Construction begins Monday on Fort Leonard Wood's first roundabout that will be crafted at the two-way-stop intersection of Alabama, Iowa and Nebraska avenues.

Detour signs will be posted, prior to the intersection's closing.

The Directorate of Public Works, working in conjunction with the U.S. Army Corps of Engineers, Kansas City District, estimates the $1.8-million project will be completed in late July or August.

Both USACE and DPW said the completion dates are dependent on the weather that may impact paving.

"We always look at ways to reduce the length of the work," said Randy Knutson, DPW Planning Division construction coordinator, who said the work start time coincides with opening of the local asphalt batch plants in the spring.

According to Knutson, the greatest traffic impact of the detour will be during the morning and evening commutes, whether traveling to or from the southern portion of the installation.

"There is a lot of traffic, both north and south on Iowa Avenue and FLW 1," Knutson said. "That traffic will also have to contend with getting around the construction site."

Fort Leonard Wood has a traffic circle in the training area on an unpaved road. However, the post will join other military installations with roundabouts such as Fort Riley, Kansas, Dyess Air Force Base, Texas and Camp Lejeune, North Carolina, to name a few, according to Bill Rector, USACE project manager.

Rector said the distinction between a traffic circle and roundabout is the latter is "generally" smaller and always has a splitter island to help channel vehicles, which causes drivers to travel at slower speeds.

"When we designed the Fort Leonard Wood roundabout, we made an assumption that some student drivers would not be familiar with and might have difficulty navigating the roundabout," Rector said.

"Therefore, we designed it with two lanes and left space inside of the actual traffic lanes of pavement," he explained.

The roundabout will be built with a 4-foot-wide-rollover curb and a truck apron, "should a student not be able to properly navigate," Rector said, noting the roundabout will contain heavy-duty concrete with a thickened edge to handle the larger, heavier vehicles.

Engineers used the Heavy Equipment Transporter and "assumed it would be hauling a tracked vehicle on the trailer" for the purposes of designing the pavement, Rector said.

As other dimensional considerations, Rector and his team configured the project to accommodate a semi-tractor trailer with a 53-foot trailer and Fort Leonard Wood's largest fire truck, "Ladder 1," which spans more than 45 feet.

The intersection was originally targeted for installation of a traffic signal, as part of another project. After a second look, the Surface Deployment and Distribution Command and Transportation Engineering Agency recommended to install a roundabout over a signalized intersection as the best solution.

Advantages
The SDDCTEA lists the following advantages of roundabouts over other types of intersections:

-- Fewer and less serious crashes.

-- Improves safety for pedestrians -- the splitter island provides a refuge for pedestrians to allow a two-stage crossing, with each stage crossing a one-way roadway.

-- Can be used for speed control, especially speed mitigation at entry control facilities.

-- Improves traffic flow with fewer stops.

-- Accommodates U-turns, even for larger trucks.

-- Safely operates during power outages.

-- No overhead traffic signals to hinder over-height loads.

-- Facilitates the junction of more than four roadway approaches.

-- Simplifies the driver decisions when entering an intersection, because all traffic is coming from the left (this is especially helpful for older drivers).

-- From an environmental standpoint -- improves air quality, reduces energy consumption, requires fewer travel lanes and provides more landscaping opportunities.

Roundabout tips
Upon entering a roundabout, all vehicles turn in the same direction -- to the right. You simply continue around the circle in a counterclockwise direction, until you come to the road or street you want. Then you leave the traffic circle by making a right turn.

Since Fort Leonard Wood's new construction will be multiple lanes, keep in mind as you travel around the circle, use the inside lane if practicable, but be sure to get in the outside lane well before you come to the place where you intend to leave the circle.

Never attempt to make a right turn from the inside lane. Look and signal before you turn or change lanes.

At traffic circles, the whole circle is considered an intersection. The vehicles already in the traffic circle have the right-of-way over those approaching the circle on the roads leading into it unless traffic signs indicate otherwise.

Background
The modern roundabout has been successfully implemented in Europe and Australia over the past few decades. Despite the tens of thousands of roundabouts in operation around the world, there are only a few hundred in the United States.

Until recently, roundabouts have been slow to gain support in this country. The lack of acceptance can generally be attributed to the negative experience with roundabouts built in the earlier half of the twentieth century. Severe safety and operational problems caused these roundabout to fall out of favor by the 1950's, according to the Department of Transportation website.

Roundabouts are additive according to a SDDCTEA study that states after initial installation local communities typically ask for more.