Proposed changes to West Cesar Chavez Street, particularly the addition of a traffic signal at a planned connection to Pressler Street, would add more than two minutes to morning commutes, according to a city of Austin master plan for the park surrounding that key thoroughfare.

City parks officials emphasize that the possible realignment of West Cesar Chavez around the area called Lamar Beach hasn’t been funded and wouldn’t happen for at least a decade. And the city Transportation Department said through a spokeswoman that further study would be required before such a major change occurs.

If so, that would be fine with the Central Texas Regional Mobility Authority, which is in the final stages of building toll lanes on North MoPac Boulevard intended to shorten trips to and from downtown Austin using West Cesar Chavez. Its executive director, Mike Heiligenstein, said the agency is concerned that introducing traffic obstacles onto the feeder street could have negative effects on MoPac traffic both north and south of Lady Bird Lake.

"We have not done our own modeling on this," Heiligenstein said. "But given the plan, it would be nice for (city officials) to reach out to us. We’d like to know what this would do to the MoPac express lanes."

RELATED: Proposed Lamar Beach master plan would remake gateway to downtown

That master plan for Lamar Beach — a patchwork of park land, athletic fields and an animal shelter running from near MoPac to Lamar Boulevard — was years in the making. The Austin City Council, on a 10-0 vote, adopted the thick plan on Dec. 8. The focus of discussion generally has been on how to make the park a better place, project manager Charles Mabry said this week, rather than on how best to move vehicles through the area.

That stretch of West Cesar Chavez, he said, "is basically a mile-long exit ramp, and why do we have that in a park? It’s a park master plan, and our goal was to improve this park. At the same time, we didn’t want to severely impact traffic."

The plan would change the 65-acre area in two phases. The first phase, which would take six to 10 years, would include changes to the youth baseball fields at Lamar Beach, reconstruction of the Austin Pets Alive shelter and the elimination of a softball field near Lamar to make way for more public parking.

The major changes to West Cesar Chavez would be in the second phase, which would take four to six years. But Mabry said the first phase would include the planting of trees lining the existing West Cesar Chavez.

"The idea is to make Cesar Chavez seem more enclosed to help slow people down," he said. "Right now, it is more like a highway."

HOW WE GOT HERE: Options for revamping the roads through Lamar Beach

Under the second phase of the plan, West Cesar Chavez would depart from its current southeasterly path just east of Austin High School, and would go east along the bluff that forms the north side of Lamar Beach. Pressler Street, which currently dead-ends before reaching that bluff from the north, would be cut through to meet this new, elevated section of West Cesar Chavez, and that new three-way intersection would have a traffic light.

The reconfigured West Cesar Chavez would then carve a gentle S-curve to the southeast and return to ground level before meeting B.R. Reynolds Drive near where the two streets currently form a T. But that signalized intersection would now include a fourth leg, Park Road, a narrowed version of the current path of West Cesar Chavez. This new, more complex intersection might have less green-light time for east-west commuter traffic than currently exists there.

Changes in the stretch would add 138 seconds to the average 111 seconds it currently takes to go about a mile from near Austin High to past Lamar in the morning eastbound commute, the park master plan says. Commuters heading westbound on that stretch in the afternoon, likewise a 111-second trip now, would be delayed an additional 94 seconds.

Average speeds would plunge from about 27 mph to 12 mph in the morning and 15 mph in the afternoon, according to a traffic consultant who helped the city with the master plan.

Mabry points out that the plan does have some improvements for West Cesar Chavez motorists, including almost 350 more on-street and off-street parking places than exist now. Beyond that, the Butler Hike and Bike Trail, which currently cuts through a thin strip between West Cesar Chavez and the river, would be moved out over the water as a short boardwalk.

That in turn would allow Cesar Chavez to be widened in the area under Lamar, making space for a 250-foot-long, left-turn bay to Sandra Muraida Way (and thus to northbound Lamar) for eastbound travelers. Left turns aren’t currently allowed at Sandra Muraida, so the change would provide a new path into downtown Austin.

RELATED: Six options for South MoPac toll lanes

Heiligenstein said he understands the desire to improve the park, and that any negative traffic effects would take awhile to occur.

"But 10 or 15 years is not that far away," he said. "An intelligent plan can’t be made until we know the impact on MoPac."