City of Hilliard, Ohio
For decades, three closely-spaced intersections in the heart of Hilliard, Ohio serving approximately 45,000 vehicles per day caused traffic back-ups and delays. Today, motorists and pedestrians in this growing suburban community have a safer and less congested commute to schools, homes, and businesses with the reconfiguration of this complex roadway system known as the Hilliard Triangle.
Named for the triangular shape formed by its three intersections, the Triangle site formerly consisted of two signalized intersections and one stop controlled intersection, all operating over capacity during peak hours. The City studied multiple alternatives to reduce traffic congestion and improve access, and determined that signalization of the stop controlled intersection and conversion of the two signalized intersections to multi-lane roundabouts would provide the best results with the least right-of-way impact.
B&N completed studies and developed plans and specifications to reconstruct the Triangle area using roundabouts. This included four conceptual layouts for the project area that addressed a skewed angle that complicated right-of-way impacts, speed reduction characteristics, and consistency with driver expectations.
Two closely-spaced roundabouts make the Hilliard Triangle a unique roadway project. The roundabouts were designed to be different sizes. One has an outside diameter of 160 feet and the other has an outside diameter of 175 feet to allow for a skewed angle. Both roundabouts were designed to accommodate cars, school buses, emergency vehicles, and 55-foot-long trucks. However, they were kept as small as possible to optimize vehicular and pedestrian safety and minimize the impact on adjacent properties.
Safety in the Triangle area was improved by eliminating sharp jogs in the roadway. Reduced speeds also improve safety, allowing pedestrians to judge gaps in traffic more easily. Shorter crossings with traffic moving in only one direction also improve safety over the former signalized intersections where traffic came from multiple directions. Signs and pavement markings alert motorists that they are to yield to pedestrians.
The redesigned intersections improve access to nearby schools and businesses. Using the roundabouts, motorists are permitted to make legal U-turns, allowing them to safely enter and exit driveways without making left-hand turns across multiple lanes of traffic.
Maintenance of Traffic
With five schools and numerous businesses located within close proximity of the project site, a complex, multiphase maintenance of traffic (MOT) plan was developed to minimize the impact of construction on travel and access within the project area. The MOT plan also allowed northbound and southbound traffic to be maintained on Main Street – a heavily traveled local roadway – during the construction of both roundabouts.