THIS MONTH’S ACCIDENT on the Chesapeake Bay Bridge, in which a car driven by a young woman was propelled into the waters below, has people still shaking their heads over her improbable survival. Morgan Lake’s remarkable resolve, cool thinking and athleticism are why she survived. Equally remarkable is how her car hurdled over the barriers put in place to prevent that very occurrence — and that’s an issue that state and federal authorities must address.

Ms. Lake was driving across the bridge on July 19 when her Chrysler Sebring was hit from behind by a tractor-trailer, causing it to hit another car. The truck struck the Sebring a second time, driving it atop and then over a 3 1 / 2-foot-tall concrete Jersey barrier and into the bay 27 feet below. Ms. Lake escaped from the sunken car and swam to safety.

There’s no question, as the Maryland Transportation Authority stressed in the aftermath of the collision, that the 61-year-old Bay Bridge has an excellent safety record. The average number of crashes is significantly lower on the bridge than on statewide roads: 43 crashes per 100 million vehicle miles traveled on the bridge compared with 166 crashes on statewide roads. Five crashes resulting in fatalities have occurred since January 2000. More than 25 million vehicles annually cross the bridge, and this is only the second time in the bridge’s history that a vehicle has plunged off one of the two spans.

The last time a vehicle went off the bridge — Aug. 10, 2008, when a truck crashed into the railing and knocked off a piece of it before toppling into the bay, killing the driver — Gov. Martin O’Malley (D) convened a panel of experts to examine bridge and tunnel safety. Among the conclusions was that bridge railings are not typically designed to withstand the unusually severe force of a crash involving an 18-wheel semi-trailer truck. But, as AAA Mid­Atlantic noted in urging a federal investigation of this month’s accident, it was a car — not a big truck — that hit the barrier and it still ended up in the water.

So, there are a number of questions — about the condition and efficacy of the barrier and the adequacy of design requirements — that must be examined. It was encouraging to see National Transportation Safety Board (NTSB) inspectors sent to Maryland on Thursday to conduct a preliminary review; we, like the auto club and Sen. Barbara A. Mikulski (D-Md.), hope it will lead to a formal investigation. Maryland officials said they would welcome federal involvement and have pledged to implement any NTSB recommendations.

Officials may well be right that “a singular process” caused the frightening events. But the public’s peace of mind depends upon diligent and thorough examination.