Kent Design - Technical Appendix - Kent County Council

OTHER SURFACING MATERIALS
The coarse aggregate in Thin Surfacing shall have a minimum PSV of 50
3.5 ENTRY RAMPS AND SPEED RESTRAINTS
In all the following cases reference should also be made to the KCC’s
Traffic Calming Code of Practice.
3.5.1 DEMARCATION RAMP AT ENTRY TO RESIDENTIAL SHARED
SURFACE
Demarcation ramps at the commencement of shared surface
environments shall have a 1:15 (6.7%) gradient. If the material
chosen for the ramp is granite setts, the construction of the ramp
should be 100mm x 100mm x 100mm deep granite setts, bedded on
at least 150mm of ST4 mix concrete on a full construction thickness
of sub-base and jointed with cement mortar.
Joints between granite setts are to be pointed flush within 1.0 metre
of kerbline in the interests of cyclists safety.
At the commencement of the ramp there should be an upstand of
not more than 6mm.
The detail of the demarcation ramp may change if it forms part of a
speed restraint device.
3.5.2 TABLE JUNCTIONS AND SPEED TABLES
The plateau of a table junction or speed table shall be constructed using
full construction thickness as detailed in Sections 3.4 to match the
adjacent carriageway construction or full block paving construction.
Ramps at the commencement of table junctions and speed tables
shall be 1.125 metres long, laid at a gradient of 1 in 15 (6.7%). The
maximum height of any vertical deflection in Kent is 75mm.
3.5.3 MINI ROUNDABOUTS
The central dome may be up to 4 metres in diameter and raised to a
maximum of 100mm in the centre. The dome height should be in
proportion to the roundabout diameter, i.e. for a 2m roundabout the
dome should be raised to a maximum of 50mm in the centre. This
should be lowered if buses or frequent H.G.V.s need to cross it. The
edge should be flush within a tolerance of 6mm above the adjacent
road surface and the dome must be finished in white.
3.5.4 SMALL ROUNDABOUTS
Small roundabouts with solid central islands may feature an outer ring of
overrunable materials, usually block paving. The profile may have a crossfall
of up to 1 in 15 (6.7%). with the outer edge flush with a tolerance of
up to 6mm above adjoining road surface. The overrun area should be in
a conspicuous contrasting colour or black and white chevrons.
3.6 KERBING, CHANNELS AND EDGE RESTRAINT
3.6.1 GENERAL
Kerbing is required to designate the carriageway edge clearly, protect
pedestrian footways, service margins and verges from vehicle
overrun and provide a channel against which water can run to the
gullies. It should be provided wherever necessary and in addition to
define the inside edge on bends and at other locations where
inadvertent vehicle over-run could damage the verge.
Kerbing shall be selected to satisfy the aesthetic requirements of the
development. The use of special kerbs, such as granite effect,
exposed aggregate or granite setts may be acceptable or may be
required by the Engineer in conservation areas or where the use of
these materials would reinforce the character and identity of the
locality, and where the use of normal kerbs would conflict with it.
Channels not only provide a means of taking water to gullies they also
provide linear features in the construction. They shall be constructed
of granite setts, proprietary channel and grating sections or small
precast concrete or clay units set rigidly in concrete. Precast
concrete channels of length greater than 300mm shall not be used
where heavy vehicle over-run may occur.
Where kerbs or channels are removed they should wherever
possible be removed in such way as to minimise damage and be
reused within the site.
3.6.2 KERBS, CHANNEL AND EDGING
Precast concrete kerbs, channels and edgings shall comply with the
requirements of Clause 1101 of the Specification and BS7263 (Parts 1
& 2). Precast concrete kerbs and channels shall be hydraulically pressed.
Clay paver kerbs shall comply with the requirements of BS 6677.
Precast concrete kerbs, channels and edgings shall be laid in
accordance with BS 7533 Part 6.
The kerb type for Local Distributor, Industrial Access and Major
Access Roads shall be generally 125mm x 255mm half battered kerb
type HB2.
The kerb type for Minor Access Roads, Minor Access Ways and
Homezones shall be either small unit block kerbs or 125mm x
225mm half battered kerb type HB2. Alternatively the use of special
kerbs and channels, manufactured in-situ from granite setts bedded
on concrete ST2 mix, may be used. The layout and location of these
shall be agreed with the Engineer at the planning stage.
Concrete channel blocks type CSI or other proprietary channel units
must be provided if the longitudinal gradient is flatter than 0.8% (1 in
125), unless on short lengths over vertical curves.
The edging type shall generally be 50mm x 150mm type EF bedded
and surrounded with concrete ST2 mix.
3.6.3 KERB FACE
In Local Distributor, Industrial Access and Major Access Roads, kerbs
shall normally show a 125mm face above the finished road surface,
(except through certain traffic calming devices if required and
through vehicular crossings and pedestrian crossings), but where it is
necessary to vary the kerb face to facilitate drainage of the
Carriageway the limits shall be between 75mm and 150mm.
On Minor Access Roads, Minor Access Ways and Homezones kerbs shall
show 100mm face above the finished road, (except through the entry
ramp, through certain traffic calming devices if required and through
vehicular crossings and pedestrian crossings). However, where small unit
block kerbs are used, this height may be reduced to a minimum of 75mm.
3.6.4 VEHICULAR CROSSINGS
At vehicular crossings the kerbing shall be lowered for the full width
of the crossings and in any case for not less than four kerbs length
(3.66metres). When using precast concrete kerbs, bullnosed kerbs
(125mm x 150mm) Type BN, shall be laid to show a 25mm face
above the finished road surface. Tapered kerbs type DL1 and DR1
are required at either side when using precast concrete kerbing. In
other cases small unit block kerbs shall be used.
Where the vehicular crossing is also a pedestrian crossing, the kerb
face shall be between zero and 6mm. At each side of the crossing
taper kerbs type DL1 and DR1 shall be used.
A minimum of three raised kerbs between vehicle or pedestrian
crossings is preferred but where less than two raised kerbs could
occur they shall be laid as one continuous crossing.
In block paved construction, temporary arrangements must be made
for vehicular access if occupation of dwellings occurs before the
blocks are laid.
Construction details of vehicular crossings are described in Section 3.7.
A G U I D E T O S U S T A I N A B L E D E V E L O P M E N T
Kent
Design
highways specification and construction
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