t tno inro chania, 14 march 2002paul van koningsbruggen & rick van der arend 1 distributed...

Chania, 14 March 2002Paul van Koningsbruggen & Rick van der Arend

1

tTNO Inro

Distributed Control from policy statements to local traffic control

Presentation at the OMNI-workshop

Chania, 14 March 2002

Towards a Concept for Distributed Control 2t

Content

• The Idea behind Traffic Management in The Netherlands

• Linking Network Policy and Local Practice• A concept for Distributed Control



The objective is a common traffic management approach

Elst

Arnhem

A12

A15

A12

A50

A50

A348

N325N225

N224

N785

N348

Urban RoadInter-urban RoadMotorwayRiver

VelpTrajectory speed 60 km/h

Less traffic in the city

Regional traffic only

Less traffic regarding construction works



Three Optima for Traffic Management

Network Optimum

User Optimum

Policy Optimum

Social & Economical Context

Utilisation of the Infrastructure

Individual Preferences Road Users

Traffic Management

Strategy



When the infrastructure capacity is insufficient to meet traffic demand …….

• Today’s reality: choices have to be made in the allocation of the scarcity in infrastructure capacity

Traffic Management Strategy

• Three Main Research Questions:• How can we balance the three optima and translate them into

operational goals for traffic control systems?• How can we balance the optimum on a network level and the

local, situational optimum?• How can we get the traffic control strategy to focus on the actual

traffic flows

Positioning services (measures)

Guide operations



The Idea is to link Network Policy and Local Practice

Network Traffic

Management Strategy

‘What we aim at’

Balancing the three optima in a control

strategy

Traffic Management

Tactics

Balancing the operation of traffic

control systems

‘What we gain’

Local Goals &Best Practices

Practice

Policy



The Blueprint for the Traffic Management Concept

Momentary Network Policy: priorities and quality levels

Operational Traffic Control a.o. Traffic Management Tactics

Traffic

Traffic State

Monitoring Data &Local, situational restrictions

Momentary ‘Reference Scheme’

Signals

= ‘translation’

TN

TL



Network Policy: assigning priorities and defining quality levels to strive for



Two possibilities for the Traffic Management Tactics

• Traffic Management Tactics: IF …A… THEN …B…

• Option 1: • A = State of the Network• B = set of traffic management measures• Direct activation of the traffic management measures

• Option 2: • A = State of the Network• B = Set of priorities and Quality Levels • Autonomous activation of the traffic management measures,

within the context of (B) Distributed Control



Linking Network Policy and Local Practice by using ‘Gerdien’ Tower Model

Network

TrajectoryTrajectory

SegmentSegment Segment

LinkLinkLinkLink

PointPoint PointPoint Point

Intersection

Trajectory Node

Segment Node

Link Node

Priorities & Quality Levels

(Situational) Constraints



The Quintessence of the proposed ‘Distributed Control’ Approach

Plausible Approach

Proposed Approach

RM 1 RM 2 RM n

Ramp MeteringManagement System

TL 1 TL 2 TL n

Traffic LightManagement System

VMS 1 VMS 2 VMS n

VMSManagement System

Traffic Manager

DN1 DN2 DNn

Partial Networks

T1 T2 Tn

Trajectories

S1 S2 Sn

Segments

L1 L2 Ln

Links

Traffic Manager



The idea is to co-ordinate local goals within the context of the network policy

Three (or more?) paradigms:• Industrialisation

• hierarchical order; command and control structure from network level to link level

• Arbitration:• conflicts on lower level will be referred to arbitration on a

higher (network) level

• Utilitarianism• negotiation on lower level, while adhering to a mutual, higher

network goal

Distributed Control based on the Multi-Agent Principles



DECISION

EVALUATIONOBSERVATION

ACTION

'TRAFFIC'

Cycle of Information Processing in the Kernel of an Agent



Link-Agent 2

Link 1

Service-Agent

Constraints

Link 2

Link-Agent 1

Traffic

Data

Traffic

DataImpact on Link

1

Impact on Link

2

Local, Network Goal

Local, Network Goal

Two Type of Logical Agents: infrastructure Agents and Service Agents

Zuidpolder, 4 Maart 2002

Agents in Verkeersbeheersing 15t

Link Agents observe en evaluate the local traffic situation and decide the required improvements in terms of ‘basic controls’ (e.g. I - V - C) and ask the relevant Service Agents for these improvements.

In case the local services are not sufficient anymore, the Link Agents start to negotiate, to gain the improvements together.

Operation of the Link Agents



Service Agents observe and evaluate incoming claims of Link Agents within their sphere of influence. Then, the Service Agents decide how to activate the actuators (traffic management systems) in order to meet with as many claims as possible.

On a network level, the Service Agents negotiate, in order to co-ordinate the actuators.

Operation of the Service Agents



Link Claims

Activating Actuators

Distributed Controller

Infrastructure Network

Communication

Resulting in a Concept for Distributed Control



State of Research:implementation of the distributed concept for a Motorway Stretch with Ramp Metering

Scenario 1: no ramp metering

Scenario 2: individual ramp metering (‘Alinea’ algorithm)

Scenario 3: distributed control, node as sphere of influence

Scenario 4: distributed control, complete motorway stretch as sphere of influence



Resume

• The Idea behind Traffic Management in The Netherlands

• Linking Network Policy and Local Practice• A concept for Distributed Control



Thank you for your attention !

t tno inro chania, 14 march 2002paul van koningsbruggen & rick van der arend 1 distributed...

Documents

traffic demand

traffic control strategy

t chania

actual traffic flows

city regional traffic

network b

distributed control10

distributed control4