Islington Streetbook Section 3 Standard Footway Materials

7/31/2019 Islington Streetbook Section 3 Standard Footway Materials

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STANDARD

FOOTWAYMATERIALS

3.1 INTRODUCTION

3.2 DESIGN PRINCIPLES

3.3 HISTORIC SURFACES

3.4 PAVEMENT PROTECTION

3.5 PRINCIPAL FOOTWAY MATERIALS

3.6 CONCRETE FLAGSTONES3.7 YORKSTONE

3.8 EXCEPTIONS

3.9 STANDARD ANCILLARY MATERIALS

3.10 TACTILE PAVING

3.11 REPAIR AND REINSTATEMENT

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3.1 INTRODUCTION

The quality of design and construction of footways sets thecontext within which buildings and other spaces are viewed. Thestandard of many streets in Islington has deteriorated. There arethree main reasons for this:

the use of inappropriate footway materials inconsistency in the use of materials

inadequate funding of some projects

The use of small element paving (principally Modular 400) hasdamaged the character of many streets in the borough, incommon with other London streets, which had traditionally beenpaved with large (900 x 600mm) rectangular units of natural stoneor concrete paving.

The scale of small element paving is visually inappropriate formany principal streets. Because they cannot be easily cut to shape,they often have to be used with block paving, resulting in an

inconsistent and untidy appearance.

The greater the number of materials on the pavement the more difficult it is to maintain the more difficult it is to reinstate

Islington Council will promote a limited range of materials whichcan be applied consistently around the borough and which willhelp achieve simplicity; simplicity in design, in construction, in themaintenance of footways and in their reinstatement in the future.

Therefore, Islington Council proposes the following for itsfootways:

MaterialsThe principal footway materials used on Islingtons streets willbe limited to concrete flagstones or Yorkstone.

Paving SizesSlab paving, whether it is natural stone or precast concrete,should be of a standard size so that there can be a seamlesstransition from one to another.

The modular 400x400mm and concrete block paving will bephased out and only used for repairs to existing areas of thattype of paving.

Inconsistency: The use of

too many materials contributes

to an untidy appearance

8

Modular and block paving

to be phased out8

STANDARDFOOTWAY MATERIALS3

Streetbook February 2005


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3.2 DESIGN PRINCIPLES

In all highway improvement and environmental improvement

schemes, the following guidelines should be followed:

design with simplicity, avoiding patterns in the floorscape for

their own sake. Selective embellishment in paving, (through

changes in colour and texture), should be restricted.

Embellishment should only be used to highlight significant

entrances; to define a context for important elements in the

streets, eg monuments or public art; denote ownerships ; or

impart interpretative information into the paving design;

define and unify space, respecting the importance of existing

kerb lines in the Islington streets. Incorporate, if necessary, the

layout of gullies/channels into the paving design. Where

overrunning by vehicles is probable, surfaces should be

designed to withstand vehicle-loading (section 3.4 deals with

the various methods of pavement protection for this purpose).

Where possible shopfront thresholds should be paved in thesame material as the rest of the footway.

Simplifying thepalette of materials

will improve the

appearance of the

streetscape

Unification of space

through consistent use of

single footway material.

(Goswell Road, Islington)

4

4

4 Integrated design: Drainage gully seamlesslyincorporated in footway. (Glasgow)

Seamless integration:Artificial stone paving laid

continuously with Yorkstone

(City Road, Islington)



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3.3 HISTORIC SURFACES

The quality of the Islington streets comes partly from the historic

paving and its street furniture. The original paving is often high-

quality stone from British quarries and is difficult to match. Often

this stone has an attractive colour, and acquired character from

years of wear. It also often displays notable masonry skill in the

way it was laid.

Designs which are specific to a location help to create a unique

sense of place and should be preserved.

Therefore, retrieving historic surfaces should be given careful

consideration and they should be preserved in situ wherever

possible. This should apply to other historic features, such as

street furniture, bollards, railings, signs.

Great care is required in saving and restoring old street features

and, if necessary, removing them for use elsewhere. For this

reason specialist contractors may be required.

Traditional Yorkstone paving

Historic surface: Refurbished footways matching the old surface.(Camden Passage, Islington)


Where necessary,save - restore - relocate

4

4



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Historic surfaces

should be preserved in

situ wherever possible.

3.4

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3.4 PAVEMENT PROTECTION

A major problem with laying large slabs of whatever material, is

the risk of vehicles mounting the pavements, and cracking them.

There are basically three means of prevention:

provision of a high kerb to the carriageway

structurally strengthening the footways

installing bollards or other street furniture and/or a soft

landscaping strip

In order to keep street furniture to a minimum, every effort should

be taken to avoid the need for bollards. Generally, the first two

measures above should negate the need for bollards.

3.4 (a) Kerbs

When kerbs are retained a minimum of 100mm is required to

prevent vehicle overrun onto the footway. This will nevertheless

not deter the most determined offenders.

Where higher kerb faces are required (for example, for road

closures see section 5.3), the existing kerb line may need to be

reset. This can only be done if the falls across the pavement can

be achieved without affecting pavement levels to private

thresholds. Alternatively the carriageway levels may need to be

planed down to reveal a greater face of kerb.

HIGH KERB DETAIL, for pavement protection

4

Every effort should

be taken to avoid the

use of bollards



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3.4(b) Pavement Strengthening

On footways which are vulnerable to vehicle overrun, pavements

will need to be strengthened. A width of 1.5 metres at the edge is

often the area most at risk.

Reinforcement should be done so that the appearance of the

strengthened paving is the same as the rest of the footway.

The first two rows of slabs against the kerb should be

strengthened where required without a change in the paving

courses or bond.

New products and technologies dealing with the issue of

pavement strengthening and protection need to be considered. For

example, there are currently experiments utilising fibre reinforced

paving. Pavement design, construction and installation are exactly

the same as for non-reinforced flags but with the advantage of no

additional handling or construction costs involved.

3.4(c) Bollards

Bollards are covered in more detail in Chapter 4, Street Furniture.

Before considering installing bollards for pavement protection,

consideration should always be given to the use of other street

furniture and/or the use of soft landscape.

STANDARDFOOTWAY

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4


PAVEMENT

STRENGTHENING DETAILS

(Strengthened areas shown hatched)



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3.5 PRINCIPAL FOOTWAY MATERIALS

There are two principal footway materials: concrete flagstones and

Yorkstone.

3.6 CONCRETE FLAGSTONES OR ARTIFICIAL STONE PAVINGS,

(ASP)

Concrete flagstones are factory produced and available in many

sizes, colours, shapes and thickness. Thicker slabs are available for

vehicular loaded pavements. They should be laid out in staggered

bonded patterns.

The most commonly used formats of concrete flagstones used in

Islington are 750x600mm and 600x600mm.

The range of large, precast concrete flagstone (based on a uniform

600mm width and standard slab sizes) also includes 450x600mm

and 900x600mm.

Depths of paving may vary.

Health and safety note: The method of laying of thick large unit

slabs should take account of the current CDM regulation and the

laying of flagstones will need to involve the appropriate equipment.

Appropriate Usage

Except where the context demands the use of Yorkstone, (refer to

3.7), concrete flagstones are the councils preferred material. Theyshould be used in all residential streets and in commercial streets

unless the project in question is a short-term repair to an area with

modular 400 paving.

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5


Simplicity: The use of

artificial stone paving,

(concrete), cut to shape.4



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Advantages of Concrete Flagstones

Easily cut and dressed to fit irregular edges. Scale and proportions relate well to building elevations and are

reminiscent of natural stone paving. Staggered bonding pattern is the characteristic appearance of

London pavements and therefore concrete flagstones can belaid next to and continuous with Yorkstone paving.

Combines well with granite kerb and setts.

They can be reinforced and laid on deeper concrete base toensure long term stability and to avoid cracking. This isgenerally necessary close to the kerb edge and other areasvulnerable to vehicle incursion.

Disadvantages of Concrete Flagstones

Cracks under heavy vehicle pressure without pavementstrengthening specification.

Like all man-made materials, precast concrete stains, take on

dirt and fades with age.

Life Span

10-20 years life, for pedestrian traffic use, if laid well. No figuresare available for the use of thicker slabs on shared surface area.

Unit Prices (Prices January 2005)

For comparison onlyStandard flagstones: approximately 16 m2

Reinforced flagstones: approximately 20 m2

Formation and Sub-Base

Concrete flagstones can be laid on either 50mm sand or 30mmmortar bed on top of a sub-base. Slabs should be laid on a flexiblebase (Type 1) for pedestrian areas. Where slabs have to withstandvehicles, it is recommended that they be laid on either a densebase macadam road-base or a concrete slab foundation.

Type 1 is a granular base to the Department for Transports (DfT)specification. The material is from a certified source and containscrushed stone, crushed slug, crushed concrete or non-plasticshale.

ARTIFICIAL STONE PAVING,

Staggered Bond Patterns:



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Specification and Workmanship Issues

In order to avoid differential settlement, slabs have to be very

carefully laid strictly in accordance to specification. Flags laid on

as rigid base should be laid on cement mortar bed. Within phased

projects consideration should be given to the fact that the relative

wear of materials will be much evident at the interface/ junction of

the different phases.

The principles for setting out should be specified, e.g. from an

important centre-line or interface.

Slabs can be successfully laid up to a building line and the council

should encourage the integration between public footway and

private forecourts to promote seamless design.

Maintenance Issues

The loading exerted by some street cleaning equipment or carrying

out other maintenance can break slabs in footways. The larger thepaving unit the more prone it will be to defected breakage.

Codes and Standards

Refer to Part 4 of BS 7533

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Inconsistent use of footway

materials between public

footway and private forecourts

to be avoided if possible

8

Integration of footway

materials between public

footway and private forecourts

to be encouraged

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3.7 YORKSTONE

Yorkstone paving is natural stone which has been quarried, cut

and dressed into paving slabs. It is a fine-grained, hard sandstone

and millstone. It is produced in a range of surface finishes and slab

sizes. It contains buff and grey colour bands.

Yorkstone and granite were the original paving materials on

Islington footways. In areas of historic sensitivity, Yorkstone

should be retained and existing patterns and detailing should be

replicated in any new paving specification.

Appropriate Usage

It should be used in streets of historic and civic importance. The

council will endeavour to retain all existing areas of Yorkstone

paving wherever it is reasonable.

Due to its exceptional weathering qualities (with the material

looking better as it ages) and its long life Yorkstone is anappropriate material in historic and sensitive high-profile sites. It is

recommended that flagstones of traditional proportions are used.

Yorkstone is traditionally laid in random courses which allows a

range of stone sizes to be used.

There are variable lengths of 900mm, 750mm, 600mm, 450mm

and 300mm and a standard width of 600mm.

Choice of nominal thickness: 50mm and 75mm

In streets with narrow footways or with vehicle overrun problems,400 x 200 x 75 slabs to be used.

Varieties used in Islington:

Diamond sawn is the preferred finish for most locations.

Flame textured or Riven should only be used if a scheme

adjoins an area of existing similar paving.

Reclaimed Yorkstone should be used for patching repairs in

historic paved areas where the pieces can be individually and

very carefully selected.

New diamond sawn

Yorkstone paving. 4

4A mixture of old and new.Diamond sawn Yorkstone

abutting riven-finish footways.

(Finsbury Square, Islington)



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STANDARDFOOTWAY MATERIALS3Advantages

Warm colour and tonal variation, improving with age

Can be cut to size and dressed for specific situations

As it can match the size of concrete flagstones it can be laid

adjacent to and continuous with the concrete

Relatively maintenance-free

Long lifespan

Disadvantages

Unless strengthened with concrete base, liable to cracking

Extremely good-quality workmanship needed in laying

Yorkstone

Expensive at the beginning because of high purchase price

Life Span

For city centre townscape surfaces, subject to service vehicle

access, the expected life-span is 60 years plus, if specified and laidcarefully to specification.

Unit Prices

For comparison only.

Yorkstone paving gauged width x 50mm x random lengths:

Approximately 120 m2 (prices January 2005)

Formation and Sub-base

Yorkstone should be mortar-bedded onto a concrete base

(possibly requiring reinforcement) or a dense bituminous

macadam (DBM) base. The depth and strength of the base

required will depend on the traffic loading envisaged, the depth of

slab specified and the unit size of the slabs.

Yorkstone should be laid on 50mm mortar bed, in accordance with

British Standard 7533, Part 4. Mortar joints of 8 to 10mm are

usually specified, but where tighter joints (5 to 6mm) are required

then these have to be gun applied.

Yorkstone paving incorporating

integrated inspection covers4



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FLAGSTONE PAVING

CUT TO SHAPE

FLAGSTONE PAVING (Concrete and Yorkstone) - Detail at corners

Around posts and bollards

Around inspection

covers

Fanning



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FLAGSTONE PAVING

Laid on curves

Detail around tree pit

FLAGSTONE PAVING (Concrete and Yorkstone) - Detail at corners

InterlockingInterlocking

Abutting



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STANDARDFOOTWAY MATERIALS33.8 FOOTWAY MATERIALS EXCEPTIONS

While concrete flagstones and Yorkstone are the standard footway

materials being proposed, they cannot be used in every

circumstance.

3.8 (a) Black Top Surfaces

Concrete flagstones and Yorkstone may need to be substituted

with black top surfaces in the following circumstances:

for short-term reinstatement purposes for example, utility

works, when a temporary making-good period is permitted

for very narrow footways where the use of paving flags would

be impractical and untidy

in locations where there is an exceptional water penetration

problem, eg above cellars

where a thin surface finish is required

There are two main traditional surfaces used in Islington: masticasphalt and bituminous macadam. And a third material bound

gravel which is beginning to be popular in new schemes in

Islington and other London boroughs.

Mastic Asphalt

This is a very fine-grained, traditional, high durability paving

surface which tones down to a dark grey appearance. It was used

extensively in the past in Finsbury bordering the City.

Application: In narrow footways and around pavement lights

where other materials are not practicable. It looks good in

combination with granite kerbs.

Bituminous Macadam

A flexible paving material easier to lay than mastic. The fine-

grained 3mm bitmac is a satisfactory alternative to mastic and

weathers down top a grey appearance.

Application: like mastic, well suited to narrow irregular footways

and relates well to streets with a strong built character.



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3.8 (b) Bound Gravel

Crushed bound gravel was once commonly used in London and is

an attractive surface finish. It is recommended that footway

wearing courses should be specified in accordance with BS 1446:

1973.

Where there are tree root issues, for example at Highbury New

Park, bound gravel could be an appropriate material.

3.8 (c) One Off Opportunities

The above are the standards for the principal footway materials on

all Islington streets. There may occasionally be one-off

opportunities to include a non-standard material as part of a

redesign of a large public space / square. This is only permissible

in exceptional circumstances: for example, as part of a public art

installation.

In order to manage its future maintenance liability effectively, theCouncil will also need to be satisfied about issues of future

upkeep, maintenance and accessibility of the non standard

material.

Permeable bound gravel

detail at tree pit.

(Newcastle upon Tyne)

ST. JOHN SQUARE, ISLINGTON

A competition winning design for a major square

A limited palette of quality

materials, some non-standard.

(St. John Square, Islington)



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STANDARDFOOTWAY MATERIALS33.9 STANDARD ANCILLARY MATERIALS

In conjunction with the two main footway materials, precast

concrete slabs and Yorkstone, a range of small element materials

is required to fulfil a number of functions, such as:

to form vehicle crossovers across footways

in speed table ramps

to form edges to tree pits

raised part of pedestrian refuges / islands

Where small element materials are to be part of a pedestrian

environment, they must be chosen with care. The conservation

requirements should be balanced with pedestrian convenience and

the need for a flat even surface. All new setts should be fine picked

and close jointed. The only exception may be in historical

situations where there are existing open jointed setts.

3.9 (a) Granite Setts and Slabs

The borough contains a great deal of granite sett paving, which is

hard-wearing and durable if laid well, and is suitable for vehicle

carriageways, crossovers, runways or pub cellars and decorative

uses.

There are three varieties of setts used in Islington

split setts: for use on carriageways and paving trims

dressed setts: fine picked or flame textured can be used where

there is a pedestrians and vehicles both use a surface, such asat crossovers

flame textured setts: for shared vehicle and pedestrian areas

The dimension of setts used are 100x100x100mm and

200x100x100mm.

Granite slabs are only used in special circumstances where extra

pavement strength is required: for example, in front of pub cellars.

The dimension of slabs used are 900x600x80mm and600x400x70mm

Raised granite sett

carriageway finished to also

provide an even pedestrian

surface adjacent to riven-finishYorkstone footway

(Camden Passage, Islington)

4

GRANITE SETTS

The width of joints to be kept to a

minimum.

Bond patterns -

3 types



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TYPICAL DIAGRAM OF GRANITE SETTS ON FOOTWAYS AND CARRIAGEWAYS



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Layout at toe crossings

3.9 (b) Yorkstone Setts

Units to be used are 100x100x100mm.

They can be used to provide articulation and extra strength in

pedestrianisation schemes. They are also suitable to pave irregular

or difficult shapes in streetscape schemes.

3.9 (c) Artificial Stone Setts / Blocks

The setts / blocks are textured and artificially worn to imitate

natural stone. They are a cheaper alternative to granite sett paving

outside of conservation areas. For example, Marshalls Tegula

reproduces the appearance of sandstone and granite setts.

Artificial stone setts / blocks have a good load-spreading ability

due to the friction generated within the joints from fine brushed-in

sand, which transmits the load to adjacent paving and the

supporting layers below. They are therefore suitable for heavily

trafficked areas and shared surfaces.

Darker charcoal coloured blocks can be used in carriageways,

parking bays and shared surfaces to hide oil spills.

3.9 (d) Kerbstones

Granite kerbstones Traditional, natural kerbstone which can be

laid as with a wide or narrow top face. It is important to retain and

match the wide kerbs where they exist. Kerbs can be worked to

specific radii, but standard radii stock should be used normally to

avoid mistakes.

Method of setting-out arcs

Yorkstone setts adjacent to

Yorkstone paving4

Charcoal colour artificialstone setts can be used in

parking bays4



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3.10 TACTILE PAVING

The issue of Access for All is at the core of this streetbooks

philosophy and Islington Council is committed to providing tactile

paving aids in the footways of the borough, in accordance with the

Department for Transport (DfT) guidelines. These guidelines are

provided in the booklet, Guidance on the Use of Tactile Paving

Surfaces (2003). Further guidance should be sought from DfTs

Inclusive Mobility A Guide to Best Practice on Access to

Pedestrian and Transport Infrastructure which can be accessed

from the councils website in the Access and Inclusive Design

section.

There are four types of tactile paving:

blister surface

corduroy paving

tactile guidance paving

shared cycle track/footway surface and central delineator strip

All types of tactile paving need to be laid with the utmost attentionto detail so that it seamlessly integrates with the adjacent paving.

The purpose of blister surface tactile paving is to inform and warn

visually impaired and blind people of the location of highway

crossing points. It is laid in conjunction with dropped kerbs and

where the footway is at the same level as the carriageway.



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STANDARDFOOTWAY MATERIALS33.10 (a) Blister Surface

The profile of the blister surface comprises rows of flat-toppedblisters, approximately 5mm high, most commonly supplied in400mm square concrete slabs.

Blister surface tactile paving is required following types oflocations:

controlled crossingsAt controlled crossings pedestrians takes priority over vehiculartraffic. They are laid out with a tail that extends to the back of thefootway to direct visually impaired pedestrians.

These occur at: zebra crossings pelicans puffins toucans

traffic signal junctions with pedestrian phases

Colour: Red blister surface to be specified.

uncontrolled crossingsAt uncontrolled crossings pedestrians do not have priority overvehicular traffic and must take a decision about whether it is safeto cross. They do not incorporate a tail.

These occur at: side road crossings

busy crossovers (vehicle crossings) kerb-to-kerb flat-top road humps signal-controlled junctions without pedestrian phases (traffic

lights) including those where studs indicating a pedestriancrossing places are provided

Colour: Buff blister surface to be specified.

pedestrian refuges and islandsBlister paving conforms to the same colour standards atpedestrian refuges and islands.

Colour: buff at uncontrolled junctions and red at controlledjunctions.

Red blister surface paving for

controlled crossings4

Buff blister surface paving

for uncontrolled crossings4

Blister paving at pedestrian

refuge controlled crossing

(Newington Green, Islington)

4



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3.10 (b) Corduroy Hazard Warning Surface

The profile of the corduroy surface comprises of rounded bars

(approximately 6mm high) running traversly across the direction

of pedestrian travel.

It is recommended that the surface is in a contrasting colour to

assist partially-sighted people and it should not be red.

Corduroy warning surfaces:

are required at the top and bottom of steps

may be used where a footway/footpath joins a shared route

It conveys the message: hazard, proceed with caution.

3.10 (c) Tactile Guidance Path

The profile of the raised guidance path surface comprises a series

of raised, flat-topped bars running in the direction of pedestriantravel.

It is used to provide a guide along a route where traditional cues

such, as building lines, street corners and notable landmarks are

not available.

3.10 (d) Shared Cycle Track/Footway Surface and Central

Delineator Strip

The profile of this tactile surface comprises a series of raised, flat-topped bars, each 5mm high x 30mm wide, and each spaced

70mm apart.

The purpose of the tactile surface used in conjunction with a

segregated shared cycle track/footway is to advise visually-

impaired people of the correct side to enter. The central delineator

strip helps visually-impaired pedestrians keep to the pedestrian

side. On the pedestrian side, the raised flat-topped bars are laid

out at right angles (in ladder pattern) with the central delineator

strip. On the cycle track side the flat-topped bars are laid out inparallel (in tramline pattern) with the central delineator strip.

Corduroy paving

(Upper Street, Islington) 4

Segregated shared cycletrack / pedestrian surface

and central delineator strip4

4Tactile guidance path



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STANDARDFOOTWAY

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FOOTWAY MATERIALS33.11 REPAIR AND REINSTATEMENT

In order to maintain the quality of public realm, repair andreinstatement have to be carried out to a high standard. Oftenthe main cause of poor pavement quality is associated withdisturbance or statutory works.

The new Road and Streetworks Act (1992) require those statutoryundertaking work to reinstate paving and carriageways to match

existing materials. It is essential that maintenance andreinstatement works are effectively controlled. All footwaymaterials should be reinstated to match the existing materials. TheAct also requires proper guarding of streetworks, whilstmaintaining access for pedestrians. Kerb ramps and guardrails fortemporary pedestrian routes on the carriageway are required.

The council is the highways authority responsible for the conditionand maintenance of all borough principal (or A roads) and localroads. Transport for London (TfL) is responsible for the conditionand maintenance of the Transport for London Road Network(TLRN). Consultation on footway materials and street furniture istherefore necessary with TfL for those areas, usually junctions,which adjoin the TLRN.

BOROUGH ROAD

NETWORK

Islington Streetbook Section 3 Standard Footway Materials

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