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SAL Structural Accessibility Layer. WU_PT1 Cecília Silva Vitor Oliveira, Ana Amante, Sílvia Sousa. Concepts. SAL: Geographical representation of comparative accessibility levels by types of transport to different types of opportunities Structural Accessibility: - PowerPoint PPT Presentation
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Structural Accessibility Layer
SALStructural Accessibility Layer
WU_PT1
Cecília SilvaVitor Oliveira, Ana Amante, Sílvia Sousa
WG2 meeting . Edinburgh UK 13 October 2011
Structural Accessibility LayerSAL – Structural Accessibility Layer
Concepts
• SAL:
– Geographical representation of comparative accessibility levels by types of transport to different types of opportunities
• Structural Accessibility:
– Assess how urban structure constrains travel choices
13 October 2011
WG2 meeting . Edinburgh UK
PeopleAccess by: different
Transport Modes
Access to:different Activities
Structural Accessibility LayerSAL – Structural Accessibility Layer
Method
• Diversity of activities accessible
– Ex: schools, hospitals, shops, services, parks
• By transport mode:
– Non-motorized, public transport and car
• Comparison between accessibility levels by different transport modes
13 October
2011
WG2 meeting . Edinburgh UK
Structural Accessibility LayerSAL – Structural Accessibility Layer
Indicators
• Diversity of Activity Index:
– Contour measure type
13 October 2011
WG2 meeting . Edinburgh UK
0
1Accessibility to all the considered activities
None of the activities is accessible
fy – ponderation factor regarding frequency of use
Structural Accessibility LayerSAL – Structural Accessibility Layer
Indicators
• Accessibility Clusters (comparative measure):
– High accessibility levels by particular transport modes
– Favourable conditions for the use of those transport modes
13 October 2011
WG2 meeting . Edinburgh UK
NMPT
CAR
III
III
IV
V
VI
VII
Structural Accessibility LayerSAL – Structural Accessibility Layer
Input
• Data:
– Statistical data (at census track)
• Population
• Employment
• Activities by type
– Geographical data
• Transport infrastructure
• Mobility system service level
13 October 2011
WG2 meeting . Edinburgh UK
Structural Accessibility LayerSAL – Structural Accessibility Layer
Input
• Case specific
– Study area boundaries
– Level of spatial disaggregation
– Relevant travel generating activities
• Use frequency of activities (relative importance in travel)
– Cut-off criteria and values (accessibility limits), such as:
• Time
• Cost
• Convenience, etc
– Meaning of high accessibility
• Decision vs Survey
13 October 2011
WG2 meeting . Edinburgh UK
Structural Accessibility LayerSAL – Structural Accessibility Layer
Output
• Accessibility levels (from 0-1) of each census track by transport mode
• Comparative accessibility:
– land use and transport conditions enabling or disabling the use of particular modes
– How urban structure constraints mode choice
13 October 2011
WG2 meeting . Edinburgh UK
Structural Accessibility LayerSAL – Structural Accessibility Layer
Output Examples
13 October 2011
WG2 meeting . Edinburgh UK
Structural Accessibility LayerSAL – Structural Accessibility Layer
Output examples
13 October 2011
WG2 meeting . Edinburgh UK
Structural Accessibility LayerSAL – Structural Accessibility Layer
Usefulness in practice
• Interviews with experts
– Robustness
• NMDivAct
• Clusters
– Usefulness as design support tool
– Practical applicability
– Legend: positive opinion uncertain negative opinion
no answer
Experts interviewed: 17 (transport, land use, practitioners,
researchers)13 October 2011
WG2 meeting . Edinburgh UK
Structural Accessibility Layer
SALStructural Accessibility Layer
WU_PT1
Cecília SilvaVitor Oliveira, Ana Amante, Sílvia Sousa
WG2 meeting . Edinburgh UK 13 October 2011
Thank you
