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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 -
document.docx Final Draft Page 1
Wilston Grange Precinct Study Transport Engineering Studies
10.0 Local Area Model DevelopmentA traffic simulation model was developed in SATURN. The model was calibrated and validated against a combination of traffic counts that were completed across the study area and surrounds in November 2013 and SCATS intersection count data.
This model is a useful tool for investigating road network operation in the study area, and considers intersection performance and route choice issues that may arise as a result of network changes. The SATURN model is at the Mesoscopic level of modelling which means that it is able to simulate intersection performance and travel time on the road network. It is regarded as a detailed strategic model and is useful for assessing road network operation and planning options at a detailed strategic level. A more detailed model would need to be used for detailed design.
This model was used to determine road and intersection performance as well as the effects that proposed future infrastructure changes might have on travel time and route choice. This analysis was needed to examine road network operation in further detail and to study the effects that the proposed infrastructure changes and proposed major road and transport network improvements might have on the study area.
10.1 Base Year NetworkThe SATURN model covers an extensive area of the study area. The SATURN Model extents are illustrated in Figure 10.1. The model area extends from Stafford Road in the north to Enoggera Creek in the south, and from Lutwyche Road in the east to Enoggera Road/South Pine Road in the west. In the base year models the network was modelled based on conditions that existed at the time of the traffic surveys in November 2013.
For the base year models traffic signal phase times were recorded from SCATS on the day of the survey in November 2013 and incorporated into the morning and afternoon peak hour models to replicate current traffic operations as closely as possible.
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Wilston Grange Precinct Study Transport Engineering Studies
Figure 10.1: Model Area and Location of Study Corridor
10.2 ValidationThe base year SATURN models were validated against available traffic count data to determine level of accuracy in the models. This study adopts GEH value as the key index to evaluate the confidence level of the built models.
GEH values are the parameters that indicate the accuracy of the matches between the modelled volumes and the observed volumes. GEH are the initials of Geoff Havers who developed the mathematical process of comparing two different values of flow on a road link. Generally the following table gives an indication of various levels of GEH values, both qualitatively and quantitatively.
displays the suggested meaning of GEH value to the calibration outputs.
Table 10.1 : GEH ValuesValue Comment Examples
GEH = 1.0 “Excellent” +/- 65 in 4,000 +/- 25 in 500
GEH = 2.0 “Good” +/- 130 in 4,000 +/- 45 in 500
GEH = 5.0 “Acceptable” +/- 325 in 4,000 +/- 120 in 500
GEH =10.0 “Poor” +/- 650 in 4,000 +/- 250 in 500
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Wilston Grange Precinct Study Transport Engineering Studies
As a rule of thumb, in comparing assigned volumes with observed volumes a GEH parameter of 5 or less would indicate an acceptable fit to a traffic modeller, whether it was a difference of 325 to 4,000 or 120 in 500, while links with GEH parameters greater than 10 require closer attention.
The base SATURN Models were validated against the surveyed link and turning volumes in key locations. The process indicated a very good level of accuracy. Table 10.2 summarises the level of accuracy achieved with surveyed links in the model.
Table 10.2: Model Flow Validation ResultsTime Period GEH < 5 GEH <10AM Peak 91% 97%PM Peak 86% 98%
Detailed flow validation outputs are presented in Appendix B
11.0 Option DevelopmentIn response to addressing transport issues within the study area, a number of potential scenarios have been developed with the aim of improving the operation of the associated road network. The purpose of the scenario testing was to see how planned road upgrades in the area influence each other and ultimately work out a staging plan.
The options developed for the road network were based on the findings of the Road Safety Audit, community concerns, impact on the road network and crash history.
11.1 Option 1: Network Restrictions This option places restrictions on the road network and predominantly involves restricting movements to streets and reducing posted speed on selected roads. Proposed changes to the base network under Option 1 have been summarised in Table 11.3 and illustrated in Figure 11..
11.2 Option 2: Improving AccessibilityThis option improves accessibility of the network for vehicles. Proposed changes to the base network under Option 2 have been summarised in Table 11.3 and illustrated in Figure 11..
11.3 Option 3: Major UpgradesThis option assesses major upgrades to the network. Proposed changes to the base network under Option 3 have been summarised in Table 11.3 and illustrated in Figure 11.
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Wilston Grange Precinct Study Transport Engineering Studies
Table 11.3 : Option Testing Spreadsheet
Issues Identified In :
Minor Improvements
RSA
(Ver
y H
igh
or
Hig
h)Si
gnifi
cant
Cra
sh
His
tory
Cap
acity
Com
mun
ity Option 1 (Restrictin
g the Network)
Option 2 (Improving Accessibilit
y of the Network)
Option 3 (Major
Upgrades)
Item Location
Proposed Scheme Proposed Benefit
1Raymont Rd/Beatson St
Left in/out or right turn in ban
Reduce traffic volumes on Beatson and improve safety
Y
2Wilston/Abuklea/Mina intersections
New Signals integrated with Boom Gates
Improve Ped & Cycle safety and vehicle safety and reduce congestion.
Y Y Y
3Grange Rd / Raymont Rd
Add a right turn pocket on Grange Rd and modify phasing
Improve vehicle safety and reduce congestion
Y Y Y
4
Beatson Tce/Progress Pde/Days Rd (up to Wilston Rd)
Reduce speed limit to 40 km/hr
Improve safety & reduce traffic volumes
Y
5 Thomas StreetConsider reducing to 40km/hr or LATM treatments
Improve safety Y
6 Thomas /DaysConsider permanent Left in/out from Thomas St
Improve safety Y
7 Maygar/BrookNew Signals with right turn pockets
Improve Safety and accessibility for vehicles and pedestrians
Y Y
8Enoggera Rd into Railway Tce I/B AM peak
Consider right turn ban I/B in AM Peak
Improve safety and reduce congestion / potential conflict on Railway level Xing
Y Y
9Enoggera into Alderley O/B PM peak
Consider right turn ban O/B in PM Peak
Improve safety and reduce congestion / potential conflict
Y Y
10 Montpelier StReduce speed limit to 40 km/hr
Improve safety & reduce traffic volumes
Y Y Y
11 Bank / MaygarConsider right turn ban - Left in/out
Improve vehicle safety Y Y
12Newmarket Rd / Silvester St / Noble St
Add protected right turn phase from Newmarket Rd to Silvester St
Improve vehicle safety and reduce congestion
Y Y Y
13Grange Rd / Howard St
Ban right turn movements to/from Grange Rd
Improve safety Y Y
14Grange Rd / Dennis St
Ban right turn movements to/from Grange Rd
Improve safety Y Y
15Grange Rd / Myrtle St
Ban right turn movements to/from Grange Rd
Improve safety Y Y
16 Grange Rd / Bega StBan right turn movements to/from Grange Rd
Improve safety Y Y
17 Inglis StReduce speed limit to 40 km/hr
Improve safety Y
18 Wilston RdReduce speed limit to 40 km/hr
Improve safety Y Y
19 Chermside StReduce speeds to 35km/hr (new LATM's)
Reduce traffic volumes and improve amenity
Y Y
20Raymont Rd/Billington St
Consider right turn ban - Left in/out
Improve vehicle safety Y
21Days Rd / Colston Rd
Upgrade Roundabout to Traffic Signals
Improve Safety for vehicles and pedestrians and reduce congestion
Y Y
22 Wilston Rd / Monpellier Rd
Ban right turn movements from
Improve safety Y Y
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Wilston Grange Precinct Study Transport Engineering Studies
Wilston Rd
23Newmarket Rd / Wilston Rd
Reconfigure Traffic signals to provide a protected right turn
Improve safety Y Y Y
24Green Tce / Newmarket Rd / Cox Rd
Consider alternative phasing to improve safety for right turn to Green Tce and include right turn to Cox in PM Peak
Improve safety Y Y Y
Major Improvements
RSA
Sign
ifica
nt C
rash
His
tory
Cap
acity
Com
mun
ity
Option 1 (Restricting the Network)
Option 2 (Improving Accessibility of the Network)
Option 3 (Major Upgrades)
Item Location Proposed Scheme Proposed Benefit25 Kedron Brook Rd Upgrade to 4 lanes Reduce congestion Y Y
26Wilston Rd / Colston Rd
Upgrade to 4 lanes Reduce congestion Y Y
27Newmarket Road
Upgrade to 4 lanes with separate right turn pockets.
Improve safety & reduce congestion
Y Y Y Y
28Kedron Brook Rd/Days
New SignalsImprove Ped & Cycle safety, reduce congestion.
Y Y Y Y
29
Kedron Brook Rd / Stain St
New SignalsImprove Ped & Cycle safety, improve safety reduce congestion.
Y Y
30Newmarket Rd / Lamont Rd
Consider new traffic signals
Improve vehicle safety and reduce congestion
Y Y Y Y
31
Stafford Rd / Lennon St
Provide right turn pocket from Stafford Rd into Lennon St
Improve safety Y Y
32
Stafford Rd / Lutana St
Provide right turn pocket from Stafford Rd into Lutana St
Improve safety Y
33
Newmarket Rd / Finsbury St
Provide right turn pocket from Newmarket Rd into Finsbury St
Improve safetyY
(5)
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Wilston Grange Precinct Study Transport Engineering Studies
Figure 11.2 : Options
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