City Council Regular Meeting, March 13th, 2023
On June 2, 2021, City Council approved the creation of Capital Improvement Project (CIP) PS 22-15 Citywide Engineering and Traffic Study.
An Engineering and Traffic Survey (Survey) is required by the California Vehicle Code (CVC), Sections 22357 through 22364 and 40800 through 40808, for the purpose of establishing legally enforceable speed limits for City roads.
Surveys need to be completed after one year of operation for newly constructed roads or every 7 years for existing roads. Existing Surveys can be extended for an additional 7 years if no significant changes have been made.
In order for Lathrop Police Department to legally enforce speed limits on local roadways, the City’s Speed Limit Ordinance and posted speed limits must match the recommendations contained in the survey prepared by a licensed traffic engineer.
Speed Survey: A technician records the speed of 100 or more freeflowing vehicles within a 3-hour period on the segment being studied. Unique environmental and physical characteristics of the segment (glare, proximity to schools, narrow roads, street parking, etc.) are noted.
Engineering and Traffic Survey: A California Registered Traffic Engineer processes the data to determine the 85th percentile speed.
Speed limits are set near the 85th percentile speed, which statistically represents one standard deviation above the average speed and establishes the upper limit of what is considered reasonable and prudent.
Recommended Speed Limit: Pursuant to the CVC, the Traffic Engineer rounds to the nearest 5 mph increment of the 85th percentile speed to determine the speed limit. Based on collision history and roadway characteristics, the Traffic Engineer can round down instead of up or take an additional 5 mph reduction only when rounding down from the 85th percentile. Justification for rounding down or taking a 5 mph reduction must be documented in the Study. Speed Trap Definition: A section of highway with a prima facie speed limit that is not justified by an engineering and traffic survey conducted within 5 years prior to the alleged violation and enforcement of the speed limit involves the use of radar or laser. CVC Section 40801: No peace officer shall use a Speed Trap to cite any person for any alleged violation of the CVC.
CVC Section 40803: No evidence as to the speed of a vehicle shall be admitted in any court under the CVC upon a charge involving the speed of a vehicle when the evidence is based upon or obtained from or by the use of a Speed Trap.
CVC Section 40804: In any prosecution under this code upon a charge involving the speed of a vehicle, an officer shall be incompetent as a witness if the testimony is based upon or obtained from the use of a Speed Trap.
14 newly constructed River Islands road segments
required surveys for the purpose of supporting a legally enforceable speed limit.
This Public Hearing is to consider the recommended
speed limits of the Surveys completed by the City’s
traffic engineering consultant, Crane Transportation
Group.
Recommended speed limits for City road segments,
all in River lslands:
SEGMENT NAME SEGMENT BEGIN SEGMENT END DESIGN
SPEED
PROPOSED
SPEED LIMIT
River Islands Pkwy. SJ River Bridge Somerston Pkwy. 35 45 River Islands Pkwy. Somerston Pkwy. Norbeck St. 40 45
Marina Dr. River Bend Dr. Somerston Pkwy. 25 25
Marina Dr. Somerston Pkwy. Taft Dr. 25 25
Academy Dr. River Bend Dr. Somerston Pkwy. 25 25
Academy Dr. Somerston Pkwy. Broadmoor Wy. 25 30
Lakeside Dr. Stewart Rd. Vega Park Roundabout 25 35
Lakeside Dr. Vega Park Roundabout Somerston Pkwy. 25 35 Lakeside Dr. Somerston Pkwy. Dell’Osso Dr. 25 35
Dell’Osso Dr. Mulholland Dr. River Islands Pkwy. 25 35
Dell’Osso Dr. River Islands Pkwy. Lakeside Dr. 35 45
Somerston Pkwy. Riverfront Dr. River Islands Pkwy. NONE 35 Somerston Pkwy. River Islands Pkwy. 800’ South of Lakeside Dr. 40 45 Commercial St. Marina Dr. Academy Dr. 25 30
Staff recommends City Council introduce an ordinance amendment to Section 10.08.030 of the Lathrop Municipal Code to establish the speed limits for the following road segments as listed below.
SEGMENT NAME SEGMENT BEGIN SEGMENT END DESIGN
SPEED
PROPOSED
SPEED
LIMIT
River Islands Pkwy. SJ River Bridge Somerston Pkwy. 35 45 River Islands Pkwy. Somerston Pkwy. Norbeck St. 40 45
Marina Dr. River Bend Dr. Somerston Pkwy. 25 25
Marina Dr. Somerston Pkwy. Taft Dr. 25 25
Academy Dr. River Bend Dr. Somerston Pkwy. 25 25
Academy Dr. Somerston Pkwy. Broadmoor Wy. 25 30
Lakeside Dr. Stewart Rd. Vega Park Roundabout 25 35
Lakeside Dr. Vega Park Roundabout Somerston Pkwy. 25 35 Lakeside Dr. Somerston Pkwy. Dell’Osso Dr. 25 35
Dell’Osso Dr. Mulholland Dr. River Islands Pkwy. 25 35
Dell’Osso Dr. River Islands Pkwy. Lakeside Dr. 35 45
Somerston Pkwy. Riverfront Dr. River Islands Pkwy. NONE 35 Somerston Pkwy. River Islands Pkwy. 800’ South of Lakeside Dr. 40 45 Commercial St. Marina Dr. Academy Dr. 25 30