Chapter 29.20
RESIDENTIAL AND COMMERCIAL STREETS, LANDSCAPING AND TRAFFIC CALMING

Sections:

29.20.010    Street standards.

29.20.020    Residential and commercial streets.

29.20.030    Block and lot dimensions.

29.20.040    Right-of-way, street lane widths, and street lengths.

29.20.050    Cul-de-sacs and dead end streets.

29.20.060    Alignments.

29.20.070    Vertical alignment.

29.20.080    Cross section.

29.20.090    Stopping sight distance.

29.20.100    Bicycle treatments.

29.20.110    Intersections.

29.20.120    Unsignalized intersections.

29.20.130    Signalized intersections.

29.20.140    Angles.

29.20.150    Grades.

29.20.160    Spacing and offsets.

29.20.170    Intersection sight distance.

29.20.180    Sight zones.

29.20.190    Pedestrian treatments.

29.20.200    Landscaping – Sight distance at intersections.

29.20.210    Traffic calming.

29.20.220    Methods to divert traffic from residential streets.

29.20.230    Methods to slow traffic on residential streets.

29.20.240    Methods to slow traffic at intersections.

29.20.250    Traffic calming in new developments.

29.20.010 Street standards.

Geometric street standards have been developed to provide livability for residents, safety for both vehicular and pedestrian traffic and efficient movement. This chapter sets the minimum standards for geometric design of residential streets and commercial streets. These streets deserve special discussion because they are the most common streets built for development. “Local residential streets” and “commercial streets” are defined as streets whose primary function is to serve the abutting land use. Design criteria for both horizontal and vertical alignments are established in this chapter. Design criteria for collector and higher classification streets are discussed in Chapter 29.28 GJMC.

(Res. 39-04 (§ 5.0), 4-21-04)

29.20.020 Residential and commercial streets.

Streets shall conform with the adopted Grand Junction Circulation Plan. Minimally, the plan identifies locations where collector street connections are desired and identifies general alignments for residential streets. Street layouts shall continue streets in adjoining subdivisions or their anticipated locations when adjoining property is not yet developed to provide interconnectivity.

(Res. 39-04 (§ 5.1), 4-21-04)

29.20.030 Block and lot dimensions.

Blocks shall not exceed 1,200 feet in length between intersections (streets providing multiple access, not cul-de-sacs) except where topography, traffic, or other conditions require longer blocks.

No lots shall be divided by street, alley, or any other thoroughfare or property, or by City boundary lines.

(Res. 39-04 (§ 5.1.1), 4-21-04)

29.20.040 Right-of-way, street lane widths, and street lengths.

The required right-of-way width for a street is stated in the City Standard Details. Additional widths may be required for needed through lanes, turn lanes, speed change lanes, and where it is necessary to accommodate slopes, irrigation crossings and drainage structures.

(a)    Urban Residential Collector.

(b)    Urban Residential Street.

(c)    Commercial Street Section.

(d)    Industrial Street Section.

(e)    Rural Roadway.

(f)    Two-Way Shared Use Off-Street Path on Separate Right-of-Way.

(g)    Cul-De-Sac Turnaround – Residential Court.

(h)    Cul-De-Sac Turnaround – Minimum Dimensions – Commercial/Industrial Court.

(Res. 39-04 (§ 5.1.2), 4-21-04)

29.20.050 Cul-de-sacs and dead end streets.

No cul-de-sac shall be more than 750 feet long, measured from the center of the intersection to the center of the turnaround.

No more than 30 lots shall be located on a cul-de-sac street. All cul-de-sacs shall have a turnaround at the terminus point.

Surface drainage of a cul-de-sac shall be conveyed toward the intersecting street, if possible, and if not possible a drainage easement shall be provided leading out of the cul-de-sac.

Fire Department access standards contain additional details to assist developers and designers in meeting the requirements of the Fire Department.

Single access street systems shall be allowed for a maximum of 100 dwelling units. The layout of the subdivision shall meet sections D104.3 and D107 of the International Fire Code. A future secondary access is required to be platted as public right-of-way and constructed to public street standards to the property line of the subdivision. A temporary turnaround shall be constructed if the stub street access is longer than 150 feet.

(Res. 39-04 (§ 5.1.3), 4-21-04)

29.20.060 Alignments.

(a)    Horizontal Alignment. Designs must conform to the pattern of thoroughfares designated in the Grand Junction Circulation Plan. Proposed streets align with existing or platted streets with which they are to connect.

    Local streets (if not ending in a cul-de-sac) shall extend to the boundary lines of the project. A temporary turnaround area paved with asphalt surfacing shall be required at the end of the street improvement if a cul-de-sac is not provided. Proposed streets with widths different from existing streets to which they are being connected must be transitioned using the pavement transition taper standards.

(b)    Curve Radii.

(1)    All curve designs shall be based on the horizontal curve design criteria.

Horizontal Curve Design Criteria

Design Criteria

Local1

Hillside2

Residential

Industrial/
Commercial

Design Speed (mph)

20

25

30

Center3 Line Radius (ft.)

100

150

300

Horiz. Sight Dist. (ft.)

150

200

200

Reverse Curve Tangent (ft.)

0

0

0

Approach4 Tangent at Intersections

50

75

100

1    These criteria are to be used without superelevation.

2    Hillside is defined as having grades of 10 percent or greater, as defined in GJMC 21.07.020.

3    Radii shown are based on the street having a crown section with a pavement cross-slope of two percent on each side of the crown.

4    Where a curved road approaches an intersection, these tangent sections must be provided on the approach to the intersection to provide for adequate sight distance for traffic control devices at the intersection. The distance shall be measured from the flowline of the through street.

(2)    Intersections shall meet minimum flowline radii at public street intersections.

Minimum Intersection Flowline Radii

Through Street2

Intersecting Street

Arterial

Collector

Local Residential

Local Commercial

Local Industrial1

Local Residential

Not Allowed

25′

20′

 

 

Local Commercial

30′

30′

20′

30′

30′

Local Industrial

 

30′

 

30′

30′

1    Radii at intersections with industrial streets shall be designed on a case-by-case basis considering the turning requirements for the type of truck that will most commonly use the street.

2    At signalized intersections where right-turn channelization islands are provided or high truck and bus volumes may use the access, a larger flowline radius may be required.

(c)    Tangent Distance Between Curve. There is no minimum tangent distance between curves for residential or commercial street design.

(d)    Superelevation. Superelevation is not allowed on residential street curves.

(Res. 39-04 (§ 5.1.4), 4-21-04)

29.20.070 Vertical alignment.

(a)    Grades. Design grades and vertical sight distance address drainage and/or safety concerns for vehicles and pedestrians. Grades of streets shall not be less than 0.5 percent, nor more than eight percent. In hilly terrain (defined as having grades of 10 percent or greater, as defined in GJMC 21.07.020), the maximum grade for local residential streets is 12 percent for a maximum distance of 500 feet.

(b)    At unsignalized intersections, the maximum grade in the intersection shall be four percent, and extends a minimum of 50 feet in each direction from flowline of the intersecting street. At signalized intersections, the maximum grade shall be two percent within the intersection and extend for 200 feet in each direction. When intersecting with State highways, refer to Section 4 of the State Access Code.

(Res. 39-04 (§ 5.1.5), 4-21-04)

29.20.080 Cross section.

(a)    Street Cross Slopes. The typical cross slope is two percent crown to provide for adequate drainage to the pavement edge. The maximum cross slope shall not exceed four percent. The minimum cross slope shall be one percent. Typical sections are shown in the City Standard Details.

(b)    Roadside Barrier and Bridge Rails. Roadside barriers shall be required in accordance with warrants, design criteria and standards for roadside barriers and bridge rails as defined in the AASHTO Roadside Design Guide, 1989 Edition or latest.

(Res. 39-04 (§ 5.1.6), 4-21-04)

29.20.090 Stopping sight distance.

“Stopping sight distance” is defined as the length of roadway ahead visible to the driver. The minimum stopping sight distance available on a roadway must be sufficiently long to enable a vehicle traveling at or near the roadway design speed to stop before reaching a stationary object in its path or react to a traffic control device such as a stop sign.

The appropriate stopping sight distance shall be provided. The distances shown assume vehicles traveling on wet pavement on flat grades. Factors that take into account the effect of grade on stopping sight distance shall be used in determining appropriate stopping sight distance where the grades are three percent or higher.

(Res. 39-04 (§ 5.1.7), 4-21-04)

29.20.100 Bicycle treatments.

Bicycle facilities shall be provided in accordance with the adopted Grand Junction Circulation Plan. Provisions for bicycle facilities shall be in accordance with the AASHTO Guide for Development of New Bicycle Facilities 1999.

The standard cross-section of off-street bicycle paths is shown in the City Standard Details.

(Res. 39-04 (§ 5.1.8), 4-21-04)

29.20.110 Intersections.

There are two general types of intersections: unsignalized and signalized. Each of these shall have several different configurations and levels of traffic control. A roundabout is a form of an unsignalized intersection and is specifically discussed in GJMC 29.28.220. All intersection design shall conform to the guidelines set forth in AASHTO and the MUTCD.

(Res. 39-04 (§ 5.2), 4-21-04)

29.20.120 Unsignalized intersections.

There are two appropriate levels of traffic control at unsignalized intersections: two-way stop controlled and all-way stop controlled. The appropriate use of each of these is discussed in the following sections.

(a)    Two-Way Stop Controlled Intersections.

(1)    Two-way stop controlled intersections shall be installed in new subdivisions.

(2)    Stop signs shall be installed in accordance with the MUTCD.

(3)    At intersections of two different types of roadways, a stop sign shall be used on the minor street to stop the lesser flow of traffic. Stop signs will generally be used at all intersections that do not meet the all-way stop control or traffic signal warrants.

(b)    All-Way Stop Controlled Intersections. An all-way or “multi-way” stop installation shall be used only as warranted in Part II of the MUTCD.

(Res. 39-04 (§ 5.2.1), 4-21-04)

29.20.130 Signalized intersections.

Signals will not normally be considered for residential streets or commercial streets. Where signals may be warranted, the criteria in GJMC 29.28.130 shall be followed, and documented in a transportation impact study.

(Res. 39-04 (§ 5.2.2), 4-21-04)

29.20.140 Angles.

Public streets shall intersect at 90-degree angles or as close to 90 degrees as topography permits, in any event no less than 80 degrees. Intersections on horizontal curves shall be avoided.

(Res. 39-04 (§ 5.2.3), 4-21-04)

29.20.150 Grades.

Intersections shall be on grades as flat as practical. At unsignalized intersections, the maximum allowable grade in the intersections is four percent and extends a minimum of 50 feet in each direction from the outside edge of the traveled way of the intersecting street. At signalized intersections, the maximum grade is two percent within the intersection and extends 200 feet in each direction. Grades above four percent will only be allowed on local and collector streets in areas with steep topography or other unusual circumstances that prevent a flatter grade, and must be documented as a design exception.

(Res. 39-04 (§ 5.2.4), 4-21-04)

29.20.160 Spacing and offsets.

(a)    Commercial Streets. Four-legged intersections shall be spaced at least 150 feet apart. Where T-intersections are used, the centerlines of streets not in alignment shall be offset a minimum of 100 feet and be 100 feet from the nearest four-legged intersection. If the left-turn storage requirements for adjacent intersections overlap, the minimum spacing must be increased to provide adequate left-turn storage in both directions. If exclusive turn lanes are required, the design shall conform to the criteria in GJMC 29.28.170(b).

(b)    Local Residential Streets. Four-legged intersections shall be spaced at least 300 feet apart. Where T-intersections are used, the centerlines of streets not in alignment shall be offset a minimum of 150 feet.

(Res. 39-04 (§ 5.2.5), 4-21-04)

29.20.170 Intersection sight distance.

Street intersections and private access to public streets shall be planned and located to provide as much sight distance as possible. At a minimum, there must be sufficient sight distance for the driver on the minor street or driveway to cross or turn onto the intersecting street. Minimum sight distance values are provided for passenger cars turning left or right from a minor street. When grades are steeper than three percent, adjustment factors must be applied.

The operating speed on each approach is assumed to be, in order of desirability, (a) the eighty-fifth percentile speed, (b) the speed limit if based on an engineering study, or (c) in the case of a new facility, 80 percent of the design speed.

(Res. 39-04 (§ 5.2.6), 4-21-04)

29.20.180 Sight zones.

Within the sight zone there shall be no sight-obscuring sign, wall, fence, berming, or other object higher than 30 inches, or in the case of trees, no foliage lower than eight feet. Vertical measurement shall be made from the flowline of the adjacent gutter or, if no gutter exists, from the edge of the nearest traveled way. Objects that may be located in the sight zones are items such as hydrants, utility poles, and traffic control devices. These shall be located to minimize visual obstruction.

(Res. 39-04 (§ 5.2.6.1), 4-21-04)

29.20.190 Pedestrian treatments.

In order to provide pedestrian safety, accommodations for pedestrians shall be designed into all intersections where pedestrians are expected to be present. This includes sidewalks, crosswalks, pedestrian refuge islands and accessible ramps. The design shall meet the details specified in the City Standard Details.

(Res. 39-04 (§ 5.2.7), 4-21-04)

29.20.200 Landscaping – Sight distance at intersections.

Any landscaping in the sight distance triangles at intersections shall be low growing, and shall meet the sight distance requirements in GJMC 29.20.180.

(Res. 39-04 (§ 5.3), 4-21-04)

29.20.210 Traffic calming.

According to the Institute of Traffic Engineers (ITE), “Traffic calming is the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users.” This differs from standard traffic control devices such as stop signs, which are regulatory. Traffic calming strategies are engineered to be self-enforcing physical measures.

GJMC 29.20.210 through 29.20.250 provide guidance for appropriate applications of traffic calming on the existing street system, as well as the application of traffic calming measures during the planning and design stages of new subdivisions.

(Res. 39-04 (§ 5.4), 4-21-04)

29.20.220 Methods to divert traffic from residential streets.

Residents frequently complain that their residential street is being used by high speed and/or cut-through traffic. One treatment of the traffic is the use of closures, diverters, and one-way treatments.

(a)    Street Closure. Streets may be closed to give drivers no choice but to travel another route; residents are given access only. A street closure is the most drastic form of traffic calming and shall be carefully considered before implementation. Street closures can very often lead to traffic problems on nearby streets as drivers are re-routed to other routes. One of the benefits of this type of method of calming is a fully walkable neighborhood.

(b)    Street Diverters. A street diverter can also be considered a partial street closure. With a diverter, traffic traveling in one direction is not given access to a street. This drawing shows the most common form of street diversion, where vehicles are allowed ingress and egress through single access points rather than from either direction. As with street closures, implementation of diverters may shift traffic to another street where access is not regulated.

(c)    One-Way Streets. One-way streets may be effective in decreasing the number of vehicles traveling on a given roadway. Traffic patterns shall be assessed to determine the effects of a one-way street on a given circulation pattern. Although traffic volumes are generally decreased by one-way treatments, speeds can often increase as drivers are channelized through the street.

(Res. 39-04 (§ 5.4.1), 4-21-04)

29.20.230 Methods to slow traffic on residential streets.

Where speed is the recognized problem, the following methods can be effective in slowing existing traffic on residential and collector streets:

(a)    Chokers. Research has shown that traffic moves slower on more narrow roads. Chokers reduce the width of a street by narrowing the road at a “choke point.” Depending on the road segment length, one or several chokers can be used.

(b)    Medians. A median can be installed on a street where width tends to encourage speed. Medians narrow the lanes, reducing the comfort of the driver while driving at higher speeds. Median treatments are particularly effective with landscaping.

(c)    Chicanes. A chicane is essentially half of a choker. A chicane is placed on one side of the road to narrow a lane of traffic. A chicane can be used singly but is usually placed as a series on both sides of the road.

(d)    Speed Humps/Speed Tables. Speed humps or tables are vertical measures to slow traffic. Rather than speed bumps, speed humps are designed to unobtrusively get vehicles to slow down. While a speed bump jolts a vehicle at any speed, a speed hump allows the vehicle to travel the speed limit with little effect.

(Res. 39-04 (§ 5.4.2), 4-21-04)

29.20.240 Methods to slow traffic at intersections.

(a)    Raised Intersections. Raised intersections are flat raised areas covering entire intersections, with ramps on all approaches and often with brick or other textured materials on the flat section.

(b)    Realigned Intersections. Realigned intersections are changes in alignment that convert T-intersections with straight approaches into curving streets meeting at right angles – a straight shot along the top of the T becomes a turning movement.

(c)    Traffic Circles. Traffic circles are set in the center of a four-way intersection to slow traffic coming from each direction. A traffic circle can be effective in creating a neighborhood gateway by providing a unique feature that can be creatively landscaped.

(Res. 39-04 (§ 5.4.3), 4-21-04)

29.20.250 Traffic calming in new developments.

Long, wide streets with limited parking will generally increase speeds. As new developments occur, traffic calming can be planned as a feature of the neighborhood to keep vehicle travel speed low for maximum livability and safety of all street users. In large developments and developments that connect to existing residential streets, designs to control speeds and volumes are required. Design features such as curvilinear streets, T-intersections and entry treatments can reduce the need for traffic calming devices such as speed humps and chokers. Generally, horizontal calming measures will provide greater efficiency and livability in new developments.

The design speed of residential streets shall be 25 miles per hour. The design of local streets shall include positive traffic calming measures and devices. Such measures and devices shall be sufficient to minimize the ability of the average motorist to exceed 25 miles per hour.

In general, traffic calming devices shall be required on new local streets with straight sections of street in excess of 300 feet in length or streets that connect to existing local street networks.

(Res. 39-04 (§ 5.4.4), 4-21-04)