Dave Reinhard, Transportation Consultant (formerly City of Eugene Transportation Engineer, Division Manager)
This paper describes an unusual design for a street improvement project in Eugene, OR. City staff and the community have moved up a “learning curve” during the past several decades in regard to on-street treatments for bicyclists in combination with traffic calming techniques. This project presented an opportunity to combine a number of design features in a new way on a suburban collector street.
In 2001–2002 the city of Eugene, OR, fully improved Ayres Road, a collector street in the northern suburban part of the city, using a number of unconventional design techniques. Ayres Road is a half-mile long collector street in a developing residential neighborhood, and the only street that provides a usable east-west connection between two north-south major collectors—Delta Highway North on the west, and Gilham Road on the east.
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. The roadway functioned reasonably well for many years in its rural setting, but was not adequate to serve the suburban residential development called for in the city’s adopted land use plan. The city began efforts to design an improved cross-section in the early 1990s when residential development began to accelerate on adjacent farm land. The project was delayed a number of years because of other projects having a higher priority for scarce funds and an extended public involvement process over the proposed design.
Over the past three decades Eugene has developed an extensive system of bikeways. The network includes off-street paths, on-street striped lanes on busy streets and designated bike routes on selected neighborhood streets to help provide continuity. 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.
In addition, Eugene has developed a number of strategies over the past decade to incorporate traffic calming features in street improvement projects. Experience with a number of techniques in various settings, in retrofit examples as well as new construction, helped shape the public input and the decision-making by city staff on the Ayres Road project. The project provided an opportunity to combine a number of bike-friendly components with proven traffic calming features in a unique way.
During the 1970s and 1980s a number of collector and arterial streets in Eugene were improved to upgrade the cross-section from a two-lane asphalt mat to an urban section including curbs, gutters, and sidewalks. In a few cases, multi-lane streets were built to respond to existing or forecasted traffic volumes, but the majority of projects were built as two- or three-lane streets, the latter using a striped center continuous two-way left turn lane. In some cases parking was retained on one or both sides of the street, and in nearly all cases, on-street, striped bicycle lanes were included in the project. Therefore a somewhat typical, default cross-section of three lanes and bicycle lanes became the norm for upgrading former county roadways to urban standards in developing areas of the city.
A typical 1970s–80s 3-lane urban street with on-street bike lanes used in Eugene.
In the early 1990s, several active neighborhood associations began petitioning the city for relief from excessive traffic speeds on collector streets in residential areas. The city went through a process of initial experimentation with speed humps, evolving to the use of other techniques that have proven more acceptable to emergency service providers. As these projects were carried out in retrofit situations in older neighborhoods, interest also began to grow rapidly in incorporating traffic calming features as part of the design of major street improvement projects. Public perception shifted, and the earlier “default” design of two lanes, a center turn lane, bike lanes and (usually) no on-street parking came to be viewed as a very unattractive design that encouraged speeding and diminished neighborhood livability.
In response to these issues, 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:
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. While some of the traffic calming features still generate controversy, the improved look and feel of major street projects has met with a high level of public acceptance.
A more recent (1990s) design with chicanes and wide curb and gutter for bike lane (example from Terry Street).
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 3 to 3.7 m (10 to 12 ft) 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.
As part of the updated design standards mentioned earlier, the city revisited its practice of requiring on-street bike lanes on all street classifications other than local streets. The new standard established a category for collectors through residential areas, termed the “neighborhood collector.” This street type calls for mixed, slow-moving bike and auto traffic, rather than requiring striped lanes on these lower-volume streets. However, on-street bicycle lanes are still the standard for major collectors and all arterial streets in Eugene. Since Ayres Road is a major collector, the city faced a challenge to come up with a design that would achieve the best balance of competing objectives — such as the goal of a bike-friendly design along with one that discourages traffic speed.
The design for the Ayres Road major improvement project evolved over a period of nearly 10 years. In about 1991 city staff initially proposed a typical three-lanes-plus- bicycle-lanes cross section. Residents of the area protested that this would result in too wide a street and increased traffic speeds in the neighborhood. The process was put on hold for several years due to other priorities, but occasional discussions took place with residents and local developers who were carrying out subdivision projects on land adjacent to Ayres Road. Eventually 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:
Travel lanes as narrow as 3.2 m (10.5 ft) would be used on Ayres Road.
Horizontal curves with bulb-outs and centerline changes on a fairly straight segment of roadway would be used to discourage high speeds.
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 helps reduce the glare and related drawbacks to the added pavement of the newly built street. By planting trees and shrubs in the median, the motorist’s view down the street is interrupted and the overall effect tends to reinforce the notion of moving slowly down a narrow street, rather than being able to see uninterrupted pavement a long distance ahead. The median islands provide a safe landing spot for pedestrians, enabling them to cross at multiple locations, not just intersections. Also, where a median island runs along the left edge of the travel lane it helps visually narrow the lane, encouraging slower speeds.
The intersections were raised to full curb height in order to provide a visual cue as well as a tactile message that helps discourage speeding in these areas. The raised intersections were an important design component in order to prevent the image of Ayres Road simply being a new and improved road race course from one end to the other.
Vehicles tend to intrude into bike lanes on curved roadways (Crescent Avenue).
The most unusual and controversial design feature is 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 1.5 to 1.8 m (5 to 6 ft) of pavement on each side of the road. Even though most motorists don’t physically occupy this space when driving along tangent sections, most use it when they create their own transitions on curved road segments.
The additional space also adds to the image of a wide roadway where it feels OK 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, but is visually nearly as powerful as a vertical curb.
Raised bike lane and other traffic calming features utilized on Ayres Road.
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, and how should transitions at accessible ramps and intersections be designed. The only information on raised bike lanes available at the time came from the Oregon Bicycle and Pedestrian Plan, which was limited to a photo of one constructed in Switzerland and a cross-section sketch showing how the raised bike lane separates bicyclists from motorists and bicyclists from pedestrians. No details or dimensions were specified in the plan. The photo as well as the sketch depicted a raised bike lane constructed of asphalt concrete, the same material used in the motor vehicle travel lane, with a sloping concrete ribbon separating the two. The city’s desire was to have at least 1.4 m (4.5 ft) of bicycle-riding surface, the same accommodated by a wide curb-and-gutter option 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 30.5 cm (1 ft) (a 7.6 cm (3 in ) rise in a 1 ft 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 seems to satisfy riding conditions as well.
At another intersection, the raised bike lane transitions to a standard on-street bike lane at the curb return. This option did not introduce any riding or accessibility issues, but it did bring up constructability issues for the asphalt paving operation.
Transition design for accessible ramp locations.
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. However, this proved to be more complicated since it was untried with no similar projects to use as an example. The first challenge for the contractor came when the company asked for a shoe from the extruding machine manufacturer based on the city’s 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, mostly 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 3 m (10 ft)–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.
Water ponding created by asphalt paving created challenges around curb return.
A few operational considerations must be kept in mind when choosing a raised bike lane — street sweeping, road drainage, and driveway access. The final version of Eugene’s raised bike lane requires two passes for the city’s 2.4 m (8 ft)–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 10.2 cm (4 in) to as much as 11.4 cm (4.5 in) in 30.5 cm (1 ft) 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 done for accessible ramps, i.e., the beveled edge dropped out at driveways.
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 rule — up to 88 km/h (55 mph) 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 zone of 56 km/h (35 mph). After the reconstruction of Ayres Road, the posting was changed to 40 km/h (25 mph), which more closely reflects the traffic calming design features and the average speed of vehicles.
|1992||2002 (Post Reconstruction)|
|Average Speed (mph)||36||26|
|85 % Speed (mph)||39||29|
|Maximum Speed (mph)||46||37|
|Posted Speed (mph)||35||25|
As with many other projects, the process of arriving at a final design for Ayres Road reinforces the notion that it’s generally better to approach the neighborhood and major stakeholders at the beginning, 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.
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. 3 or 3.4 m (10 or 11 ft) 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. 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.
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.
While it appears the city has developed a successful design in the case of Ayres Road, this example also serves to illustrate that there are probably other undiscovered “templates” for street designs that can meet these kinds of objectives. The best approach involves being open to experimentation and re-combining various design techniques to achieve the best mix of outcomes. Each project provides an example that can be copied or borrowed from to create even better designs for future projects.
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 City’s 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 (a.k.a. transportation impact fees) but about 20 percent of the project costs were paid by abutting property owners through assessments.
Bicycle & Pedestrian Program Coordinator
City of Eugene Public Works
858 Pearl Street
Eugene, OR 97401
(541) 682-5471 (voice)
(541) 682-5598 (fax)
Transportation Consultant (formerly City of Eugene Transportation Engineer, Division Manager)
Bicycle & Pedestrian Program Manager
Oregon Department of Transportation