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.
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 overrepresentation 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. In addition, 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
midblock 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."
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.
The study provided information that can be used by a variety of groups interested in
improving and promoting bicycle safety. In fact, "the report has become a key
component of WSDOT's nonmotorized Safety Management System (SMS). . . ."
Moreover, the report would suggest that a key area for action should be education, not
only of bicyclists and motorists but also of policymakers and decision makers, whose
information on bicycle issues can be incorrect and short-sighted. The author
concluded:
Safety-improvement programs that only use motor-vehicle collision records to
determine safety improvements are inherently biased against bicycles as a
transportation mode. A change in the reporting requirements for bicycle
collisions is necessary to allow problem areas to be better identified and safety
improvements to be specifically targeted toward bicycles.
