Post on 12-Apr-2021
Multi-Point and Multi-Class User Equilibrium Assignment
Yanping Zhang
DCHC MPO/City of Durham
1NC Model User Group Meeting - April 2011
Multi-Point Assignment (MPA)
• Standard User Equilibrium (UE) Assignment
– Using shortest time path between zone centroids– Weak control on trip local loading directions
• MPA
– Strong control on trip local loading directions– Not a method to assign trips from origins to
destinations – Used together with UE or other assignment
methods
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Standard User Equilibrium (UE) Assignment - Example
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6th
St
7th
St
Zone Centroid
‐
Origin
Zone Centroid
‐
Destination
CentroidConnector
Access Point
Multi-Point Assignment (MPA) - Example
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6th
St
7th
St
Zone Centroid
‐
Origin
Zone Centroid
‐
Destination
CentroidConnector
Access Point
Multi-Point Assignment (MPA) and Loading Strategy
• Fixed Rate Strategy, Robert Shull 1999 (implemented in TModel2)
• Mixed Strategy 1– Some centroid
connectors got fixed loading rates
– Other centroid
connectors got the variable rates determined by UE assignment
• Mixed Strategy 2– Part of Origin‐Destination (O‐D) trips follows the
fixed rate strategy– Other O‐D trips follows the UE assignment rules
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Fixed Rate Strategy for Loading/Receiving
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6th
St
7th
St
10%
25%
40%
50%
Mixed Strategy 1 - Example• 40% O‐D Trips Loaded onto West Ave
• 60% O‐D Trips follow UE assignment to other 3 directions,
i.e. r1+r2+r3=60%
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6th
St
7th
St
r1
r3
40%
50%
Mixed Strategy 2 - Example• 60% O‐Ds follows the fixed rates
• 40% O‐Ds follows the UE assignment rule, r1+r1+3+r4=40%
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6th
St
7th
St
6% + r1
15% + r4
24% + r3
50%
What MPA can be used for
• Large Special Zone, e.g. Airport, University Campus, Shopping mall, …
– with large amount employment– with multiple loading directions– with socio‐economic data that cannot be split into
smaller zones
• Zone with Off–Site Loading, e.g. Office with off‐site parking garage
• Zones with multiple vehicle class loading and different loading directions for each vehicle class
• Special Event Model, Stadium, Theater, …
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Example – Special Zone-RDU Airport
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TRM v4 2005PM Peak Period(3:30‐7:30)
Example – Zone with Off-Site Loading
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MPA Tool• Coded in GISDK for use in TransCAD
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MPA Application
• Kansas City Metro Area, including the Kansas City Model, 2005‐2006
• Special Event Traffic Study for the New Stadium, Scottsdale, AZ, 2009
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MPA Application• 2005 PM Peak Hour, Kansas City North Shopping Mall
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MPA Test in TRM
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Suggestions
• System‐wide use of MPA in the regional travel demand – NOT Suggest at this time
• Use of MPA for a limited number of key zones in the regional model – Strongly Suggest
• Use of MPA for corridor or small area studies – Strongly Recommend
• Use of MPA for obtaining better assignment results – No comment
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