esg uqam cirrelt - crt · cirrelt city logistics teodor gabriel crainic esg uqam & cirrelt -...

CIRRELT

City Logistics

Teodor Gabriel Crainic

ESG UQAM&

CIRRELT - CRT

2© Teodor Gabriel Crainic 2006

A Few Sources for Information

Best Urban Freight Solutionswww.bestufs.netConferences and workshopsBest practice handbook

www.transports-marchandises-en-ville.orgCity Logistics Institute www.citylogistics.org

Three International conferences (next: 2007)A book, …

The European projects, US-DOT, VERTIS web siteswww.google.com ☺


Presentation Summary

Freight transportation in urban areasThe City Logistics ideaStudies and initial deploymentsA two-tier system and some modelsPerspectives


Freight Movements in Urban Areas

Essential to most economic and social activitiesVital link in the supply chain from producers to customers: Supplies of stores, homes, officesThe means to keep cities cleanMajor source of employment

Major disturbing factorInterference with passenger trafficCities are pollutedCities are not safe …


Freight Movements in Urban Areas (2)

Significant part of trafficTokyo (94): 67% of total cargo (tonnage) with origin and destination in cityRome (00): over 30000 load&unload/day in Centro storico

Commercial distribution to supply stores, offices, industries, tourist infrastructures, ...Individual pickup and delivery activities at private addresses, stores, companies, offices, ...Express and regular courier servicesAccess to major (intermodal) facilities: ports, airports, rail yards, less-than-truckload terminals, …Through-traffic, Dangerous goods, …



Large number of different (dedicated) vehiclesAverage load levels: LOWEmpty movement levels: HIGH

Rome (00): 75% of truck trips for 1 destination onlyAverage vehicle load < 20% of vehicle capacity

Volume rapidly increasingE-business, Express courier, JIT/door-to-door, Reverse logistics, …

Major and heavy world-wide trend: urbanizationLarge cities become largerMore cities become large



Significant part of traffic-related problemsCongestion, noise, safety, pollution, …Urban network critically congested

Rome (00): Over 25 000 vehicles enter city between 8h00 - 9h00 am

Fierce competition for street and parking space Rome (00): Reserved delivery parking space used for 5% of truck parking only

Double (triple) parking of trucks for pickup and delivery (cars as well !)


The “Tradition”

No planning/control methodology“Freight transportation = private activities performed and supplied by private means”Urban (regional) transport planning models target passenger traffic and consider aggregate truck flows only

Usual controls through regulationLimited access hoursRestricted access to selected city zonesParking restrictions

Do not work very well ...


A Brief History

Beginning of the 70’sSeveral studies and research projects on both sides of the AtlanticInternational conferencesLimited yield and public enthusiasmTraffic regulations to avoid heavy truck presence in cities and “limit” impact of truck traffic on car movements

1975 – end 80’s: almost nothing


A Brief History - The 90’s and Beyond

Renewed and steady interest in urban freight transportation issuesIncreased urbanization and traffic ⇒ increased traffic-related problems“New” public awareness and pressure (the politicians take notice …)


A Brief History - The 90’s and Beyond (2)

A more holistic view of (freight) transportationFrom Intelligent Vehicle-Highway Systems (IVHS) to Intelligent Transportation Systems (ITS)The US-DOT Intermodal Surface Transportation Efficiency ActThe European projects: intermodal as keyword

“Many” projects and pilot implementationsInternational conferencesThe City Logistics concept (“brand”)A lot of work to do …


Emerging Needs

Analyze (understand), control, reduce freight vehicle movements within cities to

Reduce congestion & pollution & increase mobilityImprove living conditionsReduce/control number and dimensions of freight vehicles operating within the cityImprove efficiency of movements Reduce empty vehicle-kmKyoto targets (the spirit, at least)Do not penalize city center activities !!


Enabling Factors

Intelligent Transportation Systems : CVO, AFMSVehicle/cargo location and tracking systemsIncreased on-board computing capabilitiesImproved vehicular technologiesInformation technologies Traffic management centers and surveillance technologies

Operations Research: Advanced Fleet Management Systems (AFMS)Planning Real-time operations and management


The Fundamental Idea – City Logistics

Stop considering each shipment and company (and vehicle) individuallyConsider them as components of an integrated logistics systemConsolidation and coordination

Coordination of shippers and carriersConsolidation of several shipments of different shippers, carriers, and deliveries by the same(improved, more energy efficient) vehicle

City Logistics: Optimize this logistics system


Main R&D Avenues

Design and optimization of city logistics systemTerminal location, design, operationsReal-time operations (routing, dispatching)Underground freight systems

Mostly studies: Tokyo downtown, Amsterdam airport, …Very interesting but needs work

Impact and evaluation models and methodsNot many yet


The City Distribution Center Approach

Based on the utilization of a facility where shipments are consolidated prior to distribution: the intermodal or logistics platform or City Distribution Center (CDC)Most activities are related to distribution and less to pick up


Single-Tier Single-CDC City Logistics

Customerzone

Urban-truck

CityDistributionCenter


The City Distribution Center Approach

Based on the utilization of a facility where shipments are consolidated prior to distribution: the intermodal or logistics platform or City Distribution Center (CDC)

A single-tier systemUsed in most projects, including the pilot implementationsLimited number of shippers and carriersLimited usage of ITS technologies (initially)City administration involvement (some) but traffic regulations not adapted


Distribution Licenses

Initial idea: HollandLimited number of licenses (permits) for urban distribution

Operating rules: e.g., operate circuits, on-board loading/unloading equipmentDistribution advantages (e.g., extended hours)

Strong local and central government involvement


“City Logistik”

Initial idea: Germany“Spontaneous” grouping of carriers for coordination and consolidation activitiesRather light government involvement (“facilitator”, no particular traffic rules)Private initiative ⇒ At same time in the (near) future, the project must prove self-sustainable and profitable (…)Many applications


Public Service

Initial idea: MonacoAll large vehicles (> 8 tons) forbidden into the city and must deliver to the CDC from where distribution is ensured by unique carrierSpecialized firm, material, personnelParticular characteristics of the Monaco state/municipality


Status

License approachLimited experimentsIt works

Most experiences on the more or less voluntary grouping of carriers around a distribution center: Mix outcomes

Consolidation ⇒ extra manipulations, costs, delaysLimited utilization of ITS and decision technologyLimited adaptation of traffic regulation“Short-term” financial self-sufficiency not attainedInsufficient involvement of authorities and customers


Status (2)

Monaco approachStarts to be adapted to other locationsMostly “small” to “medium” cities in EuropeSimilar approaches to particular city zones in Japan


Status (3)

Experiences are continuingIncreased functionalities for the CDCIncreased utilization of information (electronic data exchanges) and decision (routing software) technologies“Clean” vehicle utilization is growingVarious partnership and organizational structures are tried out


Personal Perspective

Large and congested cities require several distribution platforms of possibly different characteristics and functionalitiesA pro-active role for the city similar to the one in public transport (!!)

Integrated policy regarding vehicle access and the organization of freight movements within the cityPublic-private understanding, collaboration, and innovative partnerships

ITS and Operations Research


A Two-Tier City Logistics System

Coordination of freight movements and actors (shippers, carriers, customers) within the (central or entire) urban area

City Distribution Centers (CDC)Satellite CDC - satellitesConsolidation of individual demands (customers) Limited and controlled access of vehicles to the city centerUtilization of adapted, “clean” vehiclesUtilization of ITS and Operations Research methods and technologies


Satellite City Logistics – Terminals

CityDistributionCenter

Customerzone

Satellite


Satellite City Logistics – Movements

City-freighter

Urban-truck


Main Idea

Urban trucks move cargoFrom City Distribution Centers (external zones)To satellite platforms: satellites

Urban trucks travel as little as possible through inner city

Transdock-type of operation at satellitesNo storage facilities

To customers by using dedicated vehicles on circuits(Reverse operations as well, of course)(Vehicles are loaded as fully as possible)


Terminals: City Distribution Centers

(Intermodal or Logistic Platforms)Link the city to the region, the country, the worldLocated close to access or ring highways or within air, rail or navigation terminalsAccommodate long-haul vehicles and urban (smaller) vehicles: the urban-trucks and city-freightersStorage and sorting/consolidation activities (+ accounting, legal counsel, brokerage, etc.)


Terminals: Satellites

In large cities limited number of CDC located “far” from central city ⇒

Longer vehicle tripsDifficulties in fully using the vehicle capacities, …

Idea: bring cargo “closer” to inner-city by fully loaded urban trucks (on designated corridors), transfer to small energy-efficient vehicles for circuit deliveryBetter vehicle utilization, extra handlingOptimize the system for total “system” cost


Satellites

Very light structure (human) Use existing facilities (e.g., city bus terminals, tourist bus parking lots)Transfer direct from vehicle to vehicleVehicles at satellite on a “need-to-be-there” basisNeed for ITS and real-time control


City-freighters

Relatively small capacityStandardizedEnvironment-friendly: electric or hydrogen-based tractionSeveral R&D proposals, projects, and demonstrations of such vehicles and standardized cargo packing


Issues and Decisions

System designShort-term planningReal-time operation, control, and dispatch of vehicles and terminal activities (ITS)

Politics (public involvement), social, working relations, taxation, etc.


System Design

Location and design of CDCLocation of satellites and customer allocationFleet dimensioningUrban-truck corridors…


Satellite Location Model

Proof of concept (quite preliminary) based on a real city: RomeAnalyze the “logistics” structure of the inner cityEvaluate the proposed system


Given

Intra-muros customer-zone definitionAggregation of commercial activities & locationsGeographically homogeneous (Supply/Demand)

External zones (Supply/Demand)Commodity definitionFreight urban corridors (for urban trucks)Vehicle characteristicsPossible satellite sites


Determine

Selection of satellitesAllocation of each customer zone to one or more satellitesGross fleet-size estimation


Vehicles

City-freightersTypeCapacityCost (operations)

Urban trucksTypeCapacityCost (social, operations)


Satellites

Location “Fixed” cost =

Operation cost (manpower) +Undesirability factor (social impact)

Capacity (for the opening hours)# urban trucks

# city-freightersMinimum utilization level Average handling timeAverage handling cost


Network

City networkAverage travel time (accounts for congestion)Undesirability factor: Classifies network arteries according to the maximum tolerated level of freight vehicle traffic

Simple congestion representation ⇒ no capacity ⇒single path for each demandModel defined on un-capacitated service network

CDC → satellite service arcSatellite → customer zone service arcAverage travel times


Multi-commodity Location-Allocation

Decision variables: Locate satellites (Boolean)Distribute (commodity) flows (continuous): from CDC to customer zone through satellite, using given types of urban trucks and city-freighters

Minimize total costDemand satisfactionMinimum satellite activitySatellite capacity (linking) constraints in terms of # of urban truck and city-freighter served


Rome Case Study

Historical centre51 commercial zones → customer zones

Possible satellite locations: 41Public transit depots + Tourist bus parking lots (29)Platforms at city gates (12 – hypothetical)

CDC: 12 The main entry points in Rome

1 urban truck and 1 city-freighter types (lack of data)Typical wages and vehicle characteristics in Italy


Rome Case Study (2)

Demand data from official studiesImport (85%) largely outweighs exportsAggregate figures of vehicles entering city7h00-11h00 (legal distribution time window)

Characteristics of each commercial zone known in terms of population, # of stores, total store surface and # of employees, etc.Travel times from actual urban planning model (EMME/2)


Results

Model solved efficiently by state-of-the-art commercial solver until ≈ 400 customer zonesSeveral scenarios (the “new” satellites)Reduction in vehicle flows compared to estimated number of trucksVery limited increase of total delivery timeResults are very encouraging but a more thorough experimentation is in orderIn the meantime, we continue …


Issues and Decisions

System designShort-term planning

Access times and routes of urban trucksDemand routingCity-freighter fleet allocationPersonnel scheduling…

Real-time operation and control (ITS)


Short-Term Planning Objectives

Control & schedule access of vehicles into the citySchedule inter-city vehiclesSatisfy demand on timePlan an efficient utilization of the city-freighter fleetPlan an efficient utilization of the satellitesEmpty movement controlOperating costsPersonnel scheduling


Problem Description

Planning of the next period of operations, performed a short time before (“the day before”)Most demand is known

Assumed to be at a CDCLatest due date known

Logistics structure knownSatellite location and capacityCustomer zone assignment

City access/egress corridors known


Problem Description (2)

Vehicle types and characteristics knownManagement of inter-city movements performed by external agents based on city-logistics decisionsVehicles are in sufficient numbersTime-dependent congestion measures known


Short-Term Planning Objectives

Control & schedule access of vehicles into the citySchedule inter-city vehiclesSatisfy demand on timePlan an efficient utilization of the city-freighter fleetPlan an efficient utilization of the satellitesEmpty movement controlOperating costsPersonnel scheduling


Modelling Approach

Time discretizationSet of urban-truck routes

Departure time & CDC, set of satellites, …Design (selection) {1,0} decision variable / route

Sets of city-freighter work assignments (by c-f type)Departure time from depot, [satellite, customer route], … ends at a depot at end of periodDesign {1,0} decision variable / route


Urban-Truck Routes

R(i): t(R(i))=tR(j): t(R(j))=t+1

Decision: Whichservice to run?

e

s

y(i) = {1,0}s’

R(k): t(R(k))=t; s&s’


City-freighter Work Assignments

s(t)

i

j

k

Time windowsService times

Arrive ontime !!

s(t+)s’’(t+)

s’(t+)

d(i)

d(j)

d(k)


Demand

d(e,z,p,t,[a,b])=d(k)

z

e


Modelling Approach (2)

DemandCDC & availability timeCustomer (zone) and due time(technical requirements)

Set of demand itineraries{urban-truck route, satellite, city-freighter work assignment}Feasible with respect to d

Time (& technical) requirements of demandSynchronization at satellite

Design (selection) {1,0} decision variable / itinerary


Demand Itineraries

zs’

s

Decision: Whichitinerary to use?How much to assign? (split-delivery variant)

e

M1(k):{e,R(i),t(R(i)),s(M1(k))=s(R(i))=s}

d(e,z,p,t,δ)=d(k)

z(k,j)={1,0}x(k,j)≥ 0



Minimize total vehicle costs Demand satisfactionUrban-truck capacity (linking constraints)City-freighter capacity on each leg (linking constraints)Satellite capacity in # trucks & # city-freighters Split or un-split deliveries



Large mixed-integer programThree sets of path variables

Urban-truck routesCity-freighter routesDemand itineraries

Linked and synchronized Hierarchical decomposition proposal: A Two-Tier model

Demand distribution + urban-truck service design & schedulingCity-freighter allocation & management (circulation)


First Tier Model

Approximate customer service (route) times our of satellitesSelect

Urban-truck routes and schedulesDemand itineraries


Formulation

Mixed integer program: Scheduled service network design Minimize total cost of system (services & itineraries)Demand satisfactionUrban-truck capacity (linking constraints)Satellite capacity in # trucks & # city-freighters Split or un-split deliveriesService network design solution approaches


Service Design Model – Un-split Delivery

Service capacity

Single itinerary

Satellite capacity


Second Tier: City-Freighter Fleet Management

Integer city-freighter flows (by type)Out of satellites (at each period)To serve particular customers (zones)

⇒Requirements at each satellite and periodDetermine (path versus arc-based formulations)

City-freighter routes to serve the satellite demandTo what satellites (or depots) to send vehicles following a distribution route such that they become available on time (no waiting at satellites)

Account for fleet size


City-freighter Circulation Issues

t t + 1

s

z(s)

Which satellite?What period?

Which one is thelast

customer?


Modelling Approaches (Arc Formulations)

General Fleet Management ModelTime-dependent, multi-depot, heterogeneous fleet vehicle routing with (tight) time windowsAdditional constraints: synchronization

Decomposition approachMany routing problemsMulti-commodity network flow


City-freighter Fleet Management

s(t)

i

j

kTime windowsService times

Arrive ontime !!

g(t) g(t+)

s(t+)s’’(t+)

s’(t+)

d(i)

d(j)

d(k)


Fleet Management Model: Routing

Flow cons. satellite

First customer on route

Single ass. customer2routeFlow cons. customer node

Flow cons. depot


Fleet Management Model: Timing

Satellites

Customers

Customers

City-freighter capacity


Solution Approaches

General Fleet Management ModelHead-on approach: meta-heuristics and parallelism

Decomposition (“lose” time coordination at satellites)Routing problem for each satellite/time period/city-freighter type⇒# of city-freighters & time availability for repositioning

Many (small) problems in parallelCirculation & synchronization: Multi-commodity network flow – separable by city-freighter type

Simplified version of previous network: Node = satellite at time period


s(t)

s’(t)

s’’(t)

s(t+)

s’(t+)

s’’(t+)

s(t-)

s’(t-)

s’’(t-)

g(t) g(t’) g(t’’)

F(st)

City-Freighter Circulation Network


Relation to Single-Tier Approaches

No satellites ⇒ No synchronization at satellites

All vehicles are city-freighters (urban-trucks)The problem “reduces” to routing the city-freighters to satisfy demand at minimum total system costCirculation aspect still present (multiple depots)BUT, the design dimension still present: When should the route start (demand be served, vehicle leave)?Issue: what customers (demand) to serve by a given route?

⇒ Cannot separate the design and routing aspects


Single-Tier Model: Path-based Formulation

Path = Vehicle route from depot t=0 to depot t=T+1Serves groups of customers each passage through a CDCFeasible with respect to

Customer timing requirementsVehicle capacity

Multi-depot set covering formulationMinimize total travel and service cost of the selected routes (paths)Fleet dimension given


Single-Tier Single-CDC Service & Routing Model

Unsplit delivery

Single route per vehicle

Fleet dimension


In Development

Algorithms and codes and …Alternate formulations


Technological Issues

A lot of IT / ITS and vehicular (packaging) technology already available.Decision support systems – planning and operation models are being investigated and builtData – more complex (human factors …)

What is needed?What is available? How to get what is needed?


General Issues

Social, political, administrative, financialCity-freighter fleets: public/private? But coordinated operations (a “public” service)Satellites increase the # of handling operations (costs and delays) but final cost of goods should not increasePublic financing? (environment taxation?)System must be efficientSystem must be “profitable” (i.e., globally)Labor-relation issues…


General Perspectives

The issue of freight transportation in urban areas is here to stayA number of systems may be simultaneously implementedBetter utilization of existing infrastructure (e.g., rail or subway lines) is promisingFully automatic underground systems may be interesting in particular settingsCoordination + consolidation appears the most promising


O.R. Research Perspectives

Real-time operations and control (dispatching, re-routing) of vehicles and terminals under a coordination & consolidation policyShort-term planning of operationsPersonnel schedulingCargo holding policies (at out-of-area terminals)Loading vehicles and relations to dynamic controlFleet dimensioning and selection (“what type of vehicle and packing?”)


O.R. Research Perspectives

Corridor selection for each type of vehicleSelection and dimensioning of terminals Integrating city-logistics city

Planning methods (static)ITS systems and methods (ATMS, ATIS) (dynamic)

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