LOWRY MODELPresented byK.SRIKANTH (15CE62R14)SURYA KANT SAHDEO(15CE62R15)

What is a Land Use Model?Land Use Models use economic theories and simplified

statistic methods to explain and estimate the layout of urban land uses.

Land Use Model is quantitative method to predict future changes in land use, socioeconomic and demographic data based on economic theories and social behaviours.

INTRODUCTION

Continued…

To gain a better understanding of the behaviour of urban areas, several operational transportation / land use models (TLUM) have been developed.

The reasons behind using TLUM are numerous, such as the ability to forecast future urban patterns based on a set of economic assumptions or to evaluate the potential impacts of legislations pertaining to environmental standards.

The Lowry model was one of the first transportation / land use model developed in 1964 for the Pittsburgh region.

It depicts well the relationships between transportation and land use.

Its premises were expended by several other models, known as "Lowry-type“ models.

The activities which the model defines are population , service employment and these activities correspond to residential, service and industrial land uses

LOWRY MODEL

1960s – Ira Lowry Spatial interaction model Modeling innovations

Sub-regional forecasts were generated to control to regional totals Employment, population, and transportation were combined in one model

Many variations and extension have been subsequently developed

LOWRY MODEL

Basic or Export Sector Sell their goods and services to non-locals Exogenous (Determined outside the model)

Non-basic or Residentiary or Retail Sector Sell their goods and services to locals Includes government – schools, etc. Endogenous (Determined by the model)

Household Sector Size and residential location are endogenously

determined

Sectors in Lowry Model

Basic is given (exogenous) Forecast is derived from regional projections

Retail sector Size and location are determined by size and

location of the population Household sector

Size is determined by employment opportunities (including basic and non basic)

Location is determined by accessibility, particularly to employment

SPECIFICATIONS

Basic Sector Demand for Labor

Size of Population

Demand for Non-Basic

Distribution of basic jobs across zones is givenTravel time (network) is givenModel generates population and non-basic employment by zone

Model Logic

Basic jobs by zone Transportation network: travel times between

every pair of zones (generalized cost matrix) Ratio of population to workers Ratio of service (non-basic) workers to population Friction factor (willingness to travel) Location probability matrix

Provides the basis of residential location decisions based on employment locations and travel times

Model Inputs

1) Basic job locations by zone (assumed)2) Location probability matrix residential zones

of basic workers3) # workers per zone population x zone4) Population x zone number of service jobs x

zone5) Location probability matrix residential zones

of service sector workers

Computation Sequence

Lowry Model StructureBasic Employment

by Zone - Exogenous

Residential Location of Basic

EmployeesPopulation Associated

with Non-Basic Employees

Service Workers (Non-Basic) by

Zone

Residential Location of Non-Basic Employees

Population Associated with Basic Employees

Service Workers (Non-Basic) by

ZoneResidential Location of Non-Basic Employees

Population Associated with Non-Basic

Employees

Converge to

Solution

a) The core assumption of the Lowry model assumes that regional and urban growth (or decline) is a function of the expansion (or contraction) of the basic sector. This employment is in turn having impacts on the employment of two other sectors, retail and residential.

b) It is assumed that the location of basic industry is independent of the location of residential areas and service centers.

c) Population is allocated in proportion to the population potential of each zone and service employment in proportion to market potential of each zone.

THE SALIENT FEATURES OF LOWRY MODEL

Continued..

d) The model ensures that populations located in any zones dose not violate a maximum density or holding capacity constraint is placed on each category of service employment.

e) Lowry model relates population and employment at one particular time horizon

FLOW CHART

The model can be singly constrained, that is the only constraint is the fixed location of basic employment.

It can also be doubly constrained, where the location of basic employment and housing are fixed

VARIABLES AND MODELS

The singly constrained Lowry model is solved according to these Equations:

Continued..

WTTRij and WTTSij = Willingness to travel for Residential (R) or Services (S) between zone i and j.

LPRij and LPSij = Locational probability for Residential (R) or Services (S) between zone i and j.

The Lowry model has obviously several limitations. It is notably a static model,which does not tell anything about the evolution of the transportation / land usesystem.

the model is likely the be inaccurate in the major service-oriented metropolitan areas of today where current economic changes are in the service (non-basic)sectors, forming the foundation of urban productivity and dynamics in manymetropolitan areas.

The Lowry model does not consider movements of freight in urban areas, whichare very significant and have impacts on the friction of distance

LIMITATIONS

Every model has its strengths and limitations and no model is best suited for every situation.

The selection of a land use model depends on The purpose of the modelling. Sensitivities to land use and transportation policies Data requirements and availability Modelling efforts (time, expertise and budget)

CONCLUSION

The Lowry Model Heritage by William Goldner. Dr.Jean-Paul Rodrigue,The Geography of Transport Systems,chapter-9

Methods in Transport Geography. David Levinson,Ira Lowry's LU Model. Website: http://en.wikibooks.org/wiki/Fundamentals_of_Transportation. Website: https://en.wikipedia.org/wiki/Land-

use_forecasting#Lowry_model

Reference

THANK YOU