Residents living near Highway 97 in Weed recently asked a Caltrans associated transportation planner to lower the 50 miles per hour speed limit along the highway from Weed to beyond Angel Valley to prevent accidents. They were told, in essence, it's not that simple.

Although reducing posted speed limits seems like an obvious solution to slow down drivers and make roads safer, it isn’t that simple.

Speed limits cannot be lowered just because residents want people to drive slower on streets near their homes. The California Department of Transportation’s 2014 Manual for Setting Speed Limits states that when speed limits are arbitrarily set low, it can make “violators of a disproportionate number of drivers, does not facilitate the orderly movement of traffic, and requires constant enforcement to maintain compliance.”

Recently residents living near Highway 97 in Weed asked Aaron Casas, a Caltrans Associated Transportation Planner, to lower the 50 miles per hour speed limit along the highway from Weed to beyond Angel Valley to prevent accidents.

Residents voiced their concerns during a Caltrans information-gathering meeting in Weed while Casas took notes to include those concerns in an update of the 2003 Highway 97 Transportation Concept Report.

Sharon Ray said during the meeting that she knows several people who have been killed in vehicle accidents in the area where Lincoln Avenue and Hoy Road intersect with Hwy 97. “If you would reduce the speed, you would reduce the death rate,” she said.

Weed City Council member Stacey Green, who lives in the same area as Ray, said he also knows people who have been killed there.

Casas explained that the speed limit can not be reduced without conducting a speed study, called an Engineering and Traffic Survey. However, he said, the study could result in the speed limit going up.

Caltrans public information officer Denise Yergenson wrote in an email that the 50 mph speed zone on Hwy 97 has been in place since 1996 (as far back as their records go).

She wrote that the “prevailing speeds” in the 50 mph zone and the other two zones (40 mph and 30 mph) have been “consistently higher than what is posted and collision history has been lower than statewide average for similar facilities.”

According to a Caltrans handout, the California Vehicle Code sets the maximum speed in California at 55 miles per hour, except where posted at 65 or 70 on freeways.

Statutory prima facie speed limits, meaning “on the face of it,” established by the Vehicle Code include the 15 mph limit for alleys, blind intersections, and blind railroad crossings. A 25 mph limit applies to business and residental districts, school zones, playgrounds in parks, and senior centers.

Speed limits between 25 and 55 are intermediate speed zones and require a speed study to establish the intermediate prima facie speed.

Yergenson wrote that the studies are valid for seven years, but can be extended three years if “roadside and conditions and traffic volumes have not significantly changed.”

Scott Waite, Siskiyou County’s Public Works Director, conducts speed studies on the county’s roads.

He said he has conducted unofficial speed studies for constituents, and they usually show the speed limit should be raised.

“People want us to do them all the time,” Waite said, “but typically speed limits are lower than what they should be.”

Waite said they do speed surveys every five years. If they expire, then the speed limit is not valid and a speeding ticket might not hold up in court.

Mount Shasta California Highway Patrol Public Information Officer John Tomlinson explained they make sure all the speed surveys are up to date everywhere CHP enforces.

According to the Caltrans Manual for Setting Speed Limits, the intermediate speed limit is determined by prevailing speeds, which is the free flow speeds of vehicles used to determine the 85th percentile speed.

It explains that of 100 vehicles plotted, the “85th percentile speed is determined by looking at the speed of the 15th vehicle down from the top speed. Fifteen percent of the vehicles are travelling faster than this speed, and eighty-five percent are traveling at or below this speed.”

Although the survey considers collision history, which could justify a 5 mph reduction of the speed limit, the manual explains that accidents need to be investigated to determine if they are related to the posted speed.

Weed Police Chief Martin Nicholas said accidents on Hwy 97 were caused by drivers failing to stop at stop signs coming from side streets, drivers traveling faster than the posted speed, and a person who was standing in the roadway.

He said these accidents could not be factored into the collison history, since they did not happen because someone was driving the posted speed limit.

Tomlinson said speed cannot be ruled out as a factor in accidents, but the major factors are inattention and distraction.

“A lot of it comes down to the responsibility of the driver,” he said.

Tomlinson said most drivers just look 30 feet or less out in front and follow too close behind the vehicle ahead of them.

People are in their own bubble and not looking far enough ahead or anticipating a problem, he said.

Waite said he reviews all the accident reports for county roads, and many accidents involve people who don’t live in the area, drinking and driving, and distracted driving.

He said people from out of the area are unfamiliar with local roads and driving conditions.

The Caltrans manual states that speed limits set near the 85th percentile speed are “safer and produce less variance in vehicle speeds,” while setting speed limits too high or too low can “increase collisions.”

This is based on the idea that a “reasonable speed limit is one that conforms to the actual behavior of the majority of drivers” and that limit can be determined by measuring drivers’ speeds.

Waite said, “People drive the speed that they’re comfortable with.”

Tomlinson said it can also be considered a speed trap. “We don’t endorse or support or condone artifically lowered speed limits (speed traps),” he said.

A speed limit may also be reduced from the 85th percentile speed by 5 mph for “non-apparent conditions” such as bicycles, pedestrians, vehicles, and intersections not readily visible to drivers. However if the speed limit has been reduced 5 mph due to the collision rate, it cannot be lowered another 5 mph for non-apparent conditions.

Nicholas remembers a 2013 speed study conducted by the county on College Avenue in Weed that calculated the 85th percentile speed at 34 mph. Instead of posting it at 35, the limit was reduced to 30 mph because of a park, college, and high pedestrian use in the area.

Caltrans has the authority to set speed limits on state highways. Cities and counties are responsible for roads under their jurisdiction.