Designing Service Coverage and Measuring Accessibility and Serviceability

Transcription

1 Designing Service Coverage and Measuring Accessibility and Serviceability INFORMS Annual Meeting San Francisco, CA November 9-12, 2014 EunSu Lee, Ph.D., GISP, CPIM, CSCP

2 Agenda Introduction Objectives Previous Studies Model Development Potential Accessibility Potential Serviceability Service Coverage Conclusions Q & A

3 Introduction Planning of Emergency Medical Service (EMS) Urban Area Congestion Rural Area Road condition Service distance Equality and Quality of Life

4 Source of the map:

5 EMS region 1 Introduction Emergency service unit 1 2 miles 4 miles Demand 3 Demand 2 6 miles EMS region 2 Emergency service unit 2 Demand 1 10 miles 7miles Hospital (supplier)

6 Introduction Challenges of rural EMS Insufficient revenue Difficulty in recruiting ambulance service employees and volunteers Natural barriers Changing demographics In need of collaboration and efficient operations

7 Introduction Unlikely to provide equal service and response time throughout heterogeneous service areas Needs of Scientific planning Rationalizing service coverage plans and response prediction Providing effective public service Ensuring disadvantaged groups and impaired individuals receive appropriate emergency responses

8 Objectives Designing service coverage GIS-based spatial analysis Analytical models to measure Potential accessibility with demand-covered-ratio Potential serviceability with ambulance-coveringratio Location planner and service designer to assess and provide rational service coverage Continuous improvement

9 Objectives how well the coverage matches the population distribution how quickly the ambulances serve the demands to provide maximum coverage with a fixed number of facilities.

10 Previous Studies Finding shortest path from emergency service units to crash locations searching service coverage based on the population of zip codes minimizing the required number of facilities and EMS regions using a location set covering model maximum coverage with a fixed number of facilities.

11 Previous Studies Illustration of the two-step floating catchment method (2SFCM) A F 50003=R 1U2 =2/500+5/1000 R EMS2 =5/1000 R EMS1 =2/ EMS EMS Interstate Highway

12 Data Sources Model Development Roads Network Population Data Zip codes Polygons EMS Locations Advanced Life Support Basic Life Support

13 Model Development Population density and roads

14 Gravity-Based Accessibility 2SFCA (d 0 =30minutes)

15 Response Time Fastest Routes from Ambulance to random Incidents Note: Some regions will show bias from the real practices due to unconnected roads links used in the study

16 Potential Accessibility Average response time to a zip code T t ji i z, j w N i z Potential Accessibility z i i M A z t z 0 T z

17 Potential Accessibility Index

18 Potential Accessibility Demand-covered-ratio C z (%) N( t ji N i t z 0 ) 100 i z, i M, j W i

19 Potential Accessibility Accessibility and Coverage Ratio ZIP code Required service time (t o z ) # of Random events # of events within t o z Travel Distance (miles) Response Time (minutes) Accessibility Mean Min Max Mean Min Max (A z ) Demand Covered- Ratio (C z ) % % % % % % % % % % %

20 Potential Serviceability Ambulance s average response time to serve the community without restrictions by the service boundary T j i M N j t i M ji j Serviceability index for a location t S j T j o j

21 Potential Serviceability

22 Potential Serviceability Ambulance-Covering-Ratio C j (%) N ( i M j, t ji t0 ) N i M j j 100

23 Potential Serviceability Ambulance Location Required service time (t o j ) # of Random events # of events within t o j Travel Distance (miles) Response Time (minutes) Serviceability Mean Min Max Mean Min Max (S j ) Ambulance- Covering- Ratio (C j ) % % % % % % % % % % % % % % % %

24 Service Coverage Service Coverage Estimated

25 Conclusions Developed Public Communications tool for Residents Potential accessibility with Relative demandcovered-ratio for Ambulance Service Provider Potential serviceability with Relative ambulancecovering-ratio Created Service coverage For Continuous improvement

26 Transportation Future Research Finer Traffic Analysis Zone Using the Census Block 2010 Utilize Navigable Roads Network Statewide analysis Dynamic impacts considering seasonal effects Considering first respondents response time to reach ambulance in rural area

27 Q & A Reference and contact information