Manteca isn’t the only city in California pursuing the state’s first “diverging diamond” interchange.
The City of Ceres got clearance this month from District 10 Caltrans to use the design for the future Mitchell/Service/Highway 99 interchange.
Manteca is pursuing a diverging diamond design for the Union Road interchange on the 120 Bypass.
Traffic lanes cross on either side of the bridge structure of a diverging diamond interchange so northbound traffic would cross the bridge on the west side instead of the east side with the southbound lanes on the east side instead of the west side. Once they clear the bridge they are switched back.
The on and off ramps along with the flipping of the lanes creates two semi-diamond shaped intersections on either side of the bridge. This eliminates the need for traffic from both directions on Union Road as well as that coming from the 120 Bypass avoid needing any traffic signals to exit an off ramp or to get into an on ramp. The project will also include ramp meter signals such as now are in place on the Lathrop Road/Highway 99 interchange.
The design could slash as much as $10 million from the $25 million estimated cost of converting Union Road into a partial cloverleaf.
The new overpass is being funded with money collected from growth as well as unspent redevelopment agency funds that were earmarked for the Union Road project.
Other advantages of a diverging diamond interchange according to Advanced Transportation Solutions/America are:
uFewer conflict points (14 for diverging diamond design, 26 for conventional design).
uBetter sight distance at turns.
uTraffic calming features when desired.
uAdditional right of way is rarely needed.
uVirtually no driver confusion based on a study and observation of existing diverging diamond design interchanges.
uConstruction time is reduced.
uWrong way entry to ramps extremely difficult.
uPedestrian crossings are shorter.
uMaintenance of traffic is simplified during construction.
There are 57 such interchanges now in place in the United States. The closest is in Reno on Interstate 580 at Moana Lane.
Scholl is new
Former Manteca Unified School District board member Don Scholl is the City of Tracy’s new public works director.
The 51-year-old Scholl, who was first hired by Tracy in 1999 as a parks supervisor before being promoted to Parks, Sports, Fields, & Trees Superintendent had been serving as interim public works director following the retirement of David Ferguson in October. He was appointed to the position permanently Dec. 16 following competitive recruitment process.
Scholl’s wife Becky is a fourth grade teacher in the Manteca Unified School District. Their daughter Megan teaches for the San Joaquin County Office of Education. She is married to Eric Smith who serves as firefighter for the Manteca Lathrop Fire District. Their son Collin is a junior at Cal Poly San Luis Obispo where he is majoring in molecular and cell biology. The former Manteca couple resides in Linden.