These street design requirements are intended to provide minimum standards for public streets serving the various uses permitted by this appendix, to protect the capacity of the city's street system and avoid undue congestion on these streets, and to lessen unnecessary conflicts between moving vehicles, parked vehicles, and pedestrians. Not all design features can be covered in the following text. Specific design elements not covered in the following text will be developed as directed by the City Engineer and subject to approval by the City Commission (from the Green Book "Manual of Minimum Uniform Standards").
(A) Spacing of urban intersections.
(1) Spacing for non-signalized urban street intersections by functional classification, as defined by the above-referenced "Manual of Uniform Minimum Standards."
(a) An arterial may intersect another arterial if aligned with and extending an existing arterial on the other side of the intersection or at a desirable distance of one mile from the intersection of existing arterials.
(b) A collector may intersect an arterial if aligned with and extending an existing collector which intersects the arterial or at a desirable distance of one-quarter mile from the intersection of an existing collector and the arterial.
(c) Intersections between local streets and arterials should be avoided. In cases where they do intersect, the local street shall be aligned with and extending an existing local street which intersects the arterial or at a desirable distance of 660 feet from any other street intersection.
(d) A collector may intersect another collector if aligned with and extending an existing collector on the other side of the intersection or at a desirable distance of 660 feet from the intersection of any other intersection.
(e) A local street may intersect a collector if spaced at a minimum distance of 660 feet from any other intersection, or, in the case of a intersection, at a desirable distance of 330 feet from any other street intersection.
(f) A local street may intersect another local street if aligned with and extending another local street on the other side of the intersection, or at a minimum distance of 150 feet from any other intersection.
(g) All streets shall be laid out to intersect as nearly as possible at right angles, but in no case shall the angle of the intersection be less than 60°. Multiple intersections involving the juncture of more than two streets shall be prohibited. A minimum sight distance of 200 feet from any intersection shall be maintained on the intersecting streets. This is the minimum sight distance, and greater distances may be required in order to satisfy the specifications of Section III, Paragraph 9, "Intersection Design," of the "Manual of Uniform Minimum Standards for Design, Construction, and Maintenance for Streets and Highways."
(2) Spacing for signalized urban intersections. In order that distances between signals are capable of providing reasonable cycle lengths, intersections that are planned to be signalized should be spaced a minimum of one-quarter mile.
(3) Minimum spacing requirements that may be reduced. The minimum spacing requirements of this section may be reduced upon a finding by the city that given the particular conditions of the proposed development, the minimums cannot be met, and reduction will not compromise operational and safety standards.
(4) Radii at intersections.
(a) The minimum intersection radii of back of curb at all typical intersections approximating a right angle shall be as follows:
Category | Minimum Radius (feet) |
Local to Local
|
30
|
Local or collector to collector
|
35
|
Local or collector to arterial
|
40
|
(b) A taper or deceleration lane may be required on roads with a functional classification of collector or higher, or design speeds 30 m.p.h. or greater. For other than right-angle intersections, the angle of intersection will dictate the turning radii. The "Manual of Minimum Standards" shall be used as a guide but the City Commission must approve any design.
(B) Median criteria.
(1) Median separation requirements. Median separation is required on all streets with four or more travel lanes, and design speeds in excess of 35 m.p.h., or as may be required by the city.
(2) Minimum median widths:
(a) The minimum width of a median containing a left turn lane shall be 16 feet.
(b) A median divided roadway shall have a median width adequate to accommodate crossing and left turning vehicles from a side street or drive without the front or rear of the vehicle extending into the through lanes of traffic. Twenty- two feet shall be the minimum width required.
(3) Median openings:
(a) Median openings on all streets classed as collector or above should not be spaced at a distance less than 660 feet from any other median opening unless specifically approved by the city.
(b) Dedicated public streets are given priority consideration for median openings.
(c) All median designs and provisions shall be consistent with standards provided by the "Manual of Minimum Standards for Design and Maintenance for Streets and Highways," published by the State Department of Transportation.
(d) All median openings for left turns shall include a taper and storage lane. The minimum lengths for taper and storage lanes are included in division (C).
(e) The preferred end treatment for median openings is the bulletnose design rather than the circular design.
(f) The width of median openings shall be a minimum of 40 feet, except for one-way operation.
(g) The median opening of a one-way operation shall be established by the turning radius of the largest anticipated design vehicle entering the opening or as directed by the city.
(h) No median opening shall be allowed where the median is intended to shadow a crossing or left turning vehicle (from side street or driveway), but is of insufficient width to do so.
(C) Turn lanes and tapers.
(1) Requirements for turn lanes and tapers. Turn lanes and tapers reduce conflict between the traffic on driveways or intersecting streets and the traffic on the through street. This conflict reduction is achieved by providing turning vehicles with a refuge area where acceleration, deceleration, storage, and turning maneuvers may be accomplished. Turn lanes and tapers may be required on arterial and collector streets for the following conditions.
(a) The speed limit of the accessed street is 30 m.p.h. or greater.
(b) The parcel of property accessing the street is projected to generate 500 or more vehicle trips per day, or 50 or more vehicle trips in any hour.
(c) The parcel of property accessing the street is residential and has 50 or more dwelling units.
(d) The parcel of property accessing the street is in a development that characteristically experiences peaks in its trip generation patterns, such as schools, restaurants, public assembly places.
(e) At any development as a traffic impact analysis may warrant.
(f) At any parcel of property where a use changes to one that meets one of the above conditions.
(g) At any intersecting street that has an average daily traffic of 500 or more vehicles per day or 50 or more vehicles in any hour.
(h) At any location where grade or other unusual conditions indicate turn lanes to be desirable, as determined by the City Engineer.
(2) Dedication of additional right- of-way. On any arterial or collector street within a minimum of 150 feet, or as required, of its intersection with another arterial or collector, or at any other location where provisions of this appendix require additional right-of-way, the right-of-way shall be increased by at least ten feet or as required to permit proper design of auxiliary lanes and tapers. This additional right-of- way shall be dedicated or conveyed as a public right-of-way easement.
(3) Right turn deceleration and storage lanes. The desirable requirements for lengths of tapers and storage for right turn lanes are based on the speed limit of the road, and are as follows:
Posted Speed Of Roadway (m.p.h.) | Length of Storage | ||
Length of Taper | Stop Condition | Free Right | |
Posted Speed Of Roadway (m.p.h.) | Length of Storage | ||
Length of Taper | Stop Condition | Free Right | |
30
|
150
|
50
|
50
|
35
|
170
|
105
|
80
|
40
|
190
|
135
|
110
|
45
|
210
|
165
|
140
|
50
|
230
|
195
|
170
|
55
|
250
|
210
|
200
|
(4) Acceleration lanes and tapers. The desirable requirements for lengths of acceleration lanes and tapers are based on the speed limit of the road, and are as follows:
Speed Limit (m.p.h.) | Acceleration Lane | Taper Length |
40
|
135
|
190
|
45
|
300
|
210
|
50
|
470
|
230
|
55
|
660
|
250
|
(5) Left turn deceleration and storage lanes. The desirable requirements for lengths of tapers and storage for left turn lanes are based on the speed limit of the road, and are as follows:
Posted Speed of Roadway (m.p.h.) | Length of Taper | Length of Storage |
30 | 150 | 100 |
35 | 170 | 105 |
40
|
190
|
135
|
45
|
210
|
165
|
50
|
230
|
195
|
55
|
250
|
210
|
(6) Alternate storage lengths for left turn lanes. Storage lengths for left turn lanes may be calculated in lieu of using the above tables by one of the following methods:
(a) At unsignalized intersections, the storage length, exclusive of taper, may be based on the number of turning vehicles which are likely to arrive in an average two-minute period within the peak hour, that is, storage length (in feet) = 2 x 25 (average vehicle length) x number of left turning vehicles in peak hour - by 60.
(b) At signalized intersections, the storage length may be based on the signal cycle length, the signal phasing arrangement, and the rate of arrivals and departures of left turning vehicles. The storage length should be based on 1.5 to 2 times the average number of vehicles that would store per cycle to allow for occasional surges.
(7) Minimum lengths for tapers and turn lanes. The minimum acceptable length for any turn storage length shall be 50 feet, and the minimum acceptable length for any deceleration taper shall be 150 feet.
(8) Bypass lanes. A bypass lane should be provided for left turns when a median or adequate pavement width does not exist. It is encouraged that the pavement widening be on both sides of the existing pavement to provide a smooth and safe transition. The taper shall be based on the formula: turn lane = speed x width of lateral movement.
(9) Exceptions. Turn lane provisions (left and right) may be imposed unless roadway cross section, right-of-way width, or deficient frontage prohibit compliance.
(10) Reverse curves. Reverse curves should be used in place of straight tapers on curb and gutter sections.
(D) Minimum standards for right-of-way improvements.
(1) It is the intent of the city that every new lot, residential development or commercial development construct its portion of the city's pedestrian system. Where an industrial development abuts the right-of-way, construction of the pedestrian system will be the responsibility of the property owner or developer.
(2) Only where an industrial development abuts the right-of-way will construction of the pedestrian system be the responsibility of the property owner or developer unless such responsibility is waived by the City Commission.
(3) Sidewalks are to be normally constructed adjacent to the street right-of- way line with a minimum separation between the sidewalk and the edge of pavement of four feet. Where this separation is not possible within the right-of-way, every effort will be made to locate the sidewalk on an easement on private property or otherwise achieve the desired separation. If it is not possible to maintain the minimum separation, sidewalks may be constructed adjacent to a raised standard curb. Sidewalks shall be a minimum of four feet in width. In no case shall a sidewalk be constructed adjacent to a Miami curb or ribbon curb. Other items which conflict with the sidewalk location, such as utility structures, shall be relocated at the developer's or utility's expense.
(4) Streets.
(a) Paving. Abutting rights-of- way shall be paved as hereinafter specified. A minimum of one paved access on public rights-of-way shall be provided to connect to the existing network of paved streets. Improvement of existing streets to meet the following criteria may be required for this access. More than one paved access may be required or allowed if it is consistent with the Comprehensive Plan and the level of service required, and current traffic studies demand it.
(b) Streets shall be classified based on the definitions, and with consideration of vehicle trip generation ratios unless superceded by alternative ratios adopted by the City Commission. Where the City Commission has adopted a higher classification than the classifications based on projected traffic volumes, the higher classification shall be used. All streets shall be designed in accordance with the "Manual of Uniform Minimum Standards for Design, Construction, and Maintenance for Streets and Highways" and the following minimum specifications, and improved in accordance with this appendix, except that greater requirements must be met when imposed by an agency having jurisdiction of a particular road.
Arterial St. | Commercial Collector St. | Collector St. | Local St. | Residential Frontage Roads | |
Minimum right-of- way:
| |||||
Closed Drainage (feet)
|
100
|
60
|
60
|
50
|
50
|
Open Drainage (feet)
|
120
|
80
|
80
|
70
|
70
|
Percent grade of roadway centerline:
| |||||
Maximum
|
6
|
8
|
8
|
10
|
10
|
Minimum
|
0.30
|
0.30
|
0.30
|
0.24
|
0.24
|
(c) Dedication of additional right-of-way. On any arterial or collector street within a minimum of 150 feet, or as required, of its intersection with another arterial or collector, or at any other location where provisions of this appendix require additional right-of-way, the right- of-way shall be increased by at least ten feet or as required, to permit proper design of auxiliary lanes and tapers. This additional right-of-way shall be dedicated or conveyed as a public right-of-way easement.
(d) Pave to nearest paved public road. A development shall abut or have as its primary access, a street paved to city standards. This street shall be paved by the developer from the entrance of the development to the nearest public paved road of proper functional classification.
(E) (1) Additional right-of-way and pavement width. May be required by the City Commission to promote public safety and convenience or to ensure adequate access, circulation, and parking. Whenever the Comprehensive Plan shows a need for an increase in the level of service of a street within the area to be developed, the appropriate right-of-way and pavement shall be required. Where a development abuts or contains an existing street of inadequate right-of-way or pavement width, additional right-of-way and pavement in conformance with minimum city standard shall be required to be dedicated.
(2) Where a previously dedicated incomplete street, improved or unimproved, abuts or is within a tract to be developed, the remainder of the right-of-way shall be dedicated and the full street improved according to city standards.
(3) Right-of-way requirements shall be based upon a 20-year planning period according to the most current official city transportation plan as may be adopted. All rights-of-way shall be transferred to the city by means of a recorded deed, or by dedication on a plat, in the city’s discretion. If the city right-of-way is part of a subdivision being platted, the right-of-way may be dedicated to the city on the plat. All other transfers of right-of-way shall be by deed.
(4) On divided two-lane roads (boulevards), minimum pavement widths for each lane shall be 14 feet, exclusive of curbs and gutters. On four-lane roads, minimum lane widths shall be 12 feet each, with provisions for left-turn storage, acceleration, deceleration, tapers, or channels as the required level of service and current traffic studies may demand.
(5) Whenever an island is proposed in the center of a cul-de-sac turnaround the pavement shall be 24 feet, exclusive of curbs.
(F) Development on railroads or limited access highways. Where a development abuts or contains a railroad right-of-way, limited access highway, or arterial street, the City Commission may require that the developer provide a street that shall be approximately parallel to and on each side of the right-of- way. The street shall be located at a distance suitable for the appropriate use of the intervening land, including park purposes in residential districts or commercial and industrial uses in appropriately zoned districts. The separation of the street from the adjoining right-of-way shall be determined with due regard for the requirements of approach grades, future grade separations, and signalization.
(G) Access. Access shall be provided as follows:
(1) Minimum number of access points to adequately serve the development.
(2) Tapers, deceleration lanes, left-turn lanes, bypass lanes, median modifications, or other design features will be required, as demanded by the required level of service and current traffic studies, to protect the safe and efficient operation of the access street.
(3) In order to provide ease and convenience in ingress and egress to private property and the maximum safety with the least interference to the traffic flow on public streets, classified collectors, and above, the number and location of driveways shall be regulated by the dedication of access rights to the city.
(a) Permits. The following permits are required prior to initiating access way construction.
1. A Department of Transportation driveway permit is required for all proposals to access state roads.
2. A county driveway or access permit is required for all proposals to access the county road system.
3. A county permit is required for road construction purposes in the county's right-of-way.
4. No city permit is required if construction is incident to the installation of required subdivision or site plan improvements.
(b) Access limitations.
1. No new residential development shall create any parcels zoned for single-family or duplex residential uses having access on an arterial.
2. Parcels created after adoption of this chapter building on an arterial street, or collector, shall have a minimum of 300 linear frontage feet in order to gain access to the arterial, unless one of the following conditions is met:
a. Access to the lot is provided jointly through existing cuts of an adjacent property.
b. Access to the lots is to be provided from a frontage road paralleling the arterial which has been planned and officially approved by the City Commission.
c. For corner parcels access will be provided to the collector facility where only minimum arterial frontage requirements are satisfied.
(H) Minimum design standards. All streets which are to be established within a subdivision shall meet the following minimum design standards.
(1) Where a subdivision abuts or contains an existing or proposed arterial street, the applicant shall provide one or more of the following: reverse frontage lots with a planting screen contained in a non- access reservation along the rear property lines, deep lots with rear service alleys, fences, or any other treatment necessary for adequate protection of residential properties, and to afford separation of through and local traffic.
(2) Streets shall be laid out to intersect as nearly as possible at right angles. Street jogs at intersections with centerline offsets of less than 150 feet shall be prohibited. Multiple intersections involving the juncture of more than two streets shall be prohibited. A minimum sight distance of 200 feet from any intersection shall be maintained on the intersecting streets. This requirement shall not be construed as requiring an increase in the minimum allowable intersection separation of 150 feet.
(3) For minimum pavement widths, types and thicknesses, see division (I).
(4) For minimum right-of-way width, see division (D).
(5) The minimum distance between reverse curves is 320 feet.
(6) The minimum centerline radii for horizontal curves, required where centerline deflection angle exceeds 2 degrees, are as follows:
Type of Street | Radii (feet) |
Arterial
|
600
|
Commercial Collector
|
200
|
Residential Collector
|
100
|
Local
|
75
|
(7) Vertical curves are required on all streets where vertical grade changes exceed 0.5%.
(8) For percent grade of roadway centerline, see division (I).
(9) Cul-de-sacs.
(a) Cul-de-sac streets shall not exceed 800 feet in length, including the turnaround, without special approval of the City Commission where due to unusual circumstance, a greater length may be deemed necessary. Said approval shall be conditioned upon the provision of an alternative route of ingress and egress for the entire length of the cul-de-sac street in order to ensure that each potential development lot or parcel is alternatively accessible. Where no practicable alternative access is available additional roadway width and/or laneage may be required as deemed necessary to ensure public safety.
(b) Cul-de-sacs shall be provided with a turnaround having a minimum outside roadway diameter of 80 feet, and a minimum street property line diameter of at least 106 feet for streets with closed drainage, or 126 feet for streets with open drainage (swales). All cul-de-sacs shall be designed in such a manner that they shall not interfere with the turning radius of fire apparatus. Variations of these measurements may be granted upon review and approval by the City Commission.
(10) Street stubs to adjoining unplatted areas shall be provided when required to give access to these areas or to provide for proper traffic circulation. Street stubs in excess of 250 feet shall be provided with a temporary cul-de-sac turnaround. The developer of the adjoining area shall pay the cost of restoring the street to its original design cross-section, extending the street.
(11) Half streets shall be prohibited, except where a previously platted half street, improved or unimproved, abuts a tract to be subdivided. The second half of the street shall be platted within the tract being subdivided and improved as required.
(12) Street names shall not be used which will duplicate or be confused with the names of existing streets. However, new streets which are an extension of, or in alignment with, existing streets shall bear the same name as that borne by the existing streets. All courts and circles shall have one name only. All names shall be approved by the City Commission.
(13) Alleys shall have a minimum right-of-way width of 20 feet.
(I) Standards.
(1) Improvements shall conform to the following:
(a) Standard A, for industrial subdivisions.
(b) Standard B, for commercial or high-density residential subdivisions of nine dwelling units per gross acre.
(c) Standard C, for medium- density residential subdivisions of four or more but less than nine dwelling units per gross acre.
(d) Standard D, for low-density residential subdivisions of less than four dwelling units per gross acre.
(2) Where the proposed subdivision includes or abuts an existing platted street, the street shall also be improved as required to conform to this schedule. This requirement shall not apply to any abutting street which is not connected with the proposed subdivision's street system unless lots in the proposed subdivision front on the streets.
(3) Street improvements shall be provided as required by the following schedule.
(a) Grading and centerline gradients.
1. Maximum allowable percent grade.
A 6
B 8
C D 10
2. Minimum allowable percent grade.
A B 0.30
C D 0.24
A B C D (b) Arterial streets. Two 24-foot pavements with a minimum 16-foot median. The developer shall be required to install the second 24-foot pavement only in large subdivisions where the projected average daily traffic generated on the arterial by the subdivision exceeds 7,000.
(c) Collector streets.
A 1. Thirty-six foot minimum pavement width.
B 2. Thirty-six-foot minimum pavement.
C D 3. Twenty-four-foot minimum pavement.
(d) Local streets.
A 1. Thirty-six foot minimum pavement width.
B C D 2. Twenty-four-foot pavement.
A B C D (e) Marginal access streets. Twenty four-foot pavement.
A B C D (f) Curb and gutters.
1. Type A, B, C, or D curb. (see Figure 1. All streets shall have curb and gutter or ribbon curb for edge protection, and swales shall have Type C curb for edge protection.
2. Type A, B, or C curb may be used in somewhat poorly drained to very poorly drained soils.
3. Any drainage crossing at an intersection must have the design approved by the city. If approved by the city, concrete valley gutters shall be required for surface drainage across intersections or street pavements.
A B C D (g) Swales. With or without a type C curb as pavement-edge protection. Type C curb as a pavement-edge protection may be required in applications or locations where traffic conditions warrant its use as determined by the City Commission. Type C curb is required as a minimum at all curves having less than a 75- foot radius. Type C curb is required for Standard A streets.
(h) Subgrade.
A B Subgrade shall be 12 inches thick and stabilized to a bearing of 75 p.s.i.
C D Subgrade shall be ten inches thick and stabilized to a bearing value of 75 p.s.i.
(i) Pavement base. Limerock preferred for curbed streets with a closed drainage system and where groundwater conditions will satisfy the permit. Soil cement is preferred for roads without a closed drainage system.
A B C D 1. Arterials. Eight-inch compacted limerock or soil cement, or the equivalent, approved by the City Engineer as meeting standards established by the City Commission.
2. Collector, local, and marginal-access streets.
A B a. Eight-inch compacted limerock or soil cement or the equivalent as approved by the City Engineer, and meeting standards established by the City Commission.
C D b. Six-inch compacted limerock or soil cement or the equivalent as approved by the City Engineer, and meeting standards established by the City Commission.
A B C D (j) Wearing surface.
1. On all arterial and collector roadways and all roadways in commercial or industrial subdivisions, the wearing surface shall be constructed no less than two inches thick in any place with a tolerance of one-fourth inch.
2. On all local and residential roadways, the wearing surface shall be constructed no less than one and one-half (1-1/2) inches thick in any place with a tolerance of one- fourth (1/4) inch and an absolute minimum thickness of one and one-quarter (1- 1/4) inches compacted thickness.
A B C D (k) Grassing, mulching, or sodding. As required by the City Commission for swales, parkway medians, percolation areas, easements, drainage outlets, and stream bank and planting strips, in accordance with current city standards.
A B C D (1) Street names signs. At all intersections, street name signs shall be the equivalent or better with respect to legibility and durability, and approved by the City Commission.
A B C D (m) Minimum lateral clearance to roadside obstruction shall be six feet from edge of pavement.
A B C D (n) Street trees. Street trees shall be the responsibility of the builder, and shall be planted prior to final inspection of the building.
A B C D (o) Street lighting. Per plans approved by the city, and acceptable to the utility company which will maintain the system.
A B C D (p) All street and drainage improvements shall be constructed in accordance with the city's street construction specifications, or if none have been adopted, in accordance with the materials and construction methods outlined in the State Department of Transportation, "Standard Specifications for Road and Bridge Construction," latest edition.
A B C D (q) For two years from issuance of the certificate of completion, the developer shall be responsible for the maintenance of all facilities in public rights-of-way and easements.
(J) Curb and gutter. All streets shall have curb and gutters or ribbon curb for edge protection, and swales shall have a Type C curb for edge protection.
(1) The width of the curb and gutter shall be as shown in Figure 1. Simple vertical curbing will not be acceptable to the city. Approved surmountable median curb State Department of Transportation-type may be used around median dividers on the high side of pavement. All curbing designed to handle water shall incorporate an approved gutter design. There shall be a stabilized subgrade beneath all curbs and one foot beyond the back of curb.
(2) No water valve boxes, meters, manholes, or other appurtenances of any kind relating to any underground utilities shall be located in any portion of a curb and gutter section.
(3) The minimum allowable flow line grade of curbs and gutter shall be 0.24%, except in intersections where flatter grades shall be allowable. The tolerance for ponded water in curb construction is one-fourth inch maximum; if exceeded, the section of curb shall be removed and reconstructed to grade.
(4) Plastering shall not be permitted on the face of the curb. Joints shall be sawed (unless an approved alternate method is used) at intervals of ten feet, except where shorter intervals are required for closures, but, in no case, less than four feet.
(5) After concrete has set sufficiently, but, in no case, later than three days after construction, the curbs shall be backfilled.
(6) All cross-street valley gutters where allowed by the city shall be constructed of concrete.
(K) Swales. Swales are to be encouraged and used, based on functional classification, in excessively-drained and somewhat excessively-drained to moderately well-drained soils, except where closed drainage is required in this appendix.
(Ord. 241, passed 11-27-85; Am. Ord. 344, passed 12-3-87; Am. Ord. 640, passed 6-3-93; Am. Ord. 959, passed 12-2-99; Am. Ord. 1642, passed 6-17-21) Penalty, see § 23