City of Nashua, NH Street Design and Transportation

Applicants for subdivision plan approval shall provide internal street improvements as required by this Part 4.

Where a proposed development subject to subdivision or site plan approval borders on or contains a limited-access highway right-of-way, a railroad right-of-way, or an open watercourse, the Board may require a street approximately parallel to and on one side of such right-of-way or watercourse, at a distance suitable for the appropriate use of the intervening land for park, residential, commercial, industrial or other purpose. Such distance shall also be determined with due regard for the requirements of approach grades and future intersection grade separations.

Circulation system design principles.

The street system shall respect the function of streets as the shared domain of drivers, pedestrians, and bicyclists. Street widths shall be adequate to accommodate vehicles and emergency services, but not excessively wide so as to encourage speeding. The street system shall incorporate pedestrian amenities such as sidewalks, center medians, landscaping, street trees, and narrow intersection radii so as to improve the walkability of the streetscape.

The street network shall respect the context of the land use and design of the neighborhood it serves.

The street system shall balance the public goal of connectivity with market demands for privacy.

The street system shall be designed to permit the safe, efficient, and orderly movement of traffic; to meet, the needs of the present and future population served; to have a simple and logical pattern; to respect natural features and topography; and to present an attractive streetscape.

(5)

In residential subdivisions, the street system shall be designed to serve the needs of the neighborhoods while addressing the needs of the City-wide circulation pattern necessary to functionally move traffic.

Street hierarchy.

Purpose: This section provides guidelines whereby streets can be classified in a street hierarchy system with design tailored to function.

This subsection applies only to applications for subdivision approval.

The street hierarchy system shall fall into a four-category grouping that, in descending order, includes principal arterial, minor arterial, collector, and local streets. These streets may be classified further as alleys, lanes, local streets, conservation streets, avenues, main streets, boulevards, and parkways in accordance with the Street Design Criteria, Table 207-1 below. Classification of an existing or proposed street not already identified in the Master Plan or an adopted major street plan, for the purpose of determining the appropriate design of a street or development, or for the purpose of determining the appropriateness of a location for a proposed use, shall be done by the Administrative Officer in consultation with the City Engineer. The functional description of each of these classes is as set forth in Table 207-1.

All streets shall conform to the geometric design standards in § 190-208. These requirements apply to both public and private streets.

This section applies to internal streets and off-site improvements. The Planning Board may waive the requirements of this section where compliance would not be consistent with the purposes of this section based on topographical conditions, natural or man-made barriers, or similar conditions.

Table 207-1 Street Classification
Class	Definition
Principal arterial	•	Provides corridor movement suitable for substantial state-wide or interstate travel and provides continuity for all rural arterials that intercept the urban area.
	•	Serves the major traffic movements within urbanized areas such as between central business districts and outlying residential areas, between major intercity communities or between major suburban centers.
	•	Serves a major portion of the trips entering and leaving the urban area, as well as the majority of the through traffic desiring to bypass the central City.
Minor arterial	•	Serves trips of moderate length at a somewhat lower level of travel mobility than principal arterials.
	•	Provides access to geographic areas smaller than those served by the higher system.
	•	Provides intracommunity continuity, but does not penetrate identifiable neighborhoods.
Collector	•	Collects traffic from local roads and channels it into the arterial system.
	•	Provides land access and traffic circulation within residential neighborhoods, commercial and industrial area.
Local	•	Comprises all facilities not on higher systems.
	•	Provides access to land and higher systems.
	•	Through traffic usage discouraged.

Source: Nashua 2000 Master Plan, Transportation Element, "Functional Classification System" (page X-65).

§ 190-208 Geometric design.

Applicability. This section applies only to applications for subdivision approval. The Planning Board may approve reductions in the pavement widths specified in this section if it deems that the deviation shall be in keeping with the surrounding area or neighborhood.

Curbs.

Purpose: Curbing shall be required for the purpose of drainage, safety, and delineation and protection of the pavement edge. Curbing is required:
•	For stormwater management.
•	To stabilize pavement edge.
•	To delineate parking areas.
•	Ten feet on each side of drainage inlets.
•	At intersections and at tight radii.

Curbing shall be designed to provide a ramp for wheelchairs as required by federal law. Curbing shall be constructed according to the Board of Public Works Specifications.

The developer shall construct granite slope curbs on each side of the required street. Such curbs shall be backfilled opposite the street side with either gravel, lawn or sidewalk to the top of the curb grade, extending back a minimum of three feet. The developer shall also be responsible for the provision of water mains, manholes, sanitary sewers and catch basins.

Pavement section. Street grade and intersection requirements, and pavement thickness shall comply with the Board of Public Works Specifications, which document is hereby incorporated by this reference.

Sight distance. All season safe sight distance is defined as a line which encounters no visual obstruction between two points, each at a height of three feet nine inches above the pavement, and 10 feet back from the road pavement as to represent the critical line of sight between the operator of the vehicle using the access and the operator of vehicle approaching from either direction. Safe sight distance shall be compatible with the average observed speed during a normal workday on the street as indicated in Tables 208-1, 208-2, and 208-3 below:

Comment: See § 190-16E for setback standards. See § 190-208B for standards relating to the design of access points.

Table 208-1 Minimum Intersection Sight Distance Stop-Sign and Signal-Controlled Intersections
	Sight Distance (feet)⁽¹⁾
Posted Speed (mph)	2-3 Lane Stop Control⁽²⁾	4-5 Lane Stop Control⁽²⁾	2-5 Lane Signal Control⁽³⁾
20	200	225	225
25	250	275	300
30	300	350	375
35	350	400	475
40	400	450	575
45	450	500	700
50	500	550	850
55	550	625	1,000
60	600	675	1,150

Source: adapted from AASHTO, A Policy on Geometric Design of Highways and Streets, 1990. All units rounded for design.

Rules of Interpretation for Table 208-1:
(1)	Measured along the center of the approaching travel lanes, as observed from a point 15 feet back from the edge of traveled way and measured from an eye height of 3.5 feet to a height of approaching object of 4.25 feet.
(2)	Sight distance for a vehicle turning left into a two-lane or four-lane roadway across a vehicle approaching from the left or right.
(3)	Sight distance for a vehicle turning right into a two- or four-lane roadway and attain 85% of design speed without being overtaken by a vehicle approaching from the left and reduced to 85% of design speed.

Table 208-2 Minimum Intersection Sight Distance Yield and Uncontrolled Intersections
	Sight Distance⁽¹⁾⁽²⁾ (feet)
Posted Speed (mph)	Major Street	Minor Street
20	90	90
25	110	110
30	130	130
35	155	155
40	180	180

Source: adapted from AASHTO, A Policy on Geometric Design of Highways and Streets, 1990. All units rounded for design.

Rules of Interpretation for Table 208-2:
(1)	Measured along the center of the approaching travel lanes and measured from an eye height of 3.5 feet to a height of approaching object of 4.25 feet.
(2)	If minimum sight distance requirements cannot be obtained because the cost to do so is prohibitive, other traffic control devices must be used to stop vehicles on one or both roads.

Table 208-3 Minimum Stopping Sight Distance (Approval by City Engineer or Designee Required)
	Stopping Sight Distance⁽¹⁾ (feet)
Posted Speed (mph)	-9%	-6%	-3%	Level	+3%	+6%	+9%
20	125	125	125	12	125	125	125
25	175	175	175	150	150	150	150
30	225	225	225	200	200	200	200
35	300	275	275	250	250	250	225
40	400	375	350	325	300	300	300
45	475	450	425	400	375	350	350
50	600	550	500	475	450	425	400
55	700	625	575	550	525	500	475
60	825	750	700	650	600	575	550

Source: adapted from AASHTO, A Policy on Geometric Design of Highways and Streets, 1990. All units rounded for design.

Rules of Interpretation for Table 208-3:
(1)	Measured along the center of the approaching travel lanes, as observed from a point 15 feet back from the edge of traveled way and measured from an eye height of 3.5 feet to a height of approaching object of 4.25 feet.

Cul-de-sac or dead-end streets.

Dead-end or cul-de-sac streets designed to be permanently closed at one end shall not exceed 750 feet in length. The distance of the cul-de-sac shall be measured from the edge of the right-of-way for the through road and the center point of the turnaround at the end of the cul-de-sac. A "through road" means a road with more than one access.

In extreme cases where there are existing limitations which prevent the construction of a second legal means of access to a tract of land, the Planning Board may grant a further waiver to the seven-hundred-fifty-foot maximum length of a cul-de-sac or dead-end street if it determines that a reasonable second means of emergency access will be provided and maintained to the property. This emergency access shall be cleared to a minimum width of 20 feet and parking prohibited on it. The emergency access shall be maintained by a homeowners' association unless the City formally accepts the improvement. The Board may also require a divided pavement of at least 16 feet in either direction with a wider right-of-way, if necessary, provided for improved access to the properties along it.

Closed ends of cul-de-sac streets shall be provided with a radial-shaped turnaround having a minimum right-of-way radius of 60 feet and a minimum radius to the outside edge of pavement or curb of 50 feet. Culs-de-sac that have no potential for future extension may have a permanent area in the center of the turnaround which shall be suitably landscaped by the developer prior to street acceptance in which case the minimum radius to the inside edge of pavement or curb shall be 30 feet. A covenant, or other suitable legal instrument, shall be placed on property deeds to all lots abutting the cul-de-sac turnaround indicating that the owners of such lots shall maintain the landscaped area. In cases where the center landscaped area is to be owned and maintained by a homeowners' or other appropriate organization, the minimum radius to the inside of the right-of-way shall be 20 feet. Culs-de-sac which have the potential for future extension need not have landscaped central areas installed but instead shall have a minimum fifty-foot radius paved turnaround area.

Tee (T) or ell (L) shaped turnarounds at the closed end of a dead-end street, in lieu of a radial shape, are not permitted unless: 1) under unique and extreme circumstances of land ownership, topography or lot layout, the design would provide greater traffic safety, and 2) the Fire Department certifies that the design would increase response times or create a fire safety hazard. If permitted, the design conforms to the Board of Public Works Specifications. In such cases the minimum turnaround right-of-way width shall be 40 feet with a pavement width of 15 feet.

(5)

Turnaround requirements of this subsection may be waived in whole or in part by the Planning Board for streets of record prior to the adoption of the subdivision regulations of the City, where the unavailability of sufficient land or other factors peculiar to the proposed subdivision would prevent such requirements from being met.

Lighting. The developer shall be responsible for and shall bear any costs associated with the installation of streetlighting facilities. Such facilities shall be installed and spaced in accordance with requirements of Article IX of this chapter with guidance from the generally accepted practices as established by the Illuminating Engineering Society of North America, "American National Standard and Practice for Street Lighting" (ANSI/IES RP-8, 1977).

§ 190-209 Access points and curb cuts.

Purpose: This section establishes requirements for ingress, egress openings in concrete, street curbing, commonly referred to as "curb cuts" as well as other means of vehicular access to and from private property shall be regulated in accordance with the following requirements.

Size and design of curb cuts and other access point.

Curb cuts or driveway approaches shall have minimum and maximum width as follows for two-way driveway as follows, including two-foot shoulders:

Table 209-1 Size of Curb Cuts
	Minimum Width (feet)	Maximum Width (feet)
One-way	12	15
Two-way (includes two two-foot shoulders)	24	36

Driveways with four or more lanes planned shall include a planted medians in order to reduce the visual impact of pavement.

Driveways crossing a sidewalk shall maintain and continue the sidewalk, including the sidewalk pavement and texture.

The inside turning radii shall be a minimum of 15 feet and a maximum of 30 feet and meet the minimum and maximum requirements of Table 209-2.

Table 209-2 Inside Turning Radii
Land Use	Minimum Inside Turning Radii (feet)	Maximum Inside Turning Radii (feet)
Residential only	15	20
Commercial/industrial	20	28.3
Mixed uses	15	28.3

Sight distance. See § 190-208D above.

Driveways on corner lots. Driveways on corner lots shall be located a minimum of 50 feet from an intersection.

Driveway throat length. Driveway throat length shall be measured from the edge of the property line to the end of the driveway. The "end of the driveway" means the point at which a lane or opening in the driveway permits vehicles to enter or exit the driveway lanes. A minimum driveway throat length of 25 feet shall be required. Where warranted, the Planning Board may require additional distance. The purpose of the driveway throat length is to allow for traffic entering the site to be stored on site in order to avoid a queue of traffic on the street causing delays and potentially hazardous situation.

Driveway approach angle. The angle of the driveway approach shall be approximately 90° for two-way driveways and between 60° and 90° for one-way driveways.

Shared access.

Parking lots for single tenant commercial developments shall utilize shared driveways and shall contact adjacent property owners to obtain access easements. At the time of planting or site plan approval, each development shall extend the easement to the next property. The Planning Board may waive this requirement if it determines that it is physically impossible to provide shared access to the lot or if extenuating circumstances can be demonstrated and are approved by the by the Planning Board.

Wherever a proposed development abuts unplanted land or a future development phase of the same development, stubs-out shall be installed in order to provide access to abutting properties or to logically extend the street system into the surrounding area. All street stubs shall be provided with temporary turnarounds or culs-de-sac. The restoration and extension of the street shall be the responsibility of any future developer of the abutting land. These standards may be waived by the Administrator where specific finding is made that: 1) the peculiar nature of the property results in practical difficulties or unnecessary hardships that impede carrying out the strict letter of the requirement; 2) the property will not yield a reasonable return or cannot be put to reasonable use unless relief is granted; and 3) balancing the public interest in enforcing the setback requirements and the interest of the owner, the grant of relief is required by considerations of justice and equity.

Multitenant developments shall provide a central drive entrance. Each development shall provide an "entrance throat" that will direct traffic and provide for stacking space at intersections with the corridor. This limited access will permit the City and state to control traffic at this location. The development shall extend access to adjacent properties in order to control access to the corridor.

§ 190-210 Intersections and layout.

Streets shall be laid out so as to intersect as nearly as possible at right angles and no street shall intersect any other street at less than 75°.

Property lines at street intersections shall be rounded with a radius of at least 20 feet. The Planning Board may require a greater, or allow a lesser, radius whenever lot layout, safety and convenience will be served.

Street jogs with center line offsets of less than 175 feet shall be avoided.

A tangent shall be included between reverse curves on all but residential streets. The length of the tangent shall comply with the requirements of AASHTO, A Policy on Geometric Design of Highways and Streets (1994), but in no case shall be less than 100 feet long.

When connecting street lines deflect from each other at any one point by more than 10°, they shall be connected by a curve with a radius adequate to insure a safe sight distance.

Street bounds shall be placed at all street intersections, points of curves, angle points and at intermediate points as shall be required by the City Engineer, and shall be of such material, size and length as prescribed by the City Engineer.

§ 190-211 Private streets.

Applicability. See § 190-165, Frontage.

Design standards. The design standards and construction specifications of private streets shall be the same as for public streets, subject to the additional requirements established below.

Certification. Upon completion of construction, the applicant shall provide the City Engineer with written a certification signed by a licensed professional engineer certifying that the private streets and sidewalks (as applicable) were designed and installed as required by the provisions of this chapter. In the case of lots with no frontage, access for vehicles, utilities and emergency vehicles shall be insured through the use of common area agreements or private easements. The minimum width of access easements shall conform to § 190-209.

Maintenance.

Private streets and sidewalks shall be owned and maintained by a homeowners association, corporation, community association, or other legal entity established for this purpose. No subdivision or site plan proposing a private street shall be approved unless documents establishing the entity are provided to the Planning Board. A street maintenance agreement to assure private responsibility of future maintenance and repair shall be approved as to form and content by the City Attorney and shall be recorded with the deed of each property to be served by a common private street. The agreement shall provide for:

(a)

A method to initiate and finance a private street and maintain that street in good condition;

(b)

A method of apportioning maintenance costs to current and future users;

(c)

A provision that the City may inspect and, if necessary, require that repairs be made to the private street to ensure that safe access is maintained for emergency vehicles. If required repairs are not made within six months of date of notice, the City may make the necessary repairs and assess owners of parcels on the street for the cost of all improvements plus an administrative fee, not to exceed 25% of total costs;

(d)

A provision that the majority vote of all property owners on the street shall determine how the street is maintained except in the case of emergency repairs as outlined above;

(e)

A statement that no public funds shall be used to construct repair or maintain the street;

(f)

A provision requiring mandatory upgrading of the street if additional parcels are added to reach the specified thresholds; and

(g)

A provision that property owners along that street are prohibited from restricting or in any manner interfering with normal ingress and egress by any other owners or persons needing to access properties with frontage on that street.

All purchasers of property served by a private street shall, prior to final sale, be notified that the property receives access from a private street that shall be maintained collectively by all property owners along that street; that the City shall not be held responsible for maintaining or improving the private street; and that a right-of-way easement to provide the only access to that property has been recorded in the deed for that property.

By approving private streets, the City does not assume any liability for snow plowing or other maintenance items, or for any injuries, damages, or related liabilities associated with maintenance of the streets. All such responsibilities and liabilities shall remain with the landowner or homeowners' association.

§ 190-212 Sidewalks and pedestrian rights-of-way.

Location.

Sidewalks shall be located on at least one side of the street. In standard single-family developments, sidewalks shall be placed parallel to the street, with exceptions permitted to preserve natural features or to provide visual interest. In planned developments, sidewalks may be placed away from street systems, but they may also be required parallel to the street for safety reasons. The Planning Board may require sidewalks on both sides of the street on high volume, collector or arterial streets.

Sidewalks may be placed directly over a portion of the utility easement; and/or behind the planted area provided for street trees.

For parkways, the sidewalks shall take the form of multi-use trails that may meander at a distance of between six to 15 feet from the paved section of the street. In planned developments, sidewalks may be located away from the street system to link dwelling units with other dwelling units, the street, and on-site recreation areas and parking areas.

Pavement section. Sidewalks and graded areas shall be constructed according to the Board of Public Works specifications. Sidewalks shall include additional width where required by the Americans with Disabilities Act.

Pedestrian rights-of-way. Pedestrian rights-of-way not less than 14 feet wide may be required where deemed essential to provide circulation or access to schools, playgrounds, shopping centers, transportation or other community facilities. Where such pedestrians rights-of-way are provided, the developer shall clear the areas of obstructing rocks, trees and undergrowth, bring the right-of-way to suitable grade, and construct a bituminous concrete sidewalk for bicycle use of at least five feet in width and a bituminous concrete sidewalk for pedestrian use of at least five feet in width, or a bituminous concrete sidewalk for pedestrian and bicycle of at least 10 feet in width in accordance with the City Board of Public Works specifications.

Waivers.

For commercial, industrial, and office subdivisions in the LB, GB, D-1, D-3, HB, PI, and GI Zones, the requirements for sidewalks in the subdivision shall be determined during the review of subdivision and site plans. The requirements for sidewalks in such a subdivision may be waived if the Planning Board determines that the nature and/or intensity of the proposed use or the proposed use of other pedestrian facilities would obviate the need for these improvements, and that the burden on the applicant outweighs the public benefits associated with the sidewalk requirements.

Comment: An example of a sidewalk waiver is multiple frontage lots. In these situations, sidewalk construction along frontages other than the principal frontage of the lot. In those situations, pedestrian access is only from one of the frontages. The sidewalk requirements may be waived on the other frontages.

For subdivisions in a residential zoning district, or subdivision applications for residential lots in any zoning district, a contribution in lieu of the construction of sidewalks along an existing street may be accepted when all of the following conditions are met:

(a)

None of the lots may be divided into additional buildable lots under the minimum requirements of the zone. This requirement is met where:

[1]

An additional lot would not conform to the minimum lot size or other dimensional requirements of § 190-16; or

[2]

Further subdivision is precluded by a conservation easement.

(b)

The existing street adjacent to the proposed lots has no sidewalks for a distance of 250 feet on the same side of the street as the new lots. This distance shall be measured from the nearest frontage point within the proposed subdivision.

Contribution in lieu of sidewalk construction.

The Planning Board may accept a contribution in lieu of the construction of sidewalks where:

(a)

The application proposes a residential subdivision; and

(b)

The Planning Board determines that the proposed use or the proposed use of other pedestrian facilities would obviate the need for these improvements.

The Planning Board may accept a contribution in lieu of the construction of sidewalks for culs-de-sac.

All revenues generated by contributions pursuant to this section shall be deposited in an account created for this purpose. Revenues so generated shall be separately accounted for each of the four major quadrants of the City, said quadrants corresponding to the areas divided to the north and south by the Nashua River and to the east and west by the F.E. Everett Turnpike, and shall be used solely for the purpose of construction of new sidewalks in the quadrant from which the revenue was generated.