ESG UQAM CIRRELT - CRT · CIRRELT City Logistics Teodor Gabriel Crainic ESG UQAM & CIRRELT - CRT
Transcript of ESG UQAM CIRRELT - CRT · CIRRELT City Logistics Teodor Gabriel Crainic ESG UQAM & CIRRELT - CRT
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 ☺
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Presentation Summary
Freight transportation in urban areasThe City Logistics ideaStudies and initial deploymentsA two-tier system and some modelsPerspectives
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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 …
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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, …
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Freight Movements in Urban Areas (3)
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
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Freight Movements in Urban Areas (4)
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 !)
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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 ...
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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
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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 …)
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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 …
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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 !!
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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
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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
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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
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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
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Single-Tier Single-CDC City Logistics
Customerzone
Urban-truck
CityDistributionCenter
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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
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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
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“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
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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
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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
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Status (2)
Monaco approachStarts to be adapted to other locationsMostly “small” to “medium” cities in EuropeSimilar approaches to particular city zones in Japan
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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
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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
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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
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Satellite City Logistics – Terminals
CityDistributionCenter
Customerzone
Satellite
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Satellite City Logistics – Movements
City-freighter
Urban-truck
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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)
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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.)
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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
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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
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City-freighters
Relatively small capacityStandardizedEnvironment-friendly: electric or hydrogen-based tractionSeveral R&D proposals, projects, and demonstrations of such vehicles and standardized cargo packing
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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.
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System Design
Location and design of CDCLocation of satellites and customer allocationFleet dimensioningUrban-truck corridors…
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System Design
Location and design of CDCLocation of satellites and customer allocationFleet dimensioningUrban-truck corridors…
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Satellite Location Model
Proof of concept (quite preliminary) based on a real city: RomeAnalyze the “logistics” structure of the inner cityEvaluate the proposed system
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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
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Determine
Selection of satellitesAllocation of each customer zone to one or more satellitesGross fleet-size estimation
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Vehicles
City-freightersTypeCapacityCost (operations)
Urban trucksTypeCapacityCost (social, operations)
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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
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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
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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
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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
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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)
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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 …
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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)
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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
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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
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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
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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
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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
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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’
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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)
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Demand
d(e,z,p,t,[a,b])=d(k)
z
e
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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
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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
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Modelling Approach (3)
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
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Modelling Approach (4)
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)
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First Tier Model
Approximate customer service (route) times our of satellitesSelect
Urban-truck routes and schedulesDemand itineraries
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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
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Service Design Model – Un-split Delivery
Service capacity
Single itinerary
Satellite capacity
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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
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City-freighter Circulation Issues
t t + 1
s
z(s)
Which satellite?What period?
Which one is thelast
customer?
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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
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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)
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Fleet Management Model: Routing
Flow cons. satellite
First customer on route
Single ass. customer2routeFlow cons. customer node
Flow cons. depot
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Fleet Management Model: Timing
Satellites
Customers
Customers
City-freighter capacity
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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
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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
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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
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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
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Single-Tier Single-CDC Service & Routing Model
Unsplit delivery
Single route per vehicle
Fleet dimension
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In Development
Algorithms and codes and …Alternate formulations
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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?
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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…
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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
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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?”)
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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)