Multiple Diverging Diamond Interchanges (DDI) are coming to Interstate 4 (I-4) as part of I-4 Beyond the Ultimate. These innovative interchanges allow about twice the traffic flow in the same amount of time. DDIs also reduce the number of traffic signal phases and allow motorists to enter the freeway without crossing oncoming traffic.
With two-phase traffic signals on each side of the DDI, there is no specific signal for left turns onto the freeway. The traffic signals indicate when to proceed into and out of the DDI. The design of the interchange removes more than half of the interchange’s conflict points — places where cars either turn in front of oncoming traffic or merge with other vehicles.
From a motorist’s perspective, what are the main differences between driving through a DDI and a standard interchange? After all, drivers are accustomed to being on the right side of the road, and one of the unique characteristics of a DDI is that it moves traffic temporarily to the left side.
“The DDI is very intuitive for drivers,” said Gilbert Chlewicki, P.E., the original designer of the DDI. “For many drivers, they won’t notice that they are temporarily driving on the left side of the road because it feels like driving on a one-way street. They might notice the second or third time around when they may realize that this interchange seems slightly different.”
Drivers moving through DDIs simply need to do what they always do — follow the signs, pavement markings, and traffic signals as they normally would.
“The geometry of the DDI will guide everyone to the proper location,” Chlewicki said.
Most aspects of the driver’s view will look the same. For example, bike lanes, when present, are still on the driver’s right. Pedestrians will also be on the right if the DDI has a sidewalk in the median, which is the most common design in DDIs.
With DDI construction starting this summer at County Road 532 and two more on the way — Daryl Carter Parkway in 2022 and Sand Lake Road (State Road 482) in 2023 — drivers will need to be aware of the changes that are coming. However, despite the movement to the left side of the road, the intuitive nature of DDIs makes navigating through them simple.
For more information on DDIs, visit I4Beyond.com/DDI.