Duck boats will be missing from the streets of Philadelphia today as the city marks one year since the deadly crash on the Delaware River that killed two Hungarian tourists.

The parents of the two victims - Dora Schwendtner, 16 and Szabolcs Prem, 20 - in the meantime are asking why duck boats are still allowed to operate at all in Philadelphia.

In a joint column in today's Daily News, Aniko Takacs and Sandor Prem said, "We've been living that year in the grasp of sorrow, haunted by painful memories and questions."

Chris Herschend, president of Ride the Ducks, has said today's suspension of operations for the amphibious vehicles is out of respect for the two victims.

On July 7, 2010, a barge pushed by a tug crashed into a duck boat, sending 35 passengers and two crew members overboard and killing Schwendtner and Prem.

In a report issued last month, the National Transportation Safety Board blamed the accident mostly on the first mate on the tug, who used his cellphone repeatedly in the hours before the collision because he was dealing with a family emergency.

A deckhand on the duck also was distracted because he was texting on his cellphone in the minutes before the accident, the NTSB said.

The NTSB cited the accident as an example of the increasing number of tragedies caused by using cell phones and other equipment while operating vehicles.

In their column, Takacs and Prem note that in Hungary it is illegal to drive while using a cellphone in Hungary and ask: "So how is it that in America you not only can use a cellphone for personal uses, but also a laptop, when operating a tourist boat or a tugboat? Can anybody tell us how this makes any sense?"

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