A.
General.
(1)
This chapter presents criteria and guidelines for the design of roads,
streets, driveways, and off-street parking lots. The criteria and
guidelines have been developed considering the intended role of the
street in relation to service function, land use, traffic demand,
quality of service, vehicular and pedestrian safety, economy, and
the environment.
(2)
Tables 2.01.01 and 2.01.02 (Appendix A) give a summary of the basic design criteria which are developed in this chapter.[1]
[1]
Editor's Note: These tables are included as an attachment to this chapter.
B.
Continuity of typical section. When a road is constructed in segments
at various times or traverses varying zoning districts, the County
may require certain design features (e.g., curb type, paving width,
etc.) not otherwise required by this manual or may waive these design
features in order to provide continuity of the typical section.
The three principal values controlling design of roads and streets
are average daily traffic volume (ADT), design speed, and design vehicle.
These values form the basis for the selection of the geometric elements
that are required to accommodate the anticipated traffic at a desired
quality of service.
A.
Average daily traffic volume (ADT).
B.
Design speed.
(1)
Design speed is the maximum safe speed that can be maintained over
a given section of road when the traffic volume is so low that the
geometrics of the roadway control speed. All elements should be in
balance consistent with a specified design speed. Stopping sight distance,
horizontal and vertical alignment, and superelevation are among the
roadway elements which are controlled by design speed. The minimum
design values for the various elements required for a given design
speed should be used only where controls such as topography and property
damages dictate their use. On local and minor collector residential
streets it is desirable to keep speeds low, and care must be exercised
that the design does not encourage high speeds without sacrificing
any of the design standards included herein. Speed control measures
shall be incorporated into the design of all residential local and
minor collector roads longer than 1,500 feet which are located within
the development district.
[Amended 5-12-2015 by
Bill No. 2015-03]
(2)
Unless otherwise approved by the County, the minimum design speeds listed in Tables 2.01.01 and 2.01.02 (Appendix A) shall be used for the design of roads.[1] For existing County roads whose classification is unknown
the design speed shall be the posted speed plus 10 mph.
[1]
Editor's Note: These tables are included as an attachment to this chapter.
C.
Design vehicle.
(1)
The design vehicle is the motor vehicle whose characteristics determine
such geometric elements as vertical clearance and turning radii. Vehicles
have been divided into six classes and a typical design vehicle has
been developed for each. The respective design vehicles have dimensions
and a minimum turning radius larger than those of almost all vehicles
in the respective classes.
(3)
Dimensions and turning characteristics of each design vehicle are
contained in Reference 1.[2]
[2]
Editor's Note: See Appendix H, included as an attachment to this chapter.
(4)
Though a road must be designed to accommodate the largest vehicle
likely to use it, the selection of too large a design vehicle can
have an adverse effect, such as longer crosswalks at the intersections.
The design vehicle must be selected considering the street classification
and adjacent land uses. Its selection is subject to review and approval
by the County.
(5)
In no case shall a public road, private road or commercial/industrial
entrance be so designed that it cannot accommodate a WB-40 vehicle
and a fire truck with an inside turning radius of 35.5 feet and an
outside turning radius of 46 feet and an overhang of 2.5 feet.
A.
Introduction.
(1)
General.
(a)
All roads should be designed to take full advantage of the existing
topography and offer scenic views wherever possible.
(b)
The horizontal and vertical alignment should be designed together
to assure a smooth continuous route. Design procedures which include
the careful coordination of the vertical and horizontal alignment
will result in a safer, more aesthetic and more economical design.
The horizontal curve should be longer than the vertical curve at a
given location so that the driver can easily perceive changes in horizontal
alignment. Sharp horizontal curves should be avoided at the bottom
of long steep grades because vehicular speeds may be high, making
it difficult to travel on the curve, especially under slippery conditions.
(c)
The design for both horizontal and vertical alignment should
be such that no unexpected features are presented to the driver. A
sharp horizontal curve should not be introduced after a long stretch
of tangents and flat curves; rather, the curves should become progressively
sharper to accustom the driver to the larger centrifugal forces.
(2)
Sight distance.
(a)
Sight distance is the length of visible roadway ahead of the
driver. The two types of sight distance considered in design are stopping
(or nonpassing) sight distance and passing sight distance. Sight distance
shall be made as long as feasible, but never less than the stopping
sight distance.
(3)
Stopping sight distance.
(a)
Stopping sight distance (SSD) is the distance required for a
vehicle to stop before reaching an object in its path. It is the sum
of the distance traveled from the moment the object is first visible
to the driver to the moment the brakes are applied, and the distance
required to stop after the brakes are applied.
(b)
The equation for stopping sight distance is:
 |
|
where:
|
V
|
=
|
initial speed, mph
| |
|---|---|---|---|---|
|
F
|
=
|
coefficient of friction between tires and roadways for wet pavement
| ||
|
G
|
=
|
percent of algebraic grade divided by 100
|
(c)
Stopping sight distances on a level roadway for various design speeds are shown in Table 2.02 (Appendix A).[1]
[1]
Editor's Note: This table is included as an attachment to this chapter.
(d)
Stopping sight distance is measured between an eye height of
3.5 feet and an object height of six inches.
(4)
Passing sight distance.
(a)
Passing sight distance (PSD) is the distance required for a
vehicle to pass another before meeting an opposing vehicle which might
appear after the pass began. It is applicable only to two-lane, two-way
rural major collectors, and minor arterials.
(b)
Passing sight distance is measured between an eye height of
3.5 feet and an object height of 4.25 feet.
(c)
The minimum passing sight distance should be provided at least
once per mile.
(d)
Table 2.10 (Appendix A) contains minimum passing sight distances for various design speeds.[2]
[2]
Editor's Note: This table is included as an attachment to this chapter.
B.
Horizontal alignment.
(1)
Intersection location and spacing.
(a)
Roads should be so located that sufficient length is provided between intersections for weaving, storage, and associated land uses. The minimum intersection spacing, measured along the through roadway between the centerline of intersecting roadways, shall be as indicated in Table 2.03 (Appendix A).[3]
[3]
Editor's Note: This table is included as an attachment to this chapter.
(2)
Cul-de-sac streets and turnarounds.
(a)
The design of single access streets such as cul-de-sacs shall be as specified in Tables 2.01.01 and 2.01.02 (Appendix A).[4] Streets which are permanently designed with only one end
open to traffic shall be terminated in a cul-de-sac as shown in the
Charles County Standard Detail Manual. In the event a street will
be extended in the future under a planned project for which a preliminary
plan has been approved, a temporary "T" turnaround shall be provided
as shown in the Charles County Standard Detail Manual R/2.19.
[4]
Editor's Note: These tables are included as an attachment to this chapter.
C.
Horizontal curves.
(2)
Degree of curve, superelevation, and design speed.
(a)
The relationship between design speed, curvature and superelevation
is:
 | ||||
|
where:
| ||||
|
E
|
=
|
rate of superelevation, feet/feet
| ||
|
F
|
=
|
side friction factor
| ||
|
V
|
=
|
design speed, mph
| ||
|
R
|
=
|
radius of curve, feet
| ||
|
D
|
=
|
degree of curve
| ||
(b)
The design speed shall be as set forth in Tables 2.01.01 and 2.01.02 (Appendix A).[5]
[5]
Editor's Note: These tables are included as an attachment to this chapter.
(c)
Maximum superelevation rates are dependent upon the type of
roadway, the effect of the superelevation upon vehicles operating
at less than the design speed and drainage considerations.
(d)
Roads designed with a design speed of 50 mph and greater shall
be superelevated. The maximum superelevation rate to be used is 6%.
Two-thirds of the superelevation runoff shall be placed on the tangent
and 1/3 on the curve. Roads shall be superelevated in accordance with
AASHTO standards.
(3)
Horizontal sight distance.
(a)
Another control on horizontal alignment is the sight distance across the inside of curves. Where there are sight obstructions such as building, trees, hedges, walls, guardrail, or cut slopes, efforts shall be made to provide as long a sight distance as feasible, but never less than the stopping sight distance given in Table 2.02 (Appendix A).[6]
[6]
Editor's Note: This table is included as an attachment to this chapter.
(b)
Where there are no sight obstruction within the right-of-way,
the right-of-way line shall be used as the sight obstruction or alternately
by the inclusion of an easement on a record plat to maintain a clear
line of sight zone.
D.
General controls for horizontal alignment. In addition to the specific
criteria presented in previous sections, the following general controls
shall be utilized:
(1)
In selecting the alignment for a given design speed, use of the maximum
curvature (i.e., minimum radius) for that speed should be avoided
except where beneficial for traffic calming purposes.
[Amended 5-12-2015 by
Bill No. 2015-03]
(2)
Consideration shall be given to the alignment and its effect on running
speed. The speed at the bottom of a long downgrade, for example, will
be higher than on a level grade, and this shall be considered when
introducing a horizontal curve.
(3)
The minimum radius of horizontal curves shall be as shown in Tables 2.01.01 and 2.01.02 (Appendix A).[7]
[7]
Editor's Note: These tables are included as an attachment to this chapter.
(4)
Sharp curvature shall be avoided on long high hills. The absence
of such reference items as cut slopes, trees, and buildings makes
it difficult for the driver to judge horizontal curvature.
(5)
In compound circular curves, the radius of the flatter curve should
not be more than 1.5 times greater than the radius of the sharper
curve.
(6)
Where reverse curves are used, a minimum of 100 feet tangent shall
be provided between the curves.
(7)
Broken back curves, that is, two curves in the same direction separated
by a short tangent, should be avoided.
E.
Vertical alignment.
(1)
Vertical alignment shall be designed considering the design speed
and road classification in order to provide a balance between all
geometric elements of the road.
(2)
The two components of vertical alignment are grades and vertical
curves. Minimum grades are established to assure adequate drainage,
and maximum grades are established considering the operational characteristics
of the design vehicle. Vertical curves must be at least long enough
to provide the required stopping sight distance.
(3)
Vertical alignment is controlled by a profile grade line (PGL) shown
on the standard details.
F.
Grades.
(1)
The minimum grade for all roads and streets shall be 1.0% unless
otherwise approved by the County. Where a curbed section is used,
the spacing of inlets must be carefully studied when utilizing the
minimum grade to avoid the spreading of stormwater across the pavement.
(2)
The maximum grade in a cul-de-sac bulb shall not exceed 6%.
(3)
The maximum grade varies with road classification and is shown in Tables 2.01.01 and 2.01.02 (Appendix A).[8]
[8]
Editor's Note: These tables are included as an attachment to this chapter.
G.
Vertical curves. Minimum lengths of vertical curves are shown on Table 2.04 (Appendix A).[9]
(1)
Crest vertical curves. Crest vertical curves must be sufficiently long to provide the required stopping sight distance as listed in Table 2.02 (Appendix A).[10]
[10]
Editor's Note: This table is included as an attachment to this chapter.
(2)
Sag vertical curves. Sag vertical curves must be sufficiently long
to assure that a driver has sufficient distance in which to stop after
his headlights first reveal an object on the roadway. Minimum lengths
of sag vertical curves shall therefore be based upon a headlight sight
distance equal to the stopping sight distance.
[9]
Editor's Note: This table is included as an attachment to this chapter.
H.
General controls for vertical alignment. In addition to the specific
criteria presented in previous sections, there are a number of general
controls applicable to vertical alignment.
(1)
In selecting the vertical alignment base on a given design speed,
use of the maximum gradient and minimum length of curve for that speed
should be avoided.
(2)
The length of vertical curve shall not be less than three times the
design speed in mph.
(3)
The length of vertical curve shown in the linear profile around the
cul-de-sac bulb at the curb line for closed section roadways shall
not exceed 25 feet.
(4)
A smooth profile grade, consistent with the topography, shall be
strived for in preference to a grade with numerous breaks and short
lengths of tangent.
(5)
The profile shall be such that hidden dips hazardous to passing maneuvers
are avoided.
(6)
Short tangents of less than 50 feet between vertical curves shall
be avoided.
A.
Typical sections.
(1)
Unless otherwise approved by the County, typical paving sections for the various functional classifications are shown in Tables 2.01.01 and 2.01.02 (Appendix A).[1]
[1]
Editor's Note: These tables are included as an attachment to this chapter.
(2)
Private drives. When provided for by the Zoning Ordinance and/or
Subdivision Regulations,[2] for single-family detached residential lots, the following
conditions apply:
[Amended 1-31-2017 by Bill No. 2016-10]
(a)
Where two or more lots are proposed to be served by the same
common access easement or private right-of-way, such common access
easement or private right-of-way, shall have a minimum width of 30
feet.
(b)
Parking spaces shall not be provided within that portion of
private drives which serve two or more lots.
(c)
The responsibilities for private drive maintenance shall be
clearly stated in covenants, in a form acceptable to the Planning
Commission, which shall be filed in the land records at the time of
filing of the final plat, and a certification shall be included on
the final plat to the effect that the subdivision is subject to covenants.
(d)
For lots less than one acre in size, the drive shall be a minimum
of two inches of asphalt pavement on six inches bank run gravel base.
Curbing is not required. For lots one acre or more in size, the drive
shall be a minimum of six inches bank run gravel. Where any drive
connects with a county road, an entrance apron within the county right-of-way
shall be constructed of two inches of pavement on six inches bank
run gravel base.
(e)
The minimum width of a private drive shall be as specified in Appendix Tables 2.01.01 and 2.01.02 (Appendix A).
(f)
Private drives within a common access easement or private right-of-way
shall be constructed at the time of construction of the subdivision
and shall be constructed by the developer.
(g)
A private drive shall end with a cul-de-sac or turnaround, as
shown in the Charles County Standard Detail Manual R/2.57, for either
of the following conditions:
(3)
Way. The maximum depth of a way shall be measured from the edge of
the right-of-way line of the connecting road to the furthermost portion
of the right-of-way. A way with curb and gutter may have a curbed
or uncurbed island. A way with travel in two directions shall have
a maximum depth of 300 feet. For ways with travel in one direction
only, the maximum depth shall be 100 feet.
[Amended 1-31-2017 by Bill No. 2016-10]
(5)
Alleys shall meet the following criteria:
(a)
Layout. Alleys shall provide vehicular access to lots with frontage
on a public road or frontage on a minimum twenty-four-foot-wide private
road. Vehicular access shall be provided to both ends of an alley.
No alley shall be more than 450 feet long between intersecting alleys
or roads.
(b)
Parking. Where parking on an alley is allowed, parking spaces
shall be marked with paint striping outside the minimum travel lane
width. Where additional parking width is not provided, "No Parking"
signs shall be installed.
(c)
Sight distance. Alleys shall provide minimum stopping sight distance in accordance with Table 2.02 (Appendix A).[4]
[4]
Editor's Note: This table is included as an attachment to this chapter.
(d)
Vertical clearance. Unobstructed vertical clearance of 14 feet
shall be provided overhead of the travel lane width.
B.
Pavement widths and cross-slope. Roadway pavement widths and pavement
cross-slopes shall be as shown on the typical sections. The minimum
cross slope of cul-de-sacs from the center point to any radial portion
of the cul-de-sac bulb must be 1%.
D.
Curb and gutter.
(1)
Concrete curb and gutter shall be provided in residential subdivisions
where the average lot frontage is less than 100 feet, and in front
of all commercial and industrial lots or parcels, or where required
by the State Highway Administration for properties fronting on state
roads.
(2)
Curb and gutter shall meet the requirements of the standard details.
(3)
The following are the permitted uses of the various types of curb:
(a)
Eight-inch standard combination curb and gutter: Any street.
(b)
Modified combination curb and gutter or six-inch standard combination
curb and gutter: Local roads, and minor collector roads in residential
subdivisions.
(c)
Bituminous curb: Provide in parking lots, private drives, in areas where curbing is not specifically required under Subsection D(3)(a) above and as temporary construction, transitions for roads not built to ultimate section or to provide continuity of road section.
(d)
Standard barrier (header) concrete curb: Traffic islands, private
parking lots, and private roads.
(e)
Special designs: Granite blocks, precast curb (wheel stops),
steel curb, pressure-treated wood, monolithic curb/sidewalk, or other
alternate curbing design may be used on private parking lots and private
drives or with prior approval of the County.
E.
Shoulders. Shoulders shall be as shown on the typical sections. Paved
shoulders are required for public streets in the Development District
Residential Zones (RL, RM, RH, and RO), and in planned development
zones, including PUD and WPC zones.
F.
Medians. Medians shall be as shown on the standard details. Raised
medians six feet or less in width should have a paved surface.
G.
Pedestrian travel ways: Refer to the Charles County Standard Detail
Manual. For the design of biker paths inside the right-of-way or outside
the right-of-way, refer to the most recent AASHTO "Guide for the Development
of Bicycle Facilities." (Reference 5[5].)
(1)
Sidewalks/hiker-biker paths.
(a)
Areas normally requiring sidewalks are so indicated on the typical
sections contained in the Standard Detail Manual R/2.10 through R/2.16.1.
The minimum pedestrian walk width shall be four feet outside the urban
road standards district. Where there will be a large number of pedestrians,
such as near schools and in some commercial areas, the pedestrian
paths shall be made sufficiently wide to accommodate the anticipated
pedestrian demand. The selection of a pedestrian walk width in such
areas is subject to review and approval by the County.
(b)
Typically, a hiker-biker path will be part of a continuous,
comprehensive link, as opposed to the conventional concrete sidewalk.
Residential areas, school and open space areas, and short routes connecting
residential and employment centers typically warrant provisions for
pedestrians/bicyclists.
(c)
Hiker-biker paths shall be (a) separated from the roadway but
within the street right-of-way, or (b) within open space. The County
shall be consulted when planning a hiker-biker path within or adjacent
to a street right-of-way. When planning pedestrian travel ways, the
County shall be consulted to provide coordination between the planned
pedestrian travel ways and those in surrounding areas.
(d)
Construction of a community comprehensive pedestrian travel
way network may result in a waiver of conventional sidewalk requirements
as per the approval of the Planning Commission.
(e)
Where hiker-biker paths intersect with vehicular roadways, a
visible indicator such as road striping and/or signage should be provided
as per the most recent MUTCD standards. Access to hiker-biker paths
by motor vehicles shall be discouraged by use of physical barriers,
signage, or grade separations where practical.
(2)
Maintenance of pedestrian travel way.
(a)
Within the designated Urban Road Standards District (Appendix G),[6] if any portion of the pedestrian travel way is outside
of the right-of-way and associated easement or contains any amenities
such as street furniture, dining tables, benches, etc., then the abutting
property owner, homeowners' association (HOA) or other association
as approved by the County is responsible for maintenance of the entire
pedestrian travel way, including all amenities within. An easement
document will be executed between the adjoining property owner or
respective HOA and the County to define maintenance requirements,
installation of utilities, and public access rights.
[6]
Editor's Note: Said appendix is included as an attachment to this chapter.
(b)
Maintenance for hiker-biker paths and all sidewalks within subdivisions
which are located within the County right-of-way, both of which were
designed and constructed in accordance with the 1995 Road Ordinance
or more recent revision, shall be the responsibility of Charles County.
(c)
It is the responsibility of the abutting property owners, the
respective homeowners' association or other association as approved
by the County to remove snow and ice from the hiker-biker paths and
sidewalks.
[5]
Editor's Note: See Appendix H, included as an attachment to this chapter.
H.
Side slopes.
(1)
Side slopes for excavations and embankments should be as flat as
feasible considering earthwork and right-of-way requirements. The
normal maximum slope shall be 2:1. Where poor soil conditions exist,
soil tests and a slope stability analysis shall be conducted to determine
an acceptable slope.
(2)
All slopes shall be covered with topsoil and seeded and mulched.
I.
Guardrail.
(1)
Guardrail shall be required when combinations of embankment slope and height warrant guardrail for open sections as shown in Appendix B.[7] Wherever feasible, the embankment should be adjusted to
eliminate the need for guardrail. Where guardrail is warranted, it
shall be placed as shown on the typical sections and shall conform
to the Maryland State Highway Administration Standard Details.
[7]
Editor's Note: Said appendix is included as an attachment to this chapter.
(2)
Factors to be considered when determining the need for guardrail
at fixed roadside objects include design speed, roadway functional
classification, type of obstacle, and distance from pavement edge
to the obstacle. The determination of need for guardrail is subject
to review and approval by the County.
J.
Utility location. The locations for the placement of utilities within
the road right-of-way are shown in the Standard Details Manual R/2.20.
Where conditions are such that the use of the normal location arrangements
would be infeasible, an alternate arrangement shall be developed and
submitted to the County for review and approval. All utility owners
shall have their utility installation plans approved by the County
before any construction work is commenced.
A.
Introduction. To assure that an intersection is designed to safely
and efficiently accommodate the traffic desiring to use it, certain
procedures and analyses must be performed. This section contains the
geometric design elements applicable to intersections, the procedures
to be followed in developing the best possible design layout and the
information required on the construction drawings.
B.
Geometric design.
(1)
Skew angle and horizontal curvature.
(a)
Roadway centerlines shall intersect as closely as possible to
right angles with a maximum skew of 70° and continue through the
intersection without offset or break, unless otherwise approved by
the County.
(b)
Where the radius of the horizontal curve of a street approaching
an intersection is less than or equal to 300 feet, a tangent at least
50 feet long shall be placed between the flowline of the intersecting
street and the P.C. of the curve.
(2)
Design vehicles and turning paths. Many intersection design details, such as curb radii and island locations, depend upon the choice of the design vehicle. The larger design vehicles require larger curb radii and wider lane widths between islands than do the smaller vehicles. Selection of the design vehicle depends upon the functional classifications of the intersecting streets, adjacent land use, and volume and type of vehicles that will use the intersection. Turning paths for the various design vehicles are shown in A Policy on Geometric Design of Highways and Streets (Reference #1 of Appendix H).[1]
[1]
Editor's Note: The Annotated Code of Maryland, Article
56, was repealed by Acts 1996, c. 10, § 15, effective April
9, 1996.
(3)
Minimum curvature for turning movements. Table 2.05 (Appendix A) shows the minimum fillet radius (either curb or edge of roadway) which will permit a design vehicle to make a ninety-degree turn both with and without encroachment upon adjacent lanes.[2]
[2]
Editor's Note: This table is included as an attachment to this chapter.
C.
Auxiliary lanes/turning lanes.
(1)
General. The provision of auxiliary lanes shall be required under
any of the following conditions for either public or private access
points onto a public road:
(a)
The level of service analysis indicates a need for auxiliary
lanes.
(b)
The difference between the design speeds of the through roadway
and turning roadway exceeds 20 mph and signalization is not provided.
(c)
The design speed of the roadway is 40 mph or greater and vehicles
waiting to turn left or right would pose a hazard to through traffic.
(3)
Width and length.
(a)
Auxiliary lanes shall be 12 feet wide. In closed sections, this
width shall be measured to face of curb.
(b)
On closed sections, the taper of an auxiliary lane shall consist
of reverse symmetrical curves. On open sections, the taper may consist
of either full width or a straight line.
(c)
The minimum lengths required for auxiliary lanes and taper are shown in Table 2.11 (Appendix A).[4] If storage length, based on traffic volume, exceeds the
required length of deceleration lane (excluding taper), greater deceleration
lane length shall be provided.
[4]
Editor's Note: This table is included as an attachment to this chapter.
D.
Median lanes and openings.
(1)
A median lane is a left-turning auxiliary lane located within the
median, and the determination of its need, as well as its geometries,
such as length and width, shall be as for any auxiliary lane.
(2)
The design of the median opening shall normally be based upon a fifty-foot
radius tangent to the median edge and crossroad centerline. Where
an opening will be used by a large number of turning trucks, such
as in commercial or industrial areas, a radius of 75 feet shall be
used. (Refer to Standard Detail R/2.2.1.)
(3)
The median opening design should be checked to assure that opposing
left turns can be made without conflict.
(4)
A semicircular end shall be used on all median islands six feet or
less in width. For widths greater than six feet, a bullet nose shape
shall be used.
E.
Traffic islands.
(1)
Traffic islands are areas between traffic lanes used for controlling
vehicle movements or for pedestrian refuge. All islands with an area
of at least 75 square feet shall be raised and bounded by a standard
curb or combination curb and gutter. Islands with areas less than
75 square feet shall have a normal pavement section and be marked
by paint.
(2)
Divisional islands, which are islands separating opposing traffic
flows within the intersection area, shall be a minimum of four feet
wide. The offset from the edge of travel lane to the approach nose
shall be least three feet.
(3)
The approach noses of traffic islands may be depressed to two inches
above the pavement if approved by the County.
(4)
On islands adjacent to turning roadways, the approach nose shall
be offset at least four feet from the edge of the adjacent through
lane and a minimum of two feet from the edge of the turning roadway.
(5)
The nose radii of triangular islands shall be two feet, except the
right angle corner, which shall have a five-foot radius. The approach
nose of divisional islands shall have a one-foot radius, offset as
discussed above. The end of a divisional island shall be in accordance
with median openings.
(6)
All divisional islands six feet or less in width, as well as triangular
islands of less than approximately 150 square feet, shall be paved.
Divisional islands wider than six feet, and triangular islands greater
than 150 square feet in area, shall be seeded and mulched. Sidewalks
shall be included where directed by the Office of Planning.
F.
Intersection sight distance.
(1)
At signalized intersections, the movements are controlled and provision of the stopping sight distance as given in Table 2.02 (Appendix A) is sufficient.[5]
[5]
Editor's Note: This table is included as an attachment to this chapter.
(2)
The following criteria have been established for the determination
of unsignalized intersection sight distance:
(a)
Crossing movement. Sufficient distance, both left and right,
to enable a stopped vehicle to cross the intersection before a vehicle
on the major highway reaches the intersection, even though this vehicle
appears just as the crossing maneuver begins, and without the through
vehicle have to decelerate.
(b)
Left turn. Sufficient distance on the left to enable a stopped
vehicle to turn left onto the major road before a vehicle approaching
from the left reaches the intersection, even though this vehicle appears
just as the left turn begins, and without the through vehicle having
to decelerate. Also, sufficient distance on the right to enable a
stopped vehicle to turn left onto the major road without a vehicle
on the major road, approaching from the right, having to decelerate
more than 10 mph, even though the approaching vehicle appears just
as the turn begins.
(c)
Right turn movement. Sufficient distance on the left to enable
a stopped vehicle to turn right onto the major road without a vehicle
on the major road, approaching from the left, having to decelerate
more than 10 mph, even though the approaching vehicle appears just
as the turn begins.
(3)
The minimum sight distance for each of these criteria are given in Table 2.06 (Appendix A).[6]
[6]
Editor's Note: This table is included as an attachment to this chapter.
(4)
The possible movements at each intersection shall be determined and appropriate sight distance selected from Table 2.06 (Appendix A).[7]
[7]
Editor's Note: This table is included as an attachment to this chapter.
G.
Intersection vertical alignment.
(1)
General. Typical section pavement slopes of the street with the higher
functional classification shall be carried through the intersection
without deviation. The pavement slopes of the street with the lower
classification shall be warped to meet the pavement edge of the through
street. Where two roads of the same classification intersect, they
shall be connected by considering one the more important and transitioning
the other as stated above, or by transitioning both roadways.
(2)
Intersection grades. As discussed above, one of the intersecting
roads shall be determined to be the more important and its grade carried
through the intersection without interruption. The grade of the other
road as it approaches the through road shall have a landing grade
meeting the following criteria:
|
Functional Classification
|
Maximum Grade Through Intersection
|
Distance From Intersection(1)
(feet)
| |
|---|---|---|---|
|
Arterial
|
3.0%
|
200
| |
|
Collector
|
3.0%
|
175
| |
|
Local streets
|
4.0%
|
40
|
|
(1)Distance measured from pavement
edge of intersecting road to the PVC of the vertical curve.
| ||
H.
Pedestrian facilities. Ramps for pedestrians shall be provided at
all intersections and other major points of pedestrian flow having
sidewalks. Typical ramps are contained in the Standard Details Manual.
Ramps shall meet federal, state, or local requirements as applicable.
(Reference Detail R/2.29.)
J.
Intersections with state highways. Criteria and permits related to
intersections with state highways are contained in the Maryland State
Highway Access Manual.
A.
To obtain uniformity and maximum safety, the design and location
of commercial and industrial entrances shall be in accordance to the
standards set forth in the Maryland State Highway Access Manual of
the Maryland State Highway Administration. Entrances shall be as shown
in the Standard Details Manual.
A.
Off-street parking lots must be designed to accommodate the anticipated
demand, provide parking stalls of sufficient size to accommodate the
vehicles, and provide safe and convenient traffic flows.
C.
The parking lot design shall discourage random movements and, through
the use of traffic engineering aids such as signs and islands, provide
positive guidance to the motorists. Efforts shall be made to minimize
vehicular and pedestrian conflicts. All parking lot designs shall
be considered at the time of site plan review by the County.
E.
Pedestrian ramps should be located so as to provide easy and direct
access between the handicapped parking spaces and the building entrance.
F.
The paving section of parking lots shall be in accordance with Table 2.07 (Appendix A) and the Standard Details.[3]
[3]
Editor's Note: This table is included as an attachment to this chapter.
All paving sections shall be in accordance with Table 2.07 (Appendix A)[1] and the Standard Details.
[1]
Editor's Note: This table is included as an attachment to this chapter.
A.
At-grade golf cart crossings shall only be permitted on local residential
public streets. The local residential public street shall not carry
through traffic and shall be an internal subdivision road. Stop signs
shall be placed on the golf cart path at their intersection with the
local road. The at-grade crossing shall be treated as a pedestrian
crossing and advanced crossing signs (with golf cart logo) and other
appropriate signage and pavement markings shall be installed as per
MUTCD.
B.
The roadway and golf cart path centerline shall intersect as closely
as possible at right angles to the public road with a maximum skew
of 70° and continue through the intersection without offset or
break. The golf cart path shall be tangent inside the public right-of-way.
The maximum grade of the golf cart path in the public right-of-way
shall not exceed 3%. The sight distance at the intersection shall
meet the requirements of this chapter.
C.
Golf cart paths shall be constructed with asphalt or concrete surface
within the public right-of-way. The minimum paved width of the path
shall be 12 feet. The minimum cross slope for paved surface shall
be 1%. The pavement material shall be placed upon 95% compacted subgrade.
The pavement material detail shall be as follows:
Roundabouts shall be designed in accordance with the most recent
Maryland State Highway Administration Roundabout Design Guidelines.
A.
School bus turnarounds shall be provided for residential subdivisions
in accordance with the latest Policy # 3700 (Transportation) of Series
3000 of Policies Regulations By-laws of Board of Education of Charles
County. The location of school bus turnarounds shall be shown on the
approved Preliminary Plan of Subdivision.
B.
A cul-de-sac of a minimum sixty-foot paved radius is required for
school bus turnarounds.
Curb openings shall be constructed in accordance with the MSHA
Standards.
A.
Policy in general. The access management policy defines locations
for future median openings and access points for certain roads within
the County. As residential, business, industrial, and commercial establishments
develop or redevelop land adjacent to the access managed roads, there
is an interest in how these properties gain access to the road. Where
applicable, properties that develop or redevelop along an access managed
roadway will be required to consolidate access points to both the
property itself and the adjacent properties. Minimizing access points
will increase safety and level of service of the roadway.
B.
Locating median openings and access points. Median openings, intersections, and property access points will be determined by the Board of County Commissioners for designated County roadways. The tables in Appendix F designate median openings and access points for select roadways by location or distance from a known point.[1]
(1)
Access points. Access points will be one of two types: an intersection
(median break) or right-in/right-out (no median break).
(a)
Intersection (median break). The intersection shall consist
of a median break to allow traffic to enter and exit a roadway from
an adjoining or adjacent roadway. Access points which line up with
the median openings may be either public roads or private driveways.
(b)
Right-in/right-out (no median break). Right-in/right-out access
points will be assigned to areas that are less than 1,320 feet from
the nearest intersection or to an adjoining roadway of a low traffic
volume. A minimum separation of 750 feet from adjacent access points
is used wherever possible.
(2)
Standards.
(a)
Median openings on the four-lane road are predetermined at locations
that are approximately 1,320 feet to 1,500 feet apart. Right-in/right-out
access points are approximately 750 feet apart from adjacent access
points.
(b)
All median openings, intersections, and access points to access managed roadways will be at predetermined locations as shown in the table for the corresponding roadway in Appendix F.[2]
[2]
Editor's Note: Said appendix is included as an attachment to this chapter.
(c)
The access points for developing and redeveloping properties
will be consolidated within the property and any adjacent properties,
wherever possible.
(d)
All station numbers in the tables of Appendix F correspond to those on approved plan sheets.[3] If station numbers are not used, distances from known
intersections will be given.
[3]
Editor's Note: Said appendix is included as an attachment to this chapter.
(e)
For each access point listed in the tables of Appendix F, the determination of a median opening is indicated with a "yes" or "no" in the column titled "Median Opening." "Yes" indicates that a median opening exists or has been predetermined for the subject location. "No" indicates that the subject location is determined to have right-in/right-out access only.
(3)
Inter-parcel connections. Developers shall provide inter-parcel connections
to adjacent properties where they would provide alternative access
to the properties and serve to minimize direct access to the access
managed roadway.
(4)
Access point adjustments. All locations are approximate and may be subject to adjustment based on engineering. The adjustment of an access point location up to 25 linear feet may be approved by the County Engineer. An access point adjustment greater than 25 linear feet will require a modification pursuant to Subsection C of this section.
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
C.
Addition to or modification of Access Management Tables. The County Commissioners, in their capacity as the chief executive body of the Charles County Government, are hereby authorized to add to or modify Appendix F of the Charles County Road Ordinance, "Access Management Tables," from time to time, as circumstances warrant, in accordance with procedures to be adopted by the County Commissioners.[4]
[4]
Editor's Note: Said appendix is included as an attachment to this chapter.
Urban road standards shall be applied within the Urban Road Standards District. A map of this district is shown in Appendix G.[1] Design criteria are contained in Table 2.01.02 (Appendix A).[2]
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
[2]
Editor's Note: This table is included as an attachment to this chapter.
