Low-volume roads

The goal of this research is to investigate each agencies current design method to discover similarities and differences in the way each agency designs and builds roadways for both low and high volume roads. Each agency was given design specific inputs of common climate, traffic, and existing subgrade soil (from MnROAD) and was asked to develop a design based on current design practice/standards. This paper documented the differences in construction, materials, and expectations on performance to provide and will provide a bases for future agency discussion. The initial survey contained more information that could be covered in this paper. Future goals could include the additional information for other research topics, developing possible test sections, and again to provide a common point of discussion for future efforts. This work also builds off of the efforts started with the NVF34/Nord FOU concept at the 2007 Iceland workshop.

Pervious pavement provides a solution for many highly developed urban areas where an excessive amount of contaminated water is diverted into storm and sewer systems and left untreated before entering natural water sources such as rivers and streams. By allowing water to flow through the pavement surface and infiltrate the underlying soil, pervious pavements can reduce the amount of this pollution. Test cells were constructed at MnROAD to be monitored for drainability to evaluate the possibility of using pervious pavements to mitigate this problem. Other important criteria influencing the performance of pervious concrete in pavements will also be monitored, including mechanical and structural properties, surface characteristics, noise, and durability. This document summarizes the research that went into Report 2011-23, "Pervious Concrete Test Cells on MnROAD Low-Volume Road.."

This report documents study of the field performance of an inlay type thermoplastic pavement marking material along with the two-year-old bituminous pavement to which it was applied. Evaluation included physical performance of the product and the effect on overall durability of the pavement surface. The installation was performed in May, 2006 on a bituminous test cell at MnROAD’s Low Volume Road. 524 square feet of inlaid thermoplastic pavement marking material were installed on a surface of 4 in. Superpave hot mix asphalt, including one segment installed along 100 ft of left wheel path of a lane that received standard truck load configurations, and two crosswalks that received load configurations that varied by lane. During the period between May 16, 2006 and August 1, 2007 Cell 26 received 6,809 and 2,003 repetitions of the standard 80K and overloaded 102K truck configurations respectively. The installation was a decorative treatment, not a retrofit of longitudinal lines on the existing pavement. This paper was submitted to the Transportation Research Board for the 2009 Annual Meeting.

This is an Innovation Update that shows the how MnROAD uses fly ash in pavement design, after the release of three research reports (2009-27, 2007-12, and the 2007 Low Volume Road & Farm Loop (Cells 33, 34, 35, 77, 78, 79, 83, 84) Construction Report.)

Over the past few decades, farms have consolidated and farm size has increased significantly. The farm equipment industry has responded by producing larger and heavier equipment. For example, it is not unusual to see liquid manure application equipment that hauls 9,000 gallons or more. Innovations such as steerable axles, flotation tires (spreading the load over a much larger area), and new tire designs have been implemented on the equipment in recent years. The length, width, and axle loads of the large equipment could potentially accelerate damage on roads. However, there is insufficient data to show the effects of the equipment on pavement response and performance.

The purpose of this report is to provide details on the 2007 reconstruction of several cells on MnROAD's Low Volume Road. As MnROAD enters Phase II of its existence several research projects were initiated that necessitated the reconstruction of pavement test sections. The first research study plans to test various configurations of heavy farm equipment (manure tankers in particular) and assess the resulting damage in comparison to a typical 80,000 lb truck. A new "Farm Road" was built in the MnROAD stockpile area and is comprised of Cells 83 and 84. The second consists of stabilizing a full-depth reclamation base material with off-spec fly ash and comparing its performance to both a non-stabilized FDR and a conventional aggregate base. This study removed Cells 29 and 30 on the LVR and replaced them with Cells 77, 78, and 79. The third study is a field validation of previous laboratory work on polyphosphoric acid modified asphalt binders. It is located on Cells 33, 34, and 35. A fourth study involved innovative diamond grinding of concrete pavements to optimize their surface characteristics (noise, ride, texture, friction, splash and spray). Cells 37, 7, and 8 were ground during the summer of 2007.

Annual Minnesota Department of Transportation State Aid Office reports, cost estimates, and interviews were used to determine a typical county spending history for low volume roads. It was found large initial costs for bituminous roads (HMA), but the ongoing routine annual maintenance activity in later years was less costly than for gravel. The graph of cumulative maintenance costs verifies that annual maintenance costs/mile for a gravel road increase with traffic volume.

This brief details the low-volume road at MnROAD and the work done using the low-volume road in LVR design, aggregate road studies, and the adoption of new LVR materials. As MnROAD looks forward to its second phase of operation, this brief will provides recommendations for the low volume road and continued benefits of the low-volume road.

The Minnesota Department of Transportation (Mn/DOT) built the Minnesota Road Research Project MnROAD between 1990-1993. The 2.5-mile low volume road and the 3.5-mile mainline consists of a 2-lane roadway that originally contained gravel, hot mix asphalt, and concrete test cells designed for both low volume roads and interstate traffic. The mainline interstate cells are trafficked by public interstate traffic and the low volume road has a Mn/DOT 5-axle tractor-semi-trailer to simulated conditions of rural roads in two load configurations, resulting in the same equivalent axle loads or ESALS. MnROAD is located in a wet freeze zone that has affected both its base and subgrade materials with seasonal frost movements. This movement has slowly deteriorated each test cells ride over time. MnROAD has monitored the frost movements using frost pins and has measured the ride (international ride index – IRI) using high-speed profilers over for the life of the project. This paper investigates the loss of ride from both environmental and traffic loadings and how they have combined to cause the deterioration of ride over the last 10 years at MnROAD. The findings suggest that our current process to develop a mechanistic empirical design is currently missing the fact that seasonal differential frost movements play an important role in pavement performance in northern climates and need to be taken into account.

In 1999 three cells were reconstructed on the Low Volume Road as a study specifically examining low temperature cracking. These sections were designed using the exact same Superpave mix design except for the asphalt binder type, which differed at the low temperature performance grade. The performance grades for Cells 33, 34, and 35 were PG 58-28, 58-34, and 58-40 respectively. After several years in service these sections have begun to show marked differences in performance. Cell 35 has shown the most cracking, even though it has the softest grade at -40. The cracks on Cell 35 do not look like typical thermal cracks, while Cell 33 exhibits the expected typical thermal cracks. Cell 34 had virtually no distress after six years.