TM 5-803-14
(c) Discover previously unknown conditions
posed on-site traffic. The principal purpose of the
and factors.
analysis is to determine the proper location and
b. Site Inventory and Evaluation. A site inven-
design of site access. Appropriate access location
tory documents all existing conditions, both on-
and design avoids: inadequate access capacity,
and off-site. It evaluates the impact they will have
congestion on site or on adjacent roadways, high
on site development. The evaluation may be sim-
accident rates, and limited potential for adjusting
ply a positive or negative assessment or may be
design or operation according to changing condi-
rated on a scale. The data collection procedures for
tions. Site access should not interfere with traffic
master planning, as described in TM 5-803-1,
movement on adjacent roadways. Inappropriate
provide a useful start for preparing site invento-
access location and design can create as many or
ries. The site survey map serves as the base map
more problems as the increase in traffic volume.
for the inventory. The information may be com-
Projects may require off-site improvements to ac-
piled on one or a series of maps, depending upon
commodate new traffic movement and additional
the size and complexity of the site. Usually, off-site
volume.
conditions are recorded on a single map at a scale
(b) Site Traffic Impact Study. A site traffic
which addresses sufficient area surrounding the
impact study should be prepared for projects lo-
cated near highly congested areas, high accident
site. On-site conditions usually require more than
locations, and sensitive neighborhoods. The need
one map. These maps often reflect a combination
for a study may also be established using the
of conditions which can be expected to affect each
following threshold: the project is anticipated to
other (e.g., soils and geology, drainage and topog-
generate 100 or more new peak direction trips to
raphy, or climate and vegetation). The overlay/
or from the site in the hour of peak traffic on the
composite method registers a series of maps to a
adjacent roadway(s). A transportation plan should
base map, allowing one map to overlay another.
be prepared for facilities which can be anticipated
This method helps visualize how various condi-
to expand and generate more than 500 peak hour
tions impact or reinforce each other.
c. Off-site Conditions. Site analysis should ex-
trips. (Peak refers to the greatest number of
vehicles moving in a specific direction and/or at a
tend beyond the project boundaries. Most off-site
certain time.) The plan should be prepared for the
conditions are related to man-made features and
horizon year (or final year of development) if the
activities. A site may be influenced by numerous
full buildout will be significantly larger. Data
factors (traffic, noise, light, visual conditions,
regarding the direction and time of peak traffic
drainage, etc.) which occur in the surrounding
flow may be available on the installation. Trip
area. Both existing and future conditions should
generation rates most often used in traffic studies
be considered. Figure 3-3 illustrates an analysis of
can be found in the report Parking Generation
off-site conditions for a candidate site for a battal-
prepared by the Institute of Transportation Engi-
ion complex.
(1) Surrounding Land Use. Surrounding land
neers. Guidance for determining trip generation
can be found in Transportation and Land Develop-
use should be recorded on the analysis of off-site
ment. Because a number of variations can occur
conditions map. It will be verified that the candi-
when developing trip generation data for a specific
date site for the proposed project is located in an
site, transportation and traffic engineers should be
appropriate land use area according to the master
consulted. If a site traffic impact study is needed,
plan. TM 5-803-8 provides further guidance on
Transportation and Land Development provides
surrounding land use.
(2) Transportation. All existing and proposed
further guidance. A minimum site traffic impact
study should include information about: trip gen-
transportation systems to and around the site will
eration and design-hour volumes, trip distribution
be evaluated for their accessibility. The primary
and traffic assignment, existing and projected traf-
and secondary roadways will be examined to deter-
fic volumes, capacity analysis, traffic accident
mine potential access points, traffic loads and
analysis, and the traffic improvement plan. Appen-
safety conditions including potential hazards. Un-
dix B provides an outline for a typical study
derutilized parking areas available for shared use
report.
will be identified. Bus routes and loading zones
(3) Utilities. All utility systems which may be
convenient to the site will be identified. Pedestrian
tapped for use will be located and their capacities
and bicycle paths which may be connected to
indicated. If an existing system is running at or
project development will be identified.
nearing its capacity, additional growth in the area
(a) Site Traffic Impact Analysis. Site traffic
may require improvements to the utility trunk
impact analysis examines existing and future off-
line beyond the immediate site. Underground pipe-
site traffic on adjacent roadways. It analyzes pro-
3-5
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