Guidance for Improving Foundation Layers to Increase Pavement Performance on Local Roads, TR-640, 2014

This document is the second of two deliverables for the project Optimizing Pavement Base, Subbase, and Subgrade Layers for Cost and Performance on Local Roads (TR-640). The first deliverable is the 454-page Final Field Data Report. The field data report describes test results and comparative analysis from 16 different portland cement concrete (PCC) pavement sites on local city and county roads in Iowa. At each site the surface conditions of the pavement (i.e., crack survey) and foundation layer strength, stiffness, and hydraulic conductivity properties were documented. The field test results were used to calculate in situ parameters used in pavement design methodologies for AASHTO (1993) and Iowa’s Statewide Urban Design and Specifications (SUDAS). Overall, the results of the study demonstrate how in situ and lab testing can be used to assess the support conditions and design values for pavement foundation layers and how the measurements compare to the assumed design values. This guide summarizes the study results and outlines general guidelines for applying them to optimize pavement bases, subbases, and subgrade layers of local roads with PCC pavements and thus their performance.

Yearbook of Private International Law, Volume XIV, 2012/2013

The "Yearbook of Private International Law" provides all about the conflict of laws developments of 2012 and 2013 in one book: Volume XIV (2012/2013) includes contributions on the proposed codification of the General Part of Private International Law in Europe, on the reform of the Chinese legal system as well as on defamation and violation of personality rights (the latter in a whole section). Furthermore, the book deals with the application of EU legislation on jurisdiction and enforcement of judgements, the recognition of judgements overturned by another judgement, and the conflict of decisions in international arbitration. Reports and court decisions from the Netherlands, Turkey, India, Finland, Croatia and Switzerland and a summary of two dissertations on the role of sovereignty and choice of courts agreements complete the book.

Best Practices for Low-Cost Safety Improvements on Iowa’s Local Roads, 2008

Many good maintenance practices are done routinely to ensure safe travel on low-volume local roads. In addition, there are many specific treatments that may go beyond the point of routine maintenance and in fact provide additional safety benefits with a relatively low price tag. The purpose of this publication is to try to assemble many of these treatments that are currently practiced in Iowa by local agencies into one, easy-to-reference handbook that not only provides some clarity to each treatment with photos and narrative, but also features references to agencies currently using that technique. Some strategies that are utilized by Iowa, other states, and are topics of research have also been included to allow the user more information about possible options. Even though some areas overlap, the strategies presented have been grouped together in the following areas: Signing and Delineation, Traffic "Calming," Pavement Marking and Rumble Strips/Stripes, Roadside and Clear Zone, Guardrail and Barriers, Lighting, Pavements and Shoulders, Intersections, Railroad Crossings, Bridges and Culverts, and Miscellaneous. The intention is to make this a “living” document, which will continue to be updated and expanded periodically as other existing practices are recognized or new practices come into being.

Evaluation of Rumble Stripes on Low-Volume Rural Roads in Iowa—Phase I, TR-577, 2009

Single-vehicle run-off-road crashes are the most common crash type on rural two-lane Iowa roads. Rumble strips have been proven effective in mitigating these crashes, but these strips are commonly installed in paved shoulders adjacent to higher-volume roads owned by the State of Iowa. Lower-volume paved rural roads owned by local agencies do not commonly feature paved shoulders but frequently experience run-off-road crashes. This project involved installing “rumble stripes,” which are a combination of conventional rumble strips with a painted edge line placed on the surface of the milled area, along the edge of the travel lanes but at a narrow width to avoid possible intrusion into the normal vehicle travel paths. Candidate locations were selected from a list of paved local rural roads that were most recently listed in the top 5% of roads for run-off-road crashes in Iowa. Horizontal curves were the most favored locations for rumble stripe installation because they commonly experience roadway departure crashes. The research described in this report was part of a project funded by the Federal Highway Administration, Iowa Highway Research Board, and Iowa Department of Transportation to evaluate the effectiveness of edge line rumble strips in Iowa. The project evaluated the effectiveness of “rumble stripes” in reducing run-off-road crashes and in improving the longevity and wet weather visibility of edge line markings. This project consists of two phases. The first phase was to select pilot study locations, select a set of test sites, install rumble stripes, summarize lessons learned during installation, and provide a preliminary assessment of the rumble stripes’ performance. This information is summarized in this report. The purpose of the second phase is to provide a more long-term assessment of the performance of the pavement markings, conduct preliminary crash assessments, and evaluate lane keeping. This will result in a forthcoming second report.

Criteria for the Evaluation and Disposition of Low-Traffic-Count Secondary Roads, HR-139, 1969

The State of Iowa has too many roads. Although ranking thirty-fourth in population, twenty-fifth in area, and twentieth in motor vehicle registration, it ranks seventh in the nation in miles of rural roads. In 1920 when Iowa's rural population was 1,528,000, there were 97,440 miles of secondary roads. In 1960 with rural population down 56 percent to 662,000, there were 91,000 miles of secondary roads--a 7 percent decrease. The question has been asked: "Who are these 'service roads' serving?" This excess mileage tends to dissipate road funds at a critical time of increasing public demand for better and safer roads.

Mission-Oriented Dust Control and Surface Improvement Processes for Unpaved Roads, HR-194, 1981

Six subject areas prompted the broad field of inquiry of this mission-oriented dust control and surface improvement project for unpaved roads: • DUST--Hundreds of thousands of tons of dust are created annually by vehicles on Iowa's 70,000 miles of unpaved roads and streets. Such dust is often regarded as a nuisance by Iowa's highway engineers. • REGULATIONS--Establishment of "fugitive dust" regulations by the Iowa DEQ in 1971 has created debates, conferences, legal opinions, financial responsibilities, and limited compromises regarding "reasonable precaution" and "ordinary travel," both terms being undefined judgment factors. • THE PUBLIC--Increased awareness by the public that regulations regarding dust do in fact exist creates a discord of telephone calls, petitions, and increasing numbers of legal citations. Both engineers and politicians are frustrated into allowing either the courts or regulatory agencies to resolve what is basically a professional engineering responsibility. • COST--Economics seldom appear as a tenet of regulatory strategies, and in the case of "fugitive dust," four-way struggles often occur between the highway professions, political bodies, regulatory agencies, and the general public as to who is responsible, what can be done, how much it will cost, or why it wasn't done yesterday. • CONFUSION--The engineer lacks authority, and guidelines and specifications to design and construct a low-cost surf acing system are nebulous, i.e., construct something between the present crushed stone/gravel surface and a high-type pavement. • SOLUTION--The engineer must demonstrate that dust control and surface improvement may be engineered at a reasonable cost to the public, so that a higher degree of regulatory responsibility can be vested in engineering solutions.

Evaluation of Long-Term Field Performance of Cold In-Place Recycled Roads: Field and Laboratory Testing, TR-502, 2007

Cold in-place recycling (CIR) has become an attractive method for rehabilitating asphalt roads that have good subgrade support and are suffering distress related to non-structural aging and cracking of the pavement layer. Although CIR is widely used, its use could be expanded if its performance were more predictable. Transportation officials have observed roads that were recycled under similar circumstances perform very differently for no clear reason. Moreover, a rational mix design has not yet been developed, design assumptions regarding the structural support of the CIR layer remain empirical and conservative, and there is no clear understanding of the cause-effect relationships between the choices made during the design/construction process and the resulting performance. The objective of this project is to investigate these relationships, especially concerning the age of the recycled pavement, cumulative traffic volume, support conditions, aged engineering properties of the CIR materials, and road performance. Twenty-four CIR asphalt roads constructed in Iowa from 1986 to 2004 were studied: 18 were selected from a sample of roads studied in a previous research project (HR-392), and 6 were selected from newer CIR projects constructed after 1999. This report describes the results of comprehensive field and laboratory testing for these CIR asphalt roads. The results indicate that the modulus of the CIR layer and the air voids of the CIR asphalt binder were the most important factors affecting CIR pavement performance for high-traffic roads. For low-traffic roads, the wet indirect tensile strength significantly affected pavement performance. The results of this research can help identify changes that should be made with regard to design, material selection, and construction in order to improve the performance and cost-effectiveness of future recycled roads.

Evaluation of Long-Term Field Performance of Cold In-Place Recycled Roads: Summary Report, TR-502, 2007

Cold in-place recycling (CIR) has become an attractive method for rehabilitating asphalt roads that have good subgrade support and are suffering distress related to non-structural aging and cracking of the pavement layer. Although CIR is widely used, its use could be expanded if its performance were more predictable. Transportation officials have observed roads that were recycled under similar circumstances perform very differently for no clear reason. Moreover, a rational mix design has not yet been developed, design assumptions regarding the structural support of the CIR layer remain empirical and conservative, and there is no clear understanding of the cause-effect relationships between the choices made during the design/construction process and the resulting performance. The objective of this project is to investigate these relationships, especially concerning the age of the recycled pavement, cumulative traffic volume, support conditions, aged engineering properties of the CIR materials, and road performance. Twenty-four CIR asphalt roads constructed in Iowa from 1986 to 2004 were studied: 18 were selected from a sample of roads studied in a previous research project (HR-392), and 6 were selected from newer CIR projects constructed after 1999. This report summarizes the results of a comprehensive program of field distress surveys, field testing, and laboratory testing for these CIR asphalt roads. The results of this research can help identify changes that should be made with regard to design, material selection, and construction in order to lengthen the time between rehabilitation cycles and improve the performance and cost-effectiveness of future recycled roads.

Pavement Thickness Design for Local Roads in Iowa, TR-586, 2010

Three pavement design software packages were compared with regards to how they were different in determining design input parameters and their influences on the pavement thickness. StreetPave designs the concrete pavement thickness based on the PCA method and the equivalent asphalt pavement thickness. The WinPAS software performs both concrete and asphalt pavements following the AASHTO 1993 design method. The APAI software designs asphalt pavements based on pre-mechanistic/empirical AASHTO methodology. First, the following four critical design input parameters were identified: traffic, subgrade strength, reliability, and design life. The sensitivity analysis of these four design input parameters were performed using three pavement design software packages to identify which input parameters require the most attention during pavement design. Based on the current pavement design procedures and sensitivity analysis results, a prototype pavement design and sensitivity analysis (PD&SA) software package was developed to retrieve the pavement thickness design value for a given condition and allow a user to perform a pavement design sensitivity analysis. The prototype PD&SA software is a computer program that stores pavement design results in database that is designed for the user to input design data from the variety of design programs and query design results for given conditions. The prototype Pavement Design and Sensitivity Analysis (PA&SA) software package was developed to demonstrate the concept of retrieving the pavement design results from the database for a design sensitivity analysis. This final report does not include the prototype software which will be validated and tested during the next phase.

Bridge Rail and Approach Railing for Low-Volume Roads in Iowa, TR-592, 2010

Bridge rail and approach guardrails provide safety to drivers by shielding more hazardous objects and redirecting vehicles to the roadway. However, guardrail can increase both the initial cost and maintenance cost of a bridge, while adding another object that may be struck by vehicles. Most existing low volume road (LVR) bridges in the state of Iowa are currently indicated to not possess bridge rail meeting “current acceptable standards”. The primary objective of the research summarized in this report was to provide the nations bridge and approach rail state of practice and perform a state wide crash analysis on bridge rails and approach guardrails on LVR bridges in Iowa. In support of this objective, the criteria and guidelines used by other bridge owners were investigated, non-standard and innovative bridge and approach guardrails for LVR’s were investigated, and descriptive, statistical and economical analyses were performed on a state wide crash analysis. The state wide crash analysis found the overall number of crashes at/on the more than 17,000+ inventoried and non-inventoried LVR bridges in Iowa was fewer than 350 crashes over an eight year period, representing less than 0.1% of the statewide reportable crashes. In other words, LVR bridge crashes are fairly rare events. The majority of these crashes occurred on bridges with a traffic volume less than 100 vpd and width less than 24 ft. Similarly, the majority of the LVR bridges possess similar characteristics. Crash rates were highest for bridges with lower traffic volumes, narrower widths, and negative relative bridge widths (relative bridge width is defined as: bridge width minus roadway width). Crash rate did not appear to be effected by bridge length. Statistical analysis confirmed that the frequency of vehicle crashes was higher on bridges with a lower width compared to the roadway width. The frequency of crashes appeared to not be impacted by weather conditions, but crashes may be over represented at night or in dark conditions. Statistical analysis revealed that crashes that occurred on dark roadways were more likely to result in major injury or fatality. These findings potentially highlight the importance of appropriate delineation and signing. System wide, benefit-cost (B/C) analyses yielded very low B/C ratios for statewide bridge rail improvements. This finding is consistent with the aforementioned recommendation to address specific sites where safety concerns exist.

Financial Needs of Iowa's County Roads, TR-608, 2012

The TR-608 project developed methods and processes for determining current and future Iowa secondary (county) road needs. These tools will be permanently maintained and operated by the Iowa County Engineers Association Service Bureau to provide ongoing need determination services for the state’s ninety-nine county road departments. The systems established via this project will annually tally and report a) how much funding is needed to sustain the county roads long term, b) the adequacy of the secondary roads for the traffic they carry and c) what upgrade needs exist. A “Trend Projection Engine” will also be available to project from current circumstance, with continuation of known revenue and cost trends, to estimate potential outcomes occurring in the next fifteen years. Now that it has been developed, the TR-608 system will continue as an ongoing resource of county road and bridge numbers, condition, trends and issue information for use by counties, either individually or collectively.

Superpave Mix Designs for Low-Volume Roads, TR-414, Final Report, 2004

Most research current to the time of these projects was focused on use of Superpave mix designs on higher volume roads. Low volume roads have different requirements in terms of mix design, aggregate types, aggregate sources and project budgets. The purpose of this research was to determine if the Superpave mix design strategy for low volume roads was practical and economical. Eight projects were selected in five counties. The projects were completed in the summer of 1998. Performance evaluation of the resulting pavements was carried out annually. There was no significant increase in costs related to the use of Superpave. Nor were there any significant construction issues. There were some differences noted in placement and compaction in the field, but these were not serious.

Interprofessional practices of physiotherapists working with adults with low back pain in Québec's private sector: results of a qualitative study.

BACKGROUND: Collaboration and interprofessional practices are highly valued in health systems, because they are thought to improve outcomes of care for persons with complex health problems, such as low back pain. Physiotherapists, like all health providers, are encouraged to take part in interprofessional practices. However, little is known about these practices, especially for private sector physiotherapists. This study aimed to: 1) explore how physiotherapists working in the private sector with adults with low back pain describe their interprofessional practices, 2) identify factors that influence their interprofessional practices, and 3) identify their perceived effects. METHODS: Participants were 13 physiotherapists, 10 women/3 men, having between 3 and 21 years of professional experience. For this descriptive qualitative study, we used face-to-face semi-structured interviews and conducted content analysis encompassing data coding and thematic regrouping. RESULTS: Physiotherapists described interprofessional practices heterogeneously, including numerous processes such as sharing information and referring. Factors that influenced physiotherapists' interprofessional practices were related to patients, providers, organizations, and wider systems (e.g. professional system). Physiotherapists mostly viewed positive effects of interprofessional practices, including elements such as gaining new knowledge as a provider and being valued in one's own role, as well as improvements in overall treatment and outcome. CONCLUSIONS: This qualitative study offers new insights into the interprofessional practices of physiotherapists working with adults with low back pain, as perceived by the physiotherapists' themselves. Based on the results, the development of strategies aiming to increase interprofessionalism in the management of low back pain would most likely require taking into consideration factors associated with patients, providers, the organizations within which they work, and the wider systems.

Development of a Subgrade Drainage Model for Unpaved Roads, TR-654, 2015

With over 68 thousand miles of gravel roads in Iowa and the importance of these roads within the farm-to-market transportation system, proper water management becomes critical for maintaining the integrity of the roadway materials. However, the build-up of water within the aggregate subbase can lead to frost boils and ultimately potholes forming at the road surface. The aggregate subbase and subgrade soils under these gravel roads are produced with material opportunistically chosen from local sources near the site and, many times, the compositions of these sublayers are far from ideal in terms of proper water drainage with the full effects of this shortcut not being fully understood. The primary objective of this project was to provide a physically-based model for evaluating the drainability of potential subbase and subgrade materials for gravel roads in Iowa. The Richards equation provided the appropriate framework to study the transient unsaturated flow that usually occurs through the subbase and subgrade of a gravel road. From which, we identified that the saturated hydraulic conductivity, Ks, was a key parameter driving the time to drain of subgrade soils found in Iowa, thus being a good proxy variable for accessing roadway drainability. Using Ks, derived from soil texture, we were able to identify potential problem areas in terms of roadway drainage . It was found that there is a threshold for Ks of 15 cm/day that determines if the roadway will drain efficiently, based on the requirement that the time to drain, Td, the surface roadway layer does not exceed a 2-hr limit. Two of the three highest abundant textures (loam and silty clay loam), which cover nearly 60% of the state of Iowa, were found to have average Td values greater than the 2-hr limit. With such a large percentage of the state at risk for the formation of boils due to the soil with relatively low saturated hydraulic conductivity values, it seems pertinent that we propose alternative design and/or maintenance practices to limit the expensive repair work in Iowa. The addition of drain tiles or French mattresses my help address drainage problems. However, before pursuing this recommendation, a comprehensive cost-benefit analysis is needed.

Vertical Clearance Restrictions on Primary Roads and Primary Road Extensions: Standard U.S. Measurements [Vertical Clearance Log], May 1, 2015

The Vertical Clearance Log is prepared for the purpose of providing vertical clearance restrictions by route on the primary road system. This report is used by the Iowa Department of Transportation’s Motor Carrier Services to route oversize vehicles around structures with vertical restrictions too low for the cargo height. The source of the data is the Geographic Information Management System (GIMS) that is managed by the Office of Research & Analytics in the Performance & Technology Division. The data is collected by inspection crews and through the use of LiDAR technology to reflect changes to structures on the primary road system. This log is produced annually.