Washington State Study Focused on Bicycle-Collision Statistics from
1988-1993
Historically, statistics on bicycle collisions have not found their way
into overall statistical records on collisions in Washington State. Often
bicycle collisions do not meet the collision-reporting criteria set forth
by state statute and, subsequently, do not become part of the data. In an
effort to increase the knowledge base about bicycle collisions and improve
highway/traffic safety, the Washington State Department of Transportation
(WSDOT) conducted a study on bicycle collisions in Washington State from
1988 through 1993, using data compiled by the Washington State Patrol (WSP).
Ralph L. Wessels discussed the study and its report in "Bicycle Collisions
in Washington State: A Six-Year Perspective, 1988-1993" (Transportation
Research Record 1538).
- BACKGROUND
-
- This study used demographic data from the 1990 census. By means of
a modified version of the Cross/Fisher bicycle-collision collection method,
the study identified 22 collision categories, with collision types delineated
by geographical area, age group, and road ownership. Statistics regarding
bicycle helmets were considered negligible, since only two jurisdictions
had mandatory helmet laws during the study period and enforcement had been
limited. Researchers classified roadways by the following five functional
types: interstate, state routes, county roads, city streets, and other
roads.
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- RESULTS
-
- Except for recognizing an overall annual increase in the number of
reported bicycle collisions, the author cautioned against basing trend
assumptions on this collision data, since factors related to bicycle collisions
vary from year to year.
-
- Bicycle collisions during the years studied occurred most often between
April and October, and they happened primarily between 3:00 p.m. and 8:00
p.m.
- Eighty-two percent of the collisions in the study were during daylight
hours, mostly in clear or cloudy weather. While males accounted for 80
percent of bicyclists involved in the collisions, researchers viewed this
over representation as primarily the result of a higher exposure to potential
collisions rather than as a gender-related factor.
- Approximately 1 percent of motorists and bicyclists involved in reported
collisions had been drinking. For fatal collisions, the frequency of alcohol
involvement rose to 9 percent for motorists and 11 for cyclists.
- Approximately half of all bicycle collisions involved cyclists aged
15 or less, with those age 10 to 15 comprising the largest segment of this
group.
- In fact, the 10-to-15 age category had almost twice the collision rate
of the next-highest groups' rates, ages 5 to 9 and 16 to 24.
- Of particular significance was the comparatively high number of serious
collisions involving ages 5 to 9 and 10 to 15 on county roads.
-
- Results of this study correlated closely with other national data,
which show the five most common factors involved in bicyclist fatalities
are: failure to yield (23 percent), improper crossing of roadway or intersection
(15 percent), failure to obey traffic control devices (9 percent), failure
to keep in proper lane (8 percent), and operating without required equipment
(5 percent).
-
- Results were summarized in relation to five functional classes of roadway.
The article reported data for four of these categories: city streets, county
roads, state routes, and the interstate system. The fifth category, other
roads, recorded only 4 of the 325 collisions during the study period.
-
- City Streets
-
- City streets accounted for 65 percent of bicycle collisions, followed
by county roads and state routes.
- While the majority of bicycle collisions happened on city streets,
those collisions made up only a third (33 percent) of bicycle collision
fatalities.
- Most fatalities on city streets happened at intersections, and "motorist
action at intersections accounted for a high 30% of the total bicycle collisions
on city streets."
-
- County Roads
-
- County roads were the location of 21 percent of all collisions and
45 percent of the fatalities.
- Of the five functional types of roadways analyzed, county roads had
the highest percentage of bicyclists being struck from behind by motorists.
- The percent of cyclists turning or swerving on county roads was nearly
twice that of all roads (probably a result of narrower lanes, poor shoulder
conditions, and limited sight distance).
- Most fatalities involving a bicyclist entering or exiting a roadway
at a mid block location also occurred on county roads. Of note is the "surprisingly
low" (15 percent) number of collisions on county roads that were attributable
to motorist action.
-
- State Routes
-
- On state routes, intersection collisions made up close to half (45
percent) of bicycle collisions, while "bicyclists riding the wrong
way accounted for a significant 21 percent of collisions.
- Half of the fatalities involved the bicyclist turning or swerving at
a location that was not an intersection."
-
- Interstate System
-
- Washington is one of only a few states to allow bicyclists on interstate
shoulders, and results indicated relatively few bicycle collisions took
place on interstate roadways. However, while state and interstate systems
made up only 13 percent and 1 percent respectively of all collisions, they
accounted for 18 percent and 4 percent of all fatalities. As such, "roads
with higher driving speeds are the locations of more fatalities proportional
to the overall number of accidents."
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- CONCLUSIONS/IMPLICATIONS
-
- Many people think that motorists striking bicyclists from behind represent
the majority of bicycle collisions, and decision makers have considered
improving the safety of bicyclists by having them ride against traffic.
This study revealed, however, that "the number of bicycle collisions
in which a bicyclist was riding the wrong way is two and one-half times
the number of collisions in which a bicyclist was struck from behind by
a motor vehicle." Moreover, being struck from behind accounted for
only 5.7 percent of all collisions. Again, the 5-to-9 and 10-to-15 age
groups were most involved. Of note is the fact that bicyclists being hit
from behind and bicyclists turning or swerving accounted for 12 percent
of bicycle collisions but constituted 40 percent of fatalities.
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