Technical Note
Technical Note Number : 60049433/Mod/TN004
Revision :
-
Project:
Blackheath Hill Controlled Pedestrian Crossing Project No:
60049433
Subject:
Modelling Summary
Prepared by:
Katy Thorpe
Date:
8th January 2009
Checked by:
Michael Banham
Date:
8th January 2009
THE SCHEME
This technical note provides an overview of the modelling assessment of a proposed signal controlled
staggered pedestrian crossing facility at the junction of A2 Blackheath Road / Blackheath Hill with A2211
Lewisham Road / Greenwich South Street. The proposed scheme includes:
•
Introduction of controlled staggered pedestrian crossing across Blackheath Hill;
•
Introduction of a second signal stream for the northern part of the pedestrian crossing across
the eastbound carriageway;
•
Removal of Greenwich South Street left turn filter lane; and
•
Introduction of cycle advanced stoplines on every arm.
In order to understand the potential impact of these measures on the road network the proposed
scheme has been modelled in the AM, PM and Saturday peaks.
BASE MODELS
In May 2008 Faber Maunsell undertook a modelling exercise to test the impact of a proposed scheme at
Deals Gateway. This involved the preparation of AM and PM TRANSYT12 models which covered the
A2 corridor from New Cross Road to Blackheath Hill which were approved by DTO-UTC. The Deals
Gateway schemes are now committed and these models have been used as the approved base models
to test the Blackheath Hill proposed pedestrian crossing.
The Saturday peak model was built to represent Greenwich South Street junction with Blackheath Hill as
an isolated junction in LINSIG2 in December 2008.
PROPOSED MODELS
The safety critical traffic signal timings for the proposed junction layout have been modelled per the
information submitted to and approved by DTO - Traffic Infrastructure (TI) in December 2008. The
following conclusions should be noted:
•
The introduction of cycle ASLs on each arm has the consequence of increasing every vehicle to
vehicle intergreen by one second. Thus there is an additional two seconds of lost time per cycle and
the modelled performance of the junction inevitably worsens. Any future improvements/upgrade to
this junction that includes cycle ASLs are likely to have this impact with or without the provision of a
controlled pedestrian crossing.
Direct Tel: 01904 694433
St Christopher House
T +44 (0)1904 694400
George Cayley Drive
F +44 (0)1904 694499
York YO30 4XE
E xxxxxxxxx.xxxxxx@xxxxxxxxxxxxx.xxx
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Revised: March 2008
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F:\PROJECTS\Traffic - Blackheath Hill Controlled Pedestrian Crossing\Modelling\Modelling Summary.doc
Technical Note
•
The southern stagger of the proposed pedestrian crossing has little impact on the operation of the
junction as it is called when the side roads run and does not cause additional lost time for traffic.
•
The northern stagger of the proposed pedestrian crossing has been assumed to be called every
cycle to ensure a robust assessment.
•
In all peaks the most significant changes in junction operation are due to the intergreen
amendments required due to the cycle ASLs.
•
In the AM and PM peak the reduction in green time has been allocated to the side road stage. The
impact is most obvious on Lewisham Road which is currently operating close to or at capacity. In
the AM peak this causes an increase in modelled Mean Max Queue of 15 pcus and in the PM peak
of 5 pcus.
•
The degree of saturation exceeds 100% on Lewisham Road in the AM peak.
•
In the Saturday peak model the reduction in green time was shared between the main road and the
side road stages and the increase in modelled Mean Max Queues was less than 3 pcus on all arms.
•
The Mean Modelled Queue on the eastbound internal stopline is 3 pcus or under in all scenarios
which can easily be stored within the available stacking area. This represents the worst case
scenario where the pedestrian stage is called every cycle.
RESULTS
AM PEAK
MMQ (pcus)
Degree of Saturation (%)
Link
Description
2007 AM
2007 AM
AM
AM
Committed
Committed
Proposed
Proposed
Base
Base
169
Blackheath Road eb ahead & left turn
12
12
72
72
168
Blackheath Road eb ahead & right turn
3
3
46
54
165
Blackheath Hill wb ahead and left turn
23
27
93
96
163
Blackheath Hill wb ahead and right turn
2
2
42
42
161
Greenwich South Street
7
7
65
72
166
Lewisham Road
17
32
95
107
1612
Blackheath Hill eb nearside second stopline
-
3
-
61
1613
Blackheath Hill eb farside second stopline
-
1
-
12
Direct Tel: 01904 694433
St Christopher House
T +44 (0)1904 694400
George Cayley Drive
F +44 (0)1904 694499
York YO30 4XE
E xxxxxxxxx.xxxxxx@xxxxxxxxxxxxx.xxx
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Revised: March 2008
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F:\PROJECTS\Traffic - Blackheath Hill Controlled Pedestrian Crossing\Modelling\Modelling Summary.doc
Technical Note
PM PEAK
MMQ (pcus)
Degree of Saturation (%)
Link
Description
2007 PM
2007 PM
PM
PM
Committed
Committed
Proposed
Proposed
Base
Base
169
Blackheath Road eb ahead & left turn
20
20
78
78
168
Blackheath Road eb ahead & right turn
5
6
57
64
165
Blackheath Hill wb ahead and left turn
17
18
83
85
163
Blackheath Hill wb ahead and right turn
2
2
40
40
161
Greenwich South Street
9
11
77
85
166
Lewisham Road
11
16
86
97
1612
Blackheath Hill eb nearside second stopline
-
2
-
32
1613
Blackheath Hill eb farside second stopline
-
1
-
37
SATURDAY PEAK
MMQ (pcus)
Degree of Saturation (%)
Link
Description
2008
2008
2008 Base
2008 Base
Proposed
Proposed
169
Blackheath Road eb ahead & left turn
15
16
71
74
168
Blackheath Road eb ahead & right turn
4
5
59
64
165
Blackheath Hill wb ahead and left turn
18
20
78
83
163
Blackheath Hill wb ahead and right turn
1
1
23
25
161
Greenwich South Street
6
8
72
77
166
Lewisham Road
15
17.5
95
99
1612
Blackheath Hill eb nearside second stopline
0
3
0
36
1613
Blackheath Hill eb farside second stopline
0
3
0
36
Direct Tel: 01904 694433
St Christopher House
T +44 (0)1904 694400
George Cayley Drive
F +44 (0)1904 694499
York YO30 4XE
E xxxxxxxxx.xxxxxx@xxxxxxxxxxxxx.xxx
Page: 3 of 3
Doc. F8/10
Revised: March 2008
www.fabermaunsell.com
F:\PROJECTS\Traffic - Blackheath Hill Controlled Pedestrian Crossing\Modelling\Modelling Summary.doc