1. Urban Dynamics Monitoring:
Innovative Density and Centrality Indicators
of Economic Activities
Nicolas Lachance-Bernard
Geographic Information Systems Laboratory
Ecole polytechnique fédérale de Lausanne (EPFL)
COST Action TU0602 - Land Management and Urban Dynamics
Under Shift of Contexts, 6th May 2010, Kaunas, Lithuania
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Urban Dynamics Monitoring: Network Based Density Indicator

2. Plan
• Urban transformations, indicators and monitoring
• Integrated monitoring and assessment system
• Network based kernel density evaluation (NetKDE)
• Proof-of-concept: Barcelona
• Current projects
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Urban Dynamics Monitoring: Network Based Density Indicator

3. Urban Transformations and Indicators
1. Urban planning
2. Urban monitoring
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Urban Dynamics Monitoring: Network Based Density Indicator

4. Monitoring what?
• Land use changes
• Emitted number of development/construction permits
• Apartment's turn-over rates (owner, leaser)
• Completed construction projects
• Economic activities
• Empty lots and apartments
• Socioeconomics (job, household)
• Accessibilities and mobilities
• …
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Urban Dynamics Monitoring: Network Based Density Indicator

5. NLB / 06.05.10 / p.5
Urban Dynamics Monitoring: Network Based Density Indicator

6. NLB / 06.05.10 / p.6
Urban Dynamics Monitoring: Network Based Density Indicator

7. Project : Centrality and density indicator
• Goals
– To create a density indicator that will respect network
constraints
– To complete a proof-of-concept on Barcelona
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Urban Dynamics Monitoring: Network Based Density Indicator

8. Theory
• Kernel Density Estimator (KDE)
– Operates in euclidean space
– Weights events by their radial distances from grid centroid
• Network based Kernel Density Estimator (NetKDE)
– Operates in a network constrained space
– Weights events by the distance from grid centroid measured along
this network
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Urban Dynamics Monitoring: Network Based Density Indicator

9. Indicators : KDE vs. NetKDE
KDE NetKDE
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Urban Dynamics Monitoring: Network Based Density Indicator

10. Indicators : KDE vs. NetKDE
KDE NetKDE
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Urban Dynamics Monitoring: Network Based Density Indicator

11. Project's Process and Data
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Urban Dynamics Monitoring: Network Based Density Indicator

12. Proof-of-concept: Barcelona
Raw data 2002 Treatments
(Agencia de Ecologia Urbana)
• Economic activities • 926,000 grid points
166,311 entities • 400m bandwith
• Grid (network and euclidean distance)
10m, 92.65km2 • Duration: 33 hours
Intel(R) Core(TM)2 Quad CPU
1,890,000 cellules Q950 @ 3.00GHz 8GB of RAM
• Graphe routier
11,222 segments
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Urban Dynamics Monitoring: Network Based Density Indicator

13. Results for ponctual data (activities)
KDE of activities (bandwith: 400m) NetKDE of activities (spt: 400m)
*dot could represents supperposed activities
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Urban Dynamics Monitoring: Network Based Density Indicator

14. Results for linear data (segments)
Global Betweeness KDE of segments Global Betweeness NetKDE of segments
(bandwith:400m) (spt:400m)
*input: segment’s centroid
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Urban Dynamics Monitoring: Network Based Density Indicator

15. Betweeness KDE/NetKDE of segments
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Urban Dynamics Monitoring: Network Based Density Indicator

16. Current Projects
• NetKDE vs. KDE: Barcelona
– Grid 10m, 20m, 50m, 100m, 200m
– Bandwith 100m, 200m, 400m, 500m
• Segment centralities vs. Activity densities (NetKDE):
Barcelona, Roma, Bologna, Glasgow, Geneva
– Grid 10m
– Bandwith 100m, 200m, 500m
• Over time series (real monitoring)… Bologna?
• Outside Europe… Montréal Metropolitan Area and Delhi?
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Urban Dynamics Monitoring: Network Based Density Indicator

17. References
• Produit, T., Lachance-Bernard, N., Strano, E., Porta, S., Joost, S., A
network based kernel density estimator applied to Barcelona
economic activities. The International Conference on Computational
Science and its Applications - Japan (ICCSA), Part I, LNCS 6016, Springer-
Verlag Berlin Heidelberg, 32-45 (2010)
• Porta, S., Latora, V., Wang, F., Strano, E., Cardillo, A., Scellato, S.,
Iacoviello, V., Messora, R., Street centrality and densities of retail and
services in Bologna, Italy. Environment and Planning B: Planning and
Design 36, 450–465 (2009)
• Porta, S., Crucitti, P., Latora, V., The network analysis of urban streets:
a primal approach. Environment and Planning B: Planning and Design 33,
705–725 (2006)
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Urban Dynamics Monitoring: Network Based Density Indicator