To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Daniel Sailer, Public Works Director
Title
Discussion/Direction: Knobcone Drive Neighborhood Traffic Calming Request
Body
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Executive Summary
In early November 2022 a letter (Attachment A) was presented to the Town requesting speed humps on Knobcone Drive. This street has previously been assessed for the same request as part of the Town’s Neighborhood Traffic Calming Program and did not meet criteria. Since the Town has a formal program approved by Town Council, and this request is being made outside of this program, this request must be acted on by Town Council. The purpose of this item is to report factual findings for consideration and request Town Council make a formal recommendation on this matter.
The request is made on the perception that the roadway has steep gradients, constricted sight lines, and a blind curve such that constructing speed humps is necessary to keep all vehicles traveling at, or below the speed limit. Town staff has completed an engineering review and has determined that sight lines are adequate for the typical prevailing speeds such that additional safety enhancements are not necessary and would not provide significant benefit for the expenditure of funds (approximately $12,000 - $40,000 depending on whether this request is granted using staff labor or contracted labor).
The Town has more than 500 lane-miles of residential roadways. As this street is not uniquely different than other residential streets (sufficient sight distance for speeds) staff is not recommending approval of this request. The Town has an approved program that is geared specifically for utilizing a consistent process to assess these requests. Knobcone Drive has previously been reviewed per this program and found not to meet criteria. The approval of this request to utilize public funds for installing speed humps is likely to set a precedence for other residential streets. Town Council has also recently requested that Town staff provide a review of the existing program and provide some options for Town Council to consider. This item is scheduled to be reviewed by Town Council at the same Council meeting. It would be appropriate for the HOA to apply again through program procedures after Town Council has provided direction for any program adjustments.
History of Past Town Council, Boards & Commissions, or Other Discussions
There will be a presentation on February 6, 2023 to the Public Works Commission to obtain the Commission’s recommendation to Town Council on this matter. An update on their recommendation will be provided at the Town Council meeting.
In September 2021, staff received a signed petition from Knobcone Drive residents in the Timber Canyon neighborhood for a neighborhood traffic calming request. A subsequent traffic study was done and based on those results it was communicated to the point of contact that the street did not meet both the speed and volume thresholds required to advance within the Neighborhood Traffic Calming Program (Attachment B).
Further safety concerns were presented to Town staff in early September 2022 with regards to excessive driving speed and for staff to consider additional signage or beacons on Knobcone Drive. Prior to implementing any safety improvements, it was necessary to complete an engineering evaluation. The result of that evaluation found that the existing speed limit signage and supplemental signage (Steep Grade Warnings) are adequate, and no further signage was recommended. It was also pointed out that signage has a limited effective time frame. The Police Department was also notified for additional enforcement and to provide a radar speed feedback sign to help make drivers aware of their speed. The Police found similar speed and volume information when compared to the data collected in 2021. The 85th-percentile speed was 17 to 19 mph with 80 to 120 vehicles a day. They did ot report any speeding issues.
Discussion
Location and Existing Roadway Information
The Timber Canyon neighborhood (see Figure 1) is located in the northeastern portion of Castle Rock, Colorado. Knobcone Drive generally has a north/south orientation and is classified as a local, residential roadway, serving about 50 single family residential homes in the neighborhood, about 11 of which take direct access from Knobcone. At its northern terminus, Knobcone intersects with Crowfoot Valley Road, a regional arterial roadway. At its southern terminus, it intersects with another local street, Beechnut Place, which connects with a right in / right out only access to State Highway 86 (Founders Parkway). Based on the measured vehicle traffic volumes, staff does not find this roadway is being utilized as a cut-through between Crowfoot Valley Road and Founders Parkway. The traffic is for local access only. Both access points to major roadways have an “entry street” cross-section, with divided, landscaped, center medians that aid in making drivers aware of the transition from highly mobile arterial and highway roadways, to residential, highly accessible neighborhood streets. There is no space for parking in the entry street areas, and with a 28- ft nominal flow line to flow line street width, on-street parking is only available on one side. On-street parking has been infrequent and “No Parking” signage is not provided anywhere, due to the long and large driveways, and large garages available for each lot. There is a five-foot attached sidewalk on one side, the eastside, of the street. The speed limit is posted in a couple locations on Knobcone Drive at 15 miles per hour (mph) with steep gradient supplementary plaque signs. Knobcone is circuitous and has an advisory curve warning sign with another steep gradient supplementary plaque sign. The other 900-ft plus length roadway in the neighborhood, Silver Pine Drive, has not been a discussion point with the neighborhood.
Figure 1. Timber Canyon neighborhood
Public Works staff collected traffic data in September 2021, as a part of the neighborhood traffic calming request. Neighborhood traffic observations and a site safety review occurred on September 20, 2022. The Police Department increased enforcement and placed a radar speed feedback sign in the southbound direction for seven days at the end of September 2022 (Attachment C), and for the northbound direction for seven days at the beginning of October 2022 (Attachment D). The data collected from these radar signs did not show a speeding or volume issue on Knobcone.
Engineering Facts Evaluation
Historical crash data reviewed shows no crashes for this roadway.
Based on the traffic calming speed data collected in September 2021, at 5106 Knobcone Drive, the measured 85th percentile speed was 19.5 mph and 19.9 mph on September 14th and 15th respectively.
In order to meet the requirements of the Neighborhood Traffic Calming Program (Attachment E), the measured 85th percentile speed needs to be 20 mph or greater. The 85th percentile speed measured on Knobcone Drive did not meet the 20 mph minimum requirement.
Measured Average Daily Traffic (ADT) volume on the street was 245 and 215 ADT on September 14th and 15th respectively.
The Town's program requires that the ADT volume on the street must be a minimum of 500 vehicles per day. The results of the count indicate that traffic volumes do not meet the 500 vehicles per day minimum ADT requirement.
Based on the site evaluation in September 2022 of the roadway Knobcone Drive, no further signage or devices are recommended due to the current signs being consistent with the requirements and recommendations of the Manual of Uniform Traffic Control Devices. Additionally, the roadway is curvy and hilly, and acts as natural traffic calming on Knobcone Drive that forces motorists to reduce their speed due to the sharp curves and steep gradients of the road. If there are speeders, they are doing so knowingly and without regard for these physical roadway constraints that will not change with additional signage.
Based on the radar speed feedback signage and data collection by the Police Department:
The 85th-percentile speed was 19.7 MPH with an average volume of 181 vehicles a day in the southbound direction, and
The 85th-percentile speed was 17.8 MPH with an average volume of 81 vehicle a day in the northbound direction.
The speed and volume data collected over a week in each direction by Police is consistent with the data collected by Public Works.
Staff has prepared a speed reduction primer that provides an overview of several options available for a variety of roadways and circumstances (Attachment F). Potential devices to consider on Knobcone, include an HOA owned and maintained radar speed feedback sign or signs, see policy details (Attachment G). Cost to permanently install a pair of devices is $7,500, or each unit is approximately $3,500. An eight-foot wide speed hump, requested specifically by HOA, has an initial cost of about $6,000 each if the Street’s Division constructs it and they can prioritize this work around other community needs, and approximately $20,000 if a contractor performs the work.
Engineering Evaluation Findings
The efficient and responsible investment of resources in addressing safety problems is a difficult task. Since crashes can occur on all roadways in use, it is inappropriate to say of any roadway that it is safe. However, it is correct to say that roadways can be built to be safer or less safe. Road safety is a matter of degree. When making decisions affecting road safety it is critical to understand that expenditure of limited available funds on improvements in places where it prevents few injuries and saves few lives can mean that injuries will occur and lives will be lost by not spending them in places where more crashes could have been prevented. It is the Town staff’s objective to maximize crash potential reduction within the limitations of available budgets by making road safety improvements at locations where it does the most good or prevents the most crashes.
The 85th percentile speed on Knobcone Drive is above the posted speed limit, but within the five mph threshold in the Town’s Neighborhood Traffic Calming Program such that physical improvements typically would not be a good investment of Town funds. Additionally, the low volume of vehicles measured did not meet the volume threshold of the Town funded program either. It should be pointed out that installing traffic calming devices would likely increase emergency services response times, increase school bus route times, and impede snow plow and pavement maintenance teams.
We determined that signage advising of roadway conditions and speed are more than sufficient to inform drivers and that any additional signage was an additional cost that would not produce the desired effect to slow driving speeds. Lastly, Police have verified that speeds are consistently in a range of 10-20 MPH, and they did not find speeding to be a concern during their enforcement periods.
While Knobcone Drive does not meet any of the Town’s program or safety criteria to install additional traffic calming devices, the Town does offer educational material, such as yard signs that remind drivers to slow down and drive the posted speed limit. There are also “traffic treaties” championed by residents, which are pledges by neighbors to drive the speed limit. These treaties bring awareness to the concern and promote problem-solving while neighbors go door-to-door seeking signatures. There is also a neighborhood sponsored radar speed feedback sign program that could be pursued (Attachment G). Staff are recommending these courses of action. Driving speeds can be re-evaluated in the future to determine their effectiveness or if additional steps are desired.
Further evaluation at this time is not recommended and Traffic Engineering staff will continue to monitor the safety of the roadway in this area.
Budget Impact
The Homeowners Association letter requests financial support from the Town to provide two speed humps at a cost of about $6,000 each if the Streets Division does the work between other priorities, or $20,000 each if a contractor constructs. The Town’s annual Neighborhood Traffic Calming budget is $25,000. There are a couple active NTCP petitions in the evaluation stage, but none that have determined the need for device implementation and required funds. Staff has neighborhood informational signs available and can provide those to the neighborhood within the current operations budget at no additional cost.
Staff Recommendation
Staff recommends Town Council deny the request to install speed humps. If the HOA desires, staff will work with them to provide educational material, such as yard signs that remind drivers to slow down and drive the posted speed limit, as well as encourage the neighborhood to form a “traffic treaty” championed by residents, which are pledges by neighbors to drive the speed limit. Staff are recommending these other courses of action over installing engineered devices due to their lower cost and reduced negative impact to other operations and maintenance, and because the evaluation found that the vehicles causing the issue are neighbors. Driving speeds can be re-evaluated in the future to determine their effectiveness or if additional steps are desired. In addition, the current program is under review as an item in the same meeting, and Town Council will assess options to update the program. The HOA could then consider applying through the formal
process again.
Proposed Motion
"I move that Town Council does not approve the installation of the speed humps as requested by the
Timber Canyon Homeowners Association. If the HOA agrees, it is recommended instead that educational materials be provided, and encourage the distribution of a neighborhood traffic treaty to encourage neighbors to drive the speed limit."
Alternative motions:
"I move that Town Council approve the installation of the speed humps as requested by the Timber Canyon Homeowners Association."
“I move to approve the installation of speed humps as requested, with the following conditions: (list conditions)”
“I move to continue this item to the Town Council meeting on (date) to allow additional time to (list
information needed)”
Attachments
Attachment A - HOA Letter - November 2022
Attachment B - NTCP Letter - September 2021
Attachment C - Police Southbound Speed Data Report - September 2022
Attachment D - Police Northbound Speed Data Report - October 2022
Attachment E - Town Council Approved Neighborhood Traffic Calming Program Resolution information
Attachment F - Speed Reduction Primer
Attachment G - Private Radar Speed Feedback Sign Policy information