Lec 20, Ch.11: Transportation Planning
Process (objectives)
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Understand how decisions to build
transportation facilities are made
Understand basic elements of the
transportation planning process
Understand basic elements of travel
forecasting (This topic will be discussed in detail in
CE565, winter semester. CE361 is the only prerequisite
for CE565 according to the course catalog, but I
recommend you to take CE370 (old) or CE470 (new)
before you enroll in CE565.)
What we cover in class today…
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Basic elements of transportation planning
(This concept applies to any transportation
planning including urban transportation
planning, pp.509-514)
Urban transportation forecasting process
Four-step travel demand forecasting – A
general introduction
The transportation planning process
It has become “institutionalized,” meaning federal guide
guidelines, regulations, and requirements for local planning are
often driving forces behind existing planning methods. Have you
heard of MPOs (metropolitan planning organizations) like the
Mountain Land of Governments or the Wasatch Front Regional
Council? Or, have you heard of Envision Utah?
It is intended to furnish unbiased information about the effects
that the proposed transportation project will have on the
community and on its expected users.
It is intended to give the appropriate information to those who
will be responsible for deciding whether the transportation
project should go forward.
Basic elements of transportation planning
Situation definition Inventory transportation facilities, Measure travel patterns,
Review prior studies
Problem definition
Define objectives (e.g., Reduce travel time), Establish criteria
(e.g., Average delay time), Define constraints, Establish
design standards
Search for
solutions
Consider options (e.g., locations and types, structure needs,
environmental considerations)
Analysis of
performance
For each option, determine cost, traffic flow, impacts
Evaluation of
alternatives
Determine values for the criteria set for evaluation (e.g.,
benefits vs. cost, cost-effectiveness, etc)
Choice of project
Consider factors involved (e.g., goal attainability, political
judgment, environmental impact, etc.)
Specification and
construction
Once an alternative is chosen, design necessary elements of
the facility and create construction plans
Example 11-1: Planning the relocation of a rural road
(simple, yet good enough to explain the steps…)
Step 1: Situation definition:
 to understand the situation that gave rise to the perceived need
for a transportation improvement
Step 2: Problem definition
Purpose of the step: Describe the problem in terms of the
objectives to be accomplished and translate those objectives into
criteria.
Example:
Objective = Statements of purpose: Reduce traffic congestion,
Improve safety, Maximize net highway-user benefits, etc.
Criteria = Measures of effectiveness: Travel time, accident rate,
delays (interested in reductions in these MOEs)
Step 3: Search for solutions
Brainstorm
options at
this stage.
Step 4: Analysis of performance
 Estimate how each of the proposed alternatives would perform
under present and future conditions.
Step 4: (cont) Ranking of alternatives (in
terms of MOE)
Step 5: Evaluation of alternatives
 Determine how well
each alternative will
achieve the objectives
of the project as
defined by the criteria.
Improves this way
Costwise
best
Improves this way
Improvementwise superior
This is a multi-objective
evaluation problem.
Step 6: Choice of project
 Based on the alternative
evaluation in Step 5, we will
choose the best alternative for
design and eventual
construction. The best choice
may not be built because of
opposition by the people of the
community that is affected.
Step 7: Specification and construction
 Once the project has been chosen, a detailed design phase is
begun, in which each of the components of the facility is specified.
Urban transportation (demand)
forecasting process
This task is a technical effort to analyze the performance of
various alternatives. We must define the study area first. Then
further subdivide the area into traffic (analysis) zone, TAZ, for
data tabulation and analysis.
Homogeneous socioeconomic characteristics: e.g., high-income residential
Minimum intra-zonal trips
Use of physical, political, and historical boundaries, where possible
Zones, once created, should not be subdivided into smaller zones during
analysis
Zones generating and attracting approximately equal trips, households,
population, or area
Use of census tract boundaries, where possible (easier to collect data from the
Census Bureau’s publications)
Travel
demand
model
flowchart
Four basic elements of the urban
transportation forecasting process
Data collection
(population, land
use, etc.)
Economic activity (employment, sales volume, income,
etc.), land use (type, intensity), travel characteristics (trip
and traveler profile), and transportation facilities (capacity,
travel speed, etc.), population and demography, Origindestination trip data.
Analysis of existing
conditions and
calibration
Analyze the data collected in the data collection stage. You
may build mathematical models describe the existing
conditions and then use the relationships you have found
in the existing parameters to forecast future values.
Forecast of future
travel demand
4-step transportation demand forecasting process
Analysis of the
results
Analyze what you get from the 4-stop demand forecasting
process
Analysis zones for transportation study (TAZ)
Link-node map for highway system
 Link-node maps are the starting point for the 4-step
transportation demand forecasting process
4-step transportation demand forecasting
process
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Preparation: population and economic analysis
and land use analysis
Trip generation
Determines how many trips each activity (center) (residential
area, commercial area, etc) will produce or attract
Trip distribution Determines the origin or destination of trips that are
generated at a given activity
Modal split
Determines which mode of transportation will be used to
make the trip
Traffic
assignment
Determines which route on the transportation network will be
used when making the trip
Graphical way of understanding the 4-step
demand forecasting process
200 trips from
zone 46 to
zone 29
1000 trips
attracted
1000 trips
generated
70% this route
25% this route
Auto total: 95%
Public transit: 5%