Bay Area Motorcycle Incidents

4 million Bay Area workers commute to their jobs on a typical workday. Of those 4 million, around 3 percent of the registered vehicles are motorcycles. Despite this, registered motorcycles represent 5.7 percent of the total number of motor vehicle deaths in the United States.

According to the San Jose Mercury, motorcycle-involved fatalities have more than doubled since 1997. In 2020, many Bay Area workers have found themselves working from home due to the COVID pandemic. According to ABC, "overall traffic has been holding steady at 80 to 85% of normal since mid-June." Given this reduction of overall commute, I decided to investigate motorcycle incidents across the Bay Area region (with data from the GenePilot Motorcycle Incidents project) and see what kind of an impact the COVID pandemic has had on incidents and fatalities

Incidents By Region

The California Highway Patrol division of the Bay Area is composed of multiple departments across regions. Each region encompasses hundreds of square miles and spans multiple cities and even counties. For this analysis, I take a look at motorcycle-related incidents that take place within the jurisdication of a specific CHP reporting area. The data for this chart and all of the following charts is limited to the dates of June 16th and November 16th in order to observe the changes between the previous years and 2020, a year where traffic has been holding at 80 to 85% of normal as mentioned above. In 2018 and 2019, during this time frame, the San Jose region had the most reported incidents of any other in the area, with 316 and 281 incidents total, followed by Contra Costa in 2018 with 197 incidents and Oakland in 2019 with 191 incidents. By 2020 however, a shift had taken place. The Contra Costa region, maintaining 114 incidents during the time frame in 2020, had surpassed San Jose, which had a mere 90 incidents in 2020- around one third of the incidents taking place in San Jose the previous years.

Select Year:

Between June 16th and November 16th

These variations are further exemplified when looking at the regions side by side, such as in the chart below. While some regions such as San Jose have a prominent reduction in 2020, others such as Santa Cruz, Marin, and Napa remain practically unchanged in number of incidents during the time frame in 2018, 2019, and 2020. A possible explanation as to why some regions are more drastically unchanged than others could come down to the people commuting. The San Jose, San Francisco, Redwood City, Oakland, and Hayward CHP regions are all frequently used by workers in the tech industry to commute to their offices. However, in order to see if this is really the case, we must look closely at the patterns of incidents on a typical week to determine whether weekday tech worker commuting is the reason for the disproportion level of changes between regions.

Between June 16th and November 16th

Weekly Incident Trends By Region

Across the Bay Area, between mid-June and mid-November of 2018 and 2019, rider incidents spiked on end-of-the-week days such as Thursday and Friday, while taking a notable dip on Saturday, Sunday, and Monday. During 2020, the number of incidents begins to increase on Thursday and continues until its peak on Sunday, indicating more weekend incidents than in the previous years. Across regions, many areas find themselves following the same pattern with a weekend uptick in incidents compared to the previous years. Regions that are popular commuter destinators for Bay Area tech workers such as San Francisco, San Jose, and Redwood City tend to see a more dramatic change in their weekly riding patterns in 2020 compared to the previous years than those with fewer work commuters such as Marin and Santa Cruz.

Select CHP Zone:

Incident Type Trends By Year

Not all incidents are equal in severity. The vast majority of incidents reported that we've looked at thus far result in no injury or minor traffic obstruction. However, in examining this data more deeply, we can see whether or not the number of serious incidents has dramatically changed due to the changes in ridership during this time frame in 2020. In examining the frequency of all incidents (broadly including unclassified incidents, traffic hazards, and more as well as minor/major incidents and fatalities), the density and amount of incidents can be seen as clearly reduced during 2020. However, drilling into the specific categories of minor incidents, major incidents, and fatalities, one can see a shrinking gap between 2020 and the previous years in the frequency of serious incidents. In 2020, we have seen more motorcyclist fatalities than either 2018 and 2019, and more major incidents than in 2019. However, the level of minor incidents remains at least 25 percent below the preceding years.

Select Incident Type:

Between June 16th and November 16th

In this chart, you can get a more clear idea of just how many fatalities, minor injury, major injury, and all (including unlisted) incidents there are. There is less of a difference between the number of incidents as the incidents grow in severity. It can be observed in this graph that the other unlisted incidents (such as no injury, traffic hazards, etc.) that are in included in the All category compose a large part of the total incidents, and 2020 is significantly behind the previous two years when those incidents are considered.

Incident Type Trends By Day of Week

A Bay Area motorcyclist who was presented with the previous visualizations requested the following chart, a breakdown of incidents based on the day of the week. He shared that in the motorcycle certification classes he had taken, he learned that weekends are a more dangerous time to ride due to intoxicated drivers on the road and was curious to see if the breakdown of incidents by weekday would show more incidents on the weekend. According to the U.S. Department of Transportation, there are 1.5 times as many two-vehicle motorcycle crashes during weekends than during weekdays. We observe a similar trend with fatalities in motorcycle incidents in the Bay Area. In observing the data, the amount of fatalities is indeed highest on Friday, Saturday, and Sunday for 2018, 2019, and 2020 compared to other days of the week. For incidents with major and minor injuries, the spike on weekends is less prominent, however, with the exception of incidents with minor injuries in 2019, all were more concentrated and frequent than incidents on the weekdays.

Select Year:
Select CHP Zone:

Between June 16th and November 16th


GenePilot, CHP Motorcycle Incidents,

San Jose Mercury Motorcycle Deaths,

ABC Bay Area 2020 Traffic,

Fatal Two Motorcycle Crashes, U.S. DoT,

Google Charts,


W3 Schools,