This Research Summary is part of Report 2024-25, "Development of a smart phone app to warn the driver of unintentional lane departure using GPS technology."
Unintentional lane departure is a significant safety risk. Currently, available commercial lane departure warning systems use vision-based or GPS technology with lane-level resolution. These techniques have their own performance limitations in poor weather conditions. We have previously developed a lane departure detection (LDD) algorithm using standard GPS technology. Our algorithm acquires the trajectory of a moving vehicle in real-time from a standard GPS receiver and compares it with a road reference heading (RRH) to detect any potential lane departure. The necessary RRH is obtained from one or more past trajectories using our RRH generation algorithm. This approach has a significant limitation due to its dependency on past trajectories. To overcome this limitation, we have integrated Google routes in addition to past trajectories to extract the RRH of any given road. This advancement has been incorporated into a newly developed smartphone app, which now combines our previously developed LDD algorithm with the enhanced RRH generation algorithm. The app effectively detects lane departures and provides real-time audible warnings to drivers. Additionally, we have designed the app's database structure and completed the programming of the necessary algorithms. To evaluate the performance of the newly developed smartphone app, we perform many field tests on a freeway. Our field test results show that our smartphone app can accurately detect all lane departures on long straight sections of the freeway irrespective of whether the RRH is generated from a Google route or past trajectory.
The most commonly used laboratory test in Geo-engineering research and in routine testing is the cylindrical compression test. This test is widely used to evaluate the stiffness and strength parameters of soils and other geologic materials. At the Minnesota Department of Transportation a MTS cyclic loading triaxial system is used for testing various types of subgrades and pavement materials under cyclic impulsive loading that corresponds to traffic conditions. Following some discussions between members of the Mn DOT Research Group and the University of Minnesota Soil Mechanics Group, it was decided that some improvements and modifications of the original triaxial set-up are feasible
The second part of this report is devoted to the presentation of the modifications and improvements of the triaxial apparatus that have been done in due course of the research period. In the third part the improved testing capabilities of the Mn DOT triaxial apparatus are demonstrated on the basis of one conventional and two unconventional experiments done on fat clay and on dry sand specimens, respectively.
The purpose of this three month study has been to determine whether it is feasible to simulate an asphalt pavement section using the elastic theory. This has been done by first obtaining samples from Investigation 183, Test Section 102 and determining the stress-strain properties of the various layers using the repeated load triaxial test under various conditions. Appropriate moduli have then been put. into an elastic layered system which is used to calculate stresses and strains within the system. The Benkelman beam deflections measured in the field have been simulated in this manner and the comparison between computed and measured deflections is used to show whether the elastic theory simulates a flexible pavement. The possibility of determining equivalencies between stabilized base courses and granular base courses are explored as are the use of other parameters for design purposes.
Using presently available technology, methodology was developed for evaluating flexible pavement on a system basis. It was hoped that the results could be used for setting more realistic load restrictions and designing and programming improvements on a priority basis. Data were collected on about 125 miles (200 km) of roadway in each of three counties and on about one mile (1.6 km) of street in each of six municipalities. Data consisted of a traffic study and a structural study.
The Minnesota Department of Transportation (MnDOT) investigated the use of dowels with various anchoring methods and their effects on pavement performance. In a previous study, the characteristics of various epoxy and grout anchorage systems at the interface between new construction and existing concrete were studied using cut-out slabs brought into the Minnesota Road Research Facility (MnROAD). This investigation seeks to validate the findings of that study. Twelve different anchoring materials and methods were studied and compared to a control using no grout. This study did not examine the effects of a reduced number of dowels across a lane but rather looked at only the anchorage materials and methods. This experiment was performed on westbound lanes of Interstate 94, adjacent to the MnROAD test track. The field experimentation and monitoring involved core samples and measured ride quality, International Roughness Index (IRI), and Falling Weight Deflectometer (FWD) load transfer and fault measurement. These results supplemented the findings from the previous in-house performance categorization experiment. The control experiment, conducted without any grout or epoxy, initially displayed a notably low Load Transfer Efficiency (LTE). However, over time, there was a gradual improvement, leading to a more consistent LTE, attributed to the deployment of non-mechanical load transfer. Based on the slab thickness, the 1.25-inch dowel did not indicate any statistically significant LTE or other performance improvements over the 1-inch dowel within the anchorage types examined. Overall, the Epoxy Experimental 1 performed best while the un-grouted and unrepaired cells had the lowest performance. Moreover, no material clearly indicated characteristically low performance.
The purpose of this study was to determine whether breaking a concrete pavement prior to being overlaid would result, in any reduction in the amount of crack reflectance. This report describes the design, construction and performance of a typical widening and resurfacing project, on a portion of which a 59-ton roller was used to crack the old concrete slab prior to construction. This process was found to significantly reduce some types of cracking and is recommended for future projects of this nature
The purpose of this study was to evaluate the effect of formed polystyrene concrete cylinder molds on concrete strength. This report describes the various treatments given to cylinders, which were cast in steel, fiber, and polystyrene molds and the statistical analysis which was made on the 28 day compressive strength results. A recommendation is made concerning the use of polystyrene concrete cylinder molds.
The new turbulent-mass process for mixing asphaltic concrete paving mixtures has been under study since its recent introduction in 1970. It is increasing in popularity with contractors because of two reasons: the mixing plant requires less equipment; and the process itself appears to result in a significant reduction in polluting emissions. All of this should reduce the cost of production.
Field and laboratory tests and observations indicate that a satisfactory product can be produced by this process, one that is at least equal to conventional plant-mix
Beginning in 1968, Benkelman beam deflection tests were run on 25 bituminous roadways located throughout the state. Tests were run before overlay, just after these projects were overlayed, one year after, and two years after. The results were analyzed to determine the strengthening effect of the bituminous overlay.
In conjunction with this study, Benkelman beam tests were run at various short intervals on a number of randomly selected flexible pavements. These results were used to develop a testing schedule (number and location of test points required) in order to assess the deflection characteristics of a flexible pavement within a given degree of accuracy.
