Assigning mixed traffic of cars and trucks: how to handle asymmetric interactions

1. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Assigning mixed traffic of cars and trucks:how to handle asymmetric interactions Michael Florian, Shuguang He INRO Solutions

2. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Multi-class assignment :cars and trucks the usual practice of assigning mixed traffic of cars and trucks is: use the same volume/delay functions; convert the trucks into PCE (or PCU) equivalent numbers by using a conversion factor; run a multi-class assignment with limitations on the truck sub-network; the implicit assumption is that the interaction between cars and trucks is symmetric; that is, the conversion factor is constant regardless of traffic conditions, grade, etc�

3. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Multi-class assignment :cars and trucks - the reality the actual delay depends on a variety of factors such as the mix of traffic (% trucks), average speed, grade, etc� the volume delay functions must depend on the mix of trucks and cars and other such factors like the slope of the link the cost functions are likely to be nonlinear, non-smooth and asymmetric then, it is necessary to develop a specialized assignment method that can handle such functions

4. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Volume/delay functions and PCE VDF (volume delay function). Each class has its own travel time depending on link volume and free speed on the link PCE (passenger car equivalents). Truck volume is converted to car volume. Mix of Traffic (congestion factor) percentage of each class of traffic on the link slope and length of the link by each class

5. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Application SCAG region New macro using emme/2 multi-class assignment with 0 iteration (shortest path) BPR function: It uses a look-up table to update PCE�s and delays at every iteration Step size using a variant of the Method of Successive Averages

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7. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] The SCAG Highway Network network Zone: 3325 3217 ;SCAG region zone and externals 108 ;zones converted from parking lots Regular nodes: 26290 Directional links: 108897

8. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Six classes of demand 1. Passenger cars of one person 2. Passenger car of two person 3. Passenger car of three person + 4. Light-heavy duty trucks, 8500 to 14,000 GVW 5. Medium-heavy duty trucks, 14,000 to 30,000 GVW 6. Heavy-heavy duty trucks, over 30,000 GVW

9. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Trip Tables for the Highway Assignment Total trips: drive alone: 5319853; car pool 2: 1625165; car pool 3+: 430209 light heavy duty trucks: 85040 medium heavy duty trucks: 62804 - heavy heavy duty trucks: 38333

10. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] A delay study was carried out(Meyer and Mohades) The results of this study are presented in the next slides; They consist of the computation of PCE equivalents of different trucks depending on traffic mix, length of link and grade.

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23. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Step 0: Initialization. Start with AON assignment based on free flow times; Step 1: Compute percentage of link flow, v/c ratio and link flow in PCE( look up table); Step 2: Update travel times; Step 3: Compute new shortest paths and AON assignments; Step 4: Compute successive average and update flows; Step 5: If convergence test not satisfied Go to step 1 ; Otherwise STOP.

24. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Measures of Convergence Relative difference between volume at iteration l and successive average volume at iteration l:



27. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Conclusions One can perform far more sophisticated multi-class assignments than the standard EMME/2 multi-class assignment; The computational times compare favourably with the standard EMME/2 multi-class assignment


29. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Regular slide optional elaborated title [Outline 1] heading [Outline 2] bullet [Outline 3] sub bullet [Outline 4] heading [Outline 2] bullet [Outline 3] sub bullet [Outline 4]

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31. Ontario EMME/2 Users' Group Meeting Toronto, April 2005] Text-image optional elaborated title [Outline 1] heading [Outline 2] bullet [Outline 3] sub bullet [Outline 4] heading [Outline 2] bullet [Outline 3] sub bullet [Outline 4]

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Assigning mixed traffic of cars and trucks: how to handle asymmetric interactions

Assigning mixed traffic of cars and trucks: how to handle asymmetric interactions

Presentation Transcript

Assigning mixed traffic of cars and trucks: how to handle asymmetric interactions

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Assigning mixed traffic of cars and trucks: how to handle asymmetric interactions