Interstate 44 and Missouri Route 13, Springfield, MO

DIVERGING DIAMOND INTERCHANGE

FHWA-SA-14-048 Updated July 2020

THE PROBLEM 

The original, conventional 

diamond interchange averaged 

more than 100 crashes a year 

from 2004 to 2008. In addition, 

traffic in the left turn lanes 

often caused 1 to 3 mile back 

ups in the through lanes.

THE SOLUTION 

Installation of the Nation’s first

Diverging Diamond Interchange 

with widespread outreach

to gain public acceptance by

highlighting the mobility and

safety enhancements inherent 

in the design. 

THE OUTCOME 

⯀ Total crashes declined by 24 

percent, from 91 in 2008 to 

56 in 2010. 

⯀ Minor injury crashes 

decreased by 72 percent 

from 2008 -2010. 

⯀ Significantly reduced 

interchange -related 

congestion along the 

crossroad. 

⯀ Nearly 95 percent of 

Springfield residents agreed 

the DDI resulted in a less 

congested roadway. 

CONTACT 

Jeffrey Shaw, P.E.

FHWA Office of Safety

202.738.7793

jeffrey.shaw@dot.gov

Mark Doctor, P.E.

FHWA Resource Center

404.895.6210

mark.doctor@dot.gov

INTERCHANGE LOCATION 

37°15’01.7”N 93°18’38.4”W 

Background 

In June of 2009, the Nation’s first Diverging Diamond Interchange, or DDI, opened in Greene

County, Missouri. Located in Springfield at the Interstate 44 and Missouri 13 interchange, the

DDI has two travel lanes in both directions and averages approximately 34,000 vehicles per day.1 

Challenges 

The previous conventional diamond

interchange at this location averaged over 

100 crashes a year from 2004-2008,2

 so 

safety was a primary concern. Another 

important concern was delay. The spacing and location of the adjacent signals 

along Missouri 13 meant that, during peak 

traffic, the signalized left turns onto the 

freeway would frequently back up into the 

through lanes. On a normal day, backups 

could reach nearly a mile. During events 

at the nearby fairground, backups could 

be as long as 3 miles, creating lengthy delays and contributing to unsafe conditions.3

 Furthermore, because this DDI was the first of its kind in the United States, public acceptance was also 

a factor. Missouri DOT (MoDOT) had to convince citizens that the facility was going to provide 

real improvements by reducing congestion and improving safety. 

Approach 

To address public concerns about safety and delay, the agency used a simulation tool and 

projected traffic volumes over the next 25 years to model the new interchange. MoDOT then 

created a video explaining how the DDI could reduce delay by 10 to 35 percent through to 

2035 and improve safety by eliminating just over 50 percent of vehicle conflict points.4 

Cost-effectiveness also was an important factor in MoDOT’s decision to build the DDI. The 

agency chose the DDI design because it didn’t require a new bridge, could be completed in 6 

months, and, at $3.2 million, was one-third the cost of the next best alternative.5

Results 

In a post installation MoDOT driver survey 95 percent of Springfield residents agreed the 

DDI resulted in a less congested roadway.6

 Less congestion also meant fewer crashes. Total 

crashes declined 46 percent when comparing the average across the 5-year baseline to the 

one-year post-construction period; minor injury crashes decreased 72 percent.7

 Pedestrians 

and bicyclists also have benefitted from the DDI; they now can use an illuminated and protected median walkway to cross the interchange.

Computer Simulation of the Proposed Interchange

Source: DDI Case Study Video FHWA-SA-14-047

1 Missouri DOT, Diverging Diamond Interchange Performance Evaluation (I-44 and Route 13), OR11-012 (2011). 

Available at: https://ntlrepository.blob.core.windows.net/lib/36000/36000/36038/or11012.pdf

2 Missouri DOT, OR11-012 (2011).

3 Interview with Don Saiko, Springfield, MO, November 1, 2013.

4 Missouri DOT, OR11-012 (2011). 

5 American Council of Engineering Companies, “Diverging Diamond Interchange,” 

presentation, February 2011. Available at:https://www.acecmi.org/pdf/DDI.pdf

6 Missouri DOT, Diverging Diamond Interchange - Results from the Right Transportation Solution 

Survey, January 2010. Available at: https://rosap.ntl.bts.gov/view/dot/17862

7 Missouri DOT, OR11-012 (2011).

This Fact Sheet is a companion to the Video Case Study (FHWA-SA-14-047) www.safety.fhwa.dot.gov