Planning Process ► Early Transport Planning  Engineering-oriented  1944, First “ O-D ” study  Computational advances helped launch new era in planning

Planning Process ► Factors contributing to improved planning  Rapid population growth  Rapid car ownership growth  Increased mobility  More federal involvement in transportation

Planning Process ► 1963 Federal Aid Highway Act  Instituted “ 3C ” process ► Continuing ► Comprehensive ► Cooperative  Made federal funds contingent upon 3C process

Planning Process ► Feds also acted as technical assistance  Technology transfer  Manuals and guides  Creation of standards ► Planning ► Analysis ► Implementation

Planning Process ► Federal involvement expanded  What was just the Bureau of Public Roads soon became ► FHWA ► UMTA (now FTA)  More requirements ► NEPA ► TSM ► TIP

Planning Process ► Devolution in 1980s  Feds became more or less “ advisory ”  Mandates existed, but flexibility encouraged  Planning didn ’ t change, transport patterns did

Planning Process ► Federal resurgence  Recognizing regional travel patterns ► Multi-jurisdictional solutions required involvement at a higher level  Tied transportation plans to environmental planning ► Transportation plans could not contribute to the degradation of air quality

Transportation and Land Development Cycle Land Use Change Increased Traffic Generation Increased Traffic Conflict Deterioration in Level-of-Service Arterial Improvements Increased AccessibilityIncreased Land Value

Street Classification

Transportation Planning Process Pre-Analysis Phase Problem/Issue Identification Formulation of Goals and Objectives Data Collection Generation of Alternatives Technical Analysis Phase Land Use Activity System Model UTMS (or, UTPS; or UTPP) Impact Prediction Models Post Analysis Phase Evaluation of Alternatives Decision Making Implementation of Plan Monitoring

Transportation Planning Process ► Inputs  land use activity system  transportation system characteristics ► Outputs  Quantity (volume)  Quality (speed) ► U.T.M.S.  Trip Generation  Trip Distribution  Mode Choice  Trip Assignment

Inputs for UTMS ► Transportation System Characteristics  Layout of transportation network  Speed, Directionality, Turn Restrictions ► Land Use Activity System Characteristics  Region divided into “ zones ”  Each zone has its own unique characteristics ► land use ► social and economic attributes

Watauga County V/C Boone V/C

Urban Transportation Model System ► Trip Generation  “ How many trips? ”  Predicting quantity of travel to and from a piece of land  Depends on characteristics of the land ► land use type and intensity ► socioeconomic characteristics of activities using the land

Linear Regression for TG

Urban Transportation Model System ► Trip Distribution  “ Where do they go? ”  Links origins and destinations ► how many from zone ‘ a ’ goes to all other zones? ► how many to zone ‘ a ’ comes from all other zones  Dependent upon: ► attractiveness of zone ► “ friction ”, or difficulty of travel

Simple Gravity Model Tobler’s First Law of Geography: Everything is related to everything else, but near things are more related than distant things.

Intervening Opportunities # of trips # of opportunities at destination # of intervening opportunities calibrating constant

Urban Transportation Model System ► Mode Choice  “ How do they travel? ”  Predicts the share of travel by mode ► auto ► transit  Dependent upon ► cost of travel by mode ► socioeconomic characteristics

Mode Choice Model VariableMeaning TTravel Time (in hours) CTravel Cost (in dollars) YAnnual Income (in 000’s) ModeTimeCost Drive Carpool Bus ModeY=40Y=10 Drive Carpool Bus

Urban Transportation Model System ► Trip Assignment  “ By what route? ”  Predicting what parts of the network will be used to travel between origin and destination  Dependent upon: ► all alternative routes (and their attractiveness)  distance  travel time  perceived safety

Trip Assignment ► All or nothing  Find shortest path for between two zones  Load all trips on that path

Trip Assignment ► Incremental Loading (feedback)  Split total flow in to subsets (i.e, 5% samples)  Find shortest path between zones  Load first 5% of trips onto that path  Re-analyze shortest path  Load next 5% of trips onto that path  Repeat until total flow is dispensed with

Output of UTMS ► Quantity  Volume of traffic on network ► Quality  Flow of traffic on network

Volume to Capacity Ratios (V/C) ► Traffic volume compared to the capacity of a segment of the network  Different street classifications have different capacities ► v/c = 1: volume of traffic equals capacity ► v/c less than 1: capacity of street not met ► v/c greater than 1: traffic exceeds capacity

Levels of Service (LOS) Levels of Service (LOS) ► A  Free Flow ► Freedom of Choice ► B  Stable Flow (I) ► Choice slightly affected by others ► C  Stable Flow (II) ► Choice significantly affected by others ► D  High Density Flow ► Freedom to maneuver severely restricted ► E  At or Near Capacity ► Unstable operations (small changes = large effects) ► F  Breakdown Flow ► traffic approaching exceeds traffic exiting

From: Route 228 Improvement Project – Pennsylvania DOT

Impact Prediction Models ► Assessing the consequences of alternatives ► Using UTMS predictions as inputs to estimate:  construction and operating costs  energy consumption  air quality  noise levels  accident rates

Further Readings/Review ► Transportation Models Transportation Models Transportation Models ► Impact Models Impact Models Impact Models