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HomeMy WebLinkAboutHEARTHFIRE PUD - Filed GC-GENERAL CORRESPONDENCE - 2008-12-29PBS)f An employee -owned company MEMORANDUM TO: Larry Haas, CDOT Region 4 FROM: Scott Barnhart DATE: January 3, 2002 SUBJECT: SH-1/LCR-54 SAFETY STUDY This memorandum serves to summarize the analyses performed for the safety study at the intersection of State Highway 1 and Larimer County Road 54 (Douglas Road) and the mitigation measures recommended for the intersection. Accident Analysis: Traffic accident records for the years 1998 through 2000 were collected from Larimer County and an Accident Detailed Summary Report for the period covering January 1, 1995 through September 30, 2000 was received from CDOT. Police accident reports for the period January 1, 1996 through June 30, 2001 were also obtained. From this information, a traffic collision diagram was created and is enclosed for reference. The original assumption was that the predominant collision pattern at the intersection was southbound right -turning vehicles turning with too much speed and running off the road into the property at the southwest comer of the intersection. Five of the collisions reported during the period involved vehicles hitting the property fence at the southwest corner of the intersection. However, only one of those collisions could clearly be identified as a southbound right -turning vehicle. Three of the collisions affecting the property on the southwest corner involved left -turn or right-angle collisions in the intersection where one of the vehicles was deflected into the fence at the southwest corner. In fact, the predominant collision pattern for the entire intersection involved right-angle accidents from the east and west approaches and left -turning vehicles from the north and south approaches. Two conclusions were drawn from this analysis. One conclusion is that installation of a small physical barrier on the southwest corner such as a 6-inch curb could reduce the potential for vehicles to enter the residential property on the southwest corner in the future. This conclusion was drawn from the fact that three of the five reported accidents affecting this property involved vehicles that were deflected. The other conclusion drawn from this analysis is that installation of left -turn lanes on the north and south approaches would have the largest impact on reducing accident potential at the intersection immediately due to the high number of accidents involving vehicles turning left from the north and south approaches. 5500 Greenwood Plaza Blvd., Suite 1509Greenwood Village, Colorado 80111 Phone 303-221-7275•Fax 303-221-7276•www.pbsj.com Larry Haas, CDOT Region 4 January 3, 2002 SH-1/LCR-54 Safety Study Page 2 Traffic Signal Warrant Analysis: PBS&J analyzed whether the subject intersection meets any of the MUTCD warrants for installation of a traffic signal under existing conditions. The results of the warrant analysis are enclosed. The analysis indicates that the only warrants met are the Accident Experience and Four Hour Volume warrants. The installation of left -turn lanes on the north and south approaches will likely mitigate many of the current accident trends. Although the four-hour volume warrant is met for one hour in the morning and three hours in the afternoon, the intersection currently operates at level -of -service (LOS) C. The intersection LOS can be improved more by installation of left -turn lanes on the east and west approaches. Also, warrants for installation of all -way stop control are not met. Installation of a traffic signal is not recommended at this time. Level -of -Service Analysis: Larimer County provided PB S&J with copies of intersection turning movement counts conducted in November 2000. Larimer County also provided a copy of the Hawthorne Village traffic impact study and excerpts from the Hearthfire PUD site access study. Both of the traffic studies provided short-term traffic volume projections to the year 2006 and long-term traffic volume projections to the year 2020. The projections of each study were combined for this analysis. PBS&J analyzed the intersection LOS for both the AM and PM peak hours for existing conditions, 2006 conditions and 2020 conditions. The LOS at the intersection under existing traffic volumes, lane configuration and traffic controls is LOS C for both the AM and PM peak hours. Sine the intersection is two-way stop controlled; the worst -case LOS of the stop -controlled approaches is the intersection LOS. The recommended installation of left -turn lanes on the north and south approaches to mitigate accident trends will not affect the intersection LOS since these improvements are on the uncontrolled approaches. The intersection is projected to operate at LOS D during both the AM and PM peak hours in the year 2006 with the existing geometry and traffic controls. Installation of left-tum lanes on the north and south approaches will not affect the intersection LOS. However, installation of left - turn lanes on the east and west approaches will allow the intersection to operate at LOS C during the AM and PM peak hours. The analysis of the intersection for the year 2020 with existing geometry and traffic control indicates the LOS will be F for both the AM and PM peak hours. Even the ultimate lane configuration of left -turn and right -turn lanes on the north and south approaches and left -turn lanes on the east and west approaches will not improve the intersection LOS during either the AM or PM peak hours. Installation of a traffic signal will allow the intersection to operate at LOS A in the year 2020 with the ultimate lane configuration. Ha M=m Project Suuwtxry Larry Haas, CDOT Region 4 SH-1/LCR-54 Safety Study Final Recommendations: January 3, 2002 Page 3 PBS&J recommends that left -turn lanes be installed in the immediate future. This should reduce the potential for accidents involving left -turning vehicles from the north and south approaches, which is a predominant accident pattern currently. It is further recommended that left -turn lanes be installed on the east and west approaches in the next several years. This will allow the intersection to operate at an acceptable level of service well past the year 2006. Additional installation of right -turn lanes on the north and south approaches will allow for right -turning vehicles to decelerate out of the main traffic stream. Ultimately, installation of a traffic signal will be necessary to achieve an acceptable LOS at the intersection if traffic projections prove accurate. The 2020 analysis indicates that the ultimate lane configuration will still operate at LOS F unless a traffic signal is installed. Ha M=m PMW Su=iwy