The Zion-Mount Carmel Tunnel
Construction of the 1.1 mile Zion-Mount Carmel Tunnel began in the late 1920's and was completed in 1930. At the time that the tunnel was dedicated, on July 4, 1930, it was the longest tunnel of it's type in the United States. The purpose of the building the Zion-Mount Carmel Tunnel (and the Zion-Mount Carmel Highway) was to create direct access to Bryce Canyon and Grand Canyon from Zion National Park.

Tunnel Escorts
Before 1989, large vehicles, including tour buses, motorhomes, and trailers, were involved in more and more accidents and near misses in the tunnel due to an immense increase in the volume of traffic and in the size of vehicles passing through the tunnel.
A study by the Federal Highway Administration in early 1989 found that large vehicles could not negotiate the curves of the tunnel without crossing the center line. To insure safety, the National Park Service began an escort (traffic control) service in the spring of that year.
Rangers posted at both ends of the tunnel convert two-way tunnel traffic to one-way for larger vehicles, insuring safe passage. This service, for which a $15 dollar fee is charged, was provided for over 28,640 oversized vehicles in calendar year 2009.
During the winter months, drivers of large vehicles must make advance arrangements at the entrance stations for the tunnel escort.

Arranging for a Tunnel Escort:
*Have your vehicle measured at the entrance station when you arrive at the park. Any vehicle that is 7 feet 10 inches (2.4 meters) in width and/or 11 feet 4 inches (3.4 meters) in height or larger is required to have a tunnel escort.
*Pay $15.00, in addition to the entrance fee, for tunnel escort permit at the entrance station before proceeding to the tunnel.
*Drive to the tunnel during tunnel escort hours (posted seasonally)
*Tunnel escort service will be provided by friendly NPS rangers.
*Your $15.00 tunnel escort permit is good for two trips through the tunnel for the same vehicle within seven days of purchase.

Prohibited Vehicles
Vehicles over 13 feet 1 inch tall, Semi-trucks, vehicles carrying hazardous materials, vehicles weighing more than 50,000 pounds, single vehicles over 40 feet long, combined vehicles over 50 feet long. All Bicycles. Pedestrians.

The Zion Tunnel Today
Today the tunnel is basically the same as it was upon its completion over eighty years ago. However, because of the softness of the sandstone through which it passes, much reinforcing has been done and concrete ribs now give added support to the the tunnel's entire length. Collapse of a sandstone pillar west of Gallery #3 in 1958 broke the top out of that gallery and flushed tons of debris into the tunnel, causing its closure for several weeks. Because of that collapse, the tunnel is now monitored electronically twenty-four hours a day to warn park officials to the danger of a reoccurrence.