PROPOSED STREET SYSTEM
4.3 INTERSECTION IMPROVEMENTS
Generally the cross-sections described in the previous sections are adequate for signalized intersections. However, there are two situations in which the road needs to be wider at a signalized intersection to accommodate all of the lanes necessary for the efficient movement of traffic. These two situations are at the intersection of two arterial streets and at a signalized intersection involving a minor collector. Each of these is described in more detail below.
4.3.1 Arterial-Arterial Intersection
The typical cross-section at the intersection of two arterial streets needs to be widened or flared out to accommodate the dual left-turn lanes typical of such intersections. The pavement width, as measured from lip of gutter to lip of gutter, needs to be expanded from 81 feet to 96 feet for a net increase of 15 feet. This additional width is taken equally from both sides of the street, 7.5 feet from each. The length of the left and right turn pockets should be at least 200 feet long.
When combined with the taper length, the distance from the stop bar to the beginning of the widening should be about 350 feet.
The intersection widening will also affect the park strip and sidewalk treatments depending on whether the arterials are being constructed as an in-fill project or in a previously undeveloped area. The in-fill construction with its typical 106-foot right-of-way and its 5-foot park strips and sidewalks will be widened to a 113-foot right-of-way with 6-foot sidewalks and no park strips.
Using the park strip as part of the area to be widened reduces the amount of extra right-of-way needed.
The new construction in previously undeveloped areas with its 126-foot total width and its 10-foot park strips and sidewalks will not have any increase in total width. The 7.5 feet of widening can occur within the 10-foot park strip, leaving 2.5 feet to be added to the sidewalk, since 2.5 feet is too small for a park strip. These concepts are shown in Figure 4.3.1 with the top half of the page depicting in-fill construction and the bottom half showing new construction in a previously undeveloped area.
4.3.2 Minor Collector Signalized Intersection
The signalized intersection of a minor collector and an arterial or major collector also needs to be widened or flared out to accommodate the right turn lane of the minor collector. No changes are necessary to either the arterial or the major collector. The pavement width, as measured from lip of gutter to lip of gutter, needs to be expanded from 41 feet to 48 feet for a net increase of 7 feet.
This additional width is taken entirely from the side of the street with the right turn pocket. No changes are required on the other side of the street. The length of the left and right turn pockets should be at least 100 feet long. When combined with the taper length, the distance from the stop bar to the beginning of the widening should be about 250 feet.
The intersection widening will affect the park strip and sidewalk treatments. The 66-foot right-of-way and its 5-foot park strips and sidewalks will be widened to a 69-foot right-right-of-way with a 6-foot sidewalk and no park strip on the side being widened. Using the park strip as part of the
PROPOSED STREET SYSTEM
377940
FINAL REPORT DECEMBER 2003 Page 4 - 19
West Jordan Master Transportation Plan
ENGI NEERS PL ANNERS ECON OMI STS Wilbur Smith Associates
RICHARD D CHONG AND AS SOCIATE S InterPlan Co.
Tran spo rta tio n Pla nn in g
area to be widened reduces the amount of extra right-of-way needed. This concept is shown in Figure 4.3.2.
Typically, an intersection between two minor collectors will not need to be signalized. However, it is recommended that widening take place in those locations as well. This will provide adequate capacity, regardless of the method of traffic control.
4.3.3 Intersection Radii
The radii on the corners at each intersection will vary according to the types of facilities that are crossing. The table below shows the recommended radius for each scenario. All measurements are listed for the distance in feet from the center of the curve to the top of the back of the curb (TBC).
Table 4.3.1 Intersection Corner Radii
Arterial Major
Collector
Minor Collector
Residential
Collector Local Street
Arterial 40' 40' 35' 25' 25'
Major Collector 40' 35' 30' 25' 25'
Minor Collector 35' 30' 30' 25' 25'
Residential
Collector 25' 25' 25' 25' 25'
Local Street 25' 25' 25' 25' 25'
Note: All measurements are for the TBC.
As shown in the table, larger radii are recommended for larger intersections, while smaller radii are proposed for the smaller intersections. The larger radii are necessary to accommodate truck traffic, buses, and delivery vehicles, which also allows for higher speeds around corners for passenger vehicles. In the future, West Jordan may wish to utilize even smaller corner radii on the local streets, which will act as a traffic calming device, forcing vehicles to slow down when turning a corner.
96'
48' 48'
113' 81'
53' 53'
12' 12'12'12'12'12'12' 12' 13' 12' 12' 12' 12'
10' 10'
12' 12'12'12' 12' 12'
12' 12'
126'
126'
12'12'13'12'12'
10' 10'
IN-FILL CONSTRUCTION
PREVIOUSLY UNDEVLOPED
5' PARK STRIP
& SIDEWALK 5' PARK STRIP
& SIDEWALK
6' SIDEWALK
10' PARK STRIP
& SIDEWALK 10' PARK STRIP
& SIDEWALK
(Top Half of Page)
(Bottom Half of Page)
106'
12.5' SIDEWALK
200' MIN.
(NTS)
150' (NTS)
ARTERIAL STREET
ARTERIAL
200' MIN.
(NTS) 150' (NTS)
STREET
Scale: 1" = 80'
4.3.1 Typical Arterial-Arterial Intersection
48' 27.5' 20.5'
69'
33' 36'
100' MIN.
11'11'11' 15' 8.5'12'
33' 33' 41'
12'8.5'
48' 20.5' 69'
36' 33'
11' 11'
11' 15'
27.5' 5' PARK STRIP
& SIDEWALK
5' PARK STRIP
& SIDEWALK
66'
6' SIDEWALK
5' PARK STRIP
& SIDEWALK 20.5' 20.5'
5' PARK STRIP
& 5' SIDEWALK
20.5'
100' (NTS)
COLLECTOR STREET
MINOR
ARTERIAL OR MAJOR
COLLECTOR
88' MIN.
100' (NTS)
Scale: 1" = 80'
Figure 4.3.2 Typical Minor Collector Intersection
PROPOSED STREET SYSTEM
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FINAL REPORT DECEMBER 2003 Page 4 - 22
West Jordan Master Transportation Plan
ENGI NEERS
Presently the West Jordan City street network exists only to the east of State Route 111 and is only partially complete to the west of Bangerter Highway. With growing development occurring west of 5600 West, West Jordan will soon need to extend their east west and north south streets to accommodate the traffic growth as it develops in these areas. The extensions of 7800 South and 9000 South across New and Old Bingham Highway, respectively are highway improvements for which planning is already underway. With these new street extensions, it is West Jordan City’s desire to maintain a half-mile grid pattern and intersections at typical ninety-degree angles. These types of improvements to the future street network will help reduce possible congestion on the major city streets by providing more alternate routes.
A preliminary network of arterial and collector streets along with their functional classifications was mapped out through meetings with the consultant team and city staff. In the future it was assumed that the Mountain View Corridor (MVC) would
be built. The MVC is currently undergoing environmental study by UDOT. A goal of the City is to de-emphasize Old and New Bingham Highway and maintain a grid-system of arterials and collectors following the section and mid-section lines as much as is possible. UDOT is also very supportive of this and the City and UDOT will
continue to work together on this goal. This will require the closure of some portions of Old and New Bingham Highway. This will largely be accomplished as development occurs; however, it may be necessary for the city to fill in some of the pieces since before a street can be closed the alternate route needs to be completely in place.
The travel demand model was run using this preliminary roadway network and the 2030 traffic conditions, and volume-to-capacity ratios were recorded for each arterial and collector. Some changes to the preliminary functional classifications were then made, primarily in the west. For example, some streets that were initially assumed as major collector were found to function adequately as minor collectors. The result is the future (2030) recommended roadway network for West Jordan as shown in Figure 4.4.1.
The future traffic conditions along the arterial and collector streets were once again generated using the revised roadway network. These traffic volumes were then compared with the estimated capacity for each segment in order to calculate the future volume-to-capacity ratios.
As can be expected, the majority of the major streets in the eastern portion of the city are expected to be at or exceeding their capacity. The volume-to-capacity ratios generally tend to improve progressively from east to west and north to south. The estimated 2030 volumes and capacities for the arterial and collector streets are shown in Table 4.4.1 followed by Figure 4.4.2, which shows the resultant volume-to-capacity ratios graphically.
Mountain View Corridor (MVC) A proposed freeway on the western edge of Salt Lake County that would connect to I-80 in the north and Utah County in the south.
(Formerly known as the Western Transportation Corridor).