Part of the Cottonmill to Fort Kearny Trail system.
From the City of Kearney web site:
This long trail section begins at the 2nd Avenue underpass and goes to the Great Platte River Road Archway Monument. Pioneers Path crosses under 2nd Avenue, to Central Avenue, to Avenue M, and then to the historical bridge at the Archway. This long section has some nice view of sand pits along the way and concludes at one of Kearneys most proud attractions.