I too have driven through the Lehigh tunnels* many, many times. Twice a day for three years when I was commuting, now just occasionally on the weekends when I visit my folks.
* a second tunnel was added in the early nineties; the original tunnel (now one-way northbound) is rectangular, while the new tunnel is circular. It is the only road tunnel crossed by the Appalachian Trail.
More trivia: Distance between the Blue Mountain tunnel and the Kittatinny tunnel is only 600 feet.