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
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
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
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
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