The City of Santa Clarita received the 2014 APWA Project of the Year Award from the Southern California Chapter of the American Public Works Association (APWA) for the Newhall Roundabout. This $2.2M roundabout design project created a main gateway to the historic Newhall commercial district and optimized traffic calming and pedestrian safety measures at the busy intersection. MNS Engineers, Inc. (MNS) provided engineering and construction surveying services.
History
In 2005, the Santa Clarita City Council adopted the Downtown Newhall Specific Plan (DNSP), which outlined a future vision for the Old Town Newhall and created a plan to revitalize the area. The DNSP’s primary objective for improving traffic flow through Newhall Avenue, 5th Street, and Main Street was achieved by removing the existing traffic signal components and constructing a single lane modern roundabout, which produced smoother traffic flow, less delays, and a friendly environment to promote pedestrian activity to the William S. Hart Park and DNSP businesses. Additionally, 5th Street was removed from the intersection and redirected to a new City parking lot. The new roundabout offers far fewer conflict points and additional traffic safety than the previous signaled intersection by eliminating head-on, right angle, and left-turning vehicular collisions. Studies have shown a 90% reduction in fatal crashes, a 75% reduction in injury crashes, and a 40% reduction in total crashes when compared to signalized intersections. Roundabouts can also increase traffic flow through an intersection by 30-50%. Consequently, cars stop less frequently at roundabouts compared to signalized intersections; and both fuel consumption and air pollution are reduced.
Design
In 2009, MNS began the preliminary roundabout design that created space to balance the surrounding impacts adjacent to the local businesses and the Los Angeles County William S. Hart Park entrance, reduced approaching traffic speeds with appropriate deflection, and provided opportunities for pedestrians to sit and enjoy the decorative landscaping improvements. The complex design required specific road layout, profiles, and construction details to be shown on the plans because the horizontal and vertical geometry was not consistent with a typical flat terrain level roundabout. Although roundabout transitions are not typical, they were installed due to the urban environment. The storm drainage systems required resolution of multiple utility crossings and conflicts. Further complications resulted from the existing underground utilities, which contained high pressure oil and gas lines with a very old history and service through Newhall Avenue and the Santa Clarita area.
Construction began in July of 2013 and was scheduled for completion in February of 2014; however, the project finished early, and the new Newhall Roundabout successfully opened in January of 2014.
William S. Hart Park Entrance
