wilston grange precinct transport study - brisbane city ... · web viewgeh are the initials of...

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

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.



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



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.



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


Y Y Y

13Grange Rd / Howard St

Ban right turn movements to/from Grange Rd

Improve safety Y Y

14Grange Rd / Dennis St


Improve safety Y Y

15Grange Rd / Myrtle St


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



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


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)



Figure 11.2 : Options



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