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1 Sårbarhetsanalyser av vägnät - gjort sedan förra mötet Referensgruppsmöte 18 december 2008.

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Presentation on theme: "1 Sårbarhetsanalyser av vägnät - gjort sedan förra mötet Referensgruppsmöte 18 december 2008."— Presentation transcript:

1 1 Sårbarhetsanalyser av vägnät - gjort sedan förra mötet Referensgruppsmöte 18 december 2008

2 2 Sårbarhetsanalys av utbredda avbrott

3 3 Background Past applied vulnerability studies focused on identifying important (critical, significant, vital) links Our aim: Study vulnerability to area-covering disruptions –Provide complement to single link failure analysis –Develop methodology for systematic analysis –Apply to large real-world road networks –Gain general insights

4 4 Methodology Study area is covered with grid of equally shaped and sized cell Each cell represents spatial extent of disruptive event Event representation: All links intersecting cell are closed, remaining links unaffected Hexagonal Square

5 5 Methodology Multiple, displaced grids used to increase accuracy Advantages of grid approach: –No coverage bias: Each point in study area equally covered –Avoids combinatioral issues with multiple link failures –Easy to combine with frequency data Disadvantages: –Results depend on rotation

6 6 Consequence model Indicator: Increase in travel time for users Constant, inelastic travel demand Initial travel times estimated with congestion, no change during closure

7 7 Consequence model During disruption of cell, two possibilities: 1.No alternative routes Unsatisfied demand, must delay trip until after closure 2.Alternative routes Users choose new shortest route, or if faster delay trip

8 8 System and user perspectives Cell importance: Total increase in travel time for all users when cell is disrupted Worst-case regional user exposure: Mean increase in travel time per user starting in region when most important cell for region is closed

9 9 Case study Swedish road network: 174,044 directed links, 8,764 origins/destinations Matrix of estimated travel demand (vehicles/hour) between every origin/destination pair Personal cars and light and heavy trucks Three square cell sizes: 12.5 km, 25 km, 50 km 12 hour closure duration Cell size# cells/grid# grids 12.5 km64 x 1284 25 km32 x 644 50 km16 x 3216

10 10

11 11 Cell importance 12.5 km grid

12 12 Cell importance 25 km grid

13 13 Cell importance 50 km grid

14 14 Cell importance Unsatisfied demand constitutes 60% - 90% of total increase in travel time on average Unsatisfied demand consists of internal, inbound/outbound and transit demand Consequences as function of cell size

15 15 Jämförelse mellan att stänga hela rutan eller slumpmässigt vald meter väg i rutan De 11 värsta rutorna finns i Skåne

16 16 Worst-case county user exposure Exposure depends on concentrated travel demand, not network redundancy In most exposed county, more than 60% of demand unsatisfied

17 17 Worst-case cell vs. link Area-covering disruption particularly worse in densely populated regions 12 of 21 counties: Worst-case link within worst-case cell

18 18 Some insights Other factors behind vulnerability to area-covering disruptions compared to single link failures Vulnerability reduced through allocation of restoration resources rather than increasing redundancy For important cells, unsatisfied demand constitutes nearly all increase in travel time Results depend on link and demand location and regional partition

19 19 Sårbarhetsanalys av Mexicos vägnät Detaljerat (åtminstone bitvis) nätverk (23352 noder, 54172 länkar) Gles efterfrågematris (ca 500 start/målnoder) Lastbilsmatris Mått och metoder från tidigare studier av Sverige

20 20 Vägnätet

21 21 Reseefterfrågan

22 22 Länkarnas betydelsefullhet

23 23 Delstaternas utsatthet

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