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Home My WebLink AboutMOUNTAINRIDGE FARM PUD PRELIMINARY - 18 92B - CORRESPONDENCE - MEMO / P & Z BOARD1w _ Community Planning and Environmental Services Transportation Division MEMORANDUM of Fort Collins Date: May 20, 1994 To: Planning and Zoning Board From: Tom Vosburg, Transportation Planner Re: Supplemental Traffic Impact Analysis of Stockbridge/ Mountainridge Farms This memo provides additional analysis of traffic issues raised by neighborhood residents but not addressed in the Stockbridge/Mountain Ridge site access study. Concerned neighborhood residents point out that the site access study did not specifically evaluate the impact of providing the proposed connection of Westfield Drive to Seneca Avenue. Many residents are concerned that this connection will provide an attractive alternative access to and from Seneca Avenue and will result in large amounts of traffic cutting through Imperial Estates rather than using the Horsetooth/Seneca intersection. An analysis of potential changes in traffic volumes on streets within the Imperial Estates subdivision should Westfield Drive be connected is outlined below. This analysis was developed by Transportation Division staff and is based on projections developed in the Stockbridge/Mountain ridge Farm site access study. Additional assumptions have been employed to evaluate traffic within Imperial Estates. Only average daily traffic volumes (ADT) have been estimated in this analysis. No attempt has been made to evaluate intersection operations. Also, this analysis only evaluates likely traffic volumes in regard to city standards; it does not draw conclusions regarding the impact of those volumes on the quality of life with in the neighborhood. Existing Neighborhood Conditions Imperial Estates is an existing county subdivision consisting of approximately 192 single family homes and 27 duplex units located south of Horsetooth Road and East of Taft Hill Road. The area is served by a network of 7 residential streets laid out in a grid pattern. Five streets run north/south and access Horsetooth Road, two streets run east/west and access Taft Hill Road. The southern most east/west connection, Westfield Drive is discontinuous and does not connect directly through from the interior of Imperial Estates to Taft Hill Road. The Overall Development Plan for the area includes Westfield Drive being extended to connect with Seneca Avenue. Streets within Imperial Estates are on the average 33 feet wide, and there are no sidewalks. Figure 1 illustrates the Imperial Estates neighborhood and its relationship to the Stockbridge and Mountainridge Farm developments. Trip generation factors developed by the Institute of..Trapsportation Enginee,rs.(Trip Generation, 5th ±" Edition) were used to estimate the current total traffic now generated`by Imperial -Estates. It was ;a estimated that the. subdivision now ge'nerates,.appr'oximately 2015 average trip ends a`day. It was also assumed that these trips are evenly.distributed over the,Taccess' points with each::access attracting approximately 15 % of.the total neighborhoodaraffic, ,resulting in Average Daily Trip volumes`(ADT) of approximately 310 trips per day at each access.point... Effects of Connecting Westfield Drive Connecting'Westfield Drive will have two separate effects r traffic within Imperial Estates. The first effect will be that existing. traffic generated by Imperial.Esfates residents will be re -distributed as residents take advantage of the_new access point in the southeast corner of their. neighborhood to travel to the nearby schools and park; as well as to travel by':way of other collector streets to Shields Street and Harmony 1 235 Mathews • P.O. Box 580 • Fort Collins, CO 80522-0580 • (303) 221-6608 Road. The second effect is that some traffic from outside the Imperial Estates neighborhood will also take advantage of the new connection, and new traffic will be introduced to the neighborhood. Neighborhood residents disagree with City staff regarding the extent to which outside traffic will perceive the new access point as attractive as an alternate route, and thus the amount of the new outside traffic that will enter the neighborhood. In order to be responsive to neighborhood concerns, two separate estimates of the volume of potential new cut -through traffic are provided here. The first estimate of future Imperial Estate traffic volumes is based on assumptions regarding the rate of trips deviating through the neighborhood that Transportation Division staff believe are reasonable and best reflect the traffic level of traffic that will be experienced if the connection is provided. This estimate is referred to the "Likely" estimate of future traffic. The second estimate is based on assumptions of dramatically higher rates of cut -through traffic that perhaps reflect the neighborhood's perception of how drivers will behave. This estimated is referred to as the "Maximum" estimate of traffic. The "Maximum" estimate uses assumptions that are considered by the Transportation Division to be extreamly unrealistic. Drivers would need to percieve no difference between Westfield Drive and Seneca in regard to travel time, directness or congestion in order for the "Maximum" estimate traffic volumes to be realized. Seneca will provide a direct connection to Horsetooth Road, while Westfield Drive routes will require at least two turns and travel on narrower streets. Westfield Drive is also controlled by a number of stop signs. Drivers turning left onto Horsetooth from Imperial Estates will face the same traffic volume as those turning from Seneca. Assumptions and Projected Traffic Volumes Regarding the re -distribution of existing traffic, it is reasonable to assume for this analysis that if Westfield Drive is connected, existing traffic will be re -distributed evenly over all 8 access points. This will result in the new Westfield / Seneca access attracting approximately 12.5% of the total existing traffic, as well as the other access points decreasing in their share of existing traffic to from 14.3% to 12.5%. This will result in all access points carrying approximately 271 ADT of existing Imperial Estates traffic. Regarding new traffic cutting through the neighborhood, both the "Likely" and the "Maximum" estimates assume that only the northbound left turning traffic from Seneca to Horsetooth and the eastbound right turning traffic from Horsetooth to Seneca would have the potential to cut through the neighborhood using the new Westfield / Seneca access point. The Stockbridge/Mountainridge Farm site access study estimates that future volume to be approximately 890 ADT. For the "Likely" estimate, Transportation Division staff estimates that at most 15%, or 133 of those drivers will chose to deviate through Imperial Estates each day. For the "Maximum" estimate, staff assumed that 50%, or 444 ADT would deviate through the neighborhood. Staff also assumed that all of the new external traffic would not be evenly distributed within Imperial Estates, but instead concentrated on 3 streets (Crescent and Royal to Horsetooth Road and Westfield to Taft Hill Road). It was also assumed that each of these streets would carry an equal share of the new r traffic. Table 1 below presents a summary of traffic volumes expressed as ADT projected for each access point in Imperial Estates based on these assumptions. Table 1. Summary of Estimated Imperial Estates Traffic Volumes at Access Points Expressed as Average Daily Trips (ADT) Current ADT Likely ADT Maximum ADT Access Point without Westfield with Westfield with Westfield Connection ' Connection Connection Crescent 310 315 418 Royal 310 271 271 Capitol 310 315 418 Lynda 310 271 271 Imperial 310 271 271 Westfield at Taft 310 315 315 Westfield at Seneca NA 404 715 Conclusions This analysis demonstrates that connecting Westfield drive is feasible from a traffic engineering standpoint. All projected traffic volumes projected for both the "Likely" and "Maximum" estimates will be within city standards for residential streets. City of Fort Collins design criteria and standards for streets require that streets forecasted to carry more than 2,500 ADT be built to collector standards. These standards also allow 28 foot wide public streets to be used in PUDs where parking is restricted and forecast ADT is below 750. The highest traffic volumes will be experienced on Westfield Drive at the new connection to Seneca connection. This part of Imperial Estates is now the furthest from any access point and has lower traffic than the rest of the subdivision. While the while the traffic levels forecasted in the "Likely" estimate are typical for residential streets, these levels will be a change for residents from the levels now experienced in that area. - EXISTING ------- -FUTURE HORSETOOTH ROAD U it W C. / i� Q � F- rIico i fA o �i W �,♦ N TROUTMAN PRIMARY STREETS Figure 2,