By Sheryl Hamlin
According to the staff report of Tai Chau, City Engineer, the following State mandate must be followed:
The California Vehicle Code (CVC) Section 22357 requires posted speed limits on collector and arterial roadways be established and justified by an Engineering and Traffic Survey (E&TS). Per the CVC Section 40802, the Engineering and Traffic Survey needs to be updated every seven (7) years for the posted speed limits to be enforceable.
Thai Chau reiterated the State mandates as found in this document which involve calculating the 85th percentile. He appeared to conflate percentages with percentiles, as does the State document, which is incorrect. Read here: Percentages versus Percentiles. A percentile is a value on a curve, while a percentage is the relation of that number to the rest of the curve. For example, a median is the point at which 50% of the data fall above and 50% fall below.
A percentile breaks down when the data set is small (less than 20), is bi-modal (two humps) or flat (no humps).
Traffic Study Recommends Increased Speed Limits
In support of the State mandate, the city hired Wildan Engineer to complete a traffic study of the city. The results are as follows. Note the increases in speeds:
There were no public comments on this item. Were the neighborhoods not noticed?
Council Member Sobel, also conflating percentages with percentiles, asked if we drive faster every seven years, will the speeds increase?
Tai Chau answered affirmativly stating that there is a “natural speed limit” around the 85th percentile.
Council Member Crosswhite stated that Steckel between Main and Santa Paula is congested, has no middle line with parking on both sides and is a residential street. So why increase the speed limit?
Vice Mayor Jaurez said the street conditions are not amenable to increasing speeds.
Mayor Araiza asked why no stop sign at Bradley and Santa Paula Street? This has been the scene of fatalities. He stated that never in 30 years has he seen such results and questioned the firms’s methodology. There are so many holes in this report, he said,
Ish Cordero, Acting SPPD Chief, said the increase in the congested streets is ridiculous. Why no input from SPPD?
Vice Mayor Juarez noted that the last study was in 2014, so technically Santa Paula has until 2021 for the next study.
Rather than rejecting the entire study, which would have been appropriate in this case, the council voted to approve without segments 29,33, 12, 9 and added a stop sign at Santa Paula and Bradey.
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