For the fourth time in two months, concrete from the upper deck of the Richmond-San Rafael Bridge crumbled off and fell down onto a car on the lower deck on Friday.

A female driver reported having two "baseball-sized" chunks of concrete land on her windshield while driving eastbound on the lower deck around 7:30 p.m. Friday. As the Mercury News reports, CHP officers were unable to find the offending concrete afterwards, but the woman's windshield had chips to show for it.

Caltrans officials denied that any concrete fell this time, apparently disbelieving the woman's story, and the bridge remained open on Friday night.

This incident followed another seven days earlier in which a fallen piece of concrete caused two eastbound lanes to have to close in the middle of a busy of Friday. And a similar incident occurred in late March, following the first major concrete crumbling which shut down both decks of the bridge for 9 hours on February 8. Caltrans subsequently launched an $8 million repair project, saying that the bridge remains structurally sound, but it is replacing 61 aging steel joints along the upper deck.

Caltrans told the Chronicle that crews had just doing this repair work on the upper deck when the April 5 incident occurred — the work having loosened some concrete around some rebar.

Per the Chronicle:

Concrete frequently expands and loosens, particularly when it’s jostled by jackhammers and hacksaws. A Caltrans spokeswoman said that the agency “will continue to monitor the bridge closely” and that it’s “working with the contractor to prevent additional spalling” — transportation-speak for concrete peeling off a steel bar — “as the work continues.”

But having commuters getting regularly pelted with large chunks of concrete seems wildly unsafe, and the situation had a state lawmaker calling for the bridge to be completely replaced last week.

State Assemblyman Marc Levine, D-San Rafael, issued a statement saying, "Enough with the Band-Aids — let’s have a bridge that will last for generations." He further said, "I am calling on the Metropolitan Transportation Commission (MTC) and Caltrans to prepare concepts for the new [Richmond Bridge] span this year.”

Levine has been repeating his call for a new bridge for any media outlet that will listen, and he argues that the existing, 63-year-old span will cost $900 million to maintain over the next years, and that it likely will only last another 20. A new span is estimated to cost $3 billion — but, um, we all know how cost and time estimates worked out for the eastern span of the Bay Bridge, which took 11 years to build and cost 2500% more than was originally estimated ($6.5 billion, vs. an initial estimate of $250 million).

As Curbed tells us, the Richmond-San Rafael Bridge opened in 1956 at a cost of $66 million — the equivalent of $613 million in today's dollars.

The bridge underwent emergency renovations in 2004 after holes appeared in the decks' concrete — a $50 million repair that was added to a $795 million seismic retrofit project. As the Merc reminds us, more holes showed up in 2006, shortly after that retrofit project was complete, prompting another $25 million repair.

NBC Bay Area began calling attention to the bridge's problems again in 2015, and they report that an inspection less than two years ago deemed the bridge "structurally deficient," giving it an overall rating of 60.9. That fairly low rating, to put it in perspective, is barely 11 points higher than the rating that bridge in Minneapolis had before it collapsed in 2007, killing 13 people and injuring 145.