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Title:
:
traffic .
ꐤ
Type:
:
Civil Engineering .
Evaluation of Alternatives
This phase of the process is similar in concept to what was described earlier but can be complex in practice because of the
conflicting objectives and diverse groups that will be affected by an urban transportation project.
ꥐ
鐢
Among the groups that could be affected are the traveling public (user) ;
( ꗨ )
the highway or transit agencies (operator), and the nontraveling public (community).
( ) (
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Each of these groups will have different objectives and viewpoints concerning how well the system performs.
읖 鐢
the traveling public wants to improve speed, safety, and comfort;
䤨
the transportation agency wishes to minimize cost ;
and the community wants to preserve its lifestyle and minimize any adverse impacts.
the purpose of the evaluation process is to identify feasible alternatives in terms of cost and traffic capacity, to estimate the effects of
each alternatives in terms of the objectives expressed , and to assist in identifying those alternatives that will serve the traveling
public and be acceptable to the community.
鐢 ꐤ
Choice of project .
Selection of a project will be based on a process that will ultimately involve elected officials and the public.
Quite often funds to build an urban transportation project , such as a subway system , may involve a public referendum.
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In other cases , a vote by a state legislature may be required before funds are committed
좪
A multiyear program will then be produced that outlines the projects to be carried out over the next 20 years.
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With approval in hand , the project can proceed to the specification and construction phase
Forecasting travel .
To accomplish the objectives and the tasks of the urban transportation planning process , a technical effort referred to as the urban
transportation forecasting process is carried out to analyze the performance of various alternatives .
鐢
㛐
There are for basic elements and related tasks in the process , as illustrated in figure 11.7
ꤢ
.
These are (1) data collection (or inventories) , (2) analysis of existing conditions and calibration of forecasting techniques , (3)
forecast of future travel demand , and (4) analysis of the results .
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These elements and related tasks are described in the following sections.
Defining the Study Area .
Prior to collecting and summarizing the data , it is usually necessary to delineate the study area boundaries and to further subdivide
the area into traffic zones for data tabulation and analysis .
ꐤ ()
the selection of these zones is based on the following criteria
Socioeconomic characteristics should be homogeneous .
Intrazonal trips should be minimized
Physical , political , and historical boundaries should be utilized where possible
()
Zones should not be created within other zones the zone system should generate and attract approximately equal trips , households ,
population , or area
Zones should use census tract boundaries where possible .
ꗨ ()
An illustration of analysis zones for a transportation study is shown in
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