Wilston Grange Precinct Study
Transport Engineering Studies
Wilston Grange Precinct Transport
Study
Technical Report
April 2015
Prepared for
Transport Network Operations Transport Planning & Strategy -
Prepared by
Transport Engineering Studies Group
Transport Planning & Strategy –
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12.0 Current Traffic Operation 2013
12.1 SATURN Analysis
Assessment of current traffic operation on the road network was undertaken using the
SATURN model developed for the precinct. Model results for the existing transport network
scenarios are outlined in the following sections.
Figure 0.1 and Figure 0.2 summarise the existing road network operation during the
morning and afternoon peak hours. In the figures the width of the coloured bands is scaled in
proportion to the hourly traffic flows on each link in the road network. The bands are also
coloured according to their volume capacity ratio or their degree of saturation. Bands
coloured red are over capacity and bands coloured orange have reached their capacity.
Magenta bands indicate links that are close to reaching capacity and so on.
In these figures red spots are used to highlight intersections with overcapacity movements.
The numbers within the red spots indicate the number of turning movements that have
exceeded their capacity at the intersection. Note that the term overcapacity has been used
where it is expected the intersection would become unstable. For the purposes of reporting
and trying to capture un-signalised intersections approaching practical capacity, a DOS of
90% has been selected as overcapacity. To get a true appreciation of the intersection
operating performance, reference needs to be made to the associated tables.
12.1.1
AM Peak
The intersections at capacity and the ones over capacity are illustrated in Figure 0.1and
listed in Table 0.1. Results show that much of the road network is operating with spare
capacity with a number of intersections experiencing capacity problems occurring
predominantly with side streets intersecting with Enoggera Road and Lutwyche Road albeit
not having any impact on the study area.
Table 0.1 : 2013 AM Peak Hour - Intersections with Oversaturated Turning Movements
Node
Description
No. of Over
Capacity
Movements
Max V
/C%
1083
NEWMARKET ROAD
2
195.39
7821
CONSTITUTION ROAD / GRAFTON
STREET / LUTWYCHE ROAD /ROBLANE
STREET
4
133.57
11379
SHAND STREET / SICKLEFIELD ROAD
1
122.85
7810
ASHGROVE AVENUE / ENOGGERA ROAD
3
118.26
13325
LENNON STREET / STAFFORD ROAD
2
113.36
7841
BRADSHAW STREET / LUTWYCHE ROAD
2
103.4
7825
ALBION ROAD / LUTWYCHE ROAD
1
97.37
11742
ENOGGERA ROAD / TERANG STREET /
1
95.54
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WICKHAM STREET
6279
SAMFORD ROAD / SOUTH PINE ROAD
1
92.86
7819
DAYS ROAD / KEDRON BROOK ROAD
2
91.52
7823
LUTWYCHE ROAD / MAYGAR STREET
1
91.31
11669
LAMONT ROAD / NEWMARKET ROAD
1
91.17
6264
PICKERING STREET / RAYMONT ROAD /
/SICKLEFIELD ROAD / SOUTH PINE ROAD
1
90.69
7814
NEWMARKET ROAD / WILSTON ROAD
1
90.05
Note: Thresholds for exceeding practical capacity – Traffic Signals >=90%, Roundabouts >=0.85%
Priority Control >=80%
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Overcapacity intersections outside the Arterial Road Network were chosen for further
consideration. These include:



Days Rd / Kedron Brook Rd;
Newmarket Rd / Lamont Rd;
Newmarket Rd / Wilston Rd.
For modelling purposes, node #1083 (reported as Newmarket Road in Table 0.1), reflects
the unsignalised driveway access for the Newmarket Homemaker Centre between Green
Terrace and Noble Street, south of Newmarket Road. This node has been disregarded from
further consideration in network upgrades because it relates to a private property access.
Generally street sections within the study area are operating below capacity.
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Figure 0.1 :Summary of Modelled Road Network Operation – 2013 AM Peak
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12.1.2 PM Peak
The intersections at capacity and the ones over capacity are illustrated in Figure 0.2and
listed in Table 0.2. As for AM Peak, results show that much of the road network is operating
with spare capacity with a number of intersections experiencing capacity problems occurring
predominantly with side streets intersecting with Enoggera Road and Lutwyche Road albeit
not having any impact on the study area.
Table 0.2: 2013 PM Peak Hour - Intersections with Oversaturated Turning Movements
No. of Over Capacity
Node
Description
Max V /C%
Movements
1083
Newmarket Road
2
472.29
7810
ASHGROVE AVENUE /
ENOGGERA ROAD
2
237.86
1131
EDMONDSTONE STREET /
FOSTER STREET
7
182.07
11379
SHAND STREET /
SICKLEFIELD ROAD
3
177.56
7813
BARADINE STREET /
EDMONDSTONE STREET
3
162.12
7812
BARADINE STREET /
NEWMARKET ROAD
2
139.39
11425
GAMELIN CRESCENT /
STAFFORD ROAD
2
101.14
7839
LUTWYCHE ROAD /
NEWMARKET ROAD
1
100.3
7819
DAYS ROAD / Kedron Brook
Road
2
99.87
2040
Enoggera Road / Willmington
Road
2
99.78
11669
Lamont Road / Newmarket
Road
1
94.86
7825
Albion Road / Lutwyche Road
1
93.59
Note: Thresholds for exceeding practical capacity – Traffic Signals >=90%, Roundabouts >=0.85%
Priority Control >=80%
Overcapacity intersections outside the Arterial Road Network were chosen for further
consideration. These include:




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Edmondstone Street / Foster Street;
Edmondstone Street / Baradine Street;
Newmarket Road / Baradine Street;
Days Road/Kedron Brook Road;
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
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Newmarket Road/Lamont Road.
For modelling purposes, node #1083 (reported as Newmarket Road in Table 0.2), reflects
the unsignalised driveway access for the Newmarket Homemaker Centre between Green
Terrace and Noble Street, south of Newmarket Road. This node has been disregarded from
further consideration in network upgrades because it relates to a private property access.
Generally street sections within the study area are operating below capacity.
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Figure 0.2 : Summary of Modelled Road Network Operation - 2013 PM Peak
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12.1.3 Summary of Current Study Area Performance


The analysis indicates that the study area is generally operating within capacity
during peak periods with just a few intersections that currently operate with over
capacity movements during the morning and afternoon peak periods;
Results reported for node #1083have been disregarded since it is not a true
reflection of ground conditions as this node represents all accesses along
southern side of Newmarket Road between Green Terrace and Noble Street;
12.2 SIDRA Analysis – 2013 Base Case
SATURN is able to model traffic networks in simulation at a mesoscopic level and is a very
useful tool for investigating network operation and potential improvements on the road
network. However the software does not have the level of detail needed to determine queue
lengths in short lanes and it does not consider the effects of pedestrian activity at individual
intersections. To consider these aspects of detailed intersection layouts, further assessment
of the key intersections has been undertaken using the SIDRA Intersection modelling
software. The key intersections identified were those intersections that represented the
highest surveyed volumes of traffic and included all signalised intersections.
Degree of Saturation was used as a measure of performance of the intersections analysed.
Names were given to ranges of degree of saturation to provide a meaningful description of
the status of intersection operation. The named ranges for describing the status of
intersection performance are listed in Table 0.3.
Table 0.3: Intersection Performance Status Descriptions
Performance Status
Signalised
Intersection
Roundabout
Unsignalised
Spare Capacity
< 0.80
< 0.75
< 0.70
Approaching Capacity
0.81 – 0.90
0.76 – 0.84
0.70 – 0.79
At Capacity
0.91 – 0.99
0.85 – 0.99
0.80 – 0.99
Over Capacity
> 1.00
> 1.00
> 1.00
Analysis results for the key intersections is summarised in Table 0.4. Further details of the
existing intersection performance are included in the SIDRA summary sheets in Error!
Reference source not found..
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Table 0.4 : SIDRA Summary Analysis Results – 2013
Intersection
Layout
Critical Degree of Saturation
Kedron Brook Rd/Days Rd
Newmarket Rd/Silvester
Rd/Noble St
Newmarket Rd/Green Rd/Cox
Rd
Newmarket Rd/Lamont Rd
Wilston Rd/Colston Rd
AM Peak
PM Peak
Status – Over Capacity
Status – At Capacity
Critical Movement
West (through/right) DOS – 0.91
Critical Movement
South (left) DOS – 0.87
Delay
West (right) – 18sec
Delay
South (left) – 37sec
Queue
West (through/right) – 161m
East (left) – 15m
Queue
South (left) – 120m
East (through/u-turn) – 62m
Status – Over Capacity
Status – Spare Capacity
Critical Movement
North (left) DOS = 1.00
Critical Movement
North (through/right) DOS – 0.88
Delay
North (right) – 54sec
Delay
North (through/right) – 56sec
Queue
North (through/right) – 98m
Queue
North (through/right) – 75m
Status – Over Capacity
Status – Spare Capacity
Critical Movement
North (left/through) DOS = 1.07
Critical Movement
North (left/through) DOS = 0.67
Delay
North (left/through) = 199sec
Delay
North (left) = 51sec
Queue
West (left/through) = 250m
Queue
West (left/through) = 86m
Status – Spare Capacity
Status – Spare Capacity
Critical Movement
North (left/right) DOS – 0.69
Critical Movement
East (through/right) DOS – 0.40
Delay
North (left/right) – 24sec
Delay
East (right) – 22sec
Queue
North (left/right) – 37m
Queue
East (through/right) – 34m
Status – Spare Capacity
Status – Spare Capacity
Critical Movement
East (left/through/u-turn) DOS –
0.60
Critical Movement
South (left/right) DOS – 0.42
Delay
North (u-turn) – 17sec
Queue
North (through/right/u-turn) –
40m
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Delay
West (right) – 13sec
Queue
South (left/right) – 20m
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