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Dynamics of Supply Chains: A Multilevel Network Perspective on Sustainable Freight Movements Frank Southworth* STELLA Workshop on Globalization, E-Economy and Trade University of Siena, Italy June 7- 9, 2002

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slide1

Dynamics of Supply Chains: A Multilevel Network

Perspective on Sustainable Freight Movements

Frank Southworth*

STELLA Workshop

on Globalization, E-Economy and Trade

University of Siena, Italy

June 7- 9, 2002

* On Assignment at the Bureau of Transportation Statistics,

US Department of Transportation, Washington DC 20590

slide2

Outline of This Presentation:

1. Problem Statement

2. Some Trends That Need Addressing

3. A Multilevel Modeling Framework

4. Summary

slide3

The Problem: Rapid Growth in The Freight Sector

Is Producing …

More Traffic Congestion-Induced Delays

More Fossil Fuel Consumption

More Environmental (Air, Water, Noise) Pollution

Greater Consumption of Land

How Are We Going To Handle

This Growing Demand For

Goods Movement?

slide4

The Freight Sector Is Expected To Grow Substantially:

In the United States, for example:

Some 9.1 billion tons of freight, worth $9.4 trillion, were moved into, out of, and within the USA in calendar year 1998*

Forecasts suggest that (from 1998-2020)*:

US-Domestic freight will grow at 2.8% per year

(= 87% cumulative increase)

US-International freight will grow 3.4% per year

(= 107% cumulative increase)

Implication:We’ll need a good deal more freight handling capacity

* Source: FHWA, Office of Freight Management & Operations, July 2001.

slide5

The Freight Sector Is Also Changing Rapidly:

Demand Side Changes(Market Evolution):

Advances in real time, high capacity information technology have encouraged/opened the way for:

-- Rapid growth in e-commerce

-- Growing demand for just-in-time delivery services

(transfers of costs up the supply chain) and a shift of emphasis

towards demand-driven supply chains

-- An increasingly global marketplace for low cost goods delivery

slide6

Transport

System

Inventory

“PULL”

METHODS OF

CONTROL

(relative

importance)

Information

System

Source: Based on a U.S.Department of Transportation,

Secretary’s Office of Intermodalism

Presentation

Trend Towards Customer (Demand) Driven Logistics Systems

Information

System

Transport System

“PUSH”

METHODS OF

CONTROL

(relative

importance)

Inventory

5

slide7

Supply Side Changes :

Some trends in freight handling and storage:

-- A growing interest in intermodal and containerized forms of transportation.

-- The design and use of larger, more cost-effective vehicles/vessels

-- The emergence of large consolidation/break-bulk facilities and ”freight villages”

-- Interest in/emergence ofhigh volume freight corridors.

The emergence of new business relationships:

-- The development of enterprise-wide, integrated, multi-step product supply chains.

-- The emergence of freight intermediaries, including large 3PLs & (global) 4PLs

slide8

Implication : To understand trends and policy options in the freight sector we must understand the “SOUP to NUTS” of freight transportation logistics.To do this we need to:

1) Treat transportation as part of a broader, and increasingly global logistics exercise

2) Recognize that “ON-TIME IS MONEY” and that reliability of service is now a very high priority with many shippers and receivers

3) Develop a better understanding of freight economies of scale

4) Develop sufficiently comprehensive analytic frameworks for modeling/simulating sustainable freight transport solutions.

slide10

I-O Interface

Databases

(Static and Dynamic)

Freight Traffic

Simulator (FTS)

Real-time Information

Simulator (RTIS)

Major Components of the Regional Goods Movement Simulator

Supply Chain Decision

Making Simulator

(SSDMS)

Physical Transportation

Network

Multilevel Logistical/Financial/

Informational

Network

slide11

Transaction cost

information

Raw material sources

Retail Markets

Distribution centers

Plant

Demand or order

information

Financial

Network

Raw material sources

Retail Markets

Plant

Travel time

information

Logistical

(Product Supply

Chain)

Network

Unexpected

issues

information

Information

Network

Physical Transportation Network

Two-way information exchanges between specific decision-makers

Supply Chain -Transportation Supernetwork Representation

slide12

I-O Interface

Databases

(Static and Dynamic)

Real-time Information

Simulator (RTIS)

Freight Traffic Simulator

Supply Chain Decision

Making Simulator

(SSDMS)

Freight Traffic

Simulator (FTS)

Physical Transportation

Network

Multilevel Logistical/Financial/

Informational

Network

slide14

m

1

i

Tier 1:

i = 1…m firms

(manufacturing plants)

j

n

1

Tier 2:

j = 1…n retailers

o

k

1

Tier 3:

k =1 …o demand markets

Three-Tier Supply Chain Representation Used

in Model Development

slide15

Financial Network

Flows are information on

prices and movements

(bi-directional)

p11

p1i

p1m

m

1

i

Logistical Network

m

j

n

1

i

Informational

Network

1

p2n

q11

qmn

j

n

1

o

1

k

p3o

p31

qno

1

o

k

Flows are prices (bottom-up,

market driven payments)

Flows are commodity movements

(top-down, supply driven)

Multilevel Network Structure of the Supply Chain Decision Making Simulator

* From: Nagurney, Ke, Cruz, Hancock & Southworth, 2001,“Dynamics of Supply Chains:

A Multilevel (Logistical/Informational/Financial) Network Perspective”

slide16

This Multilevel, Dynamic Supply Chain System has now been:

  • Formulated as a complex network systems problem (based on
  • Nagurney and Dong, 2000)
  • Formulated as a dynamical system with a set of behavioral rules
  • that focus on the dis-equilibrium aspects of supply chains
  • under competition.
  • Translated into a variational inequality problem with a
  • unique and stable equilibrium solution
  • Solved algorithmically using an iterative, discrete time adjustment process (based on the scheme in Dupuis & Nagurney,1993)
  • Made operational as a FORTRAN program
slide17

Supply Chain Simulator -- System Costs

Firms (producers) have production costs and transaction (with retailer) costs

Retailers have commodity purchase costs (from producers), transaction costs (with both producers and consumers) and product handling and storage costs

Consumers (market demand) have purchase costs plus transaction

(with retailer) costs.

Note Bene:“Transaction costs”can be quite general, and include transportation, financial, and information gathering costs.

slide18

Supply Chain Simulator -- Behavioral Rules

  • Producers and retailers are profit maximizers. Consumers are cost minimizers. The commodity is homogeneous.
  • The systemtends towardsa spatial equilibrium of prices and

commodity flows. ( Samuelson, 1953; Takayama and Judge, 1971; Nagurney, 1999)

  • It is assumed that a fair price for producing firms to charge for a commodity = the marginal costs of production + transaction costs.
  • At equilibrium, commodity flows occur between a producer- retailer pair if the marginal cost of production plus the marginal cost of transaction and handling is equal to the price of the commodity at the retail outlet. If marginal cost exceeds price, no shipments occur.
  • At equilibrium, the volume purchased from retailers exactly equals the demand at that product market. For shipments to occur the price paid at market must equal each retailer’s marginal production + transaction costs.
slide19

Supply Chain Simulator -- System Dynamics

  • Consumer demands drive the supply chain (based on market demand functions)
  • If a retailer’s price plus transaction costs exceeds a market’s willingness to pay, the volume of goods moved between that retailer-demand market pair decreases. If the retailer’s price is below willingness to pay the volume of goods moved increases in relation to this difference.
  • If demand at a specific market location exceeds existing retail supply, then the price consumers are willing to pay at that location increases in relation to the size of this unmet demand.
  • Prices charged at retail locations reflect both market demand conditions and producer supply conditions
  • The volume of a commodity shipped between a producing firm and a retailer evolves according to the difference between the retailer’s charged price and its marginal costs.These costs include transaction costs and the price charged for the commodity by the producing firm.
slide20

I-O Interface

Databases

(Static and Dynamic)

Real-time Information

Simulator (RTIS)

Freight Traffic Simulator

Supply Chain Decision

Making Simulator

(SSDMS)

Freight Traffic

Simulator (FTS)

Physical Transportation

Network

Multilevel Logistical/Financial/

Informational

Network

slide21

Freight Traffic Simulator

Micro-Simulation is used to assign the origin-to-destination shipment volumes estimated by the Supply Chain Simulator to the physical transportation network.

  • Complete cargo movements from production point to final consumption point

are to be modeled.

  • This may involve different modes at different stages in the physical supply

chain. These movements are simulated over the ORNL multi-modal

freight transportation network (Southworth & Peterson, 2000).

  • Congestion-induced delay costs will be modeled on each link along a route,

including congestion at intermodal terminals. These will include the economic

cost of highly variable day-to-day travel times ( as a “service reliability” cost).

  • Transportation cost calculations will eventually require vehicle/container type

and cargo size as well as type of carriage (for-hire vs. private) to be modeled.

slide22

Principal Steps in the Complete Freight Traffic Micro-Simulator

(under construction)

slide24

The ORNL Trans-Oceanic Waterways Network

This network is functionally linked to the ORNL Highway-Rail-Inland and Coastal Waterways Network

database to allow routing of foreign imported and exported freight, including US Land-Bridge Traffic.

slide26

transfer

terminal

transfer

terminal

local

terminal

access road

rail line haul

Railroad #2

Railroad #1

interline

highway network link(s)

notional local access link

to highway network

origin

destination

Route Impedance = modal line-haul travel costs

+ intra-terminal transfer costs

+ inter-carrier (interlining) costs

+ local network access and egress costs

+ network-to-terminal local access costs

local rail

spur line

slide27

I-O Interface

Databases

(Static and Dynamic)

Freight Traffic Simulator

Supply Chain Decision

Making Simulator

(SSDMS)

Freight Traffic

Simulator (FTS)

Physical Transportation

Network

Multilevel Logistical/Financial/

Informational

Network

Real-time Information

Simulator (RTIS)

slide28

Useful Applications of the Simulator Include Explorations of :

1)The benefits of more accurate and timely information on:

---- at-market commodity prices

---- the pattern of freight flows

---- fuel consumption and related pollutants production

---- profitability, and longer term facility (re)locations

2) The benefits of alternative forms of supply chain, including:

---- the use of mixed, multiple level business connections between firms

in different network tiers (e.g.direct producer-to-consumer

purchases and deliveries, as well as transactions through intermediaries).

3)The effects of traffic congestion (and the value of its avoidance) on:

---- at-market commodity prices

---- the pattern of freight flows

---- mode choice

---- fuel consumption and related pollutants production

---- profitability, and longer term facility (re)locations

4)The functional links between different supply chain configurations and different network/terminal configurations.