Richard B. Nassi, Transportation Administrator, City of Tucson
Shellie Ginn, Bicycle Coordinator, City of Tucson
Broadway Boulevard is a major, six-lane divided arterial roadway in Tucson, Arizona, that carries over 30,000 cars per day. All of the lanes were constructed between 3.7 m (12 ft) and 4.3 m (14 ft) wide, except the curb lanes which were constructed between 6.7 m (22 ft) and 7.3 m (24 ft) wide with no parking allowed. Originally, the plan intended the curb lanes to be wide enough to facilitate turns into and out of the numerous driveways along the strip shopping corridors without impacting through traffic along the arterial. The wider curb lane was designed to allow drivers to position their vehicles next to the lane stripe when traveling straight ahead and only pull closer to the curb when turning right into the business driveways, keeping the faster lanes clear. In addition, the wider curb lane was intended to assist public transit vehicle operations by giving them an opportunity to travel more slowly and stop frequently for passengers in relative safety next to the curb and not impact the main flow of traffic.
Unfortunately, the actual operation of the wider lanes did not fulfill their design intent. After the construction of the road system, a series of crashes occurred involving right-turning vehicles entering the driveways and colliding with the slower-moving public transit vehicles. In addition, there was no clear area for bicyclists to ride. The wide lane did not provide enough guidance to less-skilled drivers and a number of drivers failed to position their vehicle properly as they began their turn. Approximately 20 percent of these crashes involved turning vehicles and public transit vehicles.
A combination bus, bicycle, and right-turn lane was separated from a former 6.7–7.3 m (22–24 ft) multi-use, wide curb lane.
The problem was studied and reviewed by transit and traffic practitioners and the decision was made to divide the wide curb lane into two lanes. The wide outside lane was divided and the new curb lane was striped as a priority BUS and RIGHT TURNS ONLY, EXCEPT BIKES, lane. This treatment provided clearer direction as to how the lanes were to be used and where drivers should position their vehicles when turning into driveways. Transit vehicle operators can operate in the curb lane, away from the faster through traffic lanes, thus reducing the potential for crashes as they stop to board or disembark passengers.
The splitting of the wide curb lane worked very well and eventually was included in the design of other streets with wide curb lanes. The system now has been in operation for over 22 years throughout Tucson on about 22.5 km (14 mi) of arterials. The reoccurring sideswipe, rear-end and turning type crashes fell to very low levels, Transit management also noted that the lanes helped in other areas in addition to service and safety. Sun Tran, the local transit agency, indicated the priority lane seemed to increase bus driver morale and ultimately made their jobs easier. Equally important, the preferential transit/bike lane provided a means of making the city’s transit system more visible to the community, especially in a time of energy conservation, and encouraged alternate modes of transportation.
The priority transit lane striping worked as expected and the reoccurring crashes fell to low levels. The lanes have now been in operation, city-wide, for approximately 22 years. Once the lane system was installed in other portions of the city, crash involvement between transit vehicles and other motor vehicles was reduced.
The operation is transferable to other jurisdictions with similar roadway geometric and land use patterns. The mixing of the various transit and bicycle modes has not proven to be a problem. The separation of the turning vehicles, faster through vehicles and the transit vehicles solved the safety problems.
The project was funded under the City of Tucson maintenance budget. The cost for markings and signs is minimal — in the range of approximately $100 per sign, posted approximately every fifth of a kilometer (eighth of a mile), and painted pavement diamond adjacent to each sign.
The stripes and signs of the preferential Transit-Bicycle lane can be found in the Federal Highway Administration’s Manual on Uniform Traffic Control Devices.
Richard B. Nassi
City of Tucson
City of Tucson