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
a higher level
solutions required involvement at
 Tied transportation plans to environmental
planning
►Transportation
plans could not contribute to the
degradation of air quality
Transportation and Land Development
Cycle
Increased Traffic
Generation
Increased Traffic
Conflict
Deterioration in
Level-of-Service
Land Use Change
Arterial Improvements
Increased Land Value
Increased Accessibility
Street Classification
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
2
3
1
4
5
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
T = f (landuse, socialfactors, demographics)
T = a + b1 c1 + b2 c 2 + b3 c 3 + b4 c 4 +
c1
c2
c3
c4
Urban Transportation Model
System
► Trip
Distribution
 “Where do they go?”
 Links origins and destinations
many from zone ‘a’ goes to all other zones?
►how many to zone ‘a’ comes from all other zones
►how
 Dependent upon:
►attractiveness
of zone
►“friction”, or difficulty of travel
Simple Gravity Model
Pi Pj
I ij = k b
dij
Tobler’s First Law of Geography: Everything is related to everything else,
but near things are more related than distant things.
Intervening Opportunities
æaj ö
tij = k ç
÷
è vj ø
tij
# of trips
aj
# of opportunities at destination
vj
# of intervening opportunities
k
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
( Y)
U (T,C,Y ) = - T - 5 C
Variable Meaning
Mode
Time
Cost
T
Travel Time (in hours)
Drive
0.50
2.00
C
Travel Cost (in dollars)
Carpool
0.75
1.00
Y
Annual Income (in 000’s)
Bus
1.00
.75
Mode
Drive
Carpool
Bus
Y=40
Y=10
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)
►A
►D
 Free Flow
 High Density Flow
► Freedom
of Choice
►B
 Stable Flow (I)
► Choice
others
slightly affected by
►C
 Stable Flow (II)
► Choice
significantly affected
by others
► 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
the consequences of alternatives
► Using UTMS predictions as inputs to
estimate:
► Assessing





construction and operating costs
energy consumption
air quality
noise levels
accident rates
Further Readings/Review
► Transportation
► Impact
Models
Models