TRANSPORTATION ADVISORY BOARD AGENDA ITEM
ACTION REQUESTED:
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Receive staff’s evaluation of traffic calming measures on Gartner Road between Washington Street and Charles Avenue
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DEPARTMENT: Transportation, Engineering and Development
SUBMITTED BY: Michael Prousa, TED Project Manager
BACKGROUND:
In August of 2022, residents reached out to the Transportation, Engineering and Development Department (TED) with concerns regarding speeding on Gartner Road between Washington Street and Charles Avenue.
In 2023, staff installed several traffic calming measures on Gartner Road, these included:
• Yellow Banding the 25 mph speed limit signs on Gartner Road leaving Washington Street, Charles Avenue, Olesen Drive, and Naper Boulevard.
• Installing the “25 MPH” pavement marking on Gartner Road leaving Washington Street for eastbound traffic and leaving Naper Boulevard for westbound traffic.
• Installing marked parking boxes on Gartner Road between Julian Street and Charles Avenue.
• Installing a marked choker on Gartner Road between Edgewater Drive and Driftwood Court.
Attachment 1 is the 2022 Gartner Road before study agenda item for reference.
DISCUSSION:
TED staff in 2022 conducted a speed and volume study at four locations on Gartner Road between Washington Street and Charles Avenue:
• Gartner Road between Edgewater Drive and Driftwood Court
• Gartner Road between Driftwood Court and Julian Street
• Gartner Road between Julian Street and Watercress Drive
• Gartner Road between Whirlaway Avenue and Charles Avenue
When reviewing speed data on a street, the 85th percentile speed is the primary consideration. Per the Institute of Transportation Engineers, the 85th percentile speed is the speed at which 85 percent of free-flowing vehicles are traveling at or below. Use of the 85th percentile speed is based on the theory that the large majority of drivers are reasonable and prudent, do not want to have a crash, and desire to reach their destination in the shortest time possible.
The City’s Master Thoroughfare Plan classifies streets based upon their function, access, and connectivity. Gartner Road is classified as a Collector (connect Local and Neighborhood Connector through or adjacent to multiple neighborhoods and have continuity between arterial streets). The City has been collecting annual speed and volume data on about 30-40 segments of road for the past 20 years. With this data, staff has established typical speeds and volumes for most road classifications. Our table of the city-wide typical speeds and volumes are listed below.
|
Roadway Classification |
City-wide typical 85th percentile speed range |
City-wide typical weekday volume (two-way) |
|
Collector |
29 - 34 mph |
5,000 - 12,000 vpd |
|
Neighborhood Connector |
29 - 34 mph |
500 - 5,000 vpd |
|
Local |
27 - 32 mph |
0 - 1,500 vpd |
In November 2023, City staff conducted an after study at the same four locations to see the impact the traffic calming measure had on the Gartner Road traffic.
Attachment 2 is a table showing the before and after studies.
Gartner Road between Edgewater Drive and Driftwood Court
The 85th percentile on this stretch of Gartner Road had speeds over the City’s typical threshold in 2022. In response, the City installed traffic calming measures. During the after study, the 85th percentile for westbound traffic was 38 mph. 38 mph is over our 34 mph threshold for Collector streets and we will continue with more traffic calming measure in an attempt to lower the speeds.
To counter the higher speeds, the City will:
• Revamp the marked choker with wider pavement markings.
• Install a permanent driver feedback sign for westbound traffic.
• Install a 25 mph stamp south of Driftwood Court for westbound traffic.
Gartner Road between Driftwood Court and Julian Street
The 85th percentile for both the before study and after study were within our typical thresholds for Collector Streets. No traffic calming measures were recommended in 2022 and none are recommended after this study.
Gartner Road between Julian Street and Watercress Drive
The 85th percentile on this stretch of Gartner Road was within our typical thresholds during the before study. After the before study, staff recommended marked parking boxes for this section and the section of roadway to the east towards Charles Avenue. The 85th percentile for the eastbound traffic in the after study showed a 7 mph raise to the 85th percentile.
To counter the higher speeds, the City will:
• Increase targeted enforcement
• Install a 25 mph stamp east of Julian Street for eastbound traffic.
• Install rotating driver feedback sign
• Install a marked lateral shift by widening the marked centerline.
Gartner Road between Whirlaway Avenue and Charles Avenue
The 85th percentile on this stretch of Gartner Road was above our typical thresholds during the before study in 2022. To counter this, the City installed marked parking boxes. The after study in 2023 showed a 7 mph decrease for westbound traffic. The City will not be recommending any more traffic calming measures for this stretch of roadway.
The City will continue monitoring the traffic conditions on Gartner Road and conduct another study once the recommended traffic calming tools are installed to measure impact.