The URL can be used to link to this page

Home My WebLink About2006-08-07; Traffic Safety Commission; ; Install a STOP sign on Geranium Street at its intersection with Mimosa Drive( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: August 7, 2006 LOCATION: INITIATED BY: Geranium Street at Mimosa Drive John Reiter 7248 Mimosa Drive Carlsbad, CA 92011 ITEMNO. 6A REQUESTED ACTION: Install a STOP sign on Geranium Street at its intersection with Mimosa Drive. BACKGROUND: Geranium Street intersects Mimosa Drive in a T-intersection configuration and is located in a residential area of south Carlsbad. Geranium Street is the stem of the T-intersection and Mimosa Drive is the top of the T-intersection (see Exhibit 1). No STOP signs have been installed to assign the right-of-way at this location. DATA: Geranium Street and Mimosa Drive are both local streets within the Rancho La Cuesta subdivision and neither is classified on the Circulation Element of the General Plan. These local residential streets are part of a circuitous "through-street" connection to Aviara Parkway to the north, El Camino Real to the east, and Batiquitos Drive to the west. Each STOP sign request received by staff results in a traffic study being undertaken. STOP signs can cause substantial inconvenience to drivers and should be used only where warranted. One of the conditions at an intersection that may warrant consideration of installing a STOP sign on the minor street is when the safe approach speed to the intersection is less than 10 miles per hour. The safe approach speed to the intersection on the minor leg is typically evaluated when there is a request to install a STOP sign only on the minor street at an intersection. The minor street at a T-intersection is generally considered to be the stem of the "T" with the major street being the top of the "T". For the purpose of this report, Geranium Street will be considered the minor street and the stem of the subject T-intersection and Mimosa Drive is assumed to be the top of the T-intersection. ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: August 7, 2006 (continued) ITEMNO. 6A Drivers approaching an uncontrolled intersection consisting of either three legs or four legs have right-of-way assignment based upon the rules of the road. However, the driver should have an unobstructed view of the entire intersection and sufficient length along the intersecting street for the driver to anticipate and avoid conflicts with approaching vehicles. When a driver on the minor street is traveling towards the major street, they reach a decision point where it is necessary to determine if braking to a stop is required because of a vehicle approaching the intersection that may constitute a conflict. The decision point on the minor street must allow the driver sufficient distance to view to the driver's right and left an approaching vehicle that is on the major street. The driver on the minor street, generally not having the right-of-way, can then initiate actions to slow, stop, or avoid a conflict with other vehicles, as necessary, when the proper clear sight triangle is provided (see Exhibit 2). For the analysis of local streets, the minor street decision point is assumed to be 50 feet from the intersection conflict point when the vehicle on the minor street has an approach speed of 10 miles per hour. In general, a distance of 155 feet (stopping sight distance for 25 miles per hour) along the major street must be provided to minor street drivers to view vehicles approaching the intersection. However, when the grade of the major street exceeds three percent, grade adjustment factors are applied to the minimum sight distance required. In this case, the major street centerline grade on Mimosa Drive is 8.0 % both north and south of the intersection. Therefore, an adjusted sight distance length of 170.5 feet looking to the north and an adjusted sight distance length of 139.5 feet looking to the south is necessary for the minor street driver to view vehicles approaching the intersection. If the vehicle on the major street cannot be seen from the decision point on the minor street, a STOP sign can be considered for installation on the minor street. At the subject intersection, the driver on the minor street, Geranium Street, has sight visibility limited to less than 170.5 feet, when looking to the north, and less than 139.5 feet, when looking to the south for vehicles approaching on Mimosa Drive. From the decision point on Geranium Street, a driver can only see approximately 155 feet looking to the north, and approximately 93 feet looking to the south on Mimosa Drive due to sight visibility limitations on the northeast and southeast comers of the intersection. Consequently, the IO-mile per hour safe approach speed criteria is not being met and a STOP sign can be considered for installation on Geranium Street. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: August 7, 2006 (continued) ITEMNO. 6A The limitations to sight visibility on the northeast and southeast comers are due to landscaping, which is directly linked to the 8% centerline grade of Mimosa Drive and the intersecting centerline grade of Geranium Street, affecting the grading of the lots and slopes on the two comers. On the northeast comer, the landscaping that limits sight visibility is located on private property on a slope at the comer. This landscaping would need to be removed and nothing other than ground cover planted and maintained on the slope in order to provide the minimum 170.5 feet of required sight visibility. On the southeast comer, the landscaping limiting sight visibility is located on both public and private property at the comer. The pad of the lot on the southeast comer is located down a slope below the elevation of Geranium Street. The private property owner has planted shrubs along Geranium Street and around the comer on Mimosa Drive along the top of and down the slope to screen view and provide privacy from Geranium Street. Extensive landscaping removals would be required around the comer on public property and down the slope on private property in order to provide the minimum 139.5 feet of required sight visibility. Landscaping removals would result in a loss of visual screening and privacy from Geranium Street for both of the private properties. These lots were subdivided in 1981 and easements for comer sight visibility/sight view corridor with height limitations were not provided on the subdivision map. The private property owners of each comer lot has not been contacted regarding the limited sight visibility and the landscaping removals that would be required to provide the minimum required sight visibility. Staff conducted limited observations of driver behavior on westbound Geranium Street as the driver approached Mimosa Drive to tum right or left. Field observations of a total of 27 westbound vehicles on Geranium Street found that of the 26 right-turning vehicles, 18 "stopped" (slowed to a speed less than 10 mph), and the one left-turning vehicle "stopped" (slowed to a speed less than 10 mph) before turning onto Mimosa Drive. Results indicate that 70% of the vehicles on Geranium Street turning onto Mimosa Drive were considered "stopped" (slowed to a speed less than 10 mph) before turning onto Mimosa Drive. RECOMMENDATION: The Traffic Safety Coordinating Committee recommends the installation of a STOP sign on Geranium Street at its intersection with Mimosa Drive. NECESSARY CITY COUNCIL ACTION: The City Council must adopt an ordinance to establish the STOP sign as recommended. LOCATION MAP I AV/ARA PKWY. D ----.J LEGEND: . 0 PROPOSED STOP SIGN LOCA T/ON ~ EXISTING STOP SIGN LOCATION PROJECT NAME • PROPOSED STOP SIGN m r ALGA RD. GERANIUM STREET AND MIMOSA DRIVE DRAVrN BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 7 17/06 C: TRAFFIC STOP SIGNS STOP SIGN-GERANIUM-MIMOSAI.DWG NOT TO SCALE EXHIBIT 1 NOT TO SCALE G:l ~ 0 lJ.J a:: LO oi I<") - G:l ~ 8 ...J a:: '<:( LO i2 ~ (._) '<:( ,._. LO LO - I I I I I ...J '<:( i2 (._) '<:( t<") 0) I . I I• 50• ~t-----'--,L ___ _ I• 50' ( DECISION POINT GERANIUM ST. /MINOR) ~STREET. REQUIRED LINE OF SIGHT REQUIRED LINE OF · SIGHT NOT TO SCALE DECISION POINT GERANIUM ST. MINOR) STREET TITLE GERANIUM STREET AT MIMOSA DRIVE INTERSECTION APPROACH SIGHT TRIANGLE DRAl'IN BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 11 17 04 C: TRAFFIC STOP SIGNS STOP S/GN-GERAN/Ul,H//l,/0SA2.DWG EXHIBIT 2