Raised Bicycle Lanes and Other Traffic Calming Treatments on Ayres Road

Eugene, Oregon

Dave Reinhard, Transportation Consultant (formerly City of Eugene Transportation Engineer, Division Manager)

Background

Between 2001 and 2002, the City of Eugene, Oregon, fully improved Ayres Road by constructing a raised bicycle lane in conjunction with traffic calming treatments. Ayres Road is a half-mile long collector street in a developing residential neighborhood in the northern suburban part of the city, and the only street that provides an east-west connection between two major north-south collectors.

Ayres Road is similar to many other collector and minor arterial streets the city has inherited from Lane County through annexation. It was a two-lane, narrow oil mat roadway with no curbs, drainage, or sidewalks that functioned reasonably well for many years in its rural setting, but was not adequate to serve the suburban residential development called for in the citys adopted land use plan. The classification of Ayres Road as a major collector street and the need for bicycle connectivity in the area led to a decision to incorporate on-street striped lanes in the design for the street reconstruction project.

Prior to the reconstruction of Ayres Road, city staff began modifying design practices to incorporate traffic calming features in major improvement projects. Several projects were built in the 1990s that included some or all of the following:

• narrower lanes (i.e., greater use of 11-foot lanes than 12-foot or wider lanes)
• raised median islands
• chicanes or similar curves introduced into the alignment of otherwise straight sections of street
• provision of on-street parking, either continuously or in intermittent parking bays
• use of setback sidewalks and extensive street tree plantings between curb and sidewalk instead of curb-side sidewalks

As the city gained experience with these types of design features, they were incorporated in the major update of design standards and guidelines adopted in 1999.

The greatest disappointment with the new street design was that by continuing to include on-street bicycle lanes, the overall look and feel of the street still gave the perception of a fairly wide roadway that did little to discourage speeding. To provide a safe place for cyclists on streets with moderate to heavy vehicular traffic, an additional 10 to 12 feet of pavement width was being added, which tended to cancel out the visual enhancement brought about by the other features such as narrower lanes, medians, and landscaping.

Countermeasures

The original design for the Ayres Road,a typical three-lane with bicycle lanes cross section, was met with resistance from residents of the area who thought this would result in a street that was too wide and increased traffic speeds in the neighborhood. The city initiated a series of meetings and design charrettes with representatives of the adjacent residential neighborhoods and other interested stakeholders. The design that emerged from this process included the following elements:

Narrow lanes
Travel lanes as narrow as 10.5 feet would be used on Ayres Road.

Chicanes
Horizontal curves with bulb-outs and centerline changes on a fairly straight segment of roadway would be used to discourage high speeds.

Raised median islands
Oval-shaped, raised median islands were used to interrupt the center line and create a veer to the right, then back to the left as the island tapered and then vanished at the far end. The islands also provide space for landscaping, which interrupts the motorists view down the street and reinforces the notion of moving slowly down a narrow street.

Raised intersections at entrances to major subdivisions (Meadowview and River Pointe)
The intersections were raised to full curb height in order to provide a visual cue as well as a tactile message to discourage speeding in these areas.

Raised bicycle lanes
The most unusual and controversial design feature was the use of raised bicycle lanes. City staff knew of this technique being used in Europe, and after a great deal of internal discussion, decided to use this feature on Ayres Road. The primary reason for using raised bicycle lanes instead of the conventional on-street lane at normal street grade was the desire to provide a very strong, visible, right-hand edge to the vehicle travel lanes. Eugene's experience on many other streets has been that on-street bike lanes tend to be seen as another five to six feet of pavement on each side of the road. Even though most motorists don't physically occupy this space when driving along tangent sections, many use it on curved road segments.

The additional space also adds to the image of a wide roadway where it feels okay to drive fast. Since the raised bicycle lane is constructed of concrete and has a left edge that is beveled up to a height of half the normal curb height, it adds a very visible edge to the travel lane that a normal, striped bike lane does not provide. The 4:1 slope of the left edge is very forgiving for both bicyclists and motorists who get too close to the edge.

Issues in design, construction, and operations

Design
When it was decided that a raised bike lane would be a design feature for the Ayres Road improvement project, several design issues became apparent right away:

• How wide and elevated should the riding surface be?
• How wide and at what slope should the beveled edge or transition surface be?
• What type of material should it be constructed of?
• How should transitions at accessible ramps and intersections be designed?

The city's desire was to have at least 4.5 feet of bicycle-riding surface, the same width offered by a wide curb-and-gutter that is used as a bike lane. It was also decided that the raised bike lane would be constructed of concrete because a narrow lane of asphalt concrete would be hard to construct and to maintain. The design of the beveled edge determined how high the raised bike lane would be, and it was based on how well it would deter casual intrusion by motorists but still be traversable by motorists and bicyclists alike. Designers chose to use a 4:1 beveled edge with a transition width of 1 foot (a 3 inch rise in a 1 foot run). The treatment at intersections became a challenge also. At one intersection, the raised bike lane continues around the curb return, which brought up accessibility requirements. At this location, it was decided to transition the beveled edge near the curb return from a 4:1 slope to a straight grade all the way to the bottom of curb. This choice complies with accessibility guidelines and satisfies riding conditions as well.

Construction
When the design of the raised bike lane was completed, the city did not specify how it would be constructed. As it turned out, the contractor who was awarded the project elected to extrude the raised bike lane as is done for most curb and gutter installations. The first challenge for the contractor came when the company asked for a shoe from the extruding machine manufacturer based on the citys design. The manufacturer stated that its machine was not designed to handle that much concrete volume (three times as much) through a shoe and therefore would not provide one. At that point, the contractor elected to fabricate a shoe on his own and take his chances. It eventually worked, after minor modifications with the structural supports, but several yards of concrete were wasted because the extruding machine operators were learning how to control the operation. The finished product did not fully meet city specifications and the surface smoothness for ride-ability was less than desired. Nevertheless, the city chose to accept it since the end product did not seem to present safety hazards. Had the contractor chosen to construct the raised bike lane by using traditional wood forms, it would likely have met specifications, but would probably have been more costly due to labor expense.

Another challenge for the contractor was the narrow curvilinear travel lanes. Most paving contractors have large highway type mechanized pavers, but a narrow mechanized paver would have provided better results in this application. As a result of the contractor using a standard 10-foot-wide paver, the end product had many undesirable surface conditions (poor cross slope, poor longitudinal slope, raveling, flushing, etc.) in the final lift of the asphalt concrete.

Operations
A few operational considerations must be kept in mind when choosing a raised bike lanestreet sweeping, road drainage, and driveway access. The final version of Eugene's raised bike lane requires two passes for the city's eight-foot-wide street sweepers. The first pass is done along the raised bike lane, which pushes all of the debris to the bottom of the beveled edge. The second pass is along the bottom of the beveled edge. Another operational consideration is to be aware that the road drainage is along the joint, which can reduce the life of the asphalt pavement and create long-term maintenance headaches.

The last operational consideration, driveway access, was addressed during the design phase, but had to be re-evaluated after construction. During the design phase, it was determined that no special consideration would be given for vehicle access at driveways. However, because the raised bike lane was constructed out of specification (a rise of 4 inch to as much as 4.5 inch a 1 foot run), some homeowners complained that their vehicles were bottoming out during ingress and egress. Based on this information, the city elected to have each driveway access location reconstructed using the same design parameters for accessible ramps, which was dropping the beveled edge at driveway locations.

Evaluation and Results

This project presented an opportunity to combine a number of design features in a new way on a suburban collector street. The combined visual effect of all these features provides reinforcement for slower vehicle speeds on Ayres Road. Motorists who use the street, especially those not already familiar with it, are greeted with a set of visual cues that imply, something is really different about this street, and are probably more likely to proceed somewhat slowly and cautiously. At the same time, the raised bicycle lanes, median islands and other features help bicyclists and pedestrians feel relatively safe and at home as users of the street.

Informal feedback from motorists, bicyclists, neighborhood residents, and the general public has been mixed. A number of initial comments during the construction of the project and immediately afterward were critical, partly because the street looked so different from other typical Eugene streets, not to mention very different from the narrow Ayres Road that this project replaced. As people have gotten more used to the street and some of its visual newness has worn off, public reaction seems to be cautiously supportive or at least neutral. City staff continues to receive comments about how unusual the street looks, but there is also a growing acknowledgment that the design does help slow down traffic. In general, feedback from the bicycling community has been positive.

Before 1992, Ayres Road was under county jurisdiction, and like most roads that did not have formal speed studies conducted, operated under basic ruleup to 55 mi/h, dependent upon road and weather conditions. When the road was transferred to the city in 1992, a speed study was completed, which resulted in a speed limit of 35 mi/h. After the reconstruction of Ayres Road, the posting was changed to 25 mi/h, which more closely reflects the traffic calming design features and the average speed of vehicles.

Conclusions and Recommendations

Traffic calming
Getting motorists to slow down so bicyclists can share the space and pedestrians feel safe when crossing the street appears to depend on narrowing the travel lanes as much as possible. The lanes need to be narrow in an actual, physical sense (e.g. 10 or 11 feet wide), and they need to look and feel narrow to motorists. The look and feel, in turn, can be achieved by a combination of narrow lanes along with conspicuous edges (e.g. the use of a center island), introducing curves and chicanes, and design elements such as trees and shrubs at both the edges and in the median, to eliminate the look of a long, straight road. Use of speed tables or raised intersections at strategic locations is also a key element of traffic calming, especially when there are very few intersections or other interruptions to continuous traffic flow along the street.

Bike lanes that complement traffic calming
The most significant new feature in the Ayres Road design was the use of raised bicycle lanes. This enabled the city to meet the objective of a safe facility for bicyclists along a moderately busy roadway, while at the same time avoiding the pavement-widening effect of the typical on-street bike lane. The strong visual edge provided by the left edge of the raised bike lane helps reinforce the narrow travel lanes and discourage excessive speeds.

Public involvement
As with many other projects, the process of arriving at a final design for Ayres Road reinforces the notion that its generally better to approach the neighborhood and major stakeholders at the outset of the project with no preconceived design proposal, and let the public help develop the design. Only by struggling with the choices and trade-offs in the design process can the public come to appreciate the difficult task city staff and consultants face in designing a street to meet a number of conflicting goals and objectives. Additionally, staff cannot assume that citizens are able to fully understand engineering plans and drawings. Illustrations and 3-D pictures may be necessary to convey the look and feel of a design element, particularly one that is unique to an area.

Costs and Funding

The total construction costs for the reconstruction of Ayres Road came to just under $1 million. The unit costs for each of the bid items compared well with other local projects similar in size and nature despite the innovative design treatments utilized. The raised bike lane component came in at $15 per lineal foot as compared to the citys standard curb and gutter with asphalt street section at $13.50 per lineal foot. A majority of the project costs were funded by Transportation System Development charges (transportation impact fees) but about 20 percent of the project costs were paid by abutting property owners through assessments.

Contacts

Lee Shoemaker
Bicycle & Pedestrian Program Coordinator
City of Eugene Public Works