YELLOWSTONE NATIONAL PARK, Wyo. -

Yellowstone National Park visitors will likely to encounter new road and bridge construction projects this summer.
    
Visitors may see traffic delays of up to 30 minutes in construction areas and some night closures along the Grand Loop Road.
    
But the road work is not expected to cause visitors to have to make changes to their travel plans.
    
The most significant of the work is the start of the first phase of a construction project on the 16-mile stretch of road between Norris Geyser Basin and the Golden Gate area in Swan Lake Flats just south of Mammoth Hot Springs.
    
The work is the first significant improvement the road has received since it was first constructed in the 1920s. It will be completed in three phases over the next few years.