Michael J. Cynecki, P.E., Traffic Engineering Supervisor, City of Phoenix Street Transportation Department
Phoenix, AZ, is the sixth largest city in the United States with a population of 1.32 million and an ideal climate for cycling. In the mid-1980s Phoenix had a very small system of bike facilities, consisting of only 75 miles, including off-street paths, signed bike routes, and a few miles of on-street bike lanes.
In 1987, the City Council approved an aggressive bicycle system of 700 miles of bike lanes, bike paths, and signed bike routes to be installed over the years. The plan included providing many new miles of bike facilities as well as upgrades to existing facilities. Funding for new bike facilities increased from $300,000 per year to $500,000 per year in fiscal year 2000–2001. By 2000, Phoenix had developed over 450 miles of bike facilities, including over 222 miles of on-street bike lanes. While many of the on-street bike lanes have been installed on collector streets, bike lanes are also provided on arterial streets. Furthermore, the standard cross-section for new arterial streets built in Phoenix was modified to include on-street bike lanes.
Traffic engineering staff wanted to determine if the new bike facilities were associated with an increase in bike crashes with motor vehicles. In addition to wanting to learn more about the how, where, and why of all bicycle crashes, staff wanted to determine how many collisions occurred in the on-street bike lanes and how these crashes were occurring. There was also a desire to know if younger children were involved in the bike-lane collisions on busy arterial streets.
A comprehensive manual review of all police reports involving bicyclists on Phoenix streets in 2000 was conducted to determine where bike collisions occurred and the age of the bicyclists in the crashes. Additional data was collected to determine the classification of the street where the crash occurred and if a bike facility existed on that street. The police report was further reviewed to determine if the bicyclist was riding on the sidewalk, along the street or in an on-street bike lane, or crossing the street when the collision occurred.
This analysis was, unfortunately, limited to collisions between bicyclists and motor vehicles on the public right-of-way based on the Arizona Department of Transportation (ADOT) Accident Location Identification Surveillance System (ALISS) computerized database. Bike crashes with fixed objects, other bicyclists, or pedestrians are not in the state database, nor are private property crashes. Furthermore, non-injury bike crashes below the reporting threshold ($1,000) are not in the statewide computerized collision database.
About two percent of the 36,400 vehicle collisions reported in Phoenix during 2000 involved a crash between a motor vehicle and a bicycle. While this may not seem like many, this resulted in 682 bike collisions with motor vehicles. Thus, a motor vehicle or bike collision was reported every 12.8 hours on Phoenix streets, roughly two per day. Of the reported collisions, 35 (five percent) involved no injury, 532 (78 percent) involved ‘minor’ or ‘moderate’ injuries, 107 involved a serious or incapacitating injury (16 percent), and eight (one percent) resulted in a fatality. The number of total and fatal vehicle or bike crashes in Phoenix remained relatively stable over the five years of the study period, but peaked in 1999, as shown in the table below:
|Year||Total Bike Crashes||Fatal Bike Crashes|
During these same five years, Phoenix population increased about 15 percent from 1.15 million in 1996 to 1.32 million in 2000. The total number of reported collisions increased about 13 percent from 32,200 in 1996 to 36,400 in the year 2000.
The crash data revealed that bicyclists ages 11 to 20 were most frequently involved in motor vehicle collisions (32 percent). This age group had double the number of crashes of the next highest 10-year age group. A vast majority of bicyclists involved in collisions with motor vehicles are males (81.5 percent), and this is relatively consistent among all age categories. This largely reflects that more bicyclists are males.
Fault in the collision was determined based on the comments of the investigating police officer (Figure 1). The investigating officer could designate either the motorist or the bicyclist or both were at fault in the crash. The inexperience or errrors made by bicyclists is evident by the police report results, which indicated that bicyclists were partially or entirely at fault in nearly 79 percent of the collisions with motor vehicles, with the motorists involved in an unsafe action in 43.5 percent of the crashes. This disproportionate blame for collisions largely being attributed to bicyclists reflects the young age of bicyclists involved in many crashes. It also indicates a need for more training and education on the rights and duties of bicyclists. In some instances, the police officers may not fully understand the traffic laws as they apply to bicyclists in the right-of-way, which may result in an erroneous designation of fault.
Figure 1. Police designation of fault in bicycle-motor vehicle collisions.
Figure 2 shows the breakdown of bicycle collision types in Phoenix. Angle crashes comprised 38 percent of reported bike collisions, with 27 percent involving right-turn motorists, and 25 percent involving vehicles entering or leaving private driveways..
Figure 2. Type distribution of reported bicycle-motor vehicle crashes.
The classification of street where each bike crash occurred (local, collector, or arterial street) was identified. Figure 3 shows that only 10 percent of reported bike crashes occurred on local streets, which are the overwhelming majority of the streets in Phoenix (74 percent). These are the safest streets for bicyclists because of lower speeds, narrower street crossings, and fewer conflicting motor vehicles. Fifty-five percent of the bike crashes occurred on arterial streets, which comprise only about 15 percent of Phoenix streets. Collector streets comprise about 11 percent of our total streets but were the location of 35 percent of the reported bike crashes.
Figure 3. Street classifications of bicyclist collision locations.
The police reports were reviewed to determine if the bike crashes took place on streets with designated bike facilities (on-street bike lanes, striped shoulders, or signed bike routes). Of the 682 crashes with motor vehicles, 95 percent of the crashes occurred on streets with no designated bike facilities. Figure 4 shows where the bicyclist was riding when struck. About 40 percent of the bike/motor vehicle crashes occurred in the crosswalk area, with a similar percentage of bicyclists hit when riding in the street outside of a crosswalk or bike facility (bike lane, striped shoulder or signed route). Almost 18 percent of the bicyclists were struck while on a sidewalk. Many of the bicyclists struck crossing the street rode off a sidewalk into the street and were in the crosswalk when hit. Less than 2 percent of the bicyclists were struck while riding in an on-street bike lane, and a smaller percentage of bicyclists were struck while riding in a striped shoulder (not signed as a bike lane).
Figure 4. Bicyclists riding location when bicycle-motor vehicle crashes occured.
The actions of bicyclists involved in crashes is illustrated in Figure 5. Slightly more than half of the bicyclists struck were attempting to cross a street. For those bicyclists not crossing the street, the most common action was a bicyclist who was riding in a sidewalk ‘against’ traffic (22.6 percent). While riding in either direction on a sidewalk is legal in Phoenix, motorists generally do not expect bicycle traffic coming from the ‘wrong’ direction, especially when turning out of a driveway or side street. Most drivers are looking to their left for approaching traffic and do not expect traffic coming from their right. Generally the speeds of bicyclists on the sidewalk do not provide motorists much time to react. Only 5.8 percent of bicyclist-motor vehicle crashes involved cyclists riding on the sidewalk in the same direction as motor vehicle traffic.
State law requires bicyclists, when in the street, to obey the traffic laws established for motor vehicles and ride with traffic (ARS 28-812). About 8.7 percent of bicyclists were struck when riding in the street with traffic, and about the same percentage were riding in the street against traffic (not in bike lanes). Very few bicyclists were struck in on-street bike lanes (about 1.8 percent of total bike crashes), with 1.3 percent riding with traffic and 0.6 percent riding illegally against traffic.
Figure 5. Pre-crash riding direction and position of bicyclists involved in crashes with motor vehicles.
A special analysis was conducted to further identify where the on-street bike lane crashes occurred, how they occurred, and the age of the bicyclists. There were 13 bicyclist crashes in on-street bike lanes during 2000. Of these, five occurred at midblock locations and eight occurred at intersections. The age of bicyclists struck while riding in bike lanes ranged from 16 to 70 years old, with the median age of 38. With the exception of the 16-year-old bicyclist, all other bicyclists struck in bike lanes were adults. Six of the bike-lane crashes occurred on arterial streets while seven occurred on collector streets. Three of the crashes involved ‘wrong way’ bike riding in the bike lane. All but two of the bike-lane crashes involved collisions with motorists turning into or out of driveways or side streets. The other two bike-lane crashes were rear-end collisions where the motorist struck the bicyclist from behind. Three of the bike-lane crashes occurred during nighttime conditions, and in two of these collisions the investigating officer noted that the bicyclist did not have a front headlight (in violation of State law when riding at night). None of the on-street bike lane crashes involved alcohol, but one did involve a hit-and-run motor vehicle.
The Phoenix bike program has been highly successful in preserving more space in the right-of-way for bicycle travel and identifying desirable bicycle travel routes. While the population of Phoenix is growing, the number of crashes involving bicyclists in 2000 was virtually the same as five years earlier, despite an increase in the interim years. The number of fatal crashes involving bicyclists has remained unchanged.
The most common safety problems for bicyclists involved crossing streets, riding the ‘wrong way’ on sidewalks, colliding with right-turning motorists, and crashing into motor vehicles entering or leaving driveways. These problems should be addressed through bicyclist training and bicyclist/driver education, as well as police enforcement of unsafe bicyclist and driver actions.
The results of the study indicate that the new bike facilities in Phoenix, particularly on-street bike lanes, are not associated with motor vehicle or bicycle safety problems. Furthermore, there is not a problem with inexperienced children being encouraged to ride in busy streets with on-street bike lanes, resulting in crashes. Observation confirms that the bicyclists who use on-street bike lanes along arterial streets are mostly adults, while children most commonly ride on neighborhood streets. Because so many of the bike crashes occurred on arterial streets outside of bike lanes, the addition of bike lanes along arterial streets may result in safer conditions for bicyclists. This is especially true where the curb lane of the arterial street is only 12 ft wide, which is not conducive for a bicyclist and a motor vehicle to “share” the lane.
Phoenix has actively promoted bicycling as an alternative transportation mode that is healthy, non-polluting, and does not rely on fossil fuel. These activities will continue. There is a need to quantify the amount of bicycle travel throughout the city and monitor usage.
This evaluation of police reports for all bike/motor vehicle crashes in Phoenix was made possible through an internship program within the Street Transportation Department. Tim Cook, who was completing his Bachelor’s Degree at Arizona State University, accomplished the analysis. The cost of the study was approximately $7,000.
Michael J. Cynecki, P.E.
Traffic Engineering Supervisor
Street Transportation Department
200 W. Washington St., 6th Floor
Phoenix, AZ 85003
Bicycle Program Coordinator
Street Transportation Department
200 W. Washington St, 5th floor
Phoenix, AZ 85003