MoDOT, District 8, Springfield -- Increased driving delays are expected on National Avenue at the James River Freeway (Route 60) starting Thursday evening, Nov. 5, as a road construction project shifts to its next stage, the Missouri Department of Transportation said.

The traffic pattern change includes reducing National Avenue to only one southbound lane for a short distance south of Primrose Street.

It will be fully in place by Friday morning, Nov. 6, and will remain in effect through the spring of 2010.

Drivers who need to reach nearby CoxHealth facilities, including Cox South Hospital, and the many other businesses along National Avenue WILL be able to do so, but it probably will take more time to get there.

However, drivers who use National Avenue to commute through the area, especially southbound during afternoon rush hour, are urged to find other routes to avoid the construction and reduce the congestion along the corridor.

Construction of an underpass and service road underneath National Avenue -- half at a time -- is about to begin. That is why it is necessary to narrow down National Avenue and shift traffic to the east side of the street.

Here's what will happen:

Narrowing of National Avenue

* National Avenue will have only one southbound lane open between Bradford Parkway (south of Primrose Street) and the bridge over the James River Freeway starting some time Thursday evening, Nov. 5.

Even though only a 500-foot long section of National Avenue will be narrowed down, major driving delays are expected, especially for southbound National Avenue traffic.

Southbound National Avenue will have two through lanes open across the bridge and a separate left-turn lane to eastbound James River Freeway.

* Northbound National Avenue will have two lanes open on the bridge over the freeway -- one through lane and one left-turn lane onto westbound James River Freeway.

North of the bridge, National Avenue will have two lanes open through the work zone. The goal is to minimize traffic backups on the westbound James River Freeway off-ramp to National Avenue.

* In late March or April, traffic will be shifted to the west side of National Avenue, with two lanes open for northbound traffic and one lane open for southbound traffic. This will allow the east side of the underpass to be built.

Project Details

The project at National Avenue and the James River Freeway involves reconfiguring the National Avenue bridge into a Diverging Diamond Interchange, adding auxiliary lanes on the freeway between National Avenue and Campbell Avenue and building an underpass and service road that will connect CoxHealth facillities on both sides of National Avenue north of the bridge.

The project will cost $9.7 million, including $7.5 million for construction and $2.2 million for engineering and right-of-way acquisition. Springfield, CoxHealth and MoDOT will share the cost.

The prime contractor is Emery Sapp and Sons of Columbia. The project is scheduled for completion in August 2010.

The project will:

* Widen the National Avenue bridge (10 feet on each side) over James River Freeway to provide three lanes in each direction across the bridge. The bridge is in good condition and does not have to be replaced or undergo significant repairs. The bridge deck will be sealed.

* Widen ramps. Dual right-turn lanes will be provided from westbound James River Freeway to northbound National Avenue.

* Build a pedestrian walkway down the middle of the National Avenue bridge.

* Add a lane in each direction on National Avenue south of the bridge to Kingsley Street and north of the bridge to Bradford Parkway.

* Build an additional lane in each direction on the James River Freeway connecting the ramps at National Avenue and Campbell Avenue.

* Build a service road and underpass underneath National Avenue north of James River Freeway to improve connections between CoxHealth facilities on both sides of National Avenue and provide safer entry to Cox South Hospital, including its emergency department. This also will improve traffic flow and safety for drivers on National Avenue going past the CoxHealth facilities.

* Convert the interchange into a Diverging Diamond Interchange design where the opposing lanes of National Avenue will criss-cross at traffic signals at the ends of the bridge over the James River Freeway. Crossing the bridge, oncoming traffic will be on the right. Opposing lanes will be divided by concrete barriers, with a pedestrian walkway in between the walls.

This configuration will provide left-turning vehicles on National Avenue a "free left" onto the James River Freeway ramps. At the same time, traffic continuing north or south on National Avenue will be able to travel more steadily through the interchange, reducing backups. Signs, pavement markings and concrete islands will clearly guide drivers and help prevent making a wrong turn into the opposing lanes.