`Code
1 -
Accepted
Uncontrolled when printed
INTERNAL INFORMATION
Northern Extension of Northolt Tunnel SIFT Report
Northern Extension of Northolt Tunnel SIFT Report
C222-ATK-DS-REP-020-000034
Revision – P06
Page 51
Uncontrolled when printed
INTERNAL INFORMATION
Location:
Colne Valley
OPTIONS CONSIDERED:
Option A
The Proposed Scheme as submitted in the hybrid Bill
(Northolt Tunnel to West Ruislip/ Viaduct across the Colne
Valley/ Chiltern tunnel east of M25 between jnc 16 and
17)
Option B
Above ground section between Northolt and Chiltern tunnels
placed underground in bored tunnels with provision for
connection spurs to Heathrow
Option C
As per option B but with no passive provision for a connection
to Heathrow
OPTION DESCRIPTION
Key Sustainability
Issue
Topic
STAGE:
Constructio
n or
Operation
EDA
Considered
(incl. Topic
and Ref no.)
Comment
QUALITATIVE IMPACT DESCRIPTION
and/or QUANTITIVE ASSESSMENT
RATI
NG
QUALITATIVE IMPACT DESCRIPTION
and/or QUANTITIVE ASSESSMENT
RATI
NG
QUALITATIVE IMPACT DESCRIPTION
and/or QUANTITIVE ASSESSMENT
RATI
NG
Negligible impacts related to dust emissions have
been identified.
Op
No operational impacts
o
No operational impacts
o
As Option B.
o
Sound and
vibration
Const
SV1
Construction noise impacts which generate
significant effects have been identified at Denham
Grove (De Vere Hotel), HOAC and Denham Waterski
Club. Construction traffic on Harvil Road and B467
Swakeleys Road is likely to cause noise impacts on
adjacent residential and non-residential receptors,
which is deemed to be significant.
o
The construction of the tunnel would significantly reduce
direct noise impacts on dwellings compared to the Option
A. Although there would still be some localised and short
term sound and vibration issues for property directly over
the alignment of the tunnel during construction and close
to the vent shaft sites and the 700m ‘gap’. However,
identified noise impacts as a consequence of construction
traffic for Option A would remain as construction traffic is
not predicted to decline in numbers as a consequence of
this option. Construction noise impacts from the tunnel
portals are not likely to change in magnitude but are likely
to occur over an extended time period.
+
As Option B.
+
Op
Significant noise effects identified at South Ruislip
(inc. 55 minor & 140 moderate impacts), Savay Lane
(6 minor and 7 moderate impacts), Wyatts Covert
(66 minor and 16 moderate impacts)and Denham
grove (3 minor and 2 moderate impacts) – also the
De Vere Hotel.
o
Operation of the route in tunnel would remove all
impacts identified for Option A.
+++ As Option B.
+++
Community
integrity
Const
CO1, CO3,
CO4,
CO10, CO11
Three buildings associated with the Hillingdon
Outdoor Activity Centre (commercial properties) will
be demolished. The lake used by the centre will be
closed during construction works (a period of five
years). This considered to be a major adverse effect
and is therefore significant.
Users of Denham Waterski Club would be impacted
during construction as a result of in-combination
impacts upon amenity including noise and visual
impacts for a period of approximately one and a half
years. The combination of these effects is considered
to result in a moderate adverse effect and is
therefore significant.
In combination impacts from traffic, air quality and
noise would be experienced by properties on the
B467 Swakeleys Road. The combination of these
o
There would be no demolition of buildings associated
with community resources or residential properties
identified in the base case.
HOAC and Denham Water Ski club would remain
operational through the construction period.
1.1.9
Potential for in-combination
impacts on properties on B467
Swakeleys Lane to remain,
depending on routes for spoil
removal.
+++ As Option B.
+++
`Code
1 -
Accepted
Uncontrolled when printed
INTERNAL INFORMATION
Northern Extension of Northolt Tunnel SIFT Report
Northern Extension of Northolt Tunnel SIFT Report
C222-ATK-DS-REP-020-000034
Revision – P06
Page 52
Uncontrolled when printed
INTERNAL INFORMATION
Location:
Colne Valley
OPTIONS CONSIDERED:
Option A
The Proposed Scheme as submitted in the hybrid Bill
(Northolt Tunnel to West Ruislip/ Viaduct across the Colne
Valley/ Chiltern tunnel east of M25 between jnc 16 and
17)
Option B
Above ground section between Northolt and Chiltern tunnels
placed underground in bored tunnels with provision for
connection spurs to Heathrow
Option C
As per option B but with no passive provision for a connection
to Heathrow
OPTION DESCRIPTION
Key Sustainability
Issue
Topic
STAGE:
Constructio
n or
Operation
EDA
Considered
(incl. Topic
and Ref no.)
Comment
QUALITATIVE IMPACT DESCRIPTION
and/or QUANTITIVE ASSESSMENT
RATI
NG
QUALITATIVE IMPACT DESCRIPTION
and/or QUANTITIVE ASSESSMENT
RATI
NG
QUALITATIVE IMPACT DESCRIPTION
and/or QUANTITIVE ASSESSMENT
RATI
NG
effects will result in a major adverse effect on the
amenity of residents along this route, which is
significant.
Op
In combination noise and visual impacts for 5
properties next to Denham Grove (De Vere Hotel).
1.1.10
Should HOAC remain post-construction the use of
the lake would be restricted and noise and visual
impacts would affect the amenity for users of the
facility.
o
There would be no impact on any of the community
facilities or residential properties identified in the base
case.
+++ As Option B.
+++
Transport
accessibility
/ severance
Const
TT1, TT3,
TT4,
TT7, TT9
Construction of the Proposed Scheme is forecast to
result in changes to daily traffic flows due to
construction traffic, road closures and diversions.
Delays to vehicle users and congestion is predicted
for the following junctions:
•
A412 North Orbital Road with Denham
Green Lane (major adverse effect);
•
B467 Swakeleys Road with Harvil Road
(moderate adverse effect); and
•
A40 Western Avenue with B467 Swakeleys
Road (moderate adverse effect).
Temporary closures of Chalfont Lane and Tilehouse
Road would have an adverse impact on vehicle
occupants due to the increased travel time
associated with the length of the diversions,
resulting in a major adverse effect on vehicle
occupants.
Construction of the Proposed Scheme will result in
substantial increases in traffic flows (i.e. more than
30% for HGV or for all vehicles) and these will cause
an increase in traffic related severance for non-
motorised users at a number of locations generating
moderate and major adverse effects.
There will be moderate adverse effects on non-
motorised users due to length of temporary PROW
o
There would be no significant impacts on the cycle routes
or bridleways identified in the base case. Rickmansworth
bridleway 004 would be diverted permanently as it
currently lies across the proposed open gap at Ch 30+500,
giving a minor adverse impact
The provision of a ‘gap’ structure in the vicinity of the
M25 allows the Chiltern and the extended Northolt tunnel
to be bored from the main works compounds, enabling
works and processing area for excavated materials to take
place at the same location as the ‘base case’ option.
However, with the bulk of the Proposed Scheme now in
tunnel, the volume of excavated materials generated
would be substantially higher; conversely the
requirement for engineering fill and mitigation
earthworks is far lower. As a consequence, the bulk of the
excavated tunnel material from the Chiltern tunnels, the
‘gap’ structure and the new section of tunnel is likely to
be treated as surplus to project requirements. Material
from the extended Chiltern tunnel,700m gap structure
and the extended Northolt Tunnel from Shaft F will be
removed from site via M25 and then onwards to the
ultimate destination for disposal. The volume of surplus
excavated material needing to be taken off-site for third
party disposal, or beneficial re-use would increase to
4.22million m3 as a consequence of Option B when
compared to Option A.
This would result in an additional
---
As Option B, although the slight reduction in spoil
removal would have a consequential reduction in HGV
traffic. However, the additional traffic generation would
be significantly greater than Option A.
---