The purpose of these guidelines is to establish
criteria by which the traffic impacts of new development proposals will be
evaluated by Planning Department staff.
They define submission requirements, the need to prepare a study, study
scope and methodology, and the format of the study.
GENERAL REQUIREMENTS
§
Rezoning
§
Planned
Neighborhood Development, Planned Unit Development
§
Preliminary
Plan of Subdivision
§
Final
Subdivision (if not completed with Preliminary Subdivision)
§
Site
Plan (if not completed with Preliminary Subdivision)
Except for rezoning applications, all approvals
based on transportation adequacy shall expire after four (4) years if
subdivision has not been recorded and/or development is not substantially
underway.
Exemptions may be permitted by the Planning
Department, if it is determined that site traffic generation is anticipated to
be minimal except for irregular or seasonal events. This may include the following
types of land uses and/or events:
·
Stadium
·
Church
·
Fair
·
Festival
·
Concert (These last two actually come in as submissions??)
If the proposed zoning or
land use of a development application is not in conformance with the City’s
latest Comprehensive Plan, additional studies will be required. A trip generation study will be performed to
determine whether the development proposal will add traffic volumes above
levels anticipated in the development of the Comprehensive Plan. For those proposals, which would generate an
increase in anticipated traffic, the impact of this increase on the
Comprehensive Plan transportation network will be evaluated. Staff will determine the scope of study necessary required and, if
necessary, provide the Applicant with an electronic Synchro file of the
Comprehensive Plan Network and traffic volumes. If additions to the
Comprehensive Plan Network are required, the Applicant may be responsible for
funding a pro-rata share of these improvements.
Any study required to
address Comprehensive Plan issues will be supplemental to, and not replace, the
standard traffic impact study.
The Planning staff will notify an applicant if a traffic impact study is required and will schedule a scoping meeting with the applicant, City planning staff, County staff, and Maryland State Highway Administration (MSHA) staff as required based on the location of the project and the planned site access points.
Based on the scoping meeting, the Applicant shall
submit a standard “Scoping Agreement Form” to the planner in charge of the
development review. The information
required to be submitted shall include:
§
Size/type
of development and proposed access points
§
Conformance
with Comprehensive Plan
§
Study
Area
§
Background
developments to be included in study
§
Trip
generation/rates based on ITE guidelines
§
Directional
distribution of traffic
§
Annual
through traffic growth rates
§
Design
year (development completion) (we don’t
want to specify anything beyond build-out?)
§
Assumed
planned and programmed roadway improvements (Must be 100% funded in current
CIP)
§
Assumed
intercept trip percentages
§
Analysis
methodology, e.g. Synchro, CLV, HCS
The scoping agreement shall be signed by the
Applicant or his designee. The
agreement will be reviewed and, if acceptable, accepted, signed by the City,
and returned to the Applicant.
The following criteria will be applicable to all
traffic impact studies:
The study area for analysis will include the intersection of each site access point with a public street and extended as follows from the site access point intersection:
§
Along
public roadway in each direction to intersection with the first major
collector/arterial
§
Extend
study area in all directions to major intersections (arterial/collector or
arterial/arterial) with site impacts of > 50 peak hour trips subject to 1
mile limitation from site access point to closest signalized or unsignalized
major intersection.
The Applicant should seek
guidance from the City will notify the
Applicant regardingCity regarding whether a
signalized intersection is isolated or in a coordinated signal system.
Traffic Data
Recent traffic data, which is no more than one (1)
year old at the submission date of the Application, must
be included for all study area intersections and roadway links in excess of one
(1) mile between signalized intersections.
New counts may be requested by the City if it is determined that there
have been significant changes in the study area that would have modified
traffic patterns since the data was collected.
Typical traffic data should only be collected in 15-minute increments on
Tuesdays, Wednesdays, and Thursdays during peak periods (generally from 7-9 AM
and 4-6 PM or as directed by the City) unless higher traffic impacts are
anticipated on other days. For example,
Saturday data may be required for shopping centers and Sunday data may be
required for Churches. Current traffic
volume data at intersections and roadway links on the State Highway System may
be found at http://www.marylandroads.com/tmsreports/.
No counts should be performed from the end of the
school year through the week of Labor Day – exceptions may be allowed based on
study area, development use, and/or approval of seasonal factors. In addition, traffic data should not be
collected during the following time frames:
§
December
15 to the week which includes New Year’s Day
§
The
day before, day of, or day after a holiday unless dictated by development use
§
School
holidays or late opening/early closing
§
When
traffic patterns are influenced by an accident, road closure, inclement
weather, or other event
Other Traffic Study Data
The Applicant’s traffic study shouldshall also include the following data, or sufficient
justification for its omission:
§
Existing
traffic control devices, geometrics, and lane use designations
§
Existing
speed limits
§
Lengths
of existing turn lanes
§
Sight
distance measurements at driveways and unsignalized intersections
§
Determination
of 85th percentile speeds
§
Turning
radius into and out of the proposed development
§
Trip
generation and distribution of site generated traffic and background traffic
§
Pass-by
trips to be computed in accordance with ITE criteria
§
Annual
growth in thru traffic – compounded from traffic count date to design year
§
Estimated
build-out year of the proposed development.
§
City
to provide background (pipeline)development data to applicant
§
City
to provide Synchro file for study area
§
Identify
any access control restrictions
§
Existing
signal timing from City or SHA – any deviations must be justified.
§
Programmed
roadway improvements that are 100% funded for construction in the current City
or State CIP.
The applicant’s traffic study shall evaluate
existing, background, and total future traffic conditions. Background traffic shall include existing
traffic plus growth in through traffic (compounded percentage based on
historical data) plus traffic generated from background developments. The total traffic conditions should reflect
the addition of the background traffic volumes and trips generated by the
site. The design year of the study
shall be the build out year of the development or three (3) years from the
collection date of the traffic volume data, whichever occurs later.
METHODOLOGIES
The ability of the roadway network to accommodate
projected traffic volumes generated by the proposed development must be
assessed utilizing the appropriate techniques to measure capacity and level of
service (LOS). A description of levels
of service is included in the latest edition of the 2000 Highway Capacity Manual. The techniques selected to measure capacity
and determine corresponding levels of service will depend on the nature of the
study area and the facilities under study.
The methodologies that are identified for analyzing
the transportation network are considered to be best suited to the needs of the
Planning Board and its staff in applying County City policy. Any proposed departure from these methods
must be discussed with staff during the scoping process and prior to inclusion
in a traffic study.
An isolated
signalized intersection is defined as an intersection that is not part of a
coordinated signal system nor is its timing referenced to any other
signal. For isolated signalized
intersections, the Critical Lane Procedure (similar to the planning analysis
method from the Highway Capacity Manual, Chapter 16 Appendix) should be used to
measure the level of service. Critical
lane volume analysis is a broad evaluation of the capacity and LOS of a
signalized intersection for a given set of demand volumes and geometrics. The advantage of the technique is that it is
simple and easy to use. Appendix A herewith provides a
description of the Critical Lane Procedure, and includes a sample worksheet for
reference.
When the sum
of critical lane volumes exceeds 1400, additional analysis will be
required. The intersection(s) shall be
re-analyzed using the Highway Capacity Manual operational methodology (Chapter
16) using existing signal timing and phasing.
This analysis may be performed using Synchro to obtain the Highway
Capacity Manual Level of Service (NOT SYNCHRO LOS).
Coordinated
Signalized Intersections (Corridors)
Coordinated
signals along a corridor may be included in a computerized signal system or
their timings may be manually coordinated.
In either instance, the timing and phasing of a coordinated signal is
interrelated to the settings of nearby signals.
To evaluate
coordinated signals, the City will provide an electronic file including the
portion of the City’s Synchro network applicable to the subject study. This file will constitute the base network
for the traffic study. No changes to signal timings/phasing from those included
in the City’s Synchro model shall be made without the approval of the City and
the responsible operating agency.
For each
intersection in the corridor network, the following results from the Synchro
evaluation shall be documented:
§
Highway Capacity
Manual LOS
§
Overall
Intersection Delay
§
Approach Delays
§
Queue lengths (95th
percentile) for each intersection movement
The
Synchro and Highway Capacity Manual procedures do not take into account that the operation of a
study intersection may be affected by spillover congestion from nearby
intersection or intersections. Nor do
the methodologies detect and adjust for the impacts of turn-pocket overflows on
through traffic and intersection operation.
SimTraffic, however, analyzes the cumulative effects of corridor traffic
movements. To account for these
situations, SimTraffic simulations shall be performed whenever any of the
following results occur at an intersection from the Synchro evaluation:
§
Overall
Intersection Delay > 50 seconds
§
Queue
length for a movement exceeds the available storage length
Measures of
Effectiveness (MOE’s) that contribute to operational characteristics of the
corridor should include the following parameters obtained from SimTraffic:
§
Queue lengths
§
Intersection delays
§
Corridor delays
In areas where a significant portion of the traffic
generated by the proposed development must utilize a two or four-way stop controlled
unsignalized intersection, the procedures identified in Chapter 17 of the Highway Capacity Manual should be
employed.
When average vehicle delay for a turning movement
exceeds 50 seconds, additional studies should be conducted to determine potential
means to correct the deficiency. The
type of study deemed appropriate should be determined in consultation with
staff. If a traffic signal warrant
study is deemed appropriate, the warrant study must be conducted in accordance
with the requirements of the MUTCD , MSHA, and /or the City and
submitted with the traffic impact study.
When an intersection is proposed to be signalized in the traffic study,
the intersection should be analyzed under the CLV procedure to ensure that
further physical improvements to the intersection beyond the signalization are
not needed to achieve adequacy. If,
however, a proposed new signal would be coordinated with existing signals, then
the analysis shall include the procedure described for coordinated signals
utilizing Synchro and/or SimTraffic.
When the distance between signals is less than two
miles the intersections in the study area will generally control the flow of
traffic. However, when a proposed
development impacts a roadway segment (link) when the distance between traffic
signals is two miles or greater, link volumes should be analyzed when requested
by staff. In such cases the procedures
outlined in Chapters 20 and 21 of the Highway
Capacity Manual should be utilized.
The proposed standards for determining adequacy of
transportation facilities are listed below.
THESE STANDARDS ARE SUBJECT TO APPROVAL OF THE MAYOR AND BOARD OF
ALDERMEN
Transportation facilities are deemed to be adequate
if the following standards are met:
Isolated Signalized Intersections:
§
Level
of Service D/E
§
CLV
[ 1472
§
HCM
intersection V/C [ 0.92
Coordinated Signalized Intersections (Corridors):
(All standards must be met)
§
All
Intersections Level of Service E or better
§
All
Overall Intersection Delays [ 60 seconds
§
SimTraffic
queue lengths (95th percentile) [ storage lengths
§
All
movements Level of Service E or better (delays [ 50 sec)
§
Sight
distance (stopping and intersection) meets AASHTO criteria for 85th
percentile speeds
§
V/C
ratio [ 0.92
Mitigation of traffic impacts is required when
transportation adequacy standards are not met for full buildout or intermediate
stages of a proposed development. It is
recognized that a specific development proposal may not, in itself, create an
inadequacy, but that an inadequacy would exist regardless of whether the
property were to be developed. The
mitigation criteria takes prevailing conditions into account when assessing the
required level of mitigation.
§
If
background conditions are inadequate, then mitigation must either provide
adequacy or mitigate 120% of the development’s impact on levels of service
(critical lane volume or v/c ratio) and/or overall intersection delays
§
All
sight distance inadequacies at unsignalized intersections must be addressed
regardless of whether these conditions exist prior to consideration of the
subject development
When a traffic study identifies an inadequate
condition(s) within the study area, the applicant may choose to recommend any
action, which would result in adequate operations per the prescribed. Such action(s) can consist of physical improvements, which
add capacity to the transportation system or programs to enhance operational
efficiency or to reduce
trip generation.
Physical improvements could include roadway widening, intersection geometric improvements, or signalization improvements. The design and construction of any recommended improvement must receive the concurrence of the appropriate State or City operating agency. The design policies and standards of the agency, including provision of sidewalks, trails, and bike lanes adjacent to the roadway or intersection improvements and maintained within the agency’s right-of-way or easements, shall apply to applicants or their heirs, successor or assigns who propose to construct the improvements under permit to the agency.
There are cases when the analysis indicates that an
improved LOS could be achieved by changing the timing or phasing of an existing
signal or re-striping the approach to an intersection. The approval of the appropriate operating
agency must be obtained by the applicant before such a change will be
considered in any staff recommendation.
Larger developments may be developed in stages so
that any necessary transportation improvements may also be staged. Each stage of development must, however,
demonstrate adequacy.
An applicant may propose trip reduction measures
such as car or vanpooling. However,
such a program must be supported by an agreement that this program would be
independently monitored at the applicant’s expense. In addition, the Applicant should post a bond to cover full
roadway improvements should the trip reduction program not be successful. If after a predefined level of development,
say 50%, the anticipated reduction in trips has not been accomplished, then the
Applicant’s bond will be redeemed to provide road improvements.The
projected potential of physical improvements or trip reduction actions to
reduce anticipated traffic impacts will be evaluated as part of the review of
submitted traffic studies. Applicants
are encouraged to discuss potential actions with staff prior to submittal. The traffic study should recommend
improvements only after potential traffic impacts of the proposed development
(without considering physical improvements or trip reduction actions) have been
determined. The Applicant should
provide analysis results including the proposed mitigation measures, based on
the methodology that applies to the intersection or roadway segment
All traffic studies must be
submitted a minimum of 60 calendar days in advance of an anticipated hearing
date. The study shall be signed and sealed,
on the inside title page, by a Maryland Registered
Professional Engineer
with specific contact information.
Traffic studies must include all relevant information, as indicated in
the Study Requirements and methodologies sections of the Guidelines, for staff
to review the study in accordance with the Guidelines. The study shall include Appendices showing
the approved scoping agreement, raw traffic counts and all level of service
computation worksheets. All input
assumptions must clearly be seen on computerized worksheets. The receipt of a study does not in any way deem it
to be accepted. Any study deemed judged to provide
incomplete information will be returned to the Applicant within 5 ten (10) business days of its receipt. (Is this long
enough? Do we get to things that
quickly? If we say this, then failure to return it in that time period may
imply acceptance). The “review
clock” will be frozen until an acceptable study is re-submitted.
GLOSSARY OF TERMS USED IN
THE GUIDELINES
|
Access Controls |
Regulations by which access to a road facility
from individual driveways, minor streets or major streets may be limited for
the purpose of increasing roadway capacity and improving safety |
|
Arterial |
A roadway for through traffic with partial control
of access linking major traffic generators and communities to regional
highway facilities |
|
Intersection |
The location at which two roadways cross and join
at the same vertical elevation; access through the intersection may be
controlled by traffic signals or stop/yield signs |
|
Average Daily Traffic (ADT) |
The total traffic volume passing a point or
segment of a roadway in both directions during an average 24-hour period |
|
Background Traffic |
In a traffic analysis, current traffic in
accordance with recent traffic counts plus traffic generated by pipeline
development plus growth in through traffic, on the current road network plus
all roadway improvements which are fully funded by the State, the City or
another party |
|
Capacity |
On a roadway link, the maximum number of vehicles
which can pass a given point during one hour under prevailing roadway and
traffic conditions |
|
Collector |
A roadway with no control of access linking
residential communities with the arterial system |
|
Critical Lane Volume (CLV) |
At an intersection, the sum of the critical
movements in the north-south direction and the east-west direction |
|
Critical Movement |