SR 619 and Pickle Road Roundabout

Importance to the Traveling Public
A Roundabout Evaluation Report was prepared that found that the SR 619/Pickle Road intersection had a relatively high number of injury accidents. This was an expected finding due to the high speeds observed in the area along with substandard intersection sight distance. The report also determined that in 2038, the intersection would experience a Level-of-Service of F during the PM peak. Based on the results of the report, a roundabout at this intersection would significantly reduce injury accidents and also lead to a design year Level-of-Service of A during the PM peak.

Public education was an important component of the preliminary design of the project. Prior to construction of this project, only two roundabouts existed within the City limits. It was important to provide the public material regarding the operation of roundabouts. This provided an opportunity in achieving a positive public perception prior to construction of the project.

Complexity
Exiting geometry within the project area provided a challenge during design. The existing intersection is located along a vertical slope with a maximum grade around 6% along SR 619 east of the intersection. This grade terminates at a substandard crest curve east of the project area. The intersection at Pickle Road is not visible to westbound traffic approaching along SR 619 until after navigating the crest curve where speeds increase while traveling down the 6% slope. During the design of the roundabout, it was important to address the safety issues associated with the east leg of the intersection without adding significant cost to the project.

A measure taken to improve safety was designing the westbound leg as a high-speed approach, typically seen in rural locations. This included adding a chicane to the entry and using a long splitter island to separate opposing traffic. The chicane was designed using successive horizontal reverse curves that reduce in radii as you approach the roundabout. In addition to typical “roundabout ahead” warning signage, an LED enhanced sign was positioned east of the substandard vertical crest curve.

Another challenge encountered during the design of the roundabout was the high number of existing utilities located throughout the project area. Coordination between American Structurepoint, the City of Green, and representatives from each utility owner was crucial throughout design and construction to ensure the success of the project. When possible, existing utilities were avoided through design modifications. A shortened construction duration was important so communication with utility owners requiring relocations was critical. Relocations were preformed quickly and provided the contractor a cleared work environment with ample time to construct the project.

Innovation
Although rural in nature, the project area contained densely spaced residential properties along the west side of the intersection. Due to the high speeds along SR 619, it was important to design a longer splitter island along the west leg to split opposing traffic and promote slower speeds. Along this leg, the driveway locations for three residential properties were located in a position where the proposed splitter island would block full access to SR 619. Cuts in the splitter islands, to provide full access, were not recommended. For this reason, the splitter island was depressed in the location of these driveways to allow residents the ability to cross lanes. The depression utilized the same material so the splitter island appears continuous for through traffic and serves the purpose of separating traffic. A unique feature of this project was the design and installation of a surveillance camera within the vicinity of the roundabout. This camera is hardwired into the City’s fiber optic network which allows live viewing of the intersection. This video will be a valuable tool for accident investigation, observation of traffic patterns, and measuring the capacity of the roundabout to better understand how it is operated by the local public.

Although pedestrian facilities are not present near the intersection, the possibility of future development within area could lead to the need for pedestrian facilities at a later time. The roundabout was designed so that pedestrian facilities could be introduced at a later date with minimal cost. Some items that were included with the current design are wider right-of-way limits, benched grading where sidewalks would go, and ADA-compliant crossing locations.

Aesthetics
In order to make this project more visually appealing to the traveling public, several aesthetic features were included within the design of the roundabout. The center circle of the roundabout features a detailed landscaping design that includes low growth plantings. Washington Hawthorn trees are planted within the center of the landscaping as an aesthetically pleasing way to reduce vehicle speeds by restricting excessive intersection sight distance. Throughout the year, these trees will provide changes in scenery with blooming flowers in the spring and leaf color changes in the fall.

Additional aesthetic features utilized on the project were decorative street lighting and stamped and stained concrete for the splitter islands and truck apron. The lighting design features decorative, post top, light poles staggered along the project length. These poles are used in other high-profile locations throughout the City of Green. The stamped and stained concrete used for the splitter islands and truck apron is a gray, ashlar stone pattern that includes an antiquing agent to provide additional color contrast. Like the light poles, the same stamped and stained concrete coloring is used at other high-profile roundabouts located throughout the City of Green.