Alameda County is a diverse mix of urban density, suburbs, and countryside east of the San Francisco Bay. If you live there, or you’re passing through, keep in mind that Alameda County is neither the most dangerous place to drive nor the safest. It has about 22 auto collisions per day. That’s far fewer than in Los Angeles County, for one, but twice as many as San Francisco County to the west and Contra Costa County to the north.

If you are among the 1.6 million people who live in Alameda County, or you have family there, it’s a good idea to know about traffic safety in the area. Where and when do collisions usually occur? What are the leading causes? What can you do to minimize risk for yourself and your loved ones?

This post answers these questions using recent data and images from the UC Berkeley Transportation Injury Mapping System. TIMS pulls raw data on California auto collisions from the California Highway Patrol and local police agencies and makes it easy to analyze and visualize the results. We used 2016 data, because 2017 data had not been finalized at the time this post was published. TIMS is open to anyone who registers for a free account. Have a look for yourself at tims.berkeley.edu.

When it comes to safety, access to traffic data is essential. Knowing that unsafe speed is the key contributor in 83 percent of injury collisions in Alameda County reminds us to stay within the speed limit. The data also tells us where collisions involving bicycles and pedestrians occur and where to be extra cautious about collisions caused by driving under the influence of alcohol or drugs. This information can help keep you safe, and it can highlight traffic safety priorities for public safety officials.

Where accidents occur in Alameda County

Where accidents occur in Alameda County

In 2016, driving at an unsafe speed contributed to almost 2,900 injury collisions. The colors of the dots correspond with types of injuries. Dark blue indicates a complaint of pain. Light blue means there was a visible injury. Green is a severe injury. Red stands for a fatal injury. (Source: UC Berkeley Transportation Injury Mapping System)

In 2016, the number of auto collisions and resulting injuries in Alameda County increased almost 10 percent from the year before. Collisions and injuries were spread throughout the county. Every city saw an annual increase in the number of collisions, except Berkeley, Emeryville, and Fremont. Though Berkeley and Fremont kept collisions in check, traffic injuries went up in both cities too. Almost 60 percent of collisions happen on local roads, the rest on highways.

Which cities have the most collisions?

Oakland has the most collisions in the county, about 7 per day. Every other city averages 2 collisions per day or less.

Here are the cities with the most collisions in 2016, with the number of collisions next to each city name.

Oakland 2,541

Fremont 823

Hayward 761

Berkeley 676

Pleasanton 482

The cities with the most traffic collisions are not always the same as cities with the most traffic fatalities. In the past few years, Berkeley has had a lot of collisions but few fatalities. San Leandro has fewer collisions, but in 2016 it had a lot of fatalities.

Here are cities with the most traffic fatalities in 2016.

Oakland 29

Hayward 9

San Leandro 8

Fremont 7

Pleasanton 3

Collisions involving bike riders and pedestrians were concentrated in Oakland and Berkeley, two of the most urbanized areas in the county. However, Oakland and Berkeley saw more pedestrian-related collisions and fewer bike-related collisions.

Here are cities with the most collisions involving pedestrians in 2016.

Oakland 314

Berkeley 123

Hayward 56

And here are cities with the most collisions involving bicycles in 2016.

Oakland 199

Berkeley 131

Fremont 49

Which cities have the fewest collisions?

Piedmont, an affluent community by the North Oakland hills, has the fewest collisions in the county, just 12 collisions in one year. If you’re only looking at the local roads, not the highways, then traffic safety in Albany and Emeryville is almost as good as in Piedmont. The bulk of the collisions in both cities occur on the highway.

Here are the cities with the fewest collisions in 2016.

Piedmont 12

Albany 97

Dublin 116

Emeryville 130

Alameda 221

When accidents occur

If you want to avoid a collision, then the worst time to be on the road in Alameda County is 3 to 6 pm, every day of the week. (Source: UC Berkeley Transportation Injury Mapping System)

If you’ve ever had to commute to work and back home again, you can probably understand why collisions happen in the early morning and mid- to late afternoon. All sorts of vehicles clog local roads and highways at these times of day as drivers rush from one place to another. Nobody likes to be late.

Some of what you’ll see in this section simply reinforces the obvious about traffic safety. We see the highest rates of collisions during commute hours and lower rates when people are at home sleeping or enjoying the weekend. But have a look at some of the finer details about when collisions occur in Alameda County and each of its cities. Small changes in driving habits, like changing travel times or riding public transit even once a week, can help reduce safety risks.

Here are some useful facts about when collisions occur in each city and countywide.

In Alameda County, Mondays are generally the safest weekday to drive. This is especially true during the worst time to be on the road, 3 to 6 pm. Wednesdays have the second-fewest collision rates overall. But if you can avoid driving at any point on Wednesdays, avoid the morning commute. Collisions are highest between 6 and 9 am on Wednesdays.

In Oakland, the safest times to drive are before 6 am on weekdays and 3 to 9 am on weekends. Yes, many people are at home sleeping during these times. But in a city that sees one-third of all collisions in Alameda County, steering clear of safety risks isn’t easy.

In Fremont, Hayward, and Pleasanton, 3 to 6 pm is the worst time for collisions, including on Saturdays.

In Berkeley, 3 to 6 pm is the worst time for collisions, including on Sundays. In fact, Berkeley has more collisions at this time on Sundays than on Thursdays. On Saturdays, the worst time to be on the road is from 2 to 5 pm.

In San Leandro, 6 to 9 am on Tuesdays is the worst time of the week for collisions. Mondays and Thursdays are better days to brave the morning commute.

Albany and Dublin each had roughly 100 collisions all year in 2016. These tend to be safe places to drive at any time of day or night.

In Livermore, 3 to 6 pm is the worst time for collisions, but not on weekends. Anytime is a good time to drive on weekends in this city.

Emeryville and Newark are both generally safe places to drive. But be cautious on Saturdays from 12 to 3 pm. In each city, this is the worst time of the week for auto collisions.

In the city of Alameda, stay alert on Tuesdays when the island community has its highest collision rate of the week. In 2016, Alameda traffic police reported 107 collisions on Tuesdays, the worst day of the week, compared with 63 on Thursdays, the best weekday.

In Union City, Mondays and Wednesdays are generally the safest weekdays to drive.

Piedmont averages one collision per month. It’s always a safe place to drive.

Why accidents occur

The number one factor in Alameda County auto collisions is speeding, plain and simple. Unsafe speed was the top contributing factor in over one-third of collisions in 2016. No other driving mistake, such as failing to follow the right of way or making an improper turn, comes close in the number of collisions caused.

But the number of collisions doesn’t tell the whole story. Driving or bicycling under the influence of alcohol or drugs was a primary factor in about 6 percent of Alameda County collisions in 2016. This is a relatively small number, but driving under the influence is so dangerous, so deadly, that communities often pay closer attention to these traffic offenses than others.

We looked at every city in Alameda County to find out where driving under the influence causes the highest collision rates. Hayward topped the list with 8 percent of collisions resulting from driving under the influence. The lowest collision rates tied to alcohol or drugs were in Albany, Berkeley, Emeryville, and Union City.

What you can do

If you have learned something new about traffic safety in Alameda County, try making at least one small change in your driving routine to reduce the risk of a collision. Bypass the places where collisions are most likely to occur. Take note of the time periods when collision rates are high and take public transit or stay off the road, if you can. Most importantly, follow the speed limit.

In the event of a collision, refer to the step-by-step instructions in our car accident checklist. Get yourself and anyone else to the roadside as soon as possible. Call for medical assistance if anyone has been injured. Under all circumstances, report the incident to the police. Collect all the information you can about what happened and who was involved so you can notify your insurance provider after returning home. Lastly, consult an attorney if you have suffered harm as the result of a collision and would like to find out how the legal system can help make amends.