality Audit. NOTE: The above is an important consideration. The majority of islands are NOTE 1: Such obstructions could include likely to be introduced on 30mph streets footway build outs or parked cars at the edge which is where the overwhelming majority of the carriageway. of pedestrian casualties occur. Annual Greater London casualty statistics continue NOTE 2: In general, a suitable distance should to show inadequate nearside and far side be maintained between the start or end of the visibility for drivers to be significant factors island and any preceding or following contributing to pedestrian casualties. obstructions introduction of the feature so that cyclists can take a smooth racing line around 2.2.9 Illumination of pedestrians likely to the latter. This should provide cyclists with use islands for crossing purposes enough time and space to gradually move a. Central illumination columns CICs) are across the carriageway to position themselves columns with a white globe on top. They to pass in advance of features. On 20mph look similar to zebra crossing columns streets a distance based on a 1:5 gradient (only without the stripes). They are taper (the taper being the assumed gradual intended for placement on traffic islands movement across the carriageway of a cyclist) where there is a concern that these may is likely to be sufficient. On 30mph streets not be adequately visible to road users. then a 12.5m gradient taper is likely to be This could be due to the location of the appropriate. In applying this guidance, island on the brow of a hill, or in a dip in

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the road or even on flat roads, heavily to be demonstrated that no residual queuing traffic. safety need exists for the CIC that has not been otherwise addressed. b. The need for CICs should be avoided as they add to street clutter and use energy c. Where they are permitted, CICs should through lighting. be to BS 8442:2006.

Introduction or retention of any CIC within 3 Specific further requirements for a scheme area will require a level 2 different types of island departure. It will need to be demonstrated that a safety need exists that could not be NOTE: Requirements that are common to otherwise be addressed in a manner that all types of island are explained in section would have lesser visual impact. Removal 2.. The requirements in this section are will require a level 1 departure. It will need specific to particular types of island only.

Island type Further info Summary of use requirements Pedestrian Section 3.1 Should be avoided with other methods to improve crossing used in island preference (see note 1). Use may be considered where one or more (uncontrolled of the following apply (though other alternatives remain preferred): crossing)  Carriageway widths would still exceed 9m after introducing narrowing measures on 30mph streets, or 10m on 20mph streets.  Certain motor vehicle trafficking thresholds are exceeded.  The proposed location is close to a school, care centre, home for older people or other place likely to attract vulnerable pedestrians (applies to 30mph streets only).  Introduction in other circumstances will require agreement to a level 2 departure. Signalised Section 3.2 Should be avoided by designing junctions to provide adequate junction island crossing times for pedestrians. Subject to agreement to a level 1 departure, use may be acceptable where it can be shown that:  An island is necessary to accommodate traffic signal heads (e.g. for a right turn lane).  The width of the carriageway would exceed 12.5m after consideration of other narrowing measures.  Introduction in other circumstances will require agreement to a level 2 departure. Stand alone Section 3.3 Should be avoided. Subject to agreement to a level 1 departure, use controlled may be acceptable where it can be shown that the width of the crossing island carriageway would exceed 10m after consideration of other narrowing measures. Introduction in other circumstances will require agreement to a level 2 departure. Splitter islands Section 3.4 Should be avoided. Subject to agreement to a level 1 departure, use may be considered to protect contra flow cycle lanes. Introduction in other circumstances will require agreement to a level 2 departure. Central Section 3.5 Supported in the right circumstances. However, since these features reservations are likely to constrain future changes, a level 1 departure will be required to check that this is appropriate. NOTE Examples of preferred alternatives include narrowing of carriageways through introduction of footway build outs, or introduction of controlled crossing facilities.

Table 1 - Summary of use requirements for different types of traffic island

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3.1 Pedestrian islands i. It can be demonstrated that the residual carriageway width after NOTE: Pedestrian islands are those introduction of edge build outs could provided only for the purpose of helping not be reduced to ≤ 9m. pedestrians to cross carriageways at uncontrolled crossings. ii. It can be demonstrated via extrapolation from traffic counts that 3.1.1 Use requirements for 20mph the part of the carriageway to which streets (threshold criteria) the island would be used would have a. Where existing pedestrian islands are vehicle traffic flows within any 15 encountered then the need for these minute period of the peak hour should be reviewed with a view towards exceeding the figures in Table 2. designing them out where they do not meet the use criteria explained in NOTE 1: Table 2 requires designers to ‘3.1.1.b’. However, conversely, such know the split or ratio of the total number islands should not be removed without of vehicles using the street between the consideration where they still serve a available lanes. beneficial purpose. Design teams must consider both retention and removal and NOTE 2: Notwithstanding the above approving officers may instruct either provisions, designers should note that retention or removal as appropriate they are not obliged to introduce islands subject to the findings of the designer’s and should question carefully in all review. instances whether these are justified. See section 2.1 above for further b. Where no existing pedestrian island is discussion. present but designers wish to improve ease of crossing for pedestrians, then NOTE 3: The above requirements should the introduction of footway build outs be applied with an awareness of what that create edge narrowings of the existing mean average speeds are as carriageway (and so reduce the crossing well as signed speed limits. distance) is the preferred method. Notwithstanding this assumptions for However, subject to design 30mph streets should not be applied to requirements being met, pedestrian streets signed as 20mph without prior islands may be introduced where either: agreement.

Ratio between traffic flows in lanes / Total no. vehicles using all lanes within 15min period (beyond which island permissible) 50 : 50 55 : 45 60 : 40 70 : 30 80 : 20 One-way street (with more than one lane) 128 120 114 105 100 Two-way street 104 98 93 86 82 (see note 1) NOTE These figures assume a two lane carriageway. Where there are more than two lanes then introduction of an island may be considered where the figures for a 70:30 lane ratio are exceeded. Table 2 - Peak 15 minute vehicle traffic threshold values for 20mph street

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3.1.2 Use requirements for 30mph ii. The island is located within 225m of a streets (threshold criteria) school or college and it can be established through traffic counts that a. Where existing pedestrian islands are it would be positioned at a location encountered then the need for these used by a significant number of should be reviewed with a view towards children or young people who are designing them out where they do not unattended by adults on their journey meet the use criteria explained in ‘b’. In to or from that site. order to ensure both that this review takes iii. It can be demonstrated via places and, conversely, that such islands extrapolation from traffic counts that are not removed without consideration the carriageway at the proposed where they still serve a beneficial located will have vehicle traffic flows purpose, both retention and removal will within any 15minute period of the peak require agreement to a level 1 departure. hour that would exceed the values in This will be subject to the findings of the Table 3 (see note 1). designer’s review. iv. It can be demonstrated that the b. Where no existing pedestrian island exists residual carriageway width after but designers wish to improve ease of introduction of edge build outs could crossing for pedestrians then, as on not be reduced to ≤ 8m. 20mph streets, the introduction of footway NOTE 1: Notwithstanding the above build outs that create edge narrowings of provisions, designers should note that they the carriageway (and so reduce the are not obliged to introduce pedestrian crossing distance) is the preferred islands and should question carefully in all method. However, subject to design instances whether these are justified. In requirements being met, pedestrian particular, on 30mph streets designers islands may be introduced where it can be should consider whether the introduction of demonstrated that one of the following controlled crossing facilities would not be threshold criteria are met: more effective. i. The island is within 100m of a pedestrian entrance to a school, NOTE 2: Table 3 requires designers to know playground, medical centre, day the split or ratio of the total number of care centre for vulnerable people, or vehicles using the street between the communal home or retirement available lanes village for older people (or similar). .

Ratio between traffic flows in lanes / Total no. vehicles using all lanes within 15min period (beyond which island permissible) 50 : 50 55 : 45 60 : 40 70 : 30 80 : 20 One-way street (with more than one lane) 114 107 102 94 89

Two-way street 101 95 90 83 79 (see note 1) NOTE These figures assume a two lane carriageway. Where there are more than two lanes then introduction of an island may be considered where the figures for a 70:30 lane ratio are exceeded. Table 3 - Peak 15 minute vehicle traffic threshold values for 30mph streets

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3.2 Signalised junction islands 3.2.2 Design requirements NOTE 1: These are islands at signalised a. The width of any island accommodating junctions that accommodate traffic signals traffic signals should be such that any (which may be either signals for vehicles signals are (at their widest extent above passing along the carriageway or for users ground) set back a minimum of 300mm in wishing to cross) whilst also providing the horizontal plane from the edge of crossing facilities for pedestrians, cyclists or adjoining carriageways. The location of equestrian users. Islands provided as part of any pedestrian push buttons or near side controlled crossing facilities that are not displays will also influence the necessary associated with signalised junction overall width. arrangements are considered separately in section 3.3. Islands for traffic signals can be NOTE: See section 2.2.2. for general width particularly unsightly, generating substantial requirements. clutter and asset management liabilities. The use of such features is to be avoided b. Assuming that a crossing path passes wherever possible by designing junctions so through an island then its minimum that necessary signals are accommodated width should be as follows (though note on footways within the requirements of the that other factors may require islands to schedule to the Directions within the be substantial wider): TSRGD. As ever, edge build outs narrowing i. Where part of an ‘in-line’ crossing the carriageway should be used to improve arrangement – a minimum of 3.0m on ease of crossing where this is considered 20mph street and 4.0m on 30mph necessary whilst crossing times should be streets. This increased width is set to allow users adequate time to complete important to ensure that blind or their crossing in a single movement. partially sighted users appreciate that crossings to either side of the island 3.2.1 Use requirements are distinct entities. ii. Where part of a ‘staggered’ crossing a. Notwithstanding the above note, it is arrangement – a minimum of 1.8m accepted that, in some circumstances, wide between kerb checks or (where the introduction of such islands as part the use of such features is approved) of signalised junction arrangements may pedestrian barrier railings in General, be unavoidable (see note below). These Docks, Village and Heritage features may therefore be used subject Specification Areas and 2.5m in to agreement of a level 1 departure. This busier ‘Town Centre and World will be considered on a case specific Centre Specifications Areas. The basis by approving officers. Designers 2.5m distance should also be will be expected to be able to provided in other areas where it is demonstrate robustly that use of islands anticipated that use of the island may is unavoidable. be significant and may be instructed by approving officers where they NOTE: For instance, there may be multiple have such concerns. vehicle lanes that are required to undertake different movements and which thus require NOTE: See section 2.2.2. for general width separately located signals. Alternatively, requirements. capacity restrictions may mean that it is not possible to set signal times such that c. Where a staggered crossing pedestrians are able to cross the arrangement is used then see standard carriageway in a single movement. DS.202 for details of how that stagger is to be enclosed (and see section 2.2.4. b. An exception to ‘a’ in which new islands for further discussion). accommodating traffic signals may be introduced without any need for a departure is when these are part of a central reservation as section 3.5.

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3.3 Stand alone controlled crossing b. Where the width of the carriageway is less islands than 11m then islands should not be included as part of a pelican, puffin, zebra NOTE 1: These are islands provided as part equestrian or toucan crossing. of pelican, puffin, toucan, equestrian or zebra crossing facilities that do not form part NOTE: There are several reasons for the of a signalised junction arrangement (for above. Firstly, where islands are provided this which see section 3.2). They usually can make it difficult for pedestrians to exert accommodate both traffic signals (or belisha priority on the second half of the crossing as beacons) and pedestrian crossing facilities. vehicle users are more likely to treat these as Depending upon the type of arrangement the separate. In addition, for signalised facilities island could serve to separate the crossings statutes require additional pedestrian signals to either side of it into distinct features that to be provided on islands. This can be are subject to separate control (e.g. in the misleading for pedestrians in some instances instance of a zebra crossing so that vehicles due to potential ‘see-through’. National on one side of the island do not need to stop guidance therefore advises that islands should for pedestrians using the crossing on the be avoided save for where crossing distances other). are exceptional. Crossing times should be set to facilitate this. Finally, unlike for crossings NOTE 2: The design of most types of stand associated with signalised junctions, there is alone crossing is covered by the Pedestrian seldom if ever a need to provide separate Crossing Regulations 1997 (though for signals for different lanes which might then toucan and equestrian crossings some require the inclusion of a island to provisions are made within the TSRGD). accommodate these. This is different to crossings forming part of a c. Where the width of the carriageway is > signalised junction arrangement for which all 10m then provision of an island may be statutory requirements exist within the agreed with a level 1 departure. This will be TSRGD. The government has signalled its subject to it being demonstrated that it intention to consolidate all requirements into would not be feasible to narrow the the TSRGD through future revision to this crossing distance to ≤ 10m through the statute. introduction of footway build outs at the carriageway edge. Notwithstanding this, 3.3.1 Use requirements (threshold designers are encouraged to consider criteria) carefully whether introduction of an island a. Where existing such islands are is really necessary. encountered in streets then the need for 3.3.2 Design requirements these should be reviewed with a view towards designing them out. In order to a. Width requirements should be as per those ensure both that this review takes for signalised junction islands given in places and, conversely, that such section 3.2. islands are not removed without b. Requirements for other aspects of design consideration where they still serve a should be as per those for signalised beneficial purpose, both retention and junction islands given in section 3.2. removal will require agreement to a level 1 departure. This will be subject to the 3.4 Splitter islands findings of the designer’s review and NOTE: These are islands that have been project funding (see note). provided for the purpose of separating traffic NOTE: Removal of signals can be very lanes - a function to which the provision of any costly due. As such, even when it is pedestrian crossing facilities is purely determined that there is no need for an incidental and as a result of some obstruction existing such island, it may not always be to a crossing that the island causes. They possible within available project budgets to include islands that may be located in a remove these. junction mouth for the purpose of separating a contra-flow traffic lane from other lanes. They

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do not include islands introduced on links for providing opportunities for informal crossing the purposes of creating a central island of the carriageway, particularly in town narrowing for traffic calming reasons (these centres and other busy areas with high should always be treated as one of the other pedestrian and vehicle flows. forms). No island provided in association with a signalised junction or stand alone They may incorporate small gaps so that controlled crossing may be treated as a pedal cyclists may pass through them splitter island. providing that the overall impression of continuity of the feature is maintained. 3.4.1 Use requirements Central reservations can have several a. Where existing splitter islands are potential draw backs. The most significant of encountered then the need for these these relate to flexibility of future should be reviewed with a view towards reconfiguration of the street (including designing them out. In order to ensure opportunities to widen footways), comfort for both that this review takes places and, pedal cyclists when using the carriageway conversely, that such islands are not and access for emergency response removed without consideration where vehicles. they still serve a beneficial purpose, both retention and removal will require 3.4.2 Use requirements agreement to a level 1 departure. An a. Introduction of central reservations is exception is where the island provides supported in the right circumstances and segregation for cycle facilities. may be permitted by agreement to a b. New splinter islands should not be level 1 departure. This is in order to introduced (though see ‘c’) except where check various things including: traffic signals are being implemented i. That alternative preferred methods of and the island is a requirement of TfL improving ease of pedestrian design standard (SQA 643: islands crossing (such as edge narrowing of required in roads wider than 7m). Any the carriageway) which are less departure request will need to potentially problematic for pedal demonstrate an evidenced safety or cyclists and which provide greater statutory need and show that alternative flexibility in making further future arrangements to address these have changes to the street would not be been explored to exhaustion and are not feasible within reasonable feasible. timescales. ii. That the reservation is being c. Where contra-flow cycle lanes (including configured to minimise the need for unmarked routes) exist along a one-way associated street clutter (see street then introduction of occasional ‘3.5.2.b’’ and ‘3.5.2.c’). new splitter islands to separate the route iii. That carriageway widths are from other vehicle lanes should still be appropriate and will not result in avoided as ‘a’. However, the suitability pedal cyclists being squeezed by for cyclists of junction arrangements other road users (see ‘3.5.2.d’). along the route should be considered in iv. The views of the emergency services a Road Safety Audit (RSA). Further (see note). considerations of the findings of the Audit Report, the introduction of a NOTE: The views of the emergency services splitter island of length not exceeding will be sought by approving officers and 6m may be permitted by agreement. should not be requested or investigated by proponents. Emergency services may 3.5 Central reservations sometimes object to the introduction of central reservations on the basis that they NOTE: These are islands that run for an may constrain the ability of traffic to move extended length along the centre of the out the way to permit their passage when carriageway – so effectively separating it into they are trying to reach an emergency. two carriageways. They can be useful for

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3.4.3 Design requirements at the junction may be incompatible as the reservation may make the layout confusing. a. Such features may or may not include crossing facilities for pedestrians as d. Carriageway widths to either side of section 2.2.1. central reservations will be agreed with NOTE: Given their length and the approving officers on a case specific requirements of other standards in respect to basis. Particular concerns should be the frequency of crossing opportunities, the providing sufficient widths such that inclusion of at least some such crossing pedal cyclists are not squeezed or facilities is likely to be necessary. intimidated by other vehicles (who will likely attempt to keep clear of the b. Such features should extend for a reservation) and maintaining means of distance of ≥ 25m. That distance may access for emergency service vehicles include brief breaks of a length ≤4.5m to should carriageways be congested. allow passage through the island for vehicles (e.g. turning gaps) providing Appendix A - Background that the overall impression of continuity of the feature is maintained to the a. Traffic islands in carriageways can be satisfaction of approving officers. This is used to: in order to avoid the need for additional i. Assist pedestrians to cross the traffic signage that may otherwise be street by allowing them to do so in necessary to warn of the two movements rather than recommencement of the feature. Breaks covering all traffic lanes in one go. should be exceptional with distances ≥ ii. Separate opposing flows of traffic 25m maintained between instances. (or traffic proceeding in the same Maintaining the sense of continuity may direction) into different lanes. require use of the same or similar iii. Accommodate necessary items of paving materials to the carriageway street furniture (for example traffic within the gap to those used to the signals). raised area. Breaks should not be iv. Create carriageway narrowings for considered as contributing to meeting speed reduction purposes. the overall minimum length requirement for the feature. b. Whilst they can be cheap to construct (as c. Where several instances of central typically being positioned on or near the reservations immediately follow one crown of the carriageway camber they another along a street (being separated seldom involve complicated changes to on account of junctions that require surface drainage) and can benefit less breaks of a length greater than those mobile pedestrians they can have a discussed in above) then designers number of potential draw-backs: should consider taking steps to maintain i. They frequently require the use of the impression of continuity such that significant traffic signs and road the various sections appear as part of markings, so generating street the same central reservation. This may clutter and asset management require the use of the same or similar liabilities. paving materials to the carriageway ii. When used at junctions they can through the junction as have been used result in the location of crossings to the reservation. being shifted away from the junction (off the natural desire-line) in order NOTE: The above may not always be to provide space for turning vehicles appropriate. For instance, it may be wished to complete their movements. to emphasise a junction as a focal space. iii. They do not contribute to the The sense of priority to through movement creation of useable pedestrian created by the reservation may undermine space in the same way as this. Alternatively, the nature of traffic narrowings created by peripheral controls and permitted movements at the widening of footways do. Their use

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may contribute to an increase in the junctions which are where around 80% overall width of the carriageway. This of pedal cyclist casualties in Greater is because sufficient width then needs London occur3. The introduction of to be provided to fit the swept path of islands significantly limits the potential large vehicles to either side of the to narrow the overall width of island when turning or passing. Were carriageways and this is exacerbated by no island present then these vehicles the need to provide wider carriageways may often be able to do this by to either side of these features in order partially over running the opposing to mitigate passing conflicts with pedal lane. cyclists (see ‘iv’). iv. Research1 suggests that central vi. Though true also of many other features islands can cause significant stress for in the carriageway that serve to pedal cyclists, appear to provoke channelise traffic, carriageway negative attitudes about cyclists in pavements beside islands tend to be at other vehicle users (as cyclists may increased risk of rutting as wheel paths obstruct them at the narrowing they are concentrated into confined areas. create) and can encourage road users This has both safety and maintenance to attempt inappropriate overtaking of implications. cyclists in advance of the feature. It also suggests that the significant local Other arrangements like edge build outs speed reduction benefits of these of the footway are therefore likely to be features can reduce on repeat preferable in many circumstances – encounters. Whilst passing stresses particularly on 20mph streets (as can be mitigated somewhat by practically all pedestrian and cycle providing wider carriageways to either casualties occur on streets with speed side of the feature this would reduce limits of 30mph or greater). On 30mph the local speed reduction effect. streets, controlled crossing facilities that Because of these potential adverse allow users to cross the carriageway in a consequences for pedal cyclists, single movement may be preferable. researchers recommended that these This is reflected in the requirements for features are not used and other the use of different types of islands means of providing improved within the sections that follow. pedestrian crossing facilities are prioritised. v. Research2 suggests that absolute narrowing of carriageways (e.g. by widening the footways to either side) has a significant and durable speed reduction effect. Narrower carriageway widths correlate with reduced vehicle speeds. This is most pronounced on the approaches to

1Driver’s perceptions of cyclists - TRL549 (Basford et al, 2002), The effect of road narrowings on cyclists - TRL621 (Gibbard et al, 2004), Road safety report no.100 – Interaction between speed choice and road environment (Jamson et al, 2008) 3 Pedestrian casualties in Greater London 2Manual for Streets – Evidence and Research (Transport for London, 2011) (Department for Transport, 2007)

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