Ask anyone who has driven the Springfield interchange and without fail, they’ll have a horror story.

First there are ramps that force cars to merge into various left lanes of the highway. Then there are spots where three roadways come together, leading to games of “chicken” between cars and trucks.

The Springfield interchange, located in Springfield, VA, where I-95, I-495, and I-395 come together, is one of the largest intersections in the United States. It has been dubbed “the mixing bowl” for its odd shape, making it look as though cars are all being mixed together in it.

It also is the most accident-prone section of road in the Beltway region of Washington D.C., averaging about three accidents per day. Accidents, ranging from merging problems to trucks overturning around the bends, totaled more than 175 last year alone.

Four hundred thousand vehicles use the Springfield interchange every day and it is estimated that in the next 20 years the volume of traffic will increase to 500,000 vehicles per day.

The original Springfield interchange, built in the early 1960s, was never meant to handle the traffic it carries now. It was intended to be a simple junction of the Beltway with I-95, which was supposed to run straight through Washington.

But neighborhood protests in Washington blocked transportation officials from running I-95 through it. The solution was to designate part of the Capital Beltway, which is the section between Springfield and College Park, as I-95.

More than three decades later, cars and trucks traveling along the East Coast’s main north-south highway continue to be funneled through the ordinary exit ramps at Springfield, causing massive backups several miles long.

Virginia Department of Transportation (VDOT) officials said that the interchange was designed well for what it was supposed to do 30 years ago. It was never intended to handle all the traffic it handles now.

The interchange became dangerous by 1971when it was handling 150,000 cars a day, less than half the current volume. Planners realized they had to do something to straighten the sharply curving ramps and redesign the roadway so that motorists wouldn’t have to change lanes as much.

The Mixing Bowl was modified three times, including the addition of a second lane on northbound I-95 for exiting onto the Beltway. But these proved to be temporary fixes. Traffic continued to increase, largely because of the rapid growth of communities along I-95 south of the Beltway.

VDOT decided to revamp this major intersection into one of the most high-tech interchanges in the country. The eight-year, eight-phase project includes new ramps, widening roads, and 50 bridges with a total cost of almost $600 million. Once the changes are made, VDOT expects cars to be able to switch from one highway and highway lane to another without slowing down. In addition, they should be able to do this more safely than it could have been done previously.

The first phase of the project was begun in March of 1999. Shirley Contracting Corporation of Lorton, VA, has been awarded contracts for Phase II, III, and IV of the Springfield Interchange. Its task is to build 15 bridges, demolish five bridges, construct 41,859 sq. yds. (35,000 sq m) of MSE wall, move or place 457,778 cu. yds. (350,000 cu m) of dirt, lay more than 10,936 yds. (10,000 m) of pipe, place more than 165,000 tons (150,000 t) of stone and more than 176,000 tons (160,000 t) of asphalt. And all of this will happen while 400,000 vehicles each day travel through the interchange. It would be an understatement to say that traffic management will be a major headache.

To assist with traffic management, VDOT designed a multi-faceted Congestion Management Program. The $28-million program for the Springfield Interchange Project will keep traffic flowing through the interchange during construction. Some of the components of the program include updating and improving alternate routes around the interchange, providing fire and rescue equipment and staff plus additional police services, and providing additional travel options for commuters. These options include four additional “park and ride” lots, increased transit services, reduced transit fare packages, and vanpool subsidies.

Phase V is expected to begin in summer 2001 and be completed in the summer of 2003. It includes construction of a ramp from I-395 south to westbound I-495 and improvements on I-495 between the interchange and Hemming Avenue. Phases VI and VII, scheduled to begin in late 2002 and be completed in mid-2007, include construction of the I-95 northbound lanes and the remaining local and through ramps.

The project has three major improvements that will make the Springfield interchange safer and less prone to backups. One will be to add more signs, making it easier for drivers to get into the lanes they want. This improvement should help relieve the area of accidents caused by cars trying to merge at the last second.

The project also will add lanes to many of the roads leading up to the Springfield interchange. The most trafficked area, I-95, will become a monstrous 24-lane highway. This will help to keep traffic moving during rush hour.

Finally, the project will change all of the ramps entering and exiting the highways to the smaller streets, along with all the ramps that connect the major highways. This is what will ultimately make the intersection a high-speed interchange. The ramps will be constructed so that the turning radius is larger, allowing vehicles to exit and enter at higher speeds. This also will help alleviate trucks overturning on the ramps.

With three major roads coming together at one point, the Springfield interchange is different from other interchanges. Most interchanges consist of a highway and a small road that either goes above or below the highway. These interchanges, called diamond interchanges, are capable of handling about 150,000 vehicles per day.

When there are two major roads a cloverleaf interchange is usually used. A cloverleaf can handle anywhere from 150,000 to 250,000 vehicles per day.

But when there are two major roads and too much traffic for a cloverleaf interchange to handle, a directional interchange is used. A directional interchange is more efficient than a cloverleaf because it directly connects the roads instead of looping them, allowing vehicles to travel at higher speeds while changing roads. Because of this they are called “high-speed interchanges.” These interchanges are capable of handling more than 250,000 vehicles per day.

The Springfield interchange was originally created as a directional interchange. However, the typical directional interchange only handles two roads. The Springfield interchange handles three. So instead of using a typical design for the Springfield interchange, the design used incorporates the principle of the directional interchange and applies it to three roads.

By separating local, express and carpool lanes into their own roadways the engineers have concocted a project not seen anywhere else on the east coast. Only Los Angeles has a freeway junction that brings together so many separate roadways.

Because the Springfield interchange is such a key passage for commuters and interstate truckers alike, shutting it down for construction during the day is out of the question. Instead of using normal highway construction methods, such as closing parts of the road for days or directing traffic to alternative routes, VDOT officials have contractors close the intersection of Shirley Highway and the Capital Beltway for only 15 minutes at a time.

VDOT prohibits contractors from closing lanes during rush hours and limits any total shutdown to the hours from midnight to 5 a.m. Monday to Thursday.

Shirley Contracting has until June 2002 to complete Phases II and III of the interchange project. For every day the project is delayed beyond the deadline, Shirley will pay a $30,000 penalty.

Although penalties are common for missed deadlines in high-profile construction projects, large incentives are rare. If Shirley can wrap up Phases II and III by August 2001, nine months ahead of schedule, the company would get a $10-million bonus.

Some neighboring ramps and bridges have to be designed at similar elevations so that cars can be detoured between these roadways as construction is done on them. And they have to be built in a certain order so that higher bridges can be added after lower ones.

The new interchange will have separate roadways for express, local and carpool traffic. Highway engineers have long wanted to divide the traffic at Springfield, a key interchange for commuters in the region’s growing southern suburbs and for trucks carrying goods up and down the East Coast.

Engineers believe separating that traffic would eliminate much of the lane changing that now occurs. Some drivers who enter the interchange now have less than 1,000 yds. of roadway in which to cross up to five lanes to get to their exits, a situation that leads to delays and accidents as well as frayed nerves.

Once the interchange is built, its success may well depend on $35-million worth of signs designed to steer drivers through the many roadways. Suspended over nearly every section of the interchange will be 167 green and white signs plus 20 electronic message board signs directing drivers into the proper lanes.

One team specializing in signs has spent much of the last two years designing them at 88 different locations. The 20 variable-message signs will be used to inform drivers of congestion ahead. Another team has devoted much of the two years to mapping out the location and power source for 565 light poles.

The new sign arrangement will provide drivers with at least three warnings that their exit is coming up: the first 2 mi. before the exit, another a mile later, and finally an angled arrow pointing to the exit itself.

While the design is meant to be foolproof, it’s not forgiving. Drivers who choose the wrong exit will have to go several miles before they can turn around.

It is estimated that 20,000 to 25,000 tons (18,000 to 22,500 t) of steel will go into every 120-ft. (36.3 m) long bridge being erected during Phases II and III of the project. A total of 15 bridges will be built during those phases. Upon completion of the project’s eight phases in 2007, the interchange will be 24 lanes at its widest point, compared to its present 13.

For more than two decades, Shirley Contracting Corporation has provided comprehensive construction services to public transportation and highway authorities and private developers in Virginia, Maryland and the District of Columbia. It has completed more than 600 successful construction projects since 1974.

Shirley Contracting Corporation is a subsidiary of Clark Construction. Headquartered in Bethesda, MD, and founded in 1906, Clark now has eight regional offices throughout the United States. Clark has been involved with a variety of projects including construction and renovation of sports arenas, convention centers, hotels, correctional institutions, health care facilities, manufacturing plants, office buildings, and many highway projects.