To reduce traffic congestion, Utah in recent years introduced three newfangled types of intersections with unusual names: diverging diamonds, ThrU-Turns and CFIs (for continuous flow intersections). Now a fourth may be coming: the "Super Street."
Utah Department of Transportation officials told legislators Wednesday they are considering using that new design sometimes called a J-turn, or a restricted crossing U-turn in Provo at the intersection of University Parkway and 2230 North.
UDOT Executive Director John Njord said the design may work there because relatively few cars travel straight on 2230 North through that intersection. Most now turn onto University Parkway.
The Super Street design would force all traffic on 2230 North to turn right. Motorists who wanted to go straight or left could make a U-turn a few blocks down on University in a provided spot. Those who wanted to go straight could return to the intersection and turn right onto 2230 North.
"It would create a bit of an inconvenience for the traffic that wants to go straight, but speed up things for everyone else and increase overall mobility," Njord said.
The other new designs recently introduced by UDOT all use various means of eliminating left-turn signals to speed up traffic at intersections, but the Super Street would essentially eliminate the signal cycle for both left turns and straight-through traffic on 2230 North.
Njord said UDOT approached Provo officials last week with the idea and plans to provide more details and have more discussions before making a decision. He showed the idea to legislators Wednesday as an example of how UDOT is trying to be innovative to reduce congestion.
Super Streets have not been common nationally because of the inconvenience they create for the more minor cross streets that intersect busy highways but states that have used or propose them include North Carolina, Texas and Michigan.
A study by North Carolina State University reported that Super Streets reduce overall travel time through intersections by 20 percent and decrease accidents by 46 percent.
Njord also told legislators Wednesday that UDOT has been happy with the other innovative designs used, and data show that all have reduced congestion significantly. But he said ThrU-Turns, used on 12300 South in Draper and 5400 South in Kearns, have brought complaints despite faster travel times.
Besides those unusual intersections, Njord said other recent innovations to reduce congestion include "flex lanes" on 5400 South in Taylorsville where some lanes go one direction in the morning commute, and reverse direction in the evening and freeway-like express lanes to the side of SR-92, the Timpanogos Highway, that avoid stopping at all cross streets between Lehi and Highland.