In Berkeley, where bicyclists share the road with motorists more often than in much of the nation, debate lingers over how to interpret and respond to the city’s bicycle accidents.

Data from the California Highway Patrol show that since 2001, more than 2,000 collisions in Berkeley have involved a cyclist — numbers that officials will analyze this year as they consider improvements to the city’s bicycle infrastructure.

For sophomore Brandon Atchley, however, this data doesn’t tell the full story. In less than two years of biking in the city, he has been involved in four collisions with vehicles — two of which were hit-and-runs. Neither, however, were reported to the police. Without knowing anything about the drivers who hit him, Atchley felt it would have been pointless.

Still, when examining solely reported incidents, the area near the intersection of Center Street and Shattuck Avenue, where he was hit, shows a high rate of bicycle collisions. Almost 20 percent of accidents there since 2001 — 12 in total — have involved a bicyclist.

Below is a map showing CHP data on bicycle collisions in Berkeley. Mouse over an intersection to populate the information box. The “absolute” toggle displays information about the number of bicycle accidents near an intersection, taking into account the severity of each collision. The “rate” toggle weighs the number of bicycle collisions against the total number of accidents near that intersection. Both the absolute and rate indices range from 0 to 100.

Overall, these collisions tended to cluster around Downtown Berkeley, near UC Berkeley’s campus and at other busy intersections along Ashby Avenue.

With 18 bicycle accidents since 2001, data show that the area near the intersection of Shattuck and University avenues has seen the most bicycle-involved collisions in absolute terms — but the intersection is among the busiest in Berkeley, with 164 total accidents in that time.

The area near the intersection at Dwight Way and Milvia Street, in contrast, has a high ratio of bicycle-involved collisions, with 17 of 35 accidents since 2001 involving bicycles. Other areas with high exposure ratios include the intersections of Alcatraz and College avenues and Euclid Avenue and Crystal Way.

Regardless of the numbers, the question of whether Berkeley is safe for bicyclists is contested by students, residents and others who debate the merits of Berkeley’s bicycle infrastructure and the awareness of its drivers — issues the city will examine as it updates its bike plan this year.

Playing catch-up

Berkeley ranks among the nation’s cities with the most bicycle commuters, with about 8.6 percent of its workers age 16 and over commuting by bicycle, according to a 2009-13 estimate from the American Community Survey.

In contrast, about 2.6 percent of workers in neighboring Oakland and 3.5 percent of workers in San Francisco commute by bicycle. Nationwide, the number is close to 0.6 percent.

In 1971, the city adopted a plan to promote bicycling and improve bicycle safety, making it one of the first cities in the nation to do so, said Eric Anderson, a transportation planner for the city.

That was about the time that countries such as Denmark, Sweden and the Netherlands, regarded as some of the most bike-friendly places in the world, began creating similar plans, according to Dave Campbell, the advocacy director for Bike East Bay.

“But whereas the Netherlands, Copenhagen and other places kept going, Berkeley stalled along the way,” Campbell said. “We didn’t pick it up again until the ’90s.”

In 2000, the city adopted an updated and expanded bicycle plan, which recommended a network of bicycle boulevards to provide low-traffic routes for cyclists. Riding on these bicycle boulevards, located on thoroughfares such as California Street and Channing Way, is intended to be less intimidating than biking on the city’s main streets.

The plan received an administrative update in 2005 but hasn’t seen a comprehensive update since 2000, according to Anderson.

Reflecting on collisions

But despite Berkeley’s large population of bicycle commuters and historical emphasis on cyclists, not everyone regards Berkeley as safe to ride.

“One of the biggest (challenges in) getting new riders on bikes is fear — and rightfully so,” said Jon Suzuki, a co-owner of the Missing Link Bicycle Cooperative.

In September, local cyclist Kurt Wehner died after a collision with a vehicle at the intersection of Spruce and Eunice streets. Of six accidents that occurred at that intersection from 2001 to mid-2014, four have involved bicycles, according to CHP data.

Wehner’s death reinvigorated dialogue about the safety of Berkeley’s streets, especially for bicyclists.

Most accidents — more than 80 percent — occurred in clear conditions, with about 12 percent in cloudy conditions and only about 3 percent in rain or fog. According to the data, the year with most bicycle-involved collisions was 2009, with more than 200. There have been more than 100 bicycle-involved accidents each year since 2001. In 2013 there were about 160.

In 2013, bicycle-related accidents accounted for 30 percent of documented injury collisions, according to Berkeley Police Department spokesperson Officer Jennifer Coats.

“Both my wife and I were hit by cars last year,” Suzuki said. “I’ve been riding and living here for two decades, and in some ways, I’m surprised this didn’t happen sooner.”

Although both bicyclists and motorists break rules, Suzuki said, the blame is usually placed on the bicyclist. He added that he experiences “near misses every single day” and that the problem is only getting worse because of driving distractions.

According to Coats, bicyclists were found at fault in 55 percent of 2013 collision records. The top four primary collision factors were failing to yield right of way, unsafe speed, unsafe turning movement and unsafely opening a vehicle door into the roadway.

UC Berkeley’s campus sees few bicycle-vehicle collisions, said Lt. Marc DeCoulode, a UCPD spokesperson, but some have occurred along Centennial Drive. Of the collisions on campus, many occur when a bicyclist is traveling too fast for the road conditions — for example, on the hill next to C. V. Starr East Asian Library, he said.

“It’s safe to say enough people do questionable things in cars and bikes,” said Taylor Cody, a sales adviser at Mike’s Bikes. “I’m surprised we don’t see more (accidents).”

Designing for the future

Still, according to Campbell, Berkeley is a bike-friendly town. Motorists are more aware of bikers than in the average city, and the city’s leadership is in support of infrastructure improvements, he said.

The system of bike boulevards works, he added, and so it’s not the case that most of Berkeley’s streets are unsafe — there are just a few problematic intersections along heavily trafficked streets.

“The challenge with Berkeley is that there are a lot of busy streets, arterial streets and freeways where there’s a lot of traffic coming on and off,” Campbell said. “A lot of the busier streets are not perceived as safe, and thus a lot of people who would bike, don’t.”

Campbell expects that this year’s redesign of the bicycle plan will prioritize the intersections of bicycle boulevards with busy streets. He hopes that the plan will also discuss possible improvements to major streets such as San Pablo Avenue.

Planners have an arsenal of infrastructure changes they could implement, such as traffic signals that can be activated only by bicycles and pedestrians or a bicycle lane physically separated from the main road by a row of parked cars.

Many of those tools are detailed in a new set of design guidelines from the National Association of City Transportation Officials, which Anderson said will provide ideas that previously were not considered. The guide was inspired by bicycle infrastructure in northern European countries, he said.

In addition to examining collision data when updating the plan, Anderson added, city planners will also profile activity in the areas under consideration, incorporating information about the types of traffic and the causes of accidents to propose location-specific countermeasures.

Campbell said he expects a meeting to kick off public participation around April.

“We want to learn everything Portland has learned, New York has learned, Copenhagen has learned, Amsterdam has learned and consider all of that when coming up with the bike plan,” he said. “We’re committed to being the best in America, and there’s no reason why (we) shouldn’t be.”

Data and methodology notes

Data is from the California Highway Patrol’s Statewide Integrated Traffic Records System, which aggregates data collected at the collision scene. Its records indicate whether a bicycle was involved in each collision. In the Berkeley Police Department’s jurisdiction, about 2,200 incidents from January 2001 to October 2014 have involved a bicycle.

Collision data indicates the nearest cross streets, so each incident did not necessarily occur within the intersection indicated. Some records were removed because of incomplete data, so this map is not comprehensive.

The data indicates the severity of the accident, on a scale from one to four. Fatal accidents are assigned a one, severe injuries are assigned a two and so forth.

In calculating the absolute exposure index, incidents with a severity of one added 10 points to the index, incidents with a two added five points, incidents with a three added three points, incidents with a four added two points and incidents with a zero added one point. Each intersection was normalized against the maximum total of 46 points at Dwight Way and Milvia Street.

In calculating the rate index, the absolute index was multiplied by the ratio of the number of accidents involving bicycles to the total number of accidents near that intersection, raised to the 0.4 power. Each intersection was normalized against the maximum total of 34.5 points, again at Dwight Way and Milvia Street.

Philip Cerles contributed to the data analysis.