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