Next Generation Bridge Management Tools and Inspection

The objectives of this research were twofold. The first objective was to identify the needs for the inspection methodology, manuals, training, and the timetable needed for all bridge owners to start collecting element-level bridge inspection data. The second objective was to identify how to incorporate this new inspection methodology into the rich reporting tools and performance measures that the Minnesota Department of Transportation (MnDOT) uses for determining the bridge projects in the annual program. Working with the MnDOT Bridge Office, the research team identified the necessary changes to the bridge inspection elements that would both ensure MnDOT conforms to the new American Association of State Highway and Transportation Officials (AASHTO) Guide Manual for Bridge Element Inspection and provide the necessary data for the agency’s bridge management process. The changes needed for MnDOT’s Bridge Replacement and Improvement Management (BRIM) were also identified working with the MnDOT Bridge Office

Assessing Bridge Characteristics for Use and Importance as Roosting Habitats for Bats

Bats play an important role in the natural balance of many ecosystems. As a result, there has been a growing concern about the number and status of bats in the US and beyond. Concern over bat populations is primarily driven by the fact that habitats used by bats for roosting and foraging have been disturbed, altered, or reduced. In Iowa, at least one federal endangered bat is known to exist and thought to be potentially impacted by habitat influences. Conservation efforts targeted toward bats can be hampered by a lack of information on their habitats and usage. Although it is widely accepted that bats use bridges as roosting sites, little attention has been given to understanding the combined bridge and location characteristics associated with their use of bridges as roosting sites. Therefore, it is important to investigate how, why, and when bats use bridges as roosting sites. A major goal for this study was to better understand when bridge replacement/repair/rehabilitation projects have the potential for “taking” (i.e., harassing, injuring, or killing) bat species that have been identified as federally threatened or endangered bat species. The primary objective of this work was to better understand what type of bridges (based on bridge characteristics including local topography and habitat availability) are the most likely to be used by bats as roosting locations. The study also aimed to document the means and methods developed and followed to conduct this work so that the evaluation protocol can be used by other states/regions. The findings showed that bridge characteristics, combined with land cover and bat species distribution data, can help identify locations with higher probabilities of bat roosting. This information can be useful to transportation agencies as they plan bridge replacement/repair/rehabilitation projects and can help conservation efforts targeted toward bats

Roadway Lighting and Safety: Phase II - Monitoring Quality, Durability, and Efficiency

This Phase II project follows a previous project titled Strategies to Address Nighttime Crashes at Rural, Unsignalized Intersections. Based on the results of the previous study, the Iowa Highway Research Board (IHRB) indicated interest in pursuing further research to address the quality of lighting, rather than just the presence of light, with respect to safety. The research team supplemented the literature review from the previous study, specifically addressing lighting level in terms of measurement, the relationship between light levels and safety, and lamp durability and efficiency. The Center for Transportation Research and Education (CTRE) teamed with a national research leader in roadway lighting, Virginia Tech Transportation Institute (VTTI) to collect the data. An integral instrument to the data collection efforts was the creation of the Roadway Monitoring System (RMS). The RMS allowed the research team to collect lighting data and approach information for each rural intersection identified in the previous phase. After data cleanup, the final data set contained illuminance data for 101 lighted intersections (of 137 lighted intersections in the first study). Data analysis included a robust statistical analysis based on Bayesian techniques. Average illuminance, average glare, and average uniformity ratio values were used to classify quality of lighting at the intersections

Measuring Salt Retention

This research developed and completed a field evaluation of salt distribution equipment. The evaluation provides a direct comparison of three different types of salt spreaders at three different truck speeds and brine rates. A rubber mat was divided into eight sample areas to measure the salt distribution across the lane by each variable combination. A total of 264 samples were processed and measured. These results will support future efforts to target areas of efficiencies specific to salt and brine delivery methods. These results support Iowa Department of Transportation efforts to progress winter maintenance efficiencies and ultimately motorist safety

Evaluating the Effectiveness of Temporary Work-Zone Pavement Marking Products

BACKGROUND Work zones by nature present transitions and changes to motorists’ expectations. Given these conditions, providing proper guidance to motorists is critical. With respect to pavement markings, the challenge is to provide sufficient markings but in a temporary setting. Various pavement-marking products are currently in use within work zones; however, their effectiveness and cost can vary widely. OBJECTIVE This research evaluated the effectiveness of several common removable pavement marking products in terms of daytime presence, retroreflectivity, and removability. METHODOLOGYThe work zone pavement marking evaluation was organized into three tasks as follows: Work with industry to identify the available products specific to removable tapes having a wet night retroreflective and/or wet recoverable feature Acquire these products and coordinate installation with a local contractor for a central Iowa work zone Monitor and measure performance in terms of durability (presence and retroreflectivity) and removal The pavement marking evaluation was completed on an active work zone in central Iowa with the roadway setting and performance duration defined by the project. The desire was to select a project that would leave the markings in place for at least 30 days and have sufficient average daily traffic to provide an evaluation of wear. The evaluation included both white and yellow edge-line markings within the taper and crossover sections of a work zone. Performance was measured in terms of presence, retroreflectivity, and ease of removal. Presence was evaluated in terms of the amount of product remaining at the end of the evaluation period. Retroreflectivity was measured using a 30 meter geometry retroreflectometer. Product removal was evaluated in terms of internal tape strength, adhesive bond, and the amount of discernible markings after removal based on the American Association of State Highway and Transportation Officials (AASHTO) National Transportation Product Evaluation Program (NTPEP)

Pavement Markings and Safety

Previous research on pavement markings from a safety perspective tackled various issues such as pavement marking retroreflectivity variability, relationship between pavement marking retroreflectivity and driver visibility, or pavement marking improvements and safety. A recent research interest in this area has been to find a correlation between retroreflectivity and crashes, but a significant statistical relationship has not yet been found. This study investigates such a possible statistical relationship by analyzing five years of pavement marking retroreflectivity data collected by the Iowa Department of Transportation (DOT) on all state primary roads and corresponding crash and traffic data. This study developed a spatial-temporal database using measured retroreflectivity data to account for the deterioration of pavement markings over time along with statewide crash data to attempt to quantify a relationship between crash occurrence probability and pavement marking retroreflectivity. First, logistic regression analyses were done for the whole data set to find a statistical relationship between crash occurrence probability and identified variables, which are road type, line type, retroreflectivity, and traffic (vehicle miles traveled). The analysis looked into subsets of the data set such as road type, retroreflectivity measurement source, high crash routes, retroreflectivity range, and line types. Retroreflectivity was found to have a significant effect in crash occurrence probability for four data subsets—interstate, white edge line, yellow edge line, and yellow center line data. For white edge line and yellow center line data, crash occurrence probability was found to increase by decreasing values of retroreflectivity

Asset Management and Safety: A Performance Perspective

Incorporating safety performance measures into asset management can assist transportation agencies in managing their aging assets efficiently and improve system-wide safety. Past research has revealed the relationship between individual asset performance and safety, but the relationship between combined measures of operational asset condition and safety performance has not been explored. This project investigates the effect of pavement marking retroreflectivity and pavement condition on safety in a multi-objective manner. Data on one-mile segments for all Iowa primary roads from 2004 through 2009 were collected from the Iowa Department of Transportation and integrated using linear referencing. An asset condition index (ACI) was estimated for the road segments by scoring and weighting individual components. Statistical models were then developed to estimate the relationship between ACI and expected number of crashes, while accounting for exposure (average daily traffic). Finally, the researchers evaluated alternative treatment strategies for pavements and pavement markings using benefit-cost ratio analysis, taking into account corresponding treatment costs and safety benefits in terms of crash reduction (number of crashes proportionate to crash severity)

Use of Recursive Partitioning to Predict National Bridge Inventory Condition Ratings from National Bridge Elements Condition Data

In the United States, National Bridge Inventory (NBI) condition ratings, since the 1970s, and AASHTO’s commonly recognized (CoRe) element condition data, since the 1990s, have provided two major sources of bridge condition data. Although these separate systems of condition assessment had their individual uses, comparing the two, and mapping one from the other had uses for both state and federal agencies and the bridge management community. Alternative methods for this mapping have been proposed in the literature with varying predictive accuracy. With the publication of the new AASHTO Manual for Bridge Element Inspection in 2013, national bridge elements (NBEs) replace the CoRe element condition data as the comparable condition data for the NBI condition ratings. This paper investigates the use of the recursive partitioning method to develop classification trees that predict NBI condition ratings from NBE condition data. On the basis of data from a 2016 submission and 12 transportation agencies, classification trees were developed that presented the most likely NBI condition ratings for a set of logical conditions based on the relative element quantities and the percentage of element quantities in the condition states. The predictive accuracies for the trees are sufficient, and the percentages of exact matches and matches within one error term are better than other studies in the literature. Although the trees can be improved in the future with the availability of more NBE data submissions, the study presented preliminary decision trees with sufficient predictive accuracy that could be adopted by transportation agencies for a variety of bridge management functions