March 2, 2004
SUBJECT: Canary Drive Traffic Calming – Post-Implementation Study
REPORT IN BRIEF
In June of 2002, City Council approved the Stage II Traffic Calming Plan for Canary Drive and authorized staff to construct the indicated traffic calming measures on Canary Drive. After construction was complete, staff was to conduct a post-implementation study of the neighborhood to determine the impacts and results of the traffic calming measures after installation.
The City of Sunnyvale has conducted a post-implementation study of the traffic calming devices for the Canary Drive Neighborhood. The post-implementation study concludes that, based on the volume and speed of vehicles, the Stage II traffic calming measures installed on Canary Drive from Homestead Road to Inverness Avenue have adequately reduced the average speed to acceptable levels.
Acceptable levels are 85th percentile speeds less than 32 mph and average daily volumes less than 1000 vehicles per day for a neighborhood residential street. These are values indicated in the City’s Traffic Calming Policy as statistics of roadways that do not meet the criteria for traffic calming.
At this time, staff asks that Council accept the study results and consider Canary Drive a successful installation of traffic calming devices.
BACKGROUND
In February 1997, the City Council adopted a traffic calming policy to address residential neighborhood traffic concerns and complaints. The policy outlines the process under which circumstances staff is to conduct traffic calming studies. It also delineates thresholds of significance to determine "real" rather than perceived traffic problems, and sets forth a variety of acceptable Stage I and Stage II traffic calming methods. Stage I methods are generally comprised of studies, observations, education, public involvement, enforcement efforts, and changes in signing and pavement markings in an attempt to reduce the problem and improve the situation. They do not include the use of physical controls or impediments on the roadway system. Stage II methods are generally projects which physically alter the nature or configuration of a neighborhood street such as speed humps, traffic circles, diverters, chokers, or cul-de-sacs. The City's policy outlines an extensive community outreach and participation process for Stage II actions. The administrative process for doing studies is on a first come first served basis.
In October 1999, City staff received a letter from residents on Canary Drive expressing concerns over the speed of traffic on Canary Drive between Inverness Avenue and Homestead Road. During the initial discussion with residents, they indicated that they desired the City to conduct a Neighborhood Traffic Calming Study on Canary Drive for possible implementation of traffic calming measures.
Initial studies indicated that Canary Drive did experience speeds and traffic volumes in excess of the established City traffic calming thresholds and as cited by residents and property owners. Therefore, the street was qualified for the implementation of traffic calming measures.
Immediate actions were taken as follows: additional speed limit signs and legends were installed, the City’s radar speed trailer was deployed to the neighborhood, and additional traffic enforcement was provided by the Department of Public Safety.
Several neighborhood meetings were held, and surveys and letters were mailed to all residents and property owners throughout the course of the study, to involve them in the progress of the traffic calming study.
As a result of initial meetings, staff and the neighborhood agreed on the installation of a double yellow centerline stripe as a Stage 1 traffic calming measure. Follow-up studies showed a slight decrease in the volume of traffic and in the 85th percentile speed after the installation of the centerline stripe, but the data still indicated that the street qualified for additional traffic calming measures.
Staff and the neighborhood then gathered to discuss different Stage II traffic calming measures appropriate for implementation on Canary Drive. From the meetings, staff and the neighborhood were able to develop a recommended Stage II traffic calming plan to be voted on by the neighborhood. The plan developed by the neighborhood and staff consists of a landscaped traffic circle at the intersection of Canary Drive and Loch Lomond, a stamped concrete speed hump located on the property lines of four Canary Drive residences, and a 4 foot by 20 foot long median island with brick pavers on Canary Drive at Inverness Avenue. This plan was presented to the neighborhood through a letter and survey prepared by staff. Of the returned surveys, 71% supported the traffic calming plan and 29% were opposed to the plan.
After completing the neighborhood survey and finding neighborhood support for the traffic calming plan, staff brought the Canary Drive traffic calming plan to City Council for final approval and implementation in June of 2002. City Council approved the plan and directed staff to return with a six month post-installation study describing the results of the Stage II Traffic Calming installation.
EXISTING POLICY
The following documents contain policy direction on this issue:
Land Use and Transportation Element C3: Attain a transportation system that is effective, safe, pleasant, and convenient.
Land Use and Transportation Element N1.5: Support a roadway system that protects internal residential areas from City-wide and regional traffic.
Land Use and Transportation Element N1.5.2: Utilize the City's residential neighborhood "Traffic Calming" techniques to address specific neighborhood traffic concerns.
Land Use and Transportation Element N1.5.3: Discourage non-neighborhood traffic from using residential neighborhood streets by accommodating traffic demand on city-wide and regional streets.
DISCUSSION
City crews finished constructing the Canary Drive Stage II traffic calming measures in March 2003. The traffic calming measures installed includes a median island at the Inverness end, a speed hump midway down Canary Drive and a traffic circle at the Loch Lomond intersection.
The vast majority of comments received from residents and property owners in the Canary Drive neighborhood were positive. Two negative responses were received by staff from residents on Eagle Drive; one expressed concerns about shifting traffic from Canary to Eagle, and the other expressed concern about the actual need for traffic calming on Canary Drive.
In order to gauge the effectiveness of the Stage II traffic calming measures installed on Canary Drive, staff conducted before and after studies. The studies consist of speed and volume data collection and analysis. Studies conducted prior to installation of traffic calming devices on Canary Drive showed that the average speed was 31.3mph and the 85th percentile speed was 35.7mph. The average daily traffic on Canary Drive was 1269 vehicles per day. Approximately six months after the installation of the Stage II traffic calming measures, the average speed was reduced to 24.1mph and the 85th percentile speed was reduced to 28.6mph. The average daily traffic on Canary Drive dropped slightly to 1179 vehicles per day. This data shows that Canary Drive experienced a 7.3mph drop in average speed and a 7.1mph drop in 85th percentile speeds. With the implementation of Stage II traffic calming measures on Canary Drive, speeds have dropped below the minimum thresholds outlined in the City’s Traffic Calming Policy. Traffic volumes are still above the minimum threshold set in the City’s Traffic Calming Policy, but the volume of traffic was not indicated as a concern by the residents and property owners during the traffic calming process. As a result, the Stage II measures implemented were not designed to reduce traffic volumes on Canary Drive.
In response to comments received that Canary Drive traffic calming has diverted traffic to Eagle Drive and Langport Drive, staff conducted speed and volume studies on both streets to gauge for impacts. Speed data collected on Eagle Drive showed that the average speed is 23.1mph and the 85th percentile speed is 31.0mph. Speed data collected on Langport Drive showed that the average speed is 17.6mph and the 85th percentile speed is 22.7mph. Volume counts showed that the average daily traffic on Eagle Drive and Langport Drive are 422 vehicles per day and 437 vehicles per day, respectively. The data collected shows that the speeds and volumes are well below the thresholds set for traffic calming and conform to the expected speeds and volumes for a neighborhood residential street. There are no baseline volume and speed data for Eagle Drive and Langport Drive because during initial studies, staff felt that diversion traffic to these streets would be minimal as there are no clear direct paths between Inverness and Homestead that would reduce travel times for motorists traveling on these streets versus a traffic-calmed Canary Drive.
FISCAL IMPACT
There is no fiscal impact associated with accepting the post-installation study results. If Council chooses to have staff re-study the Canary Drive neighborhood, staff expects to be able to absorb the costs in the existing operating budget.
PUBLIC CONTACT
Public contact was made through posting of the Council agenda on the City's official notice bulletin board, posting of the agenda and report on the City's web page, and the availability of the report in the Library and the City Clerk's Office. In addition, notices were mailed directly to property owners, tenants and concerned individuals in the Canary Drive neighborhood area.
ALTERNATIVES
1. Accept the post-installation study results for Canary Drive Traffic Calming and consider the project complete.
2. Do not accept the post-installation study results for Canary Drive Traffic Calming and direct staff to restudy the neighborhood again.
RECOMMENDATION
Staff recommends alternative #1.
Prepared by:
Dennis Ng
Senior Engineer
Reviewed by:
Jack Witthaus
Transportation and Traffic Manager
Reviewed by:
Marvin A. Rose
Director, Public Works
Approved by:
Amy Chan
Acting City Manager