1. JMP EDA Transport Study South Marston Samantha Howell Principal Transport Planner Strategic Growth and Regeneration Team

2. JMP EDA Transport Study
JMP commissioned in partnership by SBC and Highways Agency to assess the transport implications of the Eastern Development Area (EDA)
Initial assessment - 12,000 dwellings
Further assessment of c7,000 dwellings to reflect lower quantum of development in Revised Proposed Submission Draft Core Strategy

3. Context WSP Swindon Transport Strategy South Marston Village Strategy
LDA Framework and Draft EDA SPD
NEW Masterplanning ‘Planning for Real’ Workshops

4. Scope of Study Transport modeling at strategic and local level
SATURN – understands how traffic assigns across the wider network
PARAMICS – microsimulation model looking at EDA area including South Marston
Local model developed for all signalised junctions in the EDA area
Scenario testing: ‘worst case’, mid-range & ‘stretch’
Appraisal of potential transport interventions/mitigation

5. South Marston Stage 1: assessment of existing issues
Stage 2: future proofing potential solutions against impact of growth at the EDA

6. Stage 1 Vehicle counts and site observations
Meetings with South Marston Parish Council,
Traffic Sub-Group and NEW Masterplanning
Key issues:
Pedestrian and vehicular conflict at Pound Corner
Perception of rat-running, high volumes of through traffic and speeding
HGV’s getting lost or taking short cuts
Noise disturbance of speed humps

7. Stage 2
Key questions:
Can the masterplanning principles set out by SBC/NEW Masterplanning be achieved in transport terms?
Are the ‘southern’ and ‘eastern’ link roads necessary?
What are the transport implications of Rowborough?

8. Scenario Testing* 955 total dwellings (SBC) 613 total dwellings
(NEW Masterplanning Option 1b)
*includes potential brownfield development at Crown Timber and Thornhill Industrial Estate and assumes 35 dwellings per hectare

9. Options Tested
‘Baseline’ – extended village, no mitigation, and connection to Rowborough
Southern Link Road
(Thornhill Road/Old Vicarage Lane/Rowborough)
Eastern Link Road
(Highworth Road to Rowborough
Combinations of the above
Journey time – proxy for congestion and delay – and length of queueing

10. Baseline Assessment - Key findings
Increase in traffic but from relatively low base
Traffic not only related to expansion of village but increase in through traffic to EV destinations
Rowborough traffic impacts mainly on Keypoint / Old Vicarage Lane/ A420 junctions
Queuing at Keypoint roundabout, particularly in the morning peak (increase in journey time variability)
PM peak traffic conditions are better than AM peak

11. Pound Corner Northern end of Old Vicarage Lane could be realigned
New junction to the west of Pound Corner (as per NEW Masterplanning proposals) could be provided
Junction to either be signalised or mini roundabout
Signalised junction – improved crossing facilities for residents
Mini roundabout – less urbanised and provides opportunity for new ‘gateway feature’
Old Vicarage Lane (Pound Corner to school) becomes local access only. Probably in northbound direction. Permits provision of new footway
BUT NOT RECOMMENDED

12. Southern Link Road Direct/no connection to Rowborough
Same evidence base
Reduces risk of uncoordinated infrastructure provision
Allows what if scenarios to be tested
Determines what impact the EDA is going to have 12

13. Southern Link Road Indirect connection to Rowborough
Same evidence base
Reduces risk of uncoordinated infrastructure provision
Allows what if scenarios to be tested
Determines what impact the EDA is going to have 13

14. Southern Link Road – Key Findings
Direct connection to Rowborough increases journey times and leads to more queuing at Gablecross
Most of the traffic leaving/arriving from Rowborough is to / from the south (limited impact on South Marston)
Indirect connection and no connection to Rowborough provides improvement in journey times at Gablecross
Increased journey times are a consequence of heavy traffic on the A420.

15. Eastern Link Road – Key Findings (indicative link Supermarine Roundabout)
Not a strong case in traffic terms
Modelling indicates that this would not be heavily utilised
(much of the traffic ‘rat running’ through village is from the north and to the EV District Centre and employment areas south of the A420)
Morning peak conditions are worst overall across the network but most of the traffic leaving Rowborough is travelling south onto the A420, not north.

16. Other Considerations
In all scenarios, existing chicanes will not be appropriate for village roads carrying higher traffic volumes
Impact on journey times influenced by traffic on A420
Balance needs to be sought between priority for strategic and local traffic
Improvements to the A419, White Hart Junction, Gablecross and A420 / Old Vicarage Lane junctions are important in mitigating full impact of EV

17. Recommendations 20mph zone in village (30mph from Keypoint and A420)
Footway improvements
Public rights of way and bridleways should be retained
Psychological traffic calming, removal of chicanes and selective carriageway widening
Signalised crossroads at Gablecross junction
Further consideration new signalised junction east of the of A420 / Old Vicarage Lane junction and links toRowborough

18. Next Steps Finalising report
Any comments must be received by 5pm on 22nd March 2011
South Marston Core Strategy Exhibition – here on 12th April between 5pm and 9pm
Additional scenario testing and further consideration of options at Pound Corner and Old Vicarage Lane/A420 Junction

19. E-mail: showell@swindon.gov.uk
Thank you.
Any questions?
Contact details
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