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Portland Bureau of Transportation

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

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What causes deadly crashes in Portland?

Most deadly crashes in Portland involve street design, speed, impairment and dangerous behaviors (such as drifting outside of lanes). These issues often overlap leading up to a crash.

Street design: Portland’s most deadly streets generally have multiple auto lanes and speeds of 35 mph or higher

More than half of deadly crashes occur on just eight percent of our streets, which make up Portland's High Crash Network. Examples of HCN streets include SW Barbur, SE Division and NE Lombard.


Speed: Nearly half of Portland’s deadly crashes involve people driving at unsafe speeds

Speed


Impairment: More than half of deadly crashes in Portland involve people who are intoxicated—usually by alcohol

What about marijuana? Researchers are actively exploring the impact of marijuana use on travel behavior; at this point, the federal government has found the crash risks associated with marijuana use to be much lower relative to alcohol

Impairment


Dangerous behaviors: The majority of deadly crashes involve people driving who do not stop for people walking, do not stop for stop signs, or exhibit other dangerous behaviors

Distractions such as phones likely contribute to these behaviors.

Dangerous behaviors


Crashes usually involve multiple factors

For example, people who drive while drunk may also speed and turn against oncoming traffic.

In addition, street designs that support high speeds while failing to separate street uses (driving, walking and biking) increase the likelihood that a crash will result in serious injury or death.

The following diagram illustrates the numerous factors involved in a deadly crash and the relationships between them. The gray lines are crashes in which speeding was a primary cause of a deadly collision. For example, this diagram indicates that many crashes primarily caused by speeding involved people who hit a fixed object (such as a utility pole), had consumed alcohol, and crashed during nighttime. (Speed is 37% on this chart because it includes only crashes in which speed was a primary causal factor. See notes below for more information.)

Crash relationships


Notes on the data

Data is from the Portland Police Bureau and the Oregon Department of Transportation for the period 2004-2013. This data only captures crashes that involve a motor vehicle, such as a person driving colliding with a person walking. Portland's 2015 Traffic Safety Report provides a preliminary analysis of crash data from 2015, along with a more detailed explanation of crash data limitations.

Most crashes involve multiple factors. The pie charts on this page include every causal factor identified. For example, the 47% figure on speed-related crashes includes crashes in which speed was a contributing, but not necessarily a primary, cause of a crash. This is why the percentages for speed, impairment and dangerous behaviors add up to more than 100%.

"Dangerous behaviors" include the following: not yielding right-of-way, disregarding a stop sign, traffic signal or other traffic control device, driving left of center on a two-way street, straddling the center line, improperly changing lanes, going the wrong way on a one-way street, improperly overtaking another street user and turning improperly.