The most significant investment in pedestrian and bicycle safety could be made as part of the Union Road and 120 Bypass interchange upgrade.

A grade separated bike path with a spiral design costing $2.1 million is being considered as part of the project to enhance bicycle and pedestrian safety. The Manteca City Council will consider that option — as well as a standard bike path that would cross traffic lanes and cost $500,000 — when they meet Tuesday at 7 p.m. at the Civic Center, 1001 W. Center St.

The Union Road interchange that is expected to break ground in 2018 will be the first diverging diamond interchange in California.

By having traffic lanes cross each other and then cross back it eliminates a number of traffic signal movements in order to allow traffic to flow more efficiently. Doing so, however, requires forcing pedestrians and bicyclists to pass through the two cross-over intersections as well as to cross on and off ramps without the benefit of traffic lights.

The $500,000 version or the traditional bike path would send pedestrians and bicyclists across four on ramps and off ramps without benefit of traffic signals. Installing traffic signals would defeat the purpose of the diverging diamond.

Even with the $2.1 million price tag of a grade separated bike path the interchange would come in at a cost less than what it would have taken to build a partial cloverleaf. That’s because the diverging diamond — besides being a  more efficient way to move traffic — doesn’t require additional land and has a shorter construction period significantly reducing cost.

Funds for the separated bicycle bridge is programmed into the traffic fees being assessed on growth.

Depending upon how effective the Union Road diverging diamond is, it could provide the template for future improvements at the Main Street and Airport Way interchanges along the120 Bypass.

A previous council pushed for a separate bicycle crossing three years ago out of concern for pedestrian safety as growth south of the 120 Bypass has seen a sharp increase in pedestrians and bicyclists crossing the 120 Bypass on Main Street, Union Road, and Airport Way.

Not only do the three interchanges not have sidewalks or concrete barriers separating walking areas from travel lanes but they also lack fencing and instead have three-foot high barriers and nothing else.

The first of what have been six pedestrian deaths in a little over three years occurred right before the council directed staff to put more emphasis on pedestrian and bicyclist sifter while planning major roads.

All but six of those deaths occurred on major streets or arterials — two on North Main Street at /or north of Edison Street, Lathrop Road, Woodward Avenue, and Center Street. The sixth was on Edison Street just east of where the two Main Street pedestrian fatalities occurred.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com