The bicycle and pedestrian path on the Bay Bridge’s new eastern span — for nearly two years a bridge to nowhere, its completion held up in part by a belated design change — could miss its latest scheduled opening date of this summer because of questions about whether support components will be strong enough to do the job.

Caltrans officials said Friday that the agency is looking into whether there is sufficient underpinning for a planned observation platform that would be built near the path’s terminus at Yerba Buena Island. The platform is the centerpiece of a project that bicyclist-advocate groups campaigned hard for when the state decided to replace the old eastern span after a section failed in the 1989 Loma Prieta earthquake.

Since the bike path opened in March 2014, it has stopped 1,200 feet short of Yerba Buena. Caltrans had to wait for the westernmost portion of the old bridge to be demolished before completion work could begin.

That part of the span is long gone, but new delays have arisen in part because of bridge officials’ last-minute redesign of the observation platform.

Too ugly

The three officials who form the panel overseeing the project — the heads of Caltrans and the California and Metropolitan transportation commissions — voted in May 2014 to scrap a design that incorporated a pair of angled steel braces rising from underneath the bridge to support the observation platform, which will extend about 35 feet from the span.

The panel members approved a $1.1 million redesign. The reason, essentially, was that they found the angled braces ugly.

Clive Endress, who at the time was the Caltrans architect working on the bridge, said the angled braces looked nothing like the rest of the bridge supports.

“I found it in 2014 when I was looking at some other architectural detail,” Endress said. “I saw the sheet and basically said, ‘Holy cow, it’s wrong, and we need to fix it.’

“It’s really quite simple,” he said. “There is an architecture vocabulary, and this fights with the overall design of the bridge.”

Not enough support?

The solution was to replace the two angled braces with three horizontal beams that look similar to other supports underneath the bridge. They jut out 25 to 30 feet to cradle the observation platform, and in turn must be anchored to the concrete bridge structure by 135 steel rods.

However, Caltrans officials said last week that the eastern span project’s chief engineer, Brian Maroney, had raised questions about the cantilever support system. The issue is whether the rods that would attach the steel arms to the bridge are strong enough.

Redesigning the support structure again to add rods could postpone the bike path’s completion beyond this summer, officials conceded.

One key figure on the project, Caltrans bridge construction manager Steve Whipple, said he is hopeful that won’t be necessary.

Whipple said Maroney’s concern is the extent of stress on the 135 rods that will hold the three cantilever arms. Caltrans is having the bridge’s design and engineering firm, T.Y. Lin International, look into the issue.

“T.Y. Lin is double and triple checking,” Whipple said. “We may need additional rods” to bolster the support system, he said.

Earlier setbacks

But Whipple also said “there are limitations” on how many rods can be added to the structure as it is now designed.

“This path will be designed and constructed to be very safe,” Whipple said.

Caltrans did not make Maroney available for comment.

Before the latest delay, the bike path project already had its share of problems — incorrectly installed bolts used to hold down the railings snapped and had to be replaced, and many of its hollow steel deck sections were left out in the rain before construction. Water got into the sections, and crews didn’t discover they were flooded until they started to lift them into place.

Caltrans officials were not able to say how much the agency had spent on the scrapped support structure for the observation platform. It was made in China and had already been delivered when the bridge oversight panel made its decision to go with another design.

Work started on the new cantilever supports in July 2015 and was supposed to have been completed in September. But shortly before they were to be shipped, Caltrans discovered that the steel arms had a bow running from side to side, probably an unwanted byproduct of the welding process.

The agency ordered the South Korean company that fabricated the arms, Hansteel, to straighten out the steel supports, leading to a three-month delay in shipping the components to the U.S.

Caltrans says that the work has been done and that the redesigned system is en route to this country. Once the winter rains stop, the agency intends to resume construction — if the engineering review it has ordered because of project manager Maroney’s concerns finds that everything is OK.

Engineering challenge

Endress, the former bridge architect, said he has conferred with Caltrans engineers on what he called the “connection issue.”

“I am optimistic they are going to find a way to solve the connection problems and move forward with the beautiful bridge,” he said.

“This thing has to stand up over time,” said Caltrans spokesman Will Shuck. “There is nothing about this bridge that has not been an engineering challenge. This is one more, and they are working out the final details.”

The final price for the bike path extension is $8 million, which will probably include the costs of reworking the support for the platform and any installation issues.

The bill for the reworked support system has not been finalized, however. “Right now we expect it to be within the budget we are working with,” Whipple said.

The recent delays have frustrated members of the bicycling community, said Renee Rivera, executive director of the Bike East Bay coalition.

While she said she had not heard what had triggered the latest delay, her members are anxious to be able to ride to Treasure Island and then on to San Francisco sometime in the future.

“Right now, we call it the world’s longest bike pier — it doesn’t go anywhere,” Rivera said. “It’s very disappointing that it’s become a date that just keeps sliding ... and we still don’t have a date we can count on.”

Jaxon Van Derbeken is a San Francisco Chronicle staff writer. E-mail: jvanderbeken@sfchronicle.com Twitter: @jvanderbeken