The life of the various types of cutting edges for use on Motor Graders and Snowplows varies with the type of steel and its treatment by the manufacturer. This is an evaluation of the wear characteristics of five types of cutting edges, both Motor Patrol and Snowplow, used in the maintenance of gravel roads.
Comparing the two sets of data (gravel and snow) excluding the Carbide edges, the Carbon is best on snowplows and second best but only slightly lower in durability than flame hardened on gravel blading. Gravel blading is about three times more severe than snowplowing on cutting edges other
than Carbide Insert.
The Minnesota Department of Transportation is investigating alternative means of culvert renewal in lieu of removal and replacement. Several state of the art renewal techniques were selected for trial on 1-35 near Hinckley, Minnesota in an effort to find an inexpensive and less disruptive alternative to removal and replacement of deteriorated culverts.
Seven different reliners were placed in concrete and metal pipe, and five joint repair options were placed in concrete pipe. These reliners and repairs were compared using costs, skills and resources required, time, culvert preparation, traffic disruption, work area requirements, placement problems, and grouting procedures. Field performance of the reliners and joint repairs was checked visually after one year to evaluate the short term effects of climate. At this point in time all reliners appeared to be performing adequately.
Relining and joint repair should be considered as an inexpensive, time saving, and minimally disruptive alternative to removal and replacement of deteriorated culverts. Smooth reliners are inexpensive, flexible, easy to install and perform better hydraulically than corrugated or ribbed reliners. Savings can be significant in both money and time with very little disruption to the driving public.
Minnesota Department of Transportation (Mn/DOT) conducted a research project to evaluate the contribution to motoring safety and durability of snowplowable pavement markers. Two styles were tried; a raised steel casting with reflector and a reflector recessed in a slot cut in the pavement. Different spacings (50 and 100 ft.) were tried and wet and dry night observations were made.
Laboratory remolded subgrade soil samples have been widely used to study subgrade resilient modulus. But physical conditions, such as moisture content and density, of such specimens may not represent in-situ conditions very well. Therefore, AASHTO and the Long-Term Pavement Performance program (LTPP) have recommended that undisturbed thin-walled tube samples should be used to study subgrade resilient behavior. The Minnesota Department of Transportation (Mn/DOT) is developing mechanistic-empirical pavement design approaches through the Minnesota Road Research project and has realized the importance of resilient modulus in the design approaches. Currently, the Mn/DOT is making an effort to study resilient modulus of unbound pavement materials through laboratory experiments. Under a research project at the Mn/DOT, several thin-walled tube samples of subgrade soil were obtained from six different pavement sections at the Minnesota Road Research project. Repeated loading triaxial tests were conducted on the soil specimens to determine resilient modulus at the Mn/DOT laboratory. Also, some soil properties, such as resistance R-value and plasticity index were obtained. R-value is an indicative value of performance when soil is placed in the subgrade of a road subjected to traffic. Two constitutive models (Uzan-Witczak universal model and the deviator stress model) were applied to describe the resilient modulus. The objective of the research was to compare these two well-known constitutive models in describing subgrade soil resilient behavior and to study effects of material properties on the resilient modulus.
From the specimens tested, the experimental results showed that the universal model described the subgrade resilient modulus slightly better than the deviator stress model and the coefficients in these two constitutive models were found to have correlation to material properties. Also, no well-defined relationships between R-value and the coefficients in the constitutive models were observed from the results of the tested specimens.
Content Note: This is the author’s version of a work that was accepted for publication in the Transportation Research Record: Journal of the Transportation Research Board, Issue Number: 1786, Publisher: Transportation Research Board ISSN: 0361-1981. The final version can be found at https://doi.org/10.3141/1786-03.
