We all want to get to the office as quickly as possible. But with nearly nine out of ten drivers distracted by their phone while behind the wheel, often telecommuting on the road, safety’s taken a back seat. We studied 1.2M trips over 21M miles along the busiest 18 commutes in the San Francisco Bay Area to find when and where the worst drivers are on the road.

Find your commute below:

Our mission is to make roads safe using data and analytics, and we do this by measuring driver safety using phone sensors. After honing our algorithms with over 50 billion miles of data (and counting!), Milliman, the leading actuary in the field, showed our model predicts future collisions six times more accurately than leaders of the industry. This means we can identify both dangerous drivers and dangerous stretches of road.

We mapped out the San Francisco Bay Area’s major highways and commute routes in November of 2017. When looking at risky driving behaviors, we analyzed phone use while driving, hard braking, fast acceleration and speeding. We found the commutes and times from 5am to 9pm with the worst driving behavior, including what times of day demonstrate peak risky behavior.

Here’s what we learned:


Here’s what you can do:

1. Change your commute. If you drive at a particularly risky time, or on one of the riskier roads, use this data to make your day safer and swap to a less risky route.

2. Get off your phone. Or, if you can’t spare the time off your phone, switch to carpooling, transit, or ridesharing so you don’t need to drive while distracted!

3. Share this. Your colleagues drive the same routes too. Let them know there’s a safer alternative!


  • Zendrive’s mission is to make roads safe using data and analytics. Our technology uses the sensors in a smartphone to measure risky driver behavior in real time. Our machine-learning algorithms then deliver actionable safety insights about driving behavior for an individual, fleet, or road.
  • With over 50 billion miles analyzed, Zendrive’s driver safety scores are 6x more predictive of future crashes than the industry standard. Our technology is used by fleets who want to measure and improve driving safety, consumer apps to offer collision detection and emergency response, and insurance apps to measure driver risk. Cities use Zendrive’s anonymized data to make city planning safer. Together, we can eliminate road collisions.

We mapped out anonymized aggregated data from 100,000 drivers, 1,250,000 trips and 21,900,000 miles of driving.

  • Timespan analyzed:
    1. November 2017
    2. Monday – Friday
    3. 5am – 9pm for overall scores
  • Behaviors analyzed:
    1. Phone use while driving (any handheld phone use while the vehicle’s moving, like texting or emailing)
    2. Hard braking
    3. Speeding
    4. Aggressive Acceleration
  • For morning commutes (6 a.m. to 11 a.m.), the Golden Gate bridge is the safest bridge; the San Mateo Bridge overall is the most dangerous.
  • Lunch-hour driving (11 a.m.-2 p.m.) is riskier than rush hour driving for either the morning or evening commute. More than 50 percent of the routes are riskier during lunch hour.
  • Bay Area bridge with the riskiest commute: San Mateo Bridge.
  • Worst commute time: 11 a.m.-2 p.m.
  • Best commute time: 6-7 a.m.
  • Best route: Oakland to San Francisco, I-580W (U.S. 101 is safest overall, with four of the five safest routes)
  • Worst route: I-280, all directions (with nearly 3x as much speeding as U.S. 101)
  • I-101 has more traffic in all directions and a greater number of collisions, but drivers on I-280 show riskier behavior behind the wheel and proportionally I-280 is a riskier commute on a per mile basis.



  • Routes were from an open-sourced mapping API and based on the major roads and highways in San Francisco Bay Area commute routes.
  • Safety scoring
    1. For each road segment, the risk score is computed by tracking all risky events (distracting phone use, aggressive acceleration, hard braking, and speeding) from all drivers on that segment in he 5AM to 9PM timeframe.
    2. For a route, a weighted average of scores on each road segment constituting that route is taken. Unsafe driving behavior data was normalized by sample size weights to account for potential sample and selection biases.


Zendrive has anonymized, aggregated driver data from drivers from our customers and partners all over the country. Some are commercial drivers, some are individual drivers, and all have the power of the Zendrive platform to keep them safe.

We took a snapshot of data from November 2017. If your route demonstrates safety improvements since then, they won’t be reflected in the data.

We’re going to be releasing periodic Safety Snapshots as we analyze more miles in more areas. Stay tuned!

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