Estimating Intrazonal Impedances in Macroscopic Travel Demand Models Matthew Bediako Okrah Technical...
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Transcript of Estimating Intrazonal Impedances in Macroscopic Travel Demand Models Matthew Bediako Okrah Technical...
Estimating Intrazonal Impedances in
Macroscopic Travel Demand Models
Matthew Bediako OkrahTechnical University of Munich
15th Transportation Planning Applications Conference
20 May 2015
Contents• Background
• Proposed Method
• Application and Suitability Checks
• Significant Observations
2
Background
• Existing approximate methods - Nearest Neighbour Techniques- Functions of Area Size
• Questions- Good estimates of intrazonal impedances?- Good estimates of intrazonal flows?
3
Intrazonal Trips
4
Intrazonal Trips
5
Proposed Method
6
Select Nodes
Calculate Weight Matrix Weighted Distance Matrix
Assign Node Weights
Compute Intrazonal Distance
Calculate Distance Matrix
Proposed Method
• Variants of Method- Unweighted Nodes- Nodes Weighted by Closeness Centrality- Nodes Weighted by Degree Centrality
7
Application of Method
• Dachau with
102 TAZ
• Area= 13 sq.mi.
• Pop= 46,000
8
Suitability Check 1
• Aggregate 102 Zones into:- 25 Zones- 10 Zones- 5 Zones- 2 Zones
• Intrazonal distance with different methods
• Compare estimated intrazonal distances
9
10
25-Zone10-Zone5-Zone2-Zone
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
RM
SE (km
)
UnweightedDegreeClosenessArea-BasedNearest Neighbor
RMSE in Estimated Intrazonal Distances
Suitability Check 2
• Trip Distribution with the different methods - Home-Work Trips - Non-Home-Based Trips- Home-Shopping Trips
• Between modeled and observed trips;- Compare TLFDs (Coincidence Ratio)- Compare Total Number of Intrazonal Trips
11
12
10987654321
25
20
15
10
5
0
Distance (km)
Perc
ent
Observed (ATL = 1.6 km)Estimated (ATL = 1.5 km)
Coincidence Ratio = 0.83
TLFD of NHB Trips (Unweighted)
Estimated Intrazonal Trips = 1215
13
10987654321
25
20
15
10
5
0
Distance (km)
Perc
ent
Observed (ATL = 1.6 km)Estimated (ATL = 1.5 km)
Coincidence Ratio = 0.83
TLFD of NHB Trips (Degree)
Estimated Intrazonal Trips = 1195
14
10987654321
20
15
10
5
0
Distance (km)
Perc
ent
Observed (ATL = 1.6 km)Estimated (ATL = 1.5 km)
Coincidence Ratio = 0.82
TLFD of NHB Trips (Closeness)
Estimated Intrazonal Trips = 1384
15
10987654321
20
15
10
5
0
Distance (km)
Perc
ent
Observed (ATL = 2.6 km)Estimated (ATL = 3.4 km)
Coincidence Ratio = 0.55
TLFD of NHB Trips (Area-Based)
Estimated Intrazonal Trips = 2136
16
10987654321
25
20
15
10
5
0
Distance (km)
Perc
ent
Observed (ATL = 1.6 km)Estimated (ATL = 1.5 km)
Coincidence Ratio = 0.82
TLFD of NHB Trips (Nearest Neighbor)
Estimated Intrazonal Trips = 1548
17
Home-Shopping(700)Non-Home-Based(1280)Home-Work(280)
60
40
20
0
-20
-40
-60
Perc
ent
UnweightedDegreeClosenessArea-BasedNearest Neighbor
Errors in Estimated Number of Intrazonal Trips
Conclusions
• Unweighted provides better estimates of
intrazonal impedances
• Better intrazonal impedance no guarantee for
better estimates of intrazonal flows
• Nearest neighbour method sufficient given
ease of measurement
• Need for smaller zones to avoid intrazonal
trips18
Thanks for your Attention
19