Diverging diamond interchange

The diverging diamond interchange has advantages in both efficiency and safety, and was cited by Popular Science as one of the best engineering innovations of 2009[3] and in the U.S. has been promoted as part of the Federal Highway Administration's Every Day Counts initiative.

[5][6] The greatest safety concern of the interchange stems from its relative rarity, as drivers instinctively trying to stay on the customary side of the road could use the crossover intersections to turn against the posted direction of travel.

This is a rare occurrence; it is possible only when traffic is so sparse that no cars from the oncoming direction are stopped at the light, and clear signage further reduces the likelihood of such errors.

The interchange in Seclin (at 50°32′41″N 3°3′21″E / 50.54472°N 3.05583°E / 50.54472; 3.05583) between the A1 and Route d'Avelin was somewhat more specialized than in the adjacent diagram: eastbound traffic on Route d'Avelin intending to enter the A1 northbound must keep left and cross the northernmost bridge before turning left to proceed north onto A1; eastbound traffic continuing east on Route d'Avelin must select a single center lane, merge with A1 traffic that is exiting to proceed east, and cross a center bridge.

[8] In 2010, the Federal Highway Administration released a publication titled "Alternative Intersections/Interchanges: Informational Report (AIIR)"[15] with a chapter dedicated to this design.

[17] Stantec, the engineers who completed the upgrades to the interchange, noted the solution while providing substantial cost savings over other possible options also has decreased accidents by 45 percent, improved traffic flow to more than 35,000 vehicles per day, and incorporated KYTC's goal to provide new paths for bicycles and pedestrians through the area.

[18] That same day in Highland, Utah the seventh U.S. diverging diamond interchange opened at the intersection of I-15 and Timpanogos Highway.

[20][21] In October, the New Mexico Department of Transportation converted the crossing of NM 14 (Cerrillos Road) and Interstate 25 in Santa Fe.

[26] The first diverging diamond interchange in Australia opened to traffic by the Queensland Department of Transport and Main Roads on November 28, 2019.