A Branch-and-Bound Based Framework for Route Set Generation

Universität StuttgartInstitut für Straßen- und VerkehrswesenLehrstuhl für Verkehrsplanung und Verkehrsleittechnik

M.Sc Yaohua XiongIDS 2012

2012.12.13

Pfaffenwaldring 7 70569 Stuttgart Tel. +49 (0)711 685-82480 www.isv.uni-stuttgart.de/vuv/

A Branch-and-Bound Based Framework for Route Set Generation

Outline

Motivation and Objective

Background

Generate Realistic Route Set

Summary

Open Questions

Outline

Motivation and Objective

Background

Generate Realistic Route Set

Summary

Open Questions

Motivation and Objective

Path Based Assignment Path Flows instead of Link Flows Detailed Result Stable Result

New Question: are the paths “realistic”? What is “realistic”? How to make paths “realistic”?

Terminology Route: Consecutive Links Path: Path + Departure Time

Outline

Motivation and Objective

Background

Generate Realistic Route Set

Summary

Open Questions

Conventional Assignment Process

A

B

Done!

Find Free Flow Shortest

Path

Network Loading

Converge?Find CongestedShortest Path

Path Flow Set

End

Start

Existing Approaches for Route Generation

Approach Procedure Result Ref

K-shortest Path Exact Deterministic Van der zijpp

Link Elimination Heuristic Deterministic

Azevedo et al.

Gateway Heuristic Deterministic Lombard

Labeled Heuristic DeterministicBen-akiva et al.

Monte-Carlo Heuristic Stochastic Ramming

Additional Approach

Outline

Motivation and Objective

Background

Generate Realistic Route Set

Summary

Open Questions

What is a Realistic Route (Set)?

Route that travelers are willing to use “Subjective” Not Operative

“Objective” and Operative Definition Coverage Rate Estimation Quality

But the definition of “realistic” route *is* subjective No Physical Rules

Solution: Ask “What is an unrealistic route?” Use Intuition Formalize the Rules The Rules are called Constraints

Subtraction Approach

Branch-and-Bound

Branch: systematically enumerate all pathsBound: eliminate unrealistic paths

Non-Cyclic Constraint

No Cycle in Route

Detour Constraint

No Excessive Detour

Detour Factor = Path Length / Shortest Path Length

(Local) Detour Constraint

Turn Constraint

Without C(8,4) = 70 C(18, 9) = 48620 C(38, 19) = 35345263800

With e.g. max_turn = 1

NNNNEEEE

EEEENNNN

ENENENEN

Other Constraints

How to identify new constraints?

Use Intuition Researcher Expert Opinion Survey

Road Hierarchy

Distance Matters

Road Hierarchy Aware Enumeration

Determine Access and Egress Point

Generate Sub-routes from origin to Access Point

Generate Sub-routes from Egress point to Destination

Generate Sub-routes from Access Point to Egress Point

Concatenate Sub-routes

Choice Set Composition

Choice Set vs Route Set

Post Process Individual Avaibility/Perception Overall Quality Control

Outline

Motivation and Objective

Background

Generate Realistic Route Set

Summary

Open Questions

Summary

OD PairGrouping

Enumeration

End

Start

RH AwareEnumeration

Constraints

Composition

Subtraction Instead of Addition. Non-cyclic Constraint Detour Constraint Turn Constraint Others...(Use the

intuition, Luke)

Road Hierarchy Aware Enumeration

Composition

Overall Framework Route Set Generation

Constrained Path Based Assignment

Converge?

Path Based Assignment ConstrainedPath Based Assignment

Find Free Flow Shortest

Path

Network Loading

Converge?Find CongestedShortest Path

Path Flow Set

End

Start

RouteEnumeration

Network Loading

Find ConstrainedShortest Path

Path Flow Set

End

Start

Thank You!

xiongyaohua@gmail.com

and

Open Question

With a given link impedance definition CPBA is not necessarily achieve equilibrium.(shortest path will not be considered due to constraints)

Equilibrium Assumption is True

Constraints are Valid

Why?

→ The impedance has latent factors which are not took into account in the current definition?

A

B