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Application of Three Types of Multi-Point Assignments. Yanping Zhang Durham-Chapel Hill-Carrboro MPO/City of Durham Soon Chung North Carolina DOT Gnani Mahalingam City of Kansas City, MO Mohsin Zaidi Virginia DOT. Finding shortest time paths between centroids - PowerPoint PPT Presentation
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Application of Three Types of Multi-Point Assignments
Yanping ZhangDurham-Chapel Hill-Carrboro MPO/City of Durham
Soon ChungNorth Carolina DOT
Gnani MahalingamCity of Kansas City, MO
Mohsin ZaidiVirginia DOT
114th TRB Transportation Planning Application Conf. - May 2013
Standard User Equilibrium (UE) Assignment
2
Zone Centroid - Origin
Zone Centroid - Destination
CentroidConnector
Access Point
14th TRB Transportation Planning Application Conf. - May 2013
East
Ave
6th St
7th St
Wes
t Av
e
60020
0
33.3
% 600
33.3%
400
400
33.3
%
200
• Finding shortest time paths between centroids• Weak control on trip local loading directions
UE Multi-Point Assignment (MPA) Type 1 - Fixed Loading Rate
3
Zone Centroid - Origin
Zone Centroid - Destination
CentroidConnector
Access Point
14th TRB Transportation Planning Application Conf. - May 2013
6th St
7th St
East
Ave
Wes
t Av
e
25%25%
10%
40%
6060
600600
240240
300
300
• Finding shortest time paths between access points• Strong control on trip local loading directions
Type 2 - Fixed/Variable Loading Rates by Centroid Connector
• 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%
4
6th St
7th St
East
Ave
Wes
t Av
e
r1
r2
r3
40%
50%
50%
14th TRB Transportation Planning Application Conf. - May 2013
Type 3 – Fixed/Variable Loading Rates by Group of Trips
• 60% trips follows the fixed rates• 40% trips follows the UE assignment rule, r1+r1+r3+r4=40%
5
6th St
7th St
East
Ave
Wes
t Av
e
6% + r1
15%
+ r2
15% +
r4
24% + r3
50%
50%
14th TRB Transportation Planning Application Conf. - May 2013
6
Summary of Three MPA Types• Type 1 - Fixed Rate Loading Strategy, Robert Shull 1999
(implemented in TModel2) • Limitations of Fixed Loading Rates.
1. Not Account for Future Land Use & Accessibility Change2. Not Account for special cases , like Partial fixed Loading
• Type 2 - Fixed/Variable Rate Loading by centroid connectors– Some centroid connectors got fixed loading rates – Other centroid connectors got the variable rates determined by
UE assignment
• Type 3 – Fix/Variable Rate Loading by Trip Groups– One Group of trips follows the fixed rate strategy– Another group of trips follows the UE assignment 14th TRB Transportation Planning Application Conf. - May 2013
MPA Tool Multi-Class MPA tool, coded in GISDK for use in TransCAD• MPA (Type) Field in node layer and it can handle MPA value=1, 2,
3 in one model• In/Out rate fields in link layer
714th TRB Transportation Planning Application Conf. - May 2013
Subarea MPA Application2005 PM Peak Hour - North Land Subarea, Kansas City. The
airport & north shopping mall are located in the subarea • MPA Result
• Non-MPA Result
814th TRB Transportation Planning Application Conf. - May 2013
0 500 1000 1500 2000 2500 3000 3500 40000
50010001500200025003000350040004500
f(x) = 0.946817857996119 x + 2.10711869933516R² = 0.912320626484753
Count vs MPA Volume (PM Peak-hour)
Traffic Counts
Mod
el V
olum
es
Type 2 - Zone with Off-Site Loading
914th TRB Transportation Planning Application Conf. - May 2013
298.39
• Triangle Regional Model (TRM) V4, 2005 PM Peak Assignment
Types 1 and 3 – Special Zone-RDU Airport
10
6946
297
1011
14th TRB Transportation Planning Application Conf. - May 2013
12374.75
116 3
. 93
6902.58
• Triangle Regional Model (TRM) V4, 2005 PM Peak Assignment
11
Conclusions1. MPA improves local traffic loading for large special zones,
such as airport, university campus, and shopping mall2. MPA improves traffic loading for off-zone (site) parking
lot/garage 3. MPA improves the assignment result for the small area
studies and/or the corridor study.
14th TRB Transportation Planning Application Conf. - May 2013