The city is to get a roundabout or traffic circle on Viaduct Street between Interstate 44 and Thornton Road as the final phase of the MoDOT Pacific interchange project.

The six-leg traffic circle will accommodate traffic in the westbound I-44 interchange with local traffic on Viaduct Street, Thornton Road and Hogan Road.

Instead of stopping at the intersection, traffic will continuously move around the circle to the desired road.

Federal and state government funds will be used for the $1.8 million project with some costs absorbed by the city.

Aldermen approved an agreement between the city of Pacific and MoDOT for the construction of a roundabout on Viaduct Street as part of the I-44 westbound interchange at the Feb. 18 board meeting.

MoDOT describes the roundabout as an intersection that accommodates traffic flow in one direction around a central circular island. It is used as a form of intersection control, like traffic signals or stop signs.

MoDOT also offers instructions on the use of roundabouts on its webpage:

Estimated cost of the project is $1.8 million with the federal government providing $1.5 million in an 80-20 matching fund grant and the state of Missouri providing $303,000.

Pacific would be responsible for providing all right of way for the roundabout, as well as design and engineering. No estimates of the city’s portion of the cost was included in the agreement.

In addition to right of way, design and engineering, Pacific would be responsible for any overruns if the cost of the project exceeds the budget.

The work would include asphalt and concrete pavement, concrete sidewalks, ADA compliant pedestrian facilities, curb and gutter, street lighting, landscaping, traffic control, signing, striping, guardrail, box culvert extensions and new drainage system.

Before work proceeds the city has to provide a Vissim Traffic Simulation Model for the proposed roundabout, an Auto Turn analysis and a design of the project.

The traffic simulation is a computer software package that simulates the exact traffic patterns, including types of traffic, including trucks, buses, cars and pedestrians and bicycles.