When improvements on Hamilton Road, from Carpenter Road to U.S. Route 62, are completed by summer 2016, the project will have a 20-year life span.
City engineer Karl Wetherholt updated Gahanna City Council about the Hamilton Road Central project March 11. He said Gahanna has been working with the Franklin County engineer on the project for many years.
It will be 80 percent funded by MORPC-attributable federal funds, and the 20 percent local match will be split between Gahanna and Franklin County.
The approximately 1-mile project involves rebuilding Hamilton Road from the bridge over Rocky Fork Creek to U.S. 62, widening it from two to five lanes and incorporating two modern roundabouts.
One roundabout will be at the intersection of Clark State Road and the other will be at the entrance to the Northeast School.
Wetherholt said the project also provides new sidewalks on the east side of Hamilton Road and a multipurpose trail on the west side. He said access to Carpenter Road would be improved by incorporating a vehicle refuge area in the median for motorists exiting Carpenter Road and waiting to turn north onto Hamilton Road.
The culvert at the northern end of the project will be replaced, and streetlights will be included.
Council member Beryl Anderson said residents have questioned the use of proposed roundabouts.
"The capacity at roundabouts is higher than a signalized intersection," Wetherholt said. "At a signalized intersection, you would also wait quite some time."
Service director Dottie Franey said another advantage of roundabouts is that they continue to work in the event of power outages.
Dating back to 2006, Wetherholt said, various alternatives were evaluated, including traffic signals and a roundabout at Clark State Road.
He said the roundabout alternative provides the highest traffic capacity, has a lower construction cost and has a lower impact on the surrounding properties than a signal.
Wetherholt said Carpenter Road is not properly aligned with Clark State Road to be incorporated into the intersection, and various roundabout positions were evaluated to try to align the two roadways.
The particular design that is planned provides an improvement in the Carpenter Road intersection by providing a vehicle refuge island for traffic attempting to turn left out of Carpenter Road, Wetherholt said.
Those traveling from northbound Hamilton Road onto Carpenter Road will be required to make a U-turn on the roundabout and then make a right onto Carpenter Road.
"The roundabout takes some of the Peace Lutheran Church property," Wetherholt said. "Their request was, they wanted a sidewalk all the way to their driveway. That's what we did."
He said the northern roundabout would serve as a traffic-calming measure in the middle of the project and provides more efficient access to the Northeast School and planned future development to the west.
At the Northeast School, Wetherholt said, buses will exit the roundabout and follow the driveway, which will loop back to orient their passenger doors to the school. When exiting the school, the buses will be able to enter the roundabout and proceed in any direction.
Wetherholt said the Creative Housing facility on the west side directly across from the school also would be accessed through the roundabout, thus removing a curb cut on Hamilton Road and providing better access for bus traffic.
Wetherholt said the project's right-of-way plans would be authorized by May.
Franklin County will proceed with right-of-way acquisition in the summer, with right-of-way completion anticipated by spring 2015.
Utility relocation is expected to occur in 2014.
Wetherholt said construction should begin in June 2015, with anticipated project completion by fall 2016.
Franklin County will bid the project and administer the construction contract, as well as provide the construction inspection.