Traditional flexible pavement design emphasizes pavement layer fatigue under repeated traffic loading, but the majority of Australian rural roads consist of bituminous surfaced unbound granular base.
The major difference between flexible and rigid pavement systems is the application of a bituminous surface layer (e.g., asphalt layer) in a flexible pavement or a Portland cement concrete layer in a rigid pavement system.
Additionally, due to the temperature and loading rate dependency of viscoelastic bituminous surface layers, the stresses transferred to the supporting granular layers will be more taxing in hot summer months.
The majority of the route had a bituminous surface, but some segments had a hard surface.
In 1961, the highway had a bituminous surface, a combination of gravel and asphalt.
Within a year, the segment from Medora to the route's northern terminus had been paved with a bituminous surface.
Between 1933 and 1936, a stretch of the route in Reno County was also given a bituminous surface.
By 1951, the road's first block from its southern terminus was improved to a graded, bituminous surface, made up of crushed rock and asphalt.
From its junction with MN 119, MN 7 was a gravel road southeasterly to Montevideo before turn east on a bituminous surface to Clara City.
By 1961, the portion designated as RM 2134 had been upgraded to a bituminous surface, made of asphalt and crushed rock.
The highway was relocated straight through Jennings and to a path with fewer turns through Oronoque in 1938; that same year, the highway was paved with a bituminous surface along the US-36 concurrency.
