The historic Fremont Avenue Bridge over the Midtown Greenway in Minneapolis will close indefinitely to motor vehicle traffic Friday morning to preserve its structural integrity, city officials said Thursday.

It will remain open to bicyclists and pedestrians.

Load restrictions were placed on the bridge following an inspection, but overweight vehicles continued to cross, authorities said.

To prevent further decay, motor vehicles will no longer be permitted to cross until Minneapolis and Hennepin County leaders “can find a long-term solution to the problem,” a city spokesman said Thursday.

The now 103-year-old structure has been in an advanced state of deterioration for at least 10 years.

A 2005 report by the Minnesota Department of Transportation gave Fremont a sufficiency rating of 29.5 out of 100, noting the worsening condition of the bridge’s girders — its primary load-bearing elements.

Concrete was weathered and cracked, allowing leaking water to trickle through.

A rating below 40 might indicate a life expectancy of less than four years, officials said.

At the behest of the city’s public works department, an engineering firm conducted a study in 2007 to analyze each of the Midtown Corridor’s historic bridges.

Of the 37 examined structures, the Fremont Avenue bridge garnered the lowest sufficiency rating.

Experts told the city that “the most fiscally responsible alternative for this structure is to program the bridge for replacement within the next three years.”

Annual inspections were recommended for maintenance.

At the time, reconstruction efforts were projected to top $1 million.

The nationally lauded Midtown Greenway crosses two bridges that are shared with freight trains. In each case, a fence separates tracks and trails. More than 1.5 million people cruise the 5.5-mile greenway each year.

Bridge safety is a particularly sensitive topic in Minneapolis, whose recent history includes the Interstate 35 bridge collapse into the Mississippi River on Aug. 1, 2007, which killed 13 people.

The National Transportation Safety Board cited a design flaw as the likely cause of its fall and said additional weight from construction vehicles on the bridge at the time of the collapse contributed to the catastrophic failure. The replacement bridge opened in September 2008.