[Ord. 381, 11/14/2005, § 500]
The following minimum subdivision principles, standards, and requirements will be applied by the Planning Commission, Borough Council, Borough staff and consultants hired to provide comment in evaluating applications for preliminary and final plat approval.
[Ord. 381, 11/14/2005, § 501]
1. 
Land shall be suitable for the intended purpose for which it is to be subdivided or developed, as demonstrated by the environmental impact statement and traffic study and other application materials submitted.
2. 
Land subject to hazards of life, health, and safety such as strip or surface mined land, quarry land, open ditched and land subject to flooding or subsidence shall not be subdivided for residential purposes until all such hazards have been eliminated or unless guarantee is given that adequate safeguards against such hazards are provided by the subdivision plat.
[Ord. 381, 11/14/2005, § 502]
1. 
Proposed streets shall be within recorded rights of way and shall be properly related to Borough, County and State road and highway plans that have been prepared and officially adopted and/or filed as prescribed by law.
2. 
Where a subdivision plat abuts or contains an existing or proposed arterial street, the Planning Commission and Borough Council may require local access streets, reverse frontage lots, or such other treatment which will provide protection for abutting properties, reduction in the number of intersections with arterial streets, and separation of local and through traffic.
3. 
Cul-de-sac end streets may be permitted when it is clear that through traffic at such a street end is not essential to the street system in that district, or to the development of adjacent properties in the area, or the topography of the ground prohibits the future extension of the streets.
A. 
The maximum length of a cul-de-sac street shall be 1,200 lineal feet, exclusive of the turn-around portion.
B. 
A turn-around with a cartway diameter of at least 80 feet with a right-of-way diameter of at least 100 feet shall be required at the end of all streets.
4. 
Maximum Allowable Grades; Centerline of Streets.
Type
Grade
Arterial Streets
6%
Collector Streets
10%
Local Streets
12%
Cul-de-Sac
Maximum grade of the turn-around pavement portion of the cul-de-sac shall be 5%
5. 
Minimum grades on all streets shall not be less than 1%.
6. 
Vertical curves of proper and adequate length shall be installed on all street grade changes exceeding 1%, and provide a minimum sight distance as follows:
Design Speed
(mph)
Type
Minimum Sight Distance
(feet)
60
Arterial Streets
500
40
Collector Streets
275
30
Local Streets
200
7. 
Alignment.
A. 
Whenever street lines are deflected in excess of 2°, connection shall be made by horizontal curves.
B. 
To ensure adequate sight distance, minimum centerline radii for horizontal curves shall be as follows:
Design Speed
(mph)
Type
Minimum Center-Line Radii
(feet)
60
Arterial Streets
1,000
40
Collector Streets
400
30
Local Streets
125
8. 
Widths. Minimum street right-of-way widths and cartway (roadway) widths shall be as follows:
Type of Street
Cartway Width
(feet)
Right-of-Way
(feet)
Arterial
40
60
Collector
26
50
Local
24
50
9. 
Street Intersections.
A. 
Curbs, where required, shall be installed by the developer along the streets or where deemed necessary for public safety as determined by Borough Council. The curbs shall be of the type and material as specified and approved by Borough Council. All curbs at intersections shall be rounded by a minimum radius of 25 feet for local streets, 30 feet for collector streets, and 40 feet for arterial streets.
B. 
Where the grade of any street at the approach to an intersection exceeds 5%, a leveling area shall be provided with a transitional grade not to exceed 2% for a distance of 25 feet from the nearest right-of-way line of the intersection.
C. 
Multiple intersections of more than four roads shall be prohibited.
10. 
Sight Distances.
A. 
Along Streets. Proper sight distance must be provided for both horizontal and vertical curves. Sight distance measurements shall be made along a simulated driver's line of vision. Minimum sight distances, thus measured, shall be:
Type
Minimum Sight Distance
(feet)
Local Street
110
Collector Street
200
B. 
At Intersections. Appropriate sight distances must be maintained on all approaches. When measured from the intersecting curb line extension along an approach vehicle travel path, there shall be uninterrupted sight distance of:
Type
Sight Distance
(feet)
Local Street
70
Collector Street
90
11. 
Street Offsets. Street offsets of less than 125 feet shall be avoided.
12. 
Reverse Curves. Reverse curves shall be designed to accommodate anticipated volumes of traffic at designed speeds.
13. 
Alleys shall be permitted subject to design approval of the Planning Commission and Borough Council.
14. 
Driveways.
A. 
Driveways shall be located to provide the best visibility possible within the limits of the property that each driveway serves, and shall be designed and constructed in accordance with the requirements of the Borough.
B. 
Private driveways which function as local streets providing access to individual residential lots shall be designed in accordance with this chapter and in compliance with the minimum standards for public streets.
[Ord. 381, 11/14/2005, § 503]
1. 
Residential lots shall be subdivided in accordance with the terms of the Zoning Ordinance [Chapter 27] and the provisions contained herein.
2. 
Subdivision and development of land other than for residential purposes shall be subject to review by the Planning Commission and Borough Council insofar as size, depth, width of lots, access to public roads and parking are concerned.
3. 
The frontage width of lots fronting a cul-de-sac shall be a minimum of 50 feet at the right-of-way line.
4. 
All lot lines shall be set perpendicular or radial to the centerline of the street whenever possible. All nonradial lines shall be denoted as such on the plat.
5. 
Flag lots shall have a reserve strip that has a minimum width of 25 feet for its total length and is for the express purpose of providing vehicular egress, ingress, and utility access to said lot. The area of the flag lot used for access shall not be used in computing the minimum lot area required by the Zoning Ordinance [Chapter 27]. The building setback line shall not be established within any part of the reserve strip. Lot width at the building setback line shall comply with the requirements of the Zoning Ordinance [Chapter 27].
[Ord. 381, 11/14/2005, § 504]
1. 
Building setback lines shall be in accordance with the terms of the Borough Zoning Ordinance [Chapter 27].
2. 
Building setback lines shall be recorded on each lot.
[Ord. 381, 11/14/2005, § 505]
1. 
Block length shall not exceed 1,200 feet nor be less than 500 feet.
2. 
Blocks shall be at least two lots in depth except for reverse frontage lots.
[Ord. 381, 11/14/2005, § 506]
1. 
Easements for sanitary sewer and stormwater sewer shall have a minimum width of 20 feet and be placed at the side or rear of lots whenever possible. When Borough Council determines that easements are required to extend proposed or future utilities the required easements shall be provided.
2. 
Anchor easements shall be approximately four feet by 30 feet and placed on a lot line, at such locations as deemed appropriate by the utility requiring such easements.
3. 
Aerial easements shall be a minimum of 15 feet, and located as deemed appropriate by the utility requiring such easements.
4. 
Where a subdivision is traversed by a watercourse, there shall be provided a drainage easement or right-of-way conforming substantially with the line of such watercourse, and of such width as will be adequate to preserve the natural flow of water and to provide sufficient width for maintenance, but not less than 20 feet.
[Ord. 381, 11/14/2005, § 507]
The developer may choose his street names subject to the approval of the Planning Commission and Borough Council. No street, other than an extension, may be given the name of an existing street in the 911 or postal service area of which the Borough of Thornburg is a part.
[Ord. 381, 11/14/2005, § 508]
In subdividing land, it shall be done in a manner that will not have the effect of barring adjacent property owners from access to any existing or proposed public streets.