[Zoning Order §7.160, 4-2-2008]
Access management entails providing (or managing) access to land development while simultaneously preserving the flow (safety, capacity and speed) of traffic on the surrounding road system. Benefits that arise from the implementation of access management guidelines include less interruptions and congestion in traffic flow, improved roadway safety and maintaining roadway capacity.
[Zoning Order §7.170, 4-2-2008]
A. 
Functional classification is the process by which all roadways and streets are grouped into classes according to the type of service that they are intended to provide. There are three (3) basic highway functional classifications: arterial, collector and local roads and streets. All roads and streets are grouped into one (1) of these classes, depending on the character of the traffic and the degree of land access that they allow.
B. 
Roadways that are a part of the public road system are functionally classified as an integral system regardless of jurisdictional control of those roads/streets. The classification process does not consider administrative or jurisdictional systems (state, County or City). Roads are separated into different functional classification systems by their geographic location in rural, small urban or urbanized areas.
C. 
Functional classification defines the nature that any particular street should play in serving the mobility and access functions within a transportation network. Urban and rural areas have fundamentally different characteristics, such as density and types of land use, density of highway and street networks, nature of travel patterns and the way in which all these elements are related. In some rural circumstances with sparse roadway networks, many of the County-maintained roads may serve a dual role, providing primary local access and regional mobility.
[Zoning Order §7.180, 4-2-2008]
A. 
Following is the functional classification system for the roadway system in unincorporated Jefferson County based on the regional network as defined by East West Gateway Council of Governments. The Public Works Department maintains an index of the individual roads/streets or segments and their functional classifications.
1. 
Principal arterial. Principal arterials are stratified into three (3) distinct classifications: interstates, freeways and other principal arterials with limited access control. Principal arterials shall not consist of local subdivision streets and shall be public Federal, State or County-maintained facilities. A principal arterial facilitates substantial County-wide and inter-County travel; in addition, virtually all urbanized areas and other significant population centers are served by principal arterials.
2. 
Minor arterial. The minor arterial system provides linkage between cities and towns and is a critical component of an integrated, County-wide roadway network. A minor arterial serves an urban area if it penetrates or comes within one (1) mile of the urban area boundary (adapted from Federal Highway Administration. Highway Functional Classification: Concepts, Criteria and Procedures, Section II, July, 1974).
3. 
Collector. A collector serves urban areas and other traffic generators of importance that are not served by higher systems and are generally maintained and operated by the Federal or State government. These roadways function to connect these areas of significant traffic generation with nearby towns or with routes of higher classification.
4. 
Local County. Local County-maintained roads connect locally important traffic generators with the less developed parts of the County. These facilities collect traffic from other local roads and streets. Local County roads shall not be located within residential subdivisions for reasons of public safety.
5. 
Major local access. Major local access streets are subdivision streets constructed and maintained by the subdivision or other development. These streets act as mini-collectors within subdivisions. Thus, direct access from individual lots to the streets should be minimized and parking within the through travel lanes should be restricted where feasible.
6. 
Local access. The local access street system is comprised of all other facilities not included on one (1) of the higher systems. Local access streets are subdivision streets constructed and maintained by the subdivision or other development. Within the context of the rural functional classification system, local streets enable travel over short distances and provide direct access to adjacent land.
7. 
Local access alley. The local access alleys are dedicated public rights-of-way or private easement that afford a secondary means of access to abutting property and are not intended for general traffic circulation. Local access alleys are constructed and maintained by the subdivision or other development.
[Zoning Order §7.190, 4-2-2008; Ord. No. 20-0406, 9-29-2020; Ord. No. 25-0117, 2-4-2025]
A. 
This code is intended to address typical design guidelines and minimum requirements for the major local access streets, local access streets and local access alleys constructed and maintained by the subdivision or other development. This code does not pertain to County roads and other highways maintained by various public agencies.
B. 
Horizontal alignment of streets at an intersection should be as near as possible a right angle as topography and other geographic features allow.
C. 
If, after review by the Planning Division, it is determined that there is no alternate location that does not conflict with the offset required by this UDO or Chapter 515 of the Code of Ordinances of Jefferson County, and that adequate sight distance may be achieved, the Director may approve an entrance, street, or driveway location without the need for a deviation or modification. The Director shall notify the Planning and Zoning Commission of approvals granted pursuant to this Section.
[Zoning Order §7.195, 4-2-2008; Ord. No. 07-30-2008A §§1 — 2(7.195), 7-30-2008]
In order to approximate the daily number of trips generated by a solely residential development, trip generation rates from the ITE Trip Generation Manual based on number of dwelling units should be used. The table below shows the approximate daily traffic volumes based on the number of residential units that the street serves.
Table 7-3. Trip Generation Estimates
Daily Traffic Volume
Dwelling Units Served
Less than 400
Under 50 dwelling units
400 — 1,519
50 — 189 dwelling units
1,520 — 1,999
190 — 249 dwelling units
2,000 — 2,500
250 — 315 dwelling units
Over 2,500
Over 315 dwelling units
Trip generation for non-residential or mixed development shall be determined using the ITE Trip Generation Manual. The most current version of the ITE Trip Generation Manual shall be used.
[Zoning Order §7.200, 4-2-2008; Ord. No. 11-12-2008A §§1 — 2(7.200, Tbls. 7-4 — 7-5), 11-12-2008]
Table 7-4. Minimum Design Standards for Two-Way Streets
Type of Street
Vehicles per Day
Drainage Type
Minimum Shoulder Width, if used
Total Improved Surface Width**
Minimum ROW***
No Parking
Parking — one side
Major local access
>2,500
a/b
8'
26'
36'
32'
Local access street
2,000 — 2,500
b
NA
26'
34'
32'
1,520 — 1,999
b
NA
24'
28'
30'
400 — 1,519
a/b
5'
22'
28'
28'
<400
a/b
2'
20'
28'
26'
Local access alley
<400
a
0'
14'
26'
0'/20'****
a
Open, streetside drainage swales or ditches are allowed for streets adjacent to residential lots one (1) acre in size or larger.
b
Curbs and gutters are required
**
All pavement measurements taken from back of curb to back of curb if present. Total improved surface width includes shoulders, where present. Where permitted, the shoulder areas can also accommodate all or part or the required parking lane width(s). If parking is added to the second (2nd) side, add seven (7) feet to the surface width.
***
Minimum right-of-way shall be three (3) feet behind back of curb on both sides, required sidewalks and any open drainage may be located within right-of-way or easement.
****
Right-of-way: Zero (0) feet for private access alleys, twenty (20) feet for dedicated public access alleys.
Figure 7-1 Major Local Access Street (> 2,500 vehicles per day) with curbs but no parking (not to scale)
Figure 7-2 Local Access Street (2,000 — 2,500 vehicles per day) with curbs and parking on one (1) side (not to scale)
Figure 7-3 Local Access Street (400 — 1,519 vehicles per day) with curbs but no parking (not to scale)
Table 7-5. Minimum Design Standards for One-Way and Median Divided Streets
Type of Street
Vehicles per Day
Drainage Type
Minimum Shoulder Width, if used
(left/right)
Total Improved Survace Width**
Minimum ROW***
No Parking
Parking — one side
Major local access
>2,500
a/b
4'/8'
15'
25'
21'
Local access street
2,000—2,500
b
NA
13'
24'
19'
1,520—1,999
b
NA
13'
24'
19'
400—1,519
a/b
2'/5'
13'
24'
19'
<400
a/b
0'/2'
13'
24'
19'
Local access alley
<400
a
0'/0'
10'
24'
0''/20'****
a
Open, streetside drainage swales or ditches are allowed for streets adjacent to residential lots one (1) acre in size or larger.
b
Curbs and gutters are required
**
All pavement measurements taken from back of curb to back of curb if present. Total improved surface width includes shoulders, where present. Where permitted, the shoulder areas can also accommodate all or part or the required parking lane width(s). If parking is added to the second (2nd) side, add seven (7) feet to the surface width.
***
Minimum right-of-way shall be three (3) feet behind back of curb on both sides, required sidewalks and any open drainage may be located within right-of-way or easement.
****
Right-of-way: Zero (0) feet for private access alleys, twenty (20) feet for dedicated public access alleys.
[Zoning Order §7.205, 4-2-2008; Ord. No. 07-30-2008A §§1 — 2(Tbl. 7-7), 7-30-2008; Resolution 1-14-2010A Exh. A, 1-14-2010; Ord. No. 10-0145 §§1 — 2, 2-18-2010; Ord. No. 16-0100 §2, 1-4-2016; Ord. No. 20-0406, 9-29-2020]
Every access shall be designed to carry a weight load of at least an HS20 design vehicle (AASHTO). Alternative methods of pavement design may be approved only by the Planning Commission with a recommendation from the Public Works Department and shall not be less than the structural equivalency of the street type in Table 7-6 by Traffic Volume Category. In the absence of a pavement construction standard in this UDO, the standards shall be in accordance with the St. Louis County Standard Specifications for Highway Construction and the Design Criteria for the preparation of Improvement Plans in effect as of the date of the adoption of this UDO as stated in Section 400.110. The following two (2) tables provide requirements for pavement thickness based on daily traffic volume.
Table 7-6. Pavement Thickness
Traffic Volume Category
Pavement Type
Concrete1
Asphalt2
Combination2, 3
Alt. Option4
Heavy/Industrial (HI)
Concrete
8
Asphalt surface
2
2
Asphalt base
7
Concrete base
7
Rock base
4
4
4
High Volume (HV)
Concrete
7
Asphalt surface
2
2
Asphalt base
6
Concrete base
6
Rock base
4
4
4
Medium Volume (MV)
Concrete
6
Asphalt surface
2
2
Asphalt base
5
Concrete base
5
Rock base
4
4
4
Low Volume (LV)
Concrete
6
Asphalt surface
2
2
Asphalt base
4
Concrete base
5
Rock base
4
4
4
Very Low Volume (VLV)
Concrete
6
Asphalt surface
2
2
3
Asphalt base
3
Concrete base
5
Rock base
4
4
4
8
1
All concrete streets shall be a six (6) sack mix with four thousand (4,000) p.s.i., twenty-eight (28) day strength. A three (3) inch slump is the maximum. Details shall be subject to approval by the County.
2
Thickness is of compacted asphalt. For asphalt streets, no layer shall have a compacted thickness of greater than four (4) inches.
3
For combination pavement, all concrete shall be a five and one-half (5½) sack mix with a four thousand (4,000) p.s.i., twenty-eight (28) day strength. A three (3) inch slump is the maximum. Details shall be subject to approval by the County.
4
Alternative Option may only be used in the "RA-5" and "LR-2" zone districts for developments less than fifty (50) lots and with each lot being four (4) or more acres in size. Any proposed alternative method shall not have less than three (3) inches of asphalt.
Table 7-7. Daily Traffic Volume by Zone District
Zone District
Daily Traffic Volume
<400
400 — 1,519
1,519 — 2,500
>2,500
"RA-5"
VLV
LV
MV
HV
"LR-2"
VLV
LV
MV
HV
"R-40"
VLV
LV
MV
HV
"R-20"
VLV
LV
MV
HV
"R-10"
VLV
LV
MV
HV
"PR-1"
VLV
LV
MV
HV
"PR-2"
VLV
LV
MV
HV
"NC-1"
LV
MV
MV
HV
"PC"
LV
MV
MV
HV
"CC-2"
LV
MV
HV
HV
"PB"
LV
MV
HV
HI
"NPI"
MV
HV
HV
HV
"PI"
HV
HV
HV
HI
VLV
=
Very Low Volume
LV
=
Low Volume
MV
=
Medium Volume
HV
=
High Volume
HI
=
High Volume
Streets in the "PM" District shall use the most applicable pavement type based upon use (residential, commercial, etc.) and daily traffic volume.
[Zoning Order §7.210, 4-2-2008]
Table 7-8. Additional Design Standards for Streets
Type of Street
Maximum percent grade of a street
Minimum horizontal radius of curve
Minimum length of vertical curve
on a street in feet
Minimum length of tangent between horizontal reverse curves
Minimum length
Feet for each algebraic difference in grade (K factor)
Major local access
12%
100 feet
75 feet
but not less than
30 feet
100 feet
Local access
14%
100 feet
50 feet
but not less than
20 feet
0 feet
Local alley access
14%
50 feet
50 feet
but not less than
10 feet
0 feet
[Zoning Order §7.205, 4-2-2008; Resolution 1-14-2010A Exh. A, 1-14-2010; Ord. No. 10-0145 §§1 — 2, 2-18-2010]
Where two (2) streets intersect, the curb at each intersection shall be rounded with a radius as indicated below.
Table 7-9. Intersection of Functionally Classified Streets
Type of Street
Minimum Corner Radius
Local Access Alley
to
Any Street
5'
Local Access or Major Local Access
to
Local Access or Major Local Access
15'
Local Access or Major Local Access
to
County Maintained Street
30'
NOTE: Measurement taken at back of curb.
[Zoning Order §7.240, 4-2-2008; Ord. No. 11-12-2008A §§1 — 2(7.240), 11-12-2008; Resolution 1-14-2010A Exh. A, 1-14-2010; Ord. No. 10-0145 §§1 — 2, 2-18-2010; Ord. No. 25-0117, 2-4-2025]
A. 
Proper lines of sight shall be maintained at all intersections and driveways. Traffic on streets classified as alley access, local access and major local access streets shall be required to stop or yield at intersections with other alley access, local access and major local access streets or higher classification streets and roads.
B. 
The minimum sight clearance is determined by the distance that must be kept clear for visibility of approaching vehicles from the stopping point to the distance along the midpoint of the approaching travel lane, measured three (3) feet above the pavement surface. (These requirements are for level conditions; for grade adjustments a more detailed analysis of a particular situation may be necessary.) Determination of the minimum sight distance should generally follow MoDOT standards as follows:
1. 
Both vertical and horizontal alignment can limit sight distance. In order to measure actual sight distance limited by horizontal or vertical alignment, place a sighting target four and one-fourth (4.25) feet above the edge of pavement at a point twelve (12) feet from the edge of pavement (approximate location of a driver approaching the street, three (3) feet right of the adjacent left lane line) at the proposed driveway location. Sighting from a height of three and one-half (3.5) feet, move along the cross street away from the proposed driveway location to a point beyond where the target disappears. Now move toward the target until it can first be seen and place a mark on the main street pavement. Measure the distance along the cross street between the mark and the target. Measurement may be made with an accurate measuring device mounted on an automobile. This measured distance is the intersection sight distance (per the MoDOT Permitting Manual, pages 17 — 19).
Figure 7-4 Intersection Clear Sight Distance
In the case of vertical sight distance, a minimum one (1) foot clearance between the direct line of sight and the crest of the roadway is required. If the determination is impractical to measure in the field, it must be demonstrated on a design plan sheet illustrating a cross section view of sight distance as described above.
2. 
Stopping sight distance shall be determined by Chapter 515 of the Code of Ordinances of Jefferson County.
a. 
No building or other type of visual obstruction shall be placed, erected or maintained within the sight triangle. Street trees, certain types of vegetation, poles and posts are allowed within the sight triangle, provided that they do not have any foliage, limbs or other obstructions between three (3) and ten (10) feet above ground level, are not more than fifteen (15) inches in diameter and are not closer than thirty-five (35) feet to the intersecting pavement edge. Certain types of decorative fences are also allowed within the sight triangle provided that their design allows a clear view to be maintained throughout the clearance area and are not placed closer than thirty-five (35) feet to the intersecting pavement edge lines at intersection corners. These requirements are applicable to intersections with rounded corners.
b. 
At roundabout intersections, the clear vision area shall include all points twenty-five (25) feet distant from the pavement edge lines of the outside curves.
c. 
Within the triangular area formed by lines thirty-five (35) feet in length along the pavement edges of intersecting streets or a driveway intersecting the right-of-way of a street, from their point of intersection, no landscaping or screening materials, signs, parked vehicles or other objects, other than essential directional signs, traffic control devices and utility structures approved by the County, shall interfere with the line of sight between a height of three (3) feet and ten (10) feet above the adjoining street or driveway pavement.
Figure 7-5 Intersection Corner Sight Clearance Triangle
C. 
Nothing in this Section shall be construed to allow placement of objects in the street right-of-way.
[Zoning Order §7.250, 4-2-2008; Ord. No. 11-12-2008A §§1 — 2(7.250), 11-12-2008; Resolution 1-14-2010A Exh. A, 1-14-2010; Ord. No. 10-0145 §§1 — 2, 2-18-2010]
Below are the standards for the minimum and maximum width of drives and driveways for multi-family residential and non-residential uses, subject to approval of the applicable State or County agency. For one- and two-family developments, the maximum driveway width at the right-of-way line (exclusive of radii at the corners) is twenty-four (24) feet. Type of developments for driveway requirements are based upon the daily traffic volume in Table 7-7 and shall be designed as follows:
Table 7-11. Minimum and Maximum Width of Driveway by Type and Volume of Use (excluding radii) for Multi-Family Residential and Non-Residential Uses
Type of Development
Minimum Width
Maximum Width
Multi-Family Residential
One-way access
Per plan
30'
Two-way access
Per plan
39'
Low Volume
One-way access
20' *
20' *
Two-way access
26' **
42' **
Medium Volume
One-way access
20' *
30' **
Two-way access
36' ***
54' ****
High Volume/Heavy Industrial
One-way access
24' *
30' *
Two-way access
36' ***
60' *****
*
One lane
**
Two lane
***
Three lane
****
Four lane
*****
Five lane
The minimum width for a driveway required by Table 7-11 shall extend the entire throat length as required per Section 400.2630.
Where non-residential or multi-family residential developments enter onto a State or County maintained street, the entrance pavement that is located in the State or County right-of-way is subject to Section 400.2560, Street Standards — Minimum Pavement Standards for pavement thickness and Section 400.2610, Driveway Requirements — Width for pavement width.
[Zoning Order §7.260, 4-2-2008; Resolution 1-14-2010A Exh. A, 1-14-2010; Ord. No. 10-0145 §§1 — 2, 2-18-2010; Ord. No. 16-0100 §2, 1-4-2016]
Driveway corner clearance is the distance between a street and the first (1st) driveway accessing a street classified below intersecting with the street. For street corner clearance affecting State or Federally maintained streets, MoDOT and/or Federal Highway (FHWA) standards shall be used. For other scenarios, Table 7-12 provides guidance on the required driveway corner clearance.
Table 7-12. Driveway Corner Clearance
Type of Street
"RA-5", "LR-2", "R-40", "R-20", "R-7", "R-10", "PM", "PR-1", "PR-2"
"NC-1", "PC", "CC-2", "PB", "NPI, "PI"
County
125'
125'
Major local access
None
50'
Local access
None
40'
Local alley access
None
30'
Corner clearance shall be measured from the edge of the travel lane to the edge of driveway.
Figure 7-6 Driveway Corner Clearance
[Zoning Order §7.270, 4-2-2008; Resolution 1-14-2010A Exh. A, 1-14-2010; Ord. No. 10-0145 §§1 — 2, 2-18-2010]
A. 
The throat length is the driveway distance between the street and the parking lot served or the first (1st) accessible interior drive. An adequate throat length helps to keep traffic conflicts within a parking lot to a minimum and provides space on the driveway for incoming and outbound traffic.
1. 
Low traffic volume non-residential and multi-family residential driveways (below one hundred fifty (150) peak hour vehicles in both directions): The minimum throat length is twenty (20) feet.
2. 
Medium traffic volume non-residential and multi-family residential driveways (one hundred fifty (150) to four hundred (400) peak hour vehicles in both directions): The minimum throat length is forty (40) feet.
3. 
High traffic volume non-residential and multi-family residential driveways (over four hundred (400) peak hour vehicles in both directions): The minimum throat length is sixty (60) feet.
Figure 7-7 Throat Length
[Zoning Order §7.280, 4-2-2008; Ord. No. 16-0100 §2, 1-4-2016]
Sidewalks requirements shall be based on the need for sidewalks in the area as well as maintaining and extending existing sidewalk networks. Sidewalks shall at a minimum be constructed in the following areas:
Table 7-13. Sidewalk Requirements
Type of Street
Zoning
Sidewalk Requirement
Local access alley
All zones
None
Local access street
Residential built at 1 unit (or less) per acre
None
Residential built at more than 1 unit per acre
One side of street
"PR-1", "PR-2"
Per plan
"NC-1", "CC-2"
Both sides of street
"PC", "PM", "PB"
Per plan
"NPI"
None
"PI"
Per plan
Major local access street
Residential built at 1 unit (or less) per acre
None
Residential built at more than 1 units per acre
Both sides of street
"PR-1", "PR-2"
Per plan
"NC-1", "CC-2"
Both sides of street
"PC", "PM", "PB"
Per plan
"NPI", "PI"
None
Sidewalks shall be constructed of concrete five (5) feet wide unless otherwise specified in this Article.