Diverging Diamond Traffic Pattern Assists Traffic Flow

Diverging Diamond Traffic Pattern Assists Traffic Flow

The “diverging diamond” has many positive believers but still a few skeptics as well.  This type of traffic pattern has been used in 22 states so far, to try to ease traffic congestion in busy intersections.  Florida opened its first Diverging Diamond traffic pattern recently on Interstate 75 along University Parkway.  It was two years in the making.  Motorists have already indicated that back-ups seem to be shorter.  One driver who encountered the new traffic configuration said that, at first it was confusing, but also exciting.  She raised the question of drivers not paying attention, especially in the beginning while still getting accustomed to the new configuration, and worried about getting “side-swiped.”  When all the work has been completed, University Parkway will have six westbound and six eastbound lanes, with extra lanes on I-75.  This construction was part of the I-75 corridor widening project.

Diverging Diamond Interchange (DDI)

The Federal Highway Administration (FHWA) has been trying to provide solutions for highly congested traffic areas, while also keeping safety standards in place.  The Diverging Diamond Traffic Pattern is one creative concept that is getting a lot of attention and becoming very popular.  Its features include:

  • It crosses traffic to the left side of the roadway.
  • It allows for left turns at signals, continuing onto access ramps without a crossing conflict.
  • At crossovers, two-phase signals are installed.
  • It reduces crossing conflicts from four (traditional diamond) to two, which, in theory, should reduce the number of accidents.
  • It offers better sight distance.
  • Pedestrian crossings are shorter.
  • Gaining entry to a ramp while going the wrong way is virtually eliminated.
  • It is a low-cost solution because it minimizes the funds needed for the new infrastructure.

The first DDI opened in 2009 in Springfield, Missouri.  Since that time, nearly every state in the United States (and including Puerto Rico) has a DDI that is either operational, in construction, in study, or a few states have even adopted a more advanced design of the system.  There are at least eight DDIs under consideration of implementation in the State of Florida.  When will one appear in Saint Petersburg?


In Charlotte, North Carolina, reports have indicated a 60 percent reduction in accidents since a DDI opened in 2014.  Statistics across the country have had similar results, so it would appear that, overall, the DDI has been met with success.  The best feature of a DDI is that it has a reduced number of traffic conflict points.  The 60 percent number was obtained by looking at periods of nine months before and after the construction of the DDI at Interstate 77’s Exit 28.  In December 2017, the North Carolina DOT is scheduled to let a contract for the construction of another DDI at Exit 23 along I-77.  A number of DDIs have been implemented and still more are being planned in North Carolina.

Impact On Traffic Accidents

The DDI design has the potential to have a very beneficial impact on traffic accidents in St. Petersburg in the future and all around the State of Florida.  Any measures that can be taken to lessen the number of automobile accidents and crashes should be applauded.

If you are involved in an automobile accident, or as a pedestrian trying to cross an intersection, and you have suffered injuries, speak to a personal injury attorney to ensure you know all the courses of action available to you.