A.
Whenever a proposed project will generate 100 new
vehicle trips in the peak direction (inbound or outbound) during the
site peak traffic hour, the applicant shall perform a traffic impact
study. Based on this study, certain improvements may be identified
to provide safe and efficient access to the development.
B.
In addition, a traffic impact study shall be prepared
whenever either one of the following conditions exist within the impact
study area:
(1)
Current traffic problems exist in the local area,
such as a high-accident location, confusing intersection or a congested
intersection which directly affects access to the development.
(2)
The ability of the existing roadway system to handle
increased traffic or the feasibility of improving the roadway system
to handle increased traffic or the feasibility of improving the roadway
system to handle increased traffic is limited.
A.
Area of traffic impact study. The traffic impact study
area shall be based on the characteristics of the surrounding area.
The intersections to be included in the study shall be adjacent to
the site or have direct impact upon the access to the site. The intersections
shall be mutually agreed upon by the municipalities in which the proposed
project is located and the traffic engineer preparing the study.
B.
Preparation by transportation engineer required. Traffic
impact studies shall be prepared under the supervision of qualified
and experienced transportation engineers with specific training in
traffic and transportation engineering and at least two years of experience
related to preparing traffic studies for existing or proposed developments.
C.
Horizon year. The traffic forecasts shall be prepared
for the anticipated opening year of the development, assuming full
buildout and occupancy. This year shall be referred to as the "horizon
year" in the remainder of this chapter.
D.
Non-site traffic estimates. Estimates of non-site
traffic shall be made and will consist of through traffic and traffic
generated by all other developments within the study area for which
preliminary or final plans have been approved. Non-site traffic may
be estimated using any one of the following three methods: buildup
technique, area transportation plan data or modeled volumes, and trends
or growth rates.
E.
Trip generation rates required. The traffic impact
study report shall include a table showing the categories and quantities
of land uses, with the corresponding trip generation rates or equations
(with justification for selection of one or the other) and resulting
number of trips. The trip generation rates used must be either from
the latest edition of Trip Generation by ITE or from a local study
of corresponding land uses and quantities. All sources must be referenced
in the study.
F.
Consideration of pass-by trips. If pass-by trips or
shared trips are a major consideration for the land use in question,
studies and interviews at similar land uses must be conducted or referenced.
G.
Rate sums. Any significant difference between the
sums of single-use rates and proposed mixed-use estimates must be
justified in the study report.
H.
Explanations required. The reasoning and data used
in developing a trip generation rate for special/unusual generators
must be justified and explained in the report.
I.
Definition of influence area. Prior to trip distribution
of site-generated trips, an influence area must be defined which contains
80% or more of the trip ends that will be attracted to the development.
A market study can be used to establish the limits of an influence
area, if available. If no market study is available, an influence
area should be estimated based on a reasonable documented estimate.
The influence area can also be based on a reasonable maximum convenient
travel time to the site or delineating area boundaries based on locations
of competing developments. Other methods such as using trip data from
an existing development with similar characteristics or using an existing
origin-destination survey of trips within the area can be used in
place of the influence area to delineate the boundaries of the impact.
J.
Estimates of trip distribution required.
(2)
Whichever method is used, trip distribution must be
estimated and analyzed for the horizon year. A multi-use development
may require more than one distribution and coinciding assignment for
each phase (for example, residential and retail phases on the same
site). Consideration must also be given to whether inbound and outbound
trips will have similar distribution.
K.
Trip assignments.
(1)
Assignments must be made considering logical routings,
available roadway capacities, left turns at critical intersections
and projected (and perceived) minimum travel times. In addition, multiple
paths should often be assigned between origins and destinations to
achieve realistic estimates rather than assigning all of the trips
to the route with the shortest travel time. The assignments must be
carried through the external site access points and in large projects
(those producing 500 or more additional peak direction trips to or
from the site during the development's peak hour) through the internal
roadways. When the site has more than one access driveway, logical
routing and possibly multiple paths should be used to obtain realistic
driveway volumes. The assignment should reflect conditions at the
time of the analysis. Assignments can be accomplished either manually
or with applicable computer models.
(2)
If a thorough analysis is required to account for
pass-by trips, the following procedure should be used:
(3)
Upon completion of the initial site traffic assignment,
the results should be reviewed to see if the volumes appear logical
given characteristics of the road system and trip distribution. Adjustments
should be made if the initial results do not appear to be logical
or reasonable.
L.
Total traffic impacts. Traffic estimates for any site
with current traffic activity must reflect not only new traffic associated
with the site's redevelopment, but also the trips subtracted from
the traffic stream because of the removal of a land use. The traffic
impact report should clearly depict the total traffic estimate and
its components.
M.
Capacity analysis.
(1)
Capacity analysis must be performed at each of the
major street and project site access intersection locations (signalized
and unsignalized) within the study area. In addition, analyses must
be completed for roadway segments deemed sensitive to site traffic
within the study area. These may include such segments as weaving
sections, ramps, internal site roadways, parking facility access points
and reservoirs for vehicles queuing off site and on site. Other locations
may be deemed appropriate depending on the situation.
(2)
The recommended level-of-service analysis procedures
detailed in the most recent edition of the Highway Capacity Manual
must be followed. The Commission considers the overall level-of-service
ratings A, B, C and D to be acceptable for signalized intersections
(levels C or better are considered desirable); level-of-service E
or F is considered to be unacceptable.
(3)
The operational analyses in the Highway Capacity Manual
should be used for analyzing existing conditions, traffic impacts,
access requirements or other future conditions for which traffic,
geometric and control parameters can be established.
N.
Required levels of service. The recommendations of
the traffic impact study shall provide safe and efficient movement
of traffic to and from and within and past the proposed development,
while minimizing the impact to non-site trips. The current levels
of service must be maintained if they are C or D, not be allowed to
deteriorate to worse than C if they are currently A or B and be improved
to D if they are E or F.
O.
Documentation required. A traffic impact study report
shall be prepared to document the purpose, procedures, findings, conclusions
and recommendations of the study.
(1)
The documentation for a traffic impact study shall
include, at a minimum:
(a)
Study purpose and objectives.
(b)
Description of the site and study area.
(c)
Existing conditions in the area of the development.
(d)
Recorded or approved nearby development.
(e)
Trip generation, trip distribution and modal
split.
(f)
Projected future traffic volumes.
(g)
An assessment of the change in roadway operating
conditions resulting from the development traffic.
(h)
Recommendations for site access and transportation
improvements needed to maintain traffic flow to, from within and past
the site at an acceptable and safe level of service.
(2)
The analysis shall be presented in a straight forward
and logical sequence. It shall lead the reader step by step through
the various stages of the process and resulting conclusions and recommendations.
(3)
The recommendations shall specify the time period
within which the improvements should be made (particularly if the
improvements are associated with various phases of the development
construction) and any monitoring of operating conditions and improvements
that may be required.
(4)
Data shall be presented in tables, graphs, maps and
diagrams wherever possible for clarity and ease of review.
(5)
To facilitate examination by the Planning Commission,
an executive summary of one or two pages shall be provided, concisely
summarizing the purpose, conclusions and recommendations.
(6)
The report documentation outlined above provides a
framework for site traffic access/impact study reports. Some studies
will be easily documented using this outline. However, the specific
issues to be addressed, local study requirements and the study results
may warrant additional sections.
A.
Responsibility for improvements. The applicant shall
be responsible for the improvements required to provide safe and convenient
ingress and egress to the development site.
B.
Coordination with municipal requirements. The applicant
shall be responsible for other improvements as may be agreed to with
the affected municipality or which are required by any municipal impact
fee ordinance to be installed or paid for by the applicant consistent
with provisions of Article V-A of the Pennsylvania Municipalities
Planning Code, Act 247 of 1968, as amended.
