By Daniel Trotta and Kim Palmer

CLEVELAND (Reuters) - Cleveland on Friday set up concrete traffic dividers and tall metal fences around next week's Republican National Convention site, measures meant to thwart an attacker like one in France who drove a truck into a crowd, killing more than 80 people.

Security experts said police, the U.S. Secret Service and other law enforcement agencies have viewed vehicles as a potential threat since early in their 18 months of planning for the convention where Donald Trump is due to be formally nominated for the Nov. 8 U.S. presidential election.

The decision to erect the protective barriers was taken before Thursday night's attack in the French city of Nice. Ron Rowe, a high-ranking special agent with the Secret Service, told a news conference on Tuesday that some of the barriers would be going up that day.

Much of the focus has been on stopping a car or truck bomb like those that struck New York's World Trade Center in 1993 and an Oklahoma City federal office building in 1995.

    "A vehicle-borne attack is always something you're concerned about," said Jason Porter, vice president for the central region of security provider Pinkerton, which is advising private sector clients on security around the convention.

    Officials in Cleveland did not respond when asked whether the Nice attack had altered their security plans. The driver there, shot dead by police, was known to police for petty crimes but not for ties to Islamist militants.

PROTESTS EXPECTED

Thousands of people, including protesters against Trump, are expected to pack into Cleveland for the July 18-21 convention.

Cleveland has banned drones, limited the size of bags people can carry and on Friday removed opaque rubbish bins near the Quicken Loans Arena convention site, replacing them with wire frames holding clear plastic waste bags that make it more difficult to hide objects.

A memorial to slain police officers was cordoned off, an apparent reaction to protests against high-profile killings of black men and youth by police in U.S. cities including St. Paul, Minnesota, Baltimore, New York and Cleveland.

After last week's killing of five police officers in Dallas by an African American angry about police killings of black men, nearly half of America's 30 biggest cities issued directives to pair up police officers on calls to boost safety, according to a Reuters survey of police departments.

    T.J. Dow, a Cleveland city councilman for the neighborhood expected to see the bulk of protests, said the security plan was designed to be flexible.

Dorothy Strauss, a 68-year-old retired customer service representative, acknowledged her fears in the face of the France attack while watching her granddaughters play in a sprinkler near the convention site.

Were she a delegate, she would attend, Strauss said. "On the flip side, I wouldn't come down here and hang out with my two granddaughters during the RNC."

(Writing by Scott Malone; Editing by Howard Goller)