When the National Park Service recently announced it was temporarily--and perhaps permanently--closing East Executive Avenue alongside the White House to through traffic, its spokeswoman explained that the narrow street was never intended to be used for traffic and that a few motorists had found it to be a short cut.

Actually, judging from the calls and comments made to MetroScene, far more than a few are inconvenienced. The alternatives, 15th and 17th streets, are sluggish in rush hours.

Now comes an expert in the matter who demolishes the Park Service's explanation. He's Joseph V. (Joe) Osterman of Bladensburg, who retired from the D.C. police force in 1972 as deputy chief after an unequaled 41 years in its traffic division. He sent MetroScene a detailed letter on the matter:

" . . . My first assignment . . . was at the intersection of Pennsylvania Avenue and East Executive Avenue" at the northeast corner of the White House grounds, Osterman recalled. "Over 50 years ago . . . we used what was known as a semaphore and traffic whistles. This was before traffic lights were installed.

"This was a very busy intersection, as all traffic that was westbound on Pennsylvania Avenue came through Treasury Place since renamed Alexander Hamilton Place, behind the Treasury Building , then north on East Executive Avenue to turn left onto Pennsylvania Avenue to proceed to Georgetown . . . .

"Turns were not permitted at 15th and Pennsylvania Avenue, as this was the main switching area for the streetcars. So you see, it was never just a short cut to anything."

"I can remember very well during the war World War II when this street was closed and became another parking area for employes and I am sure it will happen again."

As a matter of fact, White House employes' cars already park on the west side of the street.

Several readers, in their calls, have asked what they can do to persaude the Park Service to reopen the street to traffic. The answer, the Park Service says, is to send letters or petitions to M. J. (Jack) Fish, National Capital Regional Director, National Park Service, at 1100 Ohio Dr. SW, Washington, D.C. 20242.