The phrase "a tangible sign of" is correct and usable in written English.
It can be used to indicate a physical or concrete indication of something, often in contexts discussing evidence or manifestations of an idea or feeling.
Example: "The new park is a tangible sign of the community's commitment to environmental sustainability."
Alternatives: "a concrete indication of" or "a physical manifestation of".
Navy Athletic Director Chet Gladchuk said that was a "tangible sign of a unified front by those remaining schools".
"These fields are a tangible sign of our Youth Football Fund in action," Commissioner Paul Tagliabue said in a statement.
A tangible sign of their bond is the film "Présentation" ("Introduction"), from 1951, which Rohmer directed and the twenty-year-old Godard stars in.
It will be a catharsis for the city, Tekulve said, a tangible sign of progress but nothing close to the feeling of a championship.
Now it picks up anything up to 200 people – a tangible sign of the umbilical cord that connects the two cities.
Maroon "Ryan for Heisman" T-shirts dotted the scene, a tangible sign of the Heisman Trophy campaign for the quarterback Matt Ryan.
UK interlocutors made clear they would welcome U.S. CTBT ratification, which would be a tangible sign to the world of U.S. commitment to nuclear nonproliferation.
Although the Easterners turned out in droves for their first free elections, a banana (or, for that matter, a BMW) was a more tangible sign of freedom.
The delegation asked that the prayer cards be offered to inmates in SHU throughout the California prison system, as a tangible sign that communities of faith and conscience are observing the day by joining the movement to dismantle the domestic torture of solitary confinement.
At the start of last year, a Predator plunged into the Mediterranean Sea after conducting a secret mission over Libya, a rare tangible sign of U.S. surveillance operations there.
Increasingly, part of these deals is being distributed to European investors, a tangible sign that the long-awaited globalization of the markets is a reality.
