To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Daniel Sailer, P.E., Public Works Director
Title
Presentation: Downtown Land Use and Traffic Capacity Evaluation
Body
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Executive Summary
This memo is a summary to Town Council on the Downtown Land Use and Traffic Capacity Evaluation report. Town Council directed staff to hire a consultant to assess the remaining capacity of downtown streets for the purposes of better understanding additional land use growth capacity. Staff hired AECOM to complete this evaluation and report. Several growth scenarios were used to forecast future traffic volumes and the impacts to existing intersections. All intersections were analyzed in their existing configuration. No roadway or intersection improvements were assumed in the analysis.
The report divided the Downtown into three zones; North (N), Core (C), and South (S). The zones were used to help define current development conditions, and the impact areas for future development and to better understand travel patterns to, from, through, and within Downtown. Projected land use scenarios with varying development densities and land uses were defined to identify potential future development.
The question of whether or not there is available capacity to handle additional traffic from growth was explored and confirmed. There is additional intersection capacity available for new Downtown growth. Two intersections of concern were identified as first reaching capacity - the Wilcox and Plum Creek Pkwy intersection and the Wilcox and 5th Street intersection. Vehicle capacity is simply the highest amount of volume that can be moved through an intersection in optimum conditions. While different types of traffic control at intersections can negatively impact capacity, it cannot increase capacity.
In addition to intersection capacity the report assessed intersection Level of Service (LOS). In lay terms, LOS is associated with how much additional delay is added to a driver’s trip. It is rated on an A-F scale. As delay increases the LOS rating decreases. The Downtown Mobility Master Plan recommends an acceptable LOS E during peak traffic hours. However, current Town standards call for a minimum LOS D at intersections during peak hours.
History of Past Town Council, Boards & Commissions, or Other Discussions
On June 15, 2021, Town Council directed staff to contract with a consultant for the purposes of assessing traffic capacity within the Downtown area. The Town contracted with consultant AECOM to perform the analysis with assistance of Town staff. AECOM and Town staff also met with individual councilmembers, as requested, to review the assessment and answer questions.
Discussion
Downtown Castle Rock has experienced recent growth in and around the Downtown area over the past few years. This growth has raised traffic concerns and whether or not the Downtown street network can support additional development. To better understand the impacts of growth on traffic and roadway capacity, the Town hired consulting firm AECOM to conduct a study examining possible future growth conditions and the impacts it would have on the street network. (Attachment A) is the technical report performed by AECOM that discusses the results of the analysis.
A baseline traffic analysis, which included existing land uses and recently entitled land uses (e.g. the Encore and View project), was created to understand remaining roadway capacity as well as evaluate the impact of future development on the traffic Level of Service (LOS). Other work tasks performed included the following elements:
• Collect new traffic data to produce a summary of existing intersection and street service levels
• Create three land use growth scenarios with varying commercial square footage and housing units
• Use anonymous cell phone or other GPS enabled data to better understand traffic conditions, patterns, and origins and destinations of vehicles in Downtown
• Assess intersection and street capacity based on various development scenarios
Intersection capacity and the available capacity was calculated for intersections in Downtown. Of the remaining intersection capacity only half was assumed available for Downtown growth and the other half was reserved for regional through trip growth. These percentages are based on current traffic distributions occurring downtown. Therefore, when an intersection exceeded 50% of available capacity it would be considered above capacity. Further, the report used only a 90% intersection utilization rate rather than a full 100% utilization when determining available intersection capacity. This is essentially a safety factor of 10% of capacity not being utilized in the growth scenarios to be conservative.
General conclusions and recommendations from the analysis include:
• The intersection with the least amount of capacity remaining that would be available for development is Wilcox Street and Plum Creek Pkwy, which is not considered a Downtown intersection by the report. Capacity upgrades to the intersection would require significant reconstruction of intersection approaches and require right-of-way.
• The first Downtown intersection to all below capacity available for development is the Wilcox Street and 5th Street intersection.
• Crystal Valley Pkwy interchange will relieve some through traffic that has origins or destinations in the southeast part of Town. However, improvements to Plum Creek Pkwy and Wilcox are still needed to accommodate Downtown growth.
• Downtown through traffic will probably have a greater impact on traffic operations than future Downtown growth. Currently more than half (54%) of Downtown traffic is considered cut-through with no origin or destination Downtown.
• Improvements identified in the Downtown Mobility Master Plan could improve vehicle delay, or LOS, at several Downtown intersections, such as roundabouts at Wilcox and 4th, or Jerry Street and 5th Street.
• Improving routes to I-25 and other routes within Town that do not travel through Downtown would decrease the amount of through trips using Downtown which could impact available capacity at Downtown intersections; examples include Liggett Road extension to Caprice Drive.
• Since many trips to/from Downtown are less than 5 miles, improving bike and pedestrian access to Downtown would reduce vehicular trips into Downtown.
• The report can be used when assessing Downtown development applications.
This study can be used to help assess future development projects and recommendations can aid staff and Town Council in future CIP decisions to help accommodate Downtown transportation needs.
Budget Impact
The Downtown Land Use and Traffic Capacity Analysis was budgeted in Fiscal Year (FY21). The results of the report will be presented to Town Council at the July 5, 2022 meeting. There are no budget impacts of the report.
Staff Recommendation
No recommendation is provided. This agenda item is for informational purposes only.
Attachments
Attachment A: Downtown Land Use and Traffic Capacity Evaluation