Browsing by Subject "Monitoring"

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Acoustic Emission Equipment for Infrastructure Monitoring
(Minnesota Department of Transportation, 1999-01) Shield, Carol K.
This system consists of acoustic emissions sensors, preamplifiers, filers, an AE monitor, and a digital oscilloscope. The system has been applied successfully to both steel and concrete structures and used to detect brittle fracture and low-cycle fatigue failures in welded steel joints and crack propagation in cover-plated rolled bridge girders, in the field and in the laboratory. The AE system detected initial cracking during the flexural crack testing of two high-strength concrete prestressed bridge girders. The acoustic emission monitoring of bond tests also provided insight into the behavior of the bond between glass fiber reinforced polymer rebar and concrete.
Alternative methods for monitoring polar bears in the North American arctic
(2013-12) Stapleton, Seth
Because polar bears (Ursus maritimus) are dependent on sea ice, climate change poses a significant threat to their long-term existence. The forecasted impacts of sea ice loss are circumpolar, but to date, effects have been documented in only a few, well-studied populations. Data demonstrating the impacts of climate change are less conclusive or simply lacking elsewhere. In general, current inventory regimes do not enable monitoring with enough regularity to meet the information needs of decision-makers. This reality, combined with pressures from northern communities to reform invasive research techniques (i.e., capture and marking), provided the backdrop for my dissertation. My objective was to implement and evaluate novel, efficient and broadly applicable methods for monitoring polar bears. I first conducted comprehensive aerial (helicopter) surveys of the Foxe Basin population in Nunavut, Canada during the summer, ice-free season. This work demonstrated the utility of the method for estimating the abundance of polar bear populations on land and provided a model for applications in other seasonally ice-free populations. I applied this framework to a neighboring population (Western Hudson Bay) and compared the result to an estimate obtained from physical mark-recapture. This comparison suggested negative bias in the mark-recapture estimate due to spatially limited sampling and resultant capture heterogeneity. Next, I assessed the potential for employing aerial surveys on sea ice in springtime. Although results suggest that detection can be estimated with adequate precision, logistical constraints may hinder the ability to obtain a representative density estimate during springtime. Monitoring programs based on aerial surveys can be designed with sufficient power (>0.8) to detect declines of 40% and 50% over 15- and 30-year periods, with costs comparable to mark-recapture. Costs may be significantly diminished and safety concerns alleviated, however, if bears could be monitored with satellite imagery. I evaluated this technique in a low topography, ice-free setting. Results indicate that bears were reliably identified on imagery, and an estimate of abundance was highly consistent with an independent aerial survey.
Assessment of Stormwater Best Management Practices
(University of Minnesota, 2008-04) Anderson, James L.; Asleson, Brooke C.; Baker, Lawrence A.; Erickson, Andrew J.; Gulliver, John S.; Hozalski, Raymond M.; Mohseni, Omid; Nieber, John L.; Riter, Trent; Weiss, Peter; Wilson, Bruce N.; Wilson, Matt A.; Gulliver, John S.; Anderson, James L.
Bridge Scour Monitoring Technologies: Development of Evaluation and Selection Protocols for Application on River Bridges in Minnesota
(Minnesota Department of Transportation, 2010-03) Lueker, Matthew; Marr, Jeff; Ellis, Chris; Winsted, Vincent; Akula, Shankar Reddy
Bridge failure or loss of structural integrity can result from scour of riverbed sediment near bridge abutments or piers during high-flow events in rivers. In the past 20 years, several methods of monitoring bridge scour have been developed spanning a range of measurement approaches, complexities, costs, robustness, and measurement resolutions. This project brings together the expertise of Minnesota Department of Transportation (Mn/DOT) bridge engineers and researchers, university hydraulic and electrical engineers, field staff, and inspectors to take the first steps toward development of robust scour monitoring for Minnesota river bridges. The team worked with Mn/DOT engineers to identify variables of scour critical bridges that affect the application of scour monitoring technology. The research team will used this information to develop a Scour Monitoring Decision Framework (SMDF) that will aid Mn/DOT in selecting the best technologies for specific sites. The final component of the project will involve testing the SMDF on five bridges in a case-study type demonstration; work plans for two of the sites were developed for demonstration of deployed instrumentation.
Citizen-science monitoring of birds in urban greenspaces.
(2011-05) Homayoun, Tania Z.
As urban development spreads across North America, native migratory bird species face threats not only to breeding habitat but also to the stopover habitat they require to rest and refuel. The Mississippi River Twin Cities Important Bird Area (IBA) covers over 14,000 ha of residential, commercial, and open space along the Mississippi River between Minneapolis and Hastings, Minnesota. Identified as valuable habitat to waterbirds, we know less about how landbirds, especially migrating songbirds, use this habitat. This dissertation explores the process of designing and evaluating a citizen-science monitoring program to evaluate this urban IBA and analysis of the collected data to better understand relationships between urbanization and IBA landbird communities during both spring migration and breeding seasons. The first main chapter discusses the design and implementation of the Mississippi River Twin Cities IBA Landbird Monitoring Program, a citizen science project that engages local birders in counting the IBA's landbirds. The program's main goals are to (1) inventory landbird species that use the area, (2) determine these birds' use of the area during migration and breeding seasons, (3) use these data to estimate landbird species abundance, and (4) evaluate long-term trends. The second main chapter describes a targeted assessment of three related point-count techniques with the goal of identifying one that maximized species recorded, species detection probabilities, and overall flexibility/ease of use in citizen science. The next main chapter analyzes the program's point count data to investigate the relationships between land cover surrounding urban park study sites in the Mississippi River Twin Cities IBA and the composition of landbird communities present in the IBA during spring migration and summer breeding seasons, and to evaluate this habitat's value to both migrating and breeding landbirds. While species richness, diversity, evenness, and native migrant landbird densities responded negatively to increased impervious cover, the response in landbird community measures was more pronounced during breeding than during migration, suggesting that even lower-quality habitat within the IBA may serve migrating birds. The final main chapter discusses a website that houses the program materials and allows citizen scientists to submit their data online into a quality-controlled database. Conservation of native bird populations will require both breadth and depth of understanding and effort reaching from the continental to the local levels. This study provides a template for the process of developing a small-scale local citizen-science monitoring program, from planning and pilot season, to analysis, reporting, and connection of the program data to a larger coordinated bird monitoring scheme.
Continued Monitoring of Stormwater Effluents from Filter Media in Two Bioslope Sites
(Minnesota Department of Transportation, 2021-06) Cai, Meijun; Patelke, Marsha; Saftner, David
Over the last thirty years, the Minnesota Department of Transportation (MnDOT) has implemented biofilters along roadways as a stormwater control measure. The state and national regulations require that the biofilters must be able to infiltrate and treat the first inch of rainfall onsite. However, the performance of the biofilters after installation has rarely been studied. An early phase of this project monitored two newly constructed biofilter sites for two years and for three months, respectively. This study extended the monitoring of soil moisture changes and infiltration water quality for another two years (2019-2020). Over the four-year monitoring period, both salvage peat and compost materials showed the capacity to retain the first inch of runoff, and this retention capacity did not change over the study period. The drainage water quality showed significantly temporal trends, particularly phosphorus concentrations, which were declining significantly for both compost and salvage peat. The application of tailing with compost can reduce the phosphorus release. The leachate from salvage peat has similar metal concentrations but much lower phosphorus concentrations (below 100 ppb) than the compost. The lowest chemical concentrations were achieved when the soil mixture contained 10% compost and 10% salvage peat, implying the best stormwater control practice is to limit the organic ratio to around 20%. Findings from this work determined the validity of using peat and compost for future biofilters and can aid in future design.
Development of a Sensor Platform for Roadway Mapping: Part A - Road Centerline and Asset Management
(Center for Transportation Studies, University of Minnesota, 2014-06) Davis, Brian; Donath, Max
Collecting information about the roadway infrastructure is a task that DOTs at all governmental levels need to accomplish. One way to increase the operational efficiency of these efforts is to use a relatively inexpensive mobile data collection platform that acquires information that is general enough to serve multiple purposes. The design and evaluation of one such platform that costs roughly $40,000 is described. It primarily consists of a differential GPS receiver providing vehicle location, and a LIDAR scanner that generates geometric profiles of the area between the vehicle and just beyond the road’s edge. The vehicle collects data along the road by driving it in both directions. The system post-processes the data to automate feature extraction. For roads with simple geometry such as two-lane, undivided highways, the road’s centerline can be calculated by finding the midline between the vehicle’s paths from each direction of travel. Algorithms process the LIDAR scans to automatically detect the presence of curbs and guardrails, which is then combined with location information to yield the position of these features in world coordinates. The centerline calculation was determined to be accurate to within 6 cm in areas where its use was applicable. Curbs and guardrails were generally detected with an accuracy of better than 10 cm. The results demonstrate that it is feasible to use a relatively inexpensive mobile data collection system to acquire road centerline and roadside features such as curbs and guardrails.
Development of Flexural Vibration Inspection Techniques to Rapidly Assess the Structural Health of Rural Bridge Systems
(University of Minnesota Center for Transportation Studies, 2008-09) Brashaw, Brian K.; Vatalaro, Robert; Wang, Xiping; Sarvela, Kevin; Wacker, James P.
Approximately 4,000 vehicle bridges in the State of Minnesota contain structural timber members. Recent research at the University of Minnesota Duluth Natural Resources Research Institute (UMD NRRI) has been conducted on vibration testing of timber bridges as a means of developing rapid in-place testing techniques for assessing the structural health of bridges. The technique involves measuring the frequency characteristics of the bridge superstructure under forced flexural vibration. The peak frequency of vibration was measured and compared to a set of load testing data for each of 9 bridges. Each bridge was also inspected using commercially available advanced inspection equipment to identify any major structural problems with individual bridge components such as timber pilings, pile caps, and girders. Two bridges were identified that needed immediate maintenance attention. The relationship between the load deflection data and the vibration characteristics showed a useful relationship and the results indicate that forced-vibration methods have potential for quickly assessing timber bridge superstructure stiffness. However, improvements must be made to the measurement system to correctly identify the 1st bending mode frequency of the field bridges. This global vibration technique has potential benefits for routine inspections and long-term health monitoring of timber bridge superstructures.
Development of Flexural Vibration Inspection Techniques to Rapidly Assess the Structural Health of Rural Bridge Systems: Phase II
(Minnesota Department of Transportation, 2009-12) Brashaw, Brian K.; Vatalaro, Robert J.; Wang, Xiping; Verreaux, Matthew; Sarvela, Kevin
Current timber bridge inspection procedures used in Minnesota and across the United States are mostly limited to visual inspection of the wood components. Use of advanced techniques like stress wave timing, moisture meters, resistance drills will significantly improve the reliability of the inspections but these inspection techniques are time consuming. The objective of this project was to conduct vibration testing of dowel laminated timber bridge systems to better understand the potential for using vibration testing to assess the structural health and condition of bridges in Minnesota. A second key objective was to improve and automate the vibration testing system that is currently being used. This research showed that the forced vibration system developed is an effective tool for conducting forced vibration tests of timber bridges and that there is a noted increase in frequency during each successive stage of construction. A reliable means for assessing the peak frequencies and an identification of the mode still needs to be developed for this system to use the vibration response to predict the EI product for use in load ratings. Each bridge has a unique set of vibration characteristics that were identified using the automated system. These characteristics showed peaks in amplitude as the frequency of the vibration was increased from 0 - 35 Hz during testing. It is believed that monitoring of the characteristic vibration response for each bridge would be a means of identifying changes in structural health over time due to wood decay, accidents, vandalism, or lack of maintenance.
Enriched Sensor Data for Enhanced Bridge Weigh-in-Motion (eBWIM) Applications
(Center for Transportation Studies, 2018-11) Kumar, Ravi; Schultz, Arturo; Hourdos, John
Bridge weigh-in-motion (BWIM) systems, which measure bridge deformation under live loading to estimate weights of passing vehicles, have been in development since Moses first introduced the concept in 1979. Despite advances made since its introduction, important limitations for BWIM systems still exist. A feasibility study was performed to determine if some of the limitations—including poor accuracy with multiple vehicle passage, either in tandem or side-by-side; and inability to accurately capture the passage of a vehicle moving at variable speeds—could be overcome by enriching the dataset available to the BWIM system. Non-contact measurements collected in real time on the topside of the bridge can enrich the dataset, and by taking advantage of these measurements a more accurate and effective enriched bridge weigh-in-motion (eBWIM) system can be developed. Several sensing technologies were reviewed including fiber Bragg gratings, MEMS accelerometers, microwave radar sensors, magnetic sensors, active infrared detectors, and video image vehicle detection systems. Preliminary results indicated that there was no clear candidate for a fully mature sensing system that would satisfy all the criteria in this study. However, microwave radar sensors have a reasonably low cost, are the least intrusive, and perform better in all weather conditions compared to the other sensors. A testbed using radar sensors is proposed to investigate the accuracy of the eBWIM system. If the desired accuracy of the eBWIM system can be achieved, its implementations should prove to be invaluable for enforcing bridge weight limits, studying truck traffic patterns, and managing bridge inventories.
Feasibility of Vibration-Based Long-Term Bridge Monitoring Using the I-35W St. Anthony Falls Bridge
(Minnesota Department of Transportation, 2017-01) Gaebler, Karl O.; Shield, Carol K.; Linderman, Lauren E.
Vibration based structural health monitoring has become more common in recent years as the required data acquisition and analysis systems become more affordable to deploy. It has been proposed that by monitoring changes in the dynamic signature of a structure, primarily the natural frequency, one can detect damage. This approach to damage detection is made difficult by the fact that environmental factors, such as temperature, have been shown to cause variation in the dynamic signature in a structure, effectively masking those changes due to damage. For future vibration based structural health monitoring systems to be effective, the relationship between environmental factors and natural frequency must be understood such that variation in the dynamic signature due to environmental noise can be removed. A monitoring system on the I-35W St. Anthony Falls Bridge, which crosses the Mississippi River in Minneapolis, MN, has been collecting vibration and temperature data since the structures opening in 2008. This provides a uniquely large data set, in a climate that sees extreme variation in temperature, to test the relationship between the dynamic signature of a concrete structure and temperature. A system identification routine utilizing NExT-ERA/DC is proposed to effectively analyze this large data set, and the relationship between structural temperature and natural frequency is investigated.
Instrumentation, Monitoring, and Modeling of the I-35W Bridge
(Minnesota Department of Transportation, 2012-08) French, Catherine E.W.; Shield, Carol K.; Stolarski, Henryk K; Hedegaard, Brock D.; Jilk, Ben J.
The new I-35W Bridge was instrumented incorporating "smart bridge technology" by Figg Engineering Group in conjunction with Flatiron-Manson. The purpose of the instrumentation was to monitor the structure during service, and to use this information to investigate the design and performance of the bridge. Instrumentation included static sensors (vibrating wire strain gages, resistive strain gages and thermistors in the foundation, bridge piers, and superstructure, as well as fiber optic sensors and string potentiometers in the superstructure) and dynamic sensors (accelerometers in the superstructure). Finite element models were constructed, taking into account measured material properties, to further explore the behavior of the bridge. The bridge was tested using static and dynamic truck load tests, which were used, along with continually collected ambient data under changing environmental conditions, to validate the finite element models. These models were applied to gain a better understanding of the structural behavior, and to evaluate the design assumptions presented in the Load Rating Manual for the structure. This report documents the bridge instrumentation scheme, the material testing, finite element model construction methodology, the methodology and results of the truck tests, validation of the models with respect to gravity loads and thermal effects, measured and modeled dynamic modal characteristics of the structure, and documentation of the investigated assumptions from the Load Rating Manual. It was found that the models accurately recreated the response from the instrumented bridge, and that the bridge had behaved as expected during the monitoring period.
The Minnesota Bicycle and Pedestrian Counting Initiative: Implementation Study
(Minnesota Department of Transportation, 2015-06) Lindsey, Greg; Petesch, Michael; Hankey, Steve
The Minnesota Bicycle and Pedestrian Counting Initiative: Implementation Study reports results from the second in a series of three MnDOT projects to foster non-motorized traffic monitoring. The objectives were to install and validate permanent automated sensors, use portable sensors for short duration counts, develop models for extrapolating counts, and integrate continuous counts into MnDOT traffic monitoring databases. Commercially available sensors, including inductive loops, integrated inductive loops and passive infrared, pneumatic tubes, and radio beams, were installed both as permanent monitor sites and used for short-duration counts at a variety of locations in cities, suburbs, and small towns across Minnesota. All sensors tested in the study produced reasonably accurate measures of bicycle and pedestrian traffic. Most sensors undercounted because of their inability to distinguish and count bicyclists or pedestrians passing simultaneously. Accuracy varied with technology, care and configuration of deployment, maintenance, and analytic methods. Bicycle and pedestrian traffic volumes varied greatly across locations, with highest volumes being on multiuse trails in urban areas. FHWA protocols were used to estimate annual average daily traffic and miles traveled on an 80-mile multiuse trail network in Minneapolis. Project findings were incorporated in a new MnDOT guidance document, “DRAFT Bicycle and Pedestrian Data Collection Manual” used in statewide training workshops. A major challenge in implementing bicycle and pedestrian traffic monitoring is data management. Years will be required to institutionalize bicycle and pedestrian traffic successfully.
Modeling and Monitoring the Long-Term Behavior of Post-Tensioned Concrete Bridges
(Minnesota Department of Transportation, 2014-11) French, Catherine E.W.; Shield, Carol K.; Hedegaard, Brock D.
The time-dependent and temperature-dependent behavior of post-tensioned concrete bridges were investigated through a case study of the St. Anthony Falls Bridge, consisting of laboratory testing of concrete time-dependent behaviors (i.e., creep and shrinkage), examination of data from the in situ instrumented bridge, and time-dependent finite element models. Laboratory results for creep and shrinkage were measured for 3.5 years after casting, and the data were best predicted by the 1978 CEB/FIP Model Code provisions. To compare the in situ readings to constant-temperature finite element models, the time-dependent behavior was extracted from the measurements using linear regression. The creep and shrinkage rates of the in situ bridge were found to depend on temperature. An adjusted age using the Arrhenius equation was used to account for the interactions between temperature and time-dependent behavior in the measured data. Results from the time-dependent finite element models incorporating the full construction sequence revealed that the 1990 CEB/FIP Model Code and ACI-209 models best predicted the in situ behavior. Finite element analysis also revealed that problems associated with excessive deflections or development of tension over the lifetime of the bridge would be unlikely. The interactions between temperature and time-dependent behavior were further investigated using a simplified finite element model, which indicated that vertical deflections and stresses can be affected by the cyclic application of thermal gradients. The findings from this study were used to develop an anomaly detection routine for the linear potentiometer data, which was successfully used to identify short-term and long-term artificial anomalies in the data.
Monitoring an Iron-Enhanced Sand Filter Trench for the Capture of Phosphate from Stormwater Runoff
(2015-09) Erickson, Andrew J.; Gulliver, John S.; Weiss, Peter T.
This monitoring project was performed on an iron enhanced sand filtration (IESF) trench in the City of Prior Lake. Water from the pond and IESF trench discharges into a wetland that ultimately drains into Upper Prior Lake. In 2002, Upper Prior Lake was listed on Minnesota’s 303(d) List of Impaired Waters for nutrient/eutrophication biological indicators with aquatic recreation being impaired. Water quality has been reduced due to excessive phosphorus loading. According to the TMDL implementation plan developed for Spring Lake and Upper Prior Lake, the total phosphorus load must be reduced by 83% and 41%, respectively, to meet water quality goals. Overall, for 28 monitored natural rainfall/runoff events from 2013-2015, the IESF trench removed 26% of the phosphate mass load it received, though after non-routine maintenance in August 2014 the performance improved to 45% phosphate mass load reduction. These results indicate the importance of maintenance. A newer installation was previously monitored, and found to retain 71% of the phosphate (Erickson and Gulliver 2010). Most of the overall phosphate load reduction was achieved during larger events that had comparatively high influent phosphate concentrations (32.3 – 125.2 μg/L) and mass loads. Many small events in this investigation with low influent phosphate concentrations (3.8 – 38.4 μg/L) or mass loads exhibited negative removal (i.e., effluent mass load > influent mass load). The high effluent phosphate concentrations are suspected to be caused by the degradation of floating plants (primarily duckweed) that were deposited on the surface of the filter trench. As mentioned above, nonroutine maintenance to remove this material resulted in substantial performance improvement. After this maintenance, positive removal was observed for influent concentrations ranging from 6.3 – 44.1 μg/L. Detailed results, maintenance activities, design and operating & maintenance recommendations, and lessons learned are given within this report.
Monitoring the Use of HOV and HOT Lanes
(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2013-01) Holec, Eric; Somasundaram, Guruprasad; Papanikolopoulos, Nikolaos; Morellas, Vassilios
This report presents the formulation and implementation of an automated computer vision and machine learning based system for estimation of the occupancy of passenger vehicles in high-occupancy vehicles and highoccupancy toll (HOV/HOT) lanes. We employ a multi-modal approach involving near-infrared images and highresolution color video images in conjunction with strong maximum margin based classifiers such as support vector machines. We attempt to maximize the information that can be extracted from these two types of images by computing different features. Then, we build classifiers for each type of feature which are compared to determine the best feature for each imaging method. Based on the performance of the classifiers we critique the efficacy of the individual approaches as the costs involved are significantly different.
Scour Monitoring Technology Implementation
(Center for Transportation Studies, University of Minnesota, 2014-09) Lueker, Matthew; Marr, Jeff
Bridge scour is the removal of sediment around bridge foundations and can result in the failure of the bridge. Scour monitoring is performed to identify unacceptable scour on bridges considered to be scour critical and determine when scour reaches elevations that could cause potential bridge failure. Two types of monitoring are available: portable monitoring and fixed monitoring. Prior to this project, MnDOT was only using portable monitoring devices, which requires the deployment of personnel to make physical measurements of scour depths. For some scour critical bridges, especially during high-water events, fixed instrumentation capable of continuous scour monitoring was preferred, but MnDOT lacked the experience or expertise to install this type of equipment. This project installed fixed monitoring equipment at two bridge sites and monitored them for three years to determine the effectiveness and reliability of fixed scour monitoring deployments. Several device options were installed to allow MnDOT to analyze the installation and performance of different types of sensors. Both systems operated for the three years with some outages due to various causes but overall performance was acceptable. The outages were mostly related to power issues and communication issues. Valuable lessons were learned through the deployment, which may be applied to future installations. The deployment executed in this project has provided the confidence to deploy other fixed scour monitoring equipment at key bridges around the state of Minnesota. In addition, the data collected during deployment of the scour monitoring equipment has been stored and provides insight into scour processes. This data can be used by other research groups for design or research purposes.
Turbidity monitoring on construction sites: insight into the factors influencing the turbidity and TSS relationship
(2013-05) Perkins, Rebekah Lynn
Stormwater runoff from construction sites can transport eroded sediment to nearby water bodies degrading water quality and impairing biotic communities. The United States Environmental Protection Agency (EPA) is considering a turbidity limit for effluent stormwater on construction and demolition sites and is requesting data to support that limit (EPA, 2011). Laboratory protocols have been developed herein for studying the factors that impact turbidity from construction site soils. Experimental procedures include the use of a rainfall simulator to generate runoff and turbidity values from soils carefully packed in appropriate test boxes. Turbidity characteristics of fourteen different soils in Minnesota were investigated using the laboratory protocols. Trends in turbidity with sediment concentrations were well represented by power functions. The exponent of these power functions was relatively constant between soils and the log-intercept, or scaling parameter varied substantially among the different soils. Multiple soil properties were evaluated for each soil. An extensive regression analysis resulted in a model using percent silt, interrill erodibility, and maximum abstraction that best represented the intercept term. A power value of 7/5 was chosen to represent all soils. A second laboratory experiment was performed to determine how particle settling affects the coefficients of the turbidity -TSS relationship. The scaling parameter increased with sediment deposition and the power value decreased. Field studies on two construction sites in the Twin Cities of metropolitan area of Minnesota were performed for this project. Grab samples and continuously monitored turbidity were collected for each site. The grab samples also exhibited a strong power relationship between turbidity and TSS with similar coefficients as the laboratory samples. The laboratory relationships were also applied to the observed field conditions to demonstrate their usefulness in estimating turbidity, concentration, sediment load, and load reduction.
Usability Evaluation of a Smart Phone-based Teen Driver Support System (TDSS)
(Minnesota Department of Transportation Research Services Section, 2011-05) Creaser, Janet; Gorjestani, Alec; Manser, Michael; Donath, Max
Motor vehicle crashes are the leading cause of teen fatalities. A Teen Driver Support System (TDSS) was developed by the ITS Institute that can allow parents to accurately monitor their teen's driving behavior in relation to known risk factors and Graduated Driver Licensing (GDL) provisions. The TDSS, based on a teen's smart phone, provides real-time, contextual in-vehicle feedback to the teen about his or her driving behavior and helps parents monitor certain known risk factors. The system does not allow incoming or outgoing phone calls (except 911) or texting while driving. Feedback to the teen driver includes visual and auditory warnings about speeding, excessive maneuvers (e.g., hard braking, cornering), and stop sign violations. The TDSS prototype also monitors seat belt use and detects the presence of passengers (e.g., based on GDL provisions), two known factors that increase the risk of fatalities among teen drivers. The TDSS can also be programmed to monitor driving during the GDL curfew or a curfew set by parents. A usability review of the prototype TDSS using 30 parent-teen dyads from Washington Country, MN, found that teens and parents held favorable opinions about most of the TDSS functions. Teens and parents both felt that use of the system early in licensure may result in the adoption of safer driving habits even after the system is removed from the vehicle. Several recommendations to improve the system’s usability are made based on the results.

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