If you're planning to visit Zion National Park this summer, the route you choose will make a big difference in your trip. Visitors entering via the park's South entrance won't be affected, but travelers using the East Entrance and the Zion-Mount Carmel Highway will find some delays and closures.

The ten-mile Zion-Mount Carmel Highway and the mile long Zion-Mount Carmel Tunnel were completed in 1930 to create a direct link between Bryce Canyon, the North Rim of the Grand Canyon and Zion National Park. Information from the park explains why it's time for a major overall, and how the work will affect travelers:

The Zion-Mt Carmel Highway was constructed in the late 1920’s and besides being surfaced with asphalt and having CCC era rock guardrails added, has not been improved since. Unstable soils, poor drainage and heavy use have deteriorated the roadway to the point that major renovations are needed to stabilize it.

Zion National Park is anticipating that major roadwork will occur on the Zion-Mount Carmel Highway beginning as early as May of 2010. The roadwork will occur on a section of roadway known as The Switchbacks, from the junction of the Zion-Mt Carmel Highway and the Zion Canyon Scenic Drive to the west portal of the Zion-Mt Carmel Tunnel.

If you aren't familiar with the park and connecting highways, download a copy of the Zion Area Map to get the big picture; a park map will provide more details.

The work won't affect everyone traveling to and from Zion. If you come and go via the park's South Entrance and I-15, you won't notice the work.

The 2010 construction will affect travelers utilizing the Zion-Mt Carmel highway through Zion from Utah State Route 9 to U.S. Highway 89.

People visiting Zion National Park via the park’s South Entrance who are camping, accessing the shuttle system, staying at the Zion Lodge or in the town of Springdale will not be affected.

How will this work affect your plans if you intend to travel through the tunnel and enter or leave the park via Route 9 and the park's East Entrance?

Travelers going through Zion from the South Entrance to the East Entrance, or vice versa, should expect delays and temporary closures. Details are not yet available but we expect that most closures will occur in the evening hours. However, significant delays of up to an hour or more will occur throughout the day and the roadway will be one lane most of the time, even when work is not in progress.

The park has suggested some options if you'd like to avoid those delays:

Alternate routes of travel from Springdale to U.S Highway 89 are Utah State Route 59 from Hurricane, Utah to Arizona State Route 389 and Fredonia, Arizona or Utah State Route 14 from Cedar City, Utah to Long Valley Junction. Visitors may want to consider using one of these roads if traveling to Bryce Canyon or Grand Canyon National Parks from Zion.

This project is expected to take about seven months. Phase two of work on this section of road is planned for 2012, and should take about five months. It will include rehabilitation of six miles of the roadway from the east portal of the tunnel to the park’s eastern boundary.

If you're inconvenienced by this work, keep in mind there's been a lot of discussion in recent years about the deteriorating infrastructure and the "maintenance backlog" in parks all across the country. This project is one effort to actually correct some of those problems.