[Ord. No. 39-1998, § 3.1, 12-1-1998]
(a) The purpose of the street design standards in this article is to
ensure that public right-of-way improvements implemented in the City
provide for safe and efficient vehicular and pedestrian traffic, including
handicap access; provide for minimum longterm maintenance costs of
public improvements; protect the environment, the public and abutting
landowners by providing the necessary controls for stormwater runoff,
soil erosion and siltation, and groundwater; and protect the public
health and safety.
(b) These standards provide for flexibility, having the design fit into
the surroundings, attempting not to waste the City's valuable
natural resources, etc. Some previous limitations have been relaxed
by providing strict guidelines on how to deal with those situations
without loss of quality.
(c) If the road or street is to be totally owned and maintained by a
private entity and located entirely on the property of that private
entity, and the posted speed is not more than 25 miles per hour, and
side access is only permitted by curb cuts to parking areas, and no
parking is allowed anywhere on the roadway pavement, then the ADT
requirements can be waived by the planning board in the approving
of a roadway section.
[Ord. No. 39-1998, § 3.2, 12-1-1998]
Water shall be removed from any base material to protect the
roadway surface from frost damage. All subbase surfaces must be sloped
to drain, with no pools, puddles, or trapped water that would be internal
to the base material.
[Ord. No. 39-1998, § 3.2.1, 12-1-1998]
The horizontal alignment of streets proposed in all subdivisions
shall conform to the following standards:
(1) When centerline tangents deflect from each other, except at intersections,
they shall be connected by a centerline curve having a minimum radius
of 110 feet for residential streets, 175 feet for collector streets
and 75 feet for lanes.
(2) Between reverse curves, where the radius of one or both curves is
less than 200 feet, there shall be a tangent section of centerline
not less than 50 feet in length. There shall be no superelevation
in such cases.
(3) Streets intersecting an arterial street shall do so at a ninety-degree
angle. All streets intersecting collector or residential streets shall
not vary from 90° by more than 15°.
(4) At street intersections, the right-of-way lines shall be rounded
by a circular arc having a minimum radius of 20 feet. A greater radius
may be required for streets intersecting at an angle other than 90°.
(5) Dead-end streets shall be provided with a turnaround having an outside paved roadway diameter of 112 feet and a right-of-way diameter of not less than 130 feet. Where any subdivision includes a dead-end street, not designed to be so permanently, the subdivider shall make temporary provisions for a turnaround as the City engineer may deem necessary. For a circular turnaround, applicants are encouraged to utilize larger diameter turnarounds with green space at the center of the turnaround, instead of paving the entire turnaround. Plowing snow and drainage should be a consideration in the design, along with having enough width for large vehicles to negotiate the turnaround. The tee turnaround illustrated in figure 6 in section
98-85 is a permissible permanent design, if posted for no parking.
(6) Street intersections with more than four legs are prohibited.
(7) Minimum centerline offset distances of adjacent intersections shall
be as follows, unless, in the opinion of the City engineer, a shorter
distance is unavoidable due to local conditions:
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Residential to residential
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250 feet
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Residential to collector
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300 feet
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Residential to arterial
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500 feet
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Collector to collector
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300 feet
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Collector to arterial
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500 feet
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(8) See section
98-155 for sight distance standards.
[Ord. No. 39-1998, § 3.2.2, 12-1-1998]
The vertical alignment of streets proposed in all subdivisions
shall conform to the following standards:
(1) The maximum grade for the centerline profile of all streets shall
not exceed 8%, except that, in residential subdivisions, where topographic
constraints exist, the maximum grade for the centerline profile may
be increased to 10% for no more than 200 feet, or 20% of total length,
whichever is less. For rural and urban lane sections where there is
no heavy truck volume, the maximum centerline profile grade shall
not exceed 10%.
(2) The minimum desired tangent grade of the street centerline shall
not be less than 1%. Grades between 0.5% and 1% will allowed only
if strict construction control is adhered to, and as approved to by
the City engineer. As a minimum, strict construction control involves
the setting of grade stakes, utilizing a competent grade foreman,
and final field work approved by the City engineer.
(3) Street grades at an intersection shall not be more than plus or minus
3% for a distance of not less than 75 feet from the center of the
intersection on each intersecting street.
(4) Cross slopes for sidewalks shall be three-eighths inch per foot.
Cross slopes for streets shall be one-fourth inch per foot.
(5) The minimum length of vertical curves shall be based upon the stopping
sight distance, and in no case may be less than 100 feet. The stopping
sight distance is based upon the posted speed limits as determined
in the latest AASHTO publication titled "A Policy on Geometric Design
of Highways and Streets." The method of physically calculating the
stopping sight distance is found in that reference, or the ITE Handbook.
(6) All changes in grade (intersecting tangents) along a roadway shall
be connected by vertical curves, with the length determined by appropriate
engineering methods. (Reference: ITE Handbook, Transportation and
Traffic Engineering.) The following minimum stopping sight distances
are required:
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Design Speed
(mph)
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Stopping Sight Distance
(feet)
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20
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125
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25
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150
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30
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200
|
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35
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250
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Stopping sight distance shall be calculated with a height of
eye at 3.5 feet and a height of object of 0.5 foot. (Reference: Transportation
and Traffic Engineering Handbook, Institute of Transportation Engineers,
latest edition.)
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[Ord. No. 39-1998, §§ 3.2.4, 3.2.4.2, 12-1-1998]
(a) Street and lane summary. The following table provides a summary of
the design requirements for streets and lanes. This table, and the
street and line drawings in this section, replace appendices D and
G found in the subdivision ordinance. The table is to be used with
the appropriate figure.
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Description
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Urban Lane
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Rural Lane
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Residential Street
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Collector Street
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Industrial/ Commercial Street
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Reference drawing
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Figure 1
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Figure 1A
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Figure 2
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Figure 3
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Figure 4
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Minimum right-of-way (feet)
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40
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50
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50
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60
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60
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Minimum pavement (feet)
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24
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20
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30
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34
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32
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Minimum shoulders (2)
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Included
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3 feet
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Included
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Included
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Included
|
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Sidewalkd
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Yes
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No/Yes
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Yes
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Yes
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No/Yes
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Minimum grade
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0.5%
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0.5%
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0.5%
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0.5%
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0.5%
|
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Maximum grade
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10%
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10%
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8%
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6%
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6%
|
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Minimum centerline radius (feet)
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75
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75
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110
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175
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250
|
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Minimum tangent between curvesa
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Variable
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Variable
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Variable
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Variable
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Variable
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Roadway crown
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2%
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2%
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2%
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2%
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2%
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Street intersection angle (minimum)
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75°
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75°
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75°
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90°
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90°
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Grade within 75 feet of main road
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-3% to +3%
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-3% to +3%
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-3% to +3%
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-3% to +3%
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-3% to +3%
|
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Minimum curb radius at intersection (feet)
|
15
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15
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15
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20
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20
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Minimum right-of-way radius (feet)
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20
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20
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20
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20
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30
|
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Curbed section
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Yes
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No
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Yes
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Yes
|
Yes
|
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Parking status
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See figure 1
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See figure 1A
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Both sides
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Both sides
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None
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a
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See section 98-83(2). A standard of good engineering practice is required where no specification exists.
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b
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Curbed section with no parking permitted consists of two ten-foot
traffic lanes, plus three feet either side of lanes, for a total of
26 feet of pavement. Using a rural section (non-curbed) with no parking
requires a three-foot gravel shoulder with two ten-foot paved traffic
lanes (with parking use six-foot gravel shoulders).
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c
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For aesthetic effect, increasing vegetated area, and for phosphorous
reduction, it is permitted to place two inches of loam on the gravel
base in the shoulder area for the purpose of maintaining a mowed grass
area.
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d
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See section 98-90 for sidewalk specifics.
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e
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An urban lane section (featuring curbs and closed drainage)
can be used in the rural zones, and a rural lane section (featuring
gravel shoulders and open ditches) can be used in the urban zones.
The names of such are taken from the predominant usage for that zone.
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(b) Drainage system requirements. Closed drainage systems are required
for all curbed streets. Ditches may be allowed where the lot layout
provides an average lot frontage of at least 200 feet. If the portion
of the lot abutting the ditch is to be lawn, a 3:1 minimum backslope
will be required.
(c) Figures. Street design figures referred to in this chapter are as
follows:
[Ord. No. 39-1998, § 3.2.5, 12-1-1998]
Streetlights shall meet electrical utility standards.
[Ord. No. 39-1998, § 3.2.6, 12-1-1998]
(a) Horizontal controls.
(1)
Monumentation of streets along the right-of-way shall include
the following points:
a.
Points of curvature (PC's).
b.
Points of tangency (PT's).
c.
Points of compound curvature (PCC's).
(2)
A minimum of two intervisible right-of-way monuments shall be
tied into the Maine State Plane Coordinate System. This survey connection
shall be required when the monuments are within 1/2 mile of a triangulation
or traverse station established in conformity with the standards prescribed
in 33 M.R.S.A. § 805.
(3)
The code enforcement officer/planner will maintain an updated
list of control stations located within the City.
(b) Vertical controls.
(1)
All established elevations must be based on NGVD mean sea level
datum and referenced from a specific benchmark.
(2)
A minimum of two right-of-way monuments within each development
shall be a benchmark monument with an established elevation.
(3)
Maximum distance between benchmarks shall be 800 inches horizontally,
and 50 inches vertically.
(c) Surveying standards. Survey control determination shall be to third
order national control standards and specifications, as outlined in
publications prepared by the Federal Geodetic Control Committee, NOS,
NOAA, by a registered land surveyor licensed to practice in the state.
Boundary surveys shall be in accordance with state board of registration
for land surveyors standards, category 1, condition 2 (or better),
with no exceptions.
[Ord. No. 39-1998, § 3.2.7, 12-1-1998]
(a) Stormwater runoff collection from streets and sidewalks shall be handled in accordance with the standards of article
VI of this chapter.
(b) Storm drainage systems must be designed in accordance with standards
for a ten-year storm for a rural or residential street and a twenty-five-year
storm for a collector, commercial/industrial, or arterial street.
[Ord. No. 39-1998, § 3.2.8, 12-1-1998]
All public portions of the development shall be handicap accessible
in accordance with current federal, state or City laws or regulations.
[Ord. No. 39-1998, § 3.2.9, 12-1-1998]
(a) Unless other pedestrian accommodations are made, all residential
subdivisions shall provide for a sidewalk on at least one side of
the street, with the width of the sidewalk to be a minimum of 48 inches.
(b) Sidewalks may be provided, but shall not be required, where lot frontages
in a residential subdivision are an average of 300 feet or where lot
sizes average more than two acres.
(c) Municipal sidewalks shall be provided a clear passage width of 60
inches.
[Ord. No. 39-1998, § 3.2.10, 12-1-1998]
There shall be an esplanade located between the curb and sidewalk on residential and collector streets in accordance with the design standards found in section
98-85. Esplanades shall be planted with trees, bushes, shrubbery or grass.
[Ord. No. 39-1998, § 3.2.11, 12-1-1998]
(a) Guardrails shall be used in any locations where street embankments
exceed three to one, or 33% (downslopes only). Street intersections
which form a "T" shall have a reflective guardrail opposite the street
which terminates at the intersection. MDOT specifications shall be
used.
(b) The face of any guardrail shall be aligned so as not to reduce the
width requirement of any section feature, such as shoulder width,
sidewalk width, etc. This will require an additional width (usually
two feet) to allow for the guardrail. A guardrail can be any suitable
device designed for the purpose that meets AASHTO or MDOT standards.
Other systems such as ornamental stones must be approved by the planning
board, based on review by the City engineer.