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Home My WebLink About2005-03-07; Traffic Safety Commission; ; Investigate the need for a STOP sign on Rancho Cortes at its intersection with Carrillo Way( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: March 7, 2005 LOCATION: INITIATED BY: Rancho Cortes at Carrillo Way Ladi Hamer, a Carlsbad resident ITEMNO. 6A REQUESTED ACTION: Investigate the need for a STOP sign on Rancho Cortes at its intersection with Carrillo Way. BACKGROUND: Rancho Cortes intersects Carrillo Way in a T-intersection configuration. This intersection is located in a residential area with Rancho Cortes being the stem of the T-intersection (see Exhibit 1). No STOP signs have been installed to assign the right-of-way at this intersection. DATA: Rancho Cortes and Carrillo Way are both local streets and neither is classified on the Circulation Element of the General Plan. For each request for STOP signs, staff conducts a traffic study. 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 the installation of a STOP sign on the minor street is when the safe approach speed to the intersection is less than 16 km/h (10 miles per hour). The safe approach speed is typically evaluated when there is a request to install a STOP sign 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. Drivers approaching an uncontrolled intersection have the right-of-way assigned 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. A driver on the minor street (stem of the T) when approaching the major street reaches a decision point when braking to a stop is necessary if there is another vehicle approaching the intersection on the major street. The decision point on the minor street must allow the driver to view to the right and to the left, an approaching vehicle on the major street. The driver on the minor street, generally not having the right-of-way, can then slow, stop, or avoid a conflict with other vehicles, as necessary, when the proper clear sight triangle is provided (see Exhibit 2). ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: March 7, 2005 ( continued) ITEMNO. 6A For local streets, the minor street decision point is assumed to be 50 feet from the intersection for an approach speed of 10 miles per hour. In general, a distance of 155 feet (stopping sight distance for 25 mph) along the major (local) street needs to be provided to view vehicles approaching the intersection. However, when the grade of the major street exceeds 3 percent, grade adjustment factors are applied to the sight distance. In this case, the major street grade is 8.2% west and 7.7% east of the intersection. Therefore, an adjusted distance of 140 feet looking to both the west and the east is necessary for the minor street driver to view vehicles approaching the intersection. If the major street vehicle cannot be seen from the decision point on the minor street, a STOP sign can be considered for installation on the minor street. For the subject location, the driver on the minor street, Rancho Cortes, can adequately view approaching major street (Carrillo Way) vehicles when the eastbound vehicle is approximately 165 feet west of the intersection. However, approaching vehicles from the east cannot be seen when they are 140 feet east of the intersection. A driver can only see approximately 135 feet to the east on Carrillo Way from Rancho Cortes due to the horizontal and vertical alignment of Carrillo Way. Consequently, the 10-mile per hour safe approach speed criteria is not being met and a STOP sign can be considered for installation on Rancho Cortes, the minor street. In general, the prevailing speed on a local road is higher than the prima facie 25 mile per hour speed limit. Carrillo Way has a posted speed limit of 25 miles per hour. Staff has observed that many westbound drivers on Carrillo Way are traveling between 31 miles per hour and 36 miles per hour as they approach the intersection of Rancho Cortes. As indicated on Exhibit 3 and Exhibit 4, the required stopping sight distance for 31 miles per hour and 36 miles per hour is 210 feet and 260 feet, respectively. As for the case with an assumed 25 mile per hour speed on Carrillo Way, the clear approach sight triangle results in only 135 feet of actual stopping sight distance being available on Carrillo Way. Because the 10 mile per hour safe approach speed criteria is not met for the higher westbound Carrillo Way operating speeds, a STOP sign can be considered for installation on Rancho Cortes, the minor street. Staff observed driver behavior on northbound Rancho Cortes on December 1, 2004 as the vehicle approached Carrillo Way and made either a right or a left tum in the morning (7: 15am -8:15am). Field observations of a total of 18 vehicles found that of the 15 right-turning vehicles, four vehicles "stopped" (slowed to a speed less than 10 mph), and of the three left-turning vehicles, all three "stopped" (slowed to a speed less than 10 mph) before turning. The results indicate that 39% of the vehicles on Rancho Cortes turning onto Carrillo Way were considered "stopped" (slowed to a speed less than 10 mph) before turning the comer during this time period. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: March 7, 2005 (continued) ITEMNO. 6A Staff conducted additional studies and observations of driver behavior on northbound Rancho Cortes on February 1, 2005 and February 10, 2005 as the vehicle approached Carrillo Way and the driver turned right or left. The additional studies consisted of an evening peak hour (5:00pm -6:00pm) turning movement count and driver behavior observations and an off-peak hour (10:30am -11:30am) turning movement count and driver behavior observations. During the evening peak hour, field observations of a total of 27 n01thbound vehicles on Rancho Cortes found that of the 19 right turning vehicles, 10 "stopped" (slowed to a speed less than 10 mph) and of the eight left-turning vehicles, seven "stopped" (slowed to a speed less than 10 mph) before turning to Carrillo Way. Results indicate that 63% of the vehicles on Rancho Cortes turning onto Carrillo Way were considered "stopped" (slowed to a speed less than 10 mph) before turning the corner during the evening peak hour. During the off-peak hour, field observations of a total of 14 n01thbound vehicles on Rancho Cortes found that of the 10 right-turning vehicles, three "stopped" (slowed to a speed less than 10 mph) and of the four left-turning vehicles, all four "stopped" (slowed to a speed less than 10 mph). Results indicate that 50% of the vehicles on Rancho Cortes turning onto Canillo Way were considered "stopped" (slowed to a speed less than 10 mph) before turning to Carrillo Way during the off-peak hour. There have been no reported collisions at the Rancho Cortes/Carrillo Way intersection since it was constructed and opened to traffic approximately five years ago. RECOMMENDATION: The Traffic Safety Coordinating Committee recommends installing a STOP sign on Rancho Cortes at its intersection with Carrillo Way. NECESSARY CITY COUNCIL ACTION: The City Council will have to adopt an ordinance to establish the STOP sign as recommended. ( LOCATION MAP CARRILLO RANCHO CORTES LEGEND: 0 PROPOSED STOP SIGN LOCATION NOT TO SCALE PROJECT NAME EXHIBIT PROPOSED STOP SIGN 1 DRA'MJ BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 12 10 04 C: 1RAmc STOP SIGNS STOP SIGN-CARRILLO-RANCHO CORTE:SI.DWG 140' REQUIRED (MAJOR STREET) CARRILLO WY. REQUIRED LINE OF SIGHT NOT TO SCALE (MAJOR STREET) CARRILLO WY. 165' ACTUAL (MINOR) \STREET CF) 50' ~ a:: a (.) ~ <: ~ (MINOR) \STREET 50' DECISION POINT 140' REQUIRED 135' ACTUAL DECISION POINT TITLE CARILLO WAY I RANCHO CORTES INTERSECTION APPROACH SIGHT TRIANGLE FOR 25 MPH DRA'ltN BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 12 10 04 C: TRAFFIC STOP SIGNS STOP SIGN-CARILLO-RANCHO CORTES2.DWG NOT TO SCALE EXHIBIT 2 NOT TO SCALE (MAJOR STREET) CARRILLO WY. ( ( 210' REQUIRED 135' ACTUAL DECISION POINT TITLE CARILLO WAY I RANCHO CORTES INTERSECT/ON APPROACH SIGHT TRIANGLE FOR 31 MPH DRAVtN BY: SCOTT EVANS, CARLSBAD ENGINEERING .DEPT. 12 10 04 C: TRAFAC STOP SIGNS STOP SIGN-CARILLO-RANCHO CORTES2.DWG EXHIBIT 3 NOT TO SCALE (MAJOR STREET) CARRILLO WY. ( ( ~ 260' REQUIRED ___ 135' ACTUAL __ ►1 50' U) ~ a:: a (.) a t5 I I I I I I I I I ~ (MINOR) a:: \STREET TITLE CARILLO WAY /RANCHO CORTES INTERSECTION APPROACH SIGHT TRIANGLE FOR 36 MPH DRAWN BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 12 10 04 C: TRAFFIC STOP SIGNS STOP SIGN-CARILLO-RANCHO CORTES2.0WG EXHIBIT 4