Statistical Analysis of Highway Needs Condition Data: Manual vs. Automated, TR-494

This project examines similarities and differences between the automated condition data collected on and off county paved roads and the manual condition data collected by Iowa Department of Transportation (DOT) staff in 2000 and 2001. Also, the researchers will provide staff support to the advisory committee in exploring other options to the highway need process. The results show that the automated condition data can be used in a converted highway needs process with no major differences between the two methods. Even though the foundation rating difference was significant, the foundation rating weighting factor in HWYNEEDS is minimal and should not have a major impact. In terms of RUTF formula based distribution, the results clearly show the superiority of the condition-based analysis compared to the non-condition based. That correlation can be further enhanced by adding more distress variables to the analysis

Pavement Management Performance Modeling: Evaluating the Existing PCI Equations,

The work described in this report documents the activities performed for the evaluation, development, and enhancement of the Iowa Department of Transportation (DOT) pavement condition information as part of their pavement management system operation. The study covers all of the Iowa DOT’s interstate and primary National Highway System (NHS) and non-NHS system. A new pavement condition rating system that provides a consistent, unified approach in rating pavements in Iowa is being proposed. The proposed 100-scale system is based on five individual indices derived from specific distress data and pavement properties, and an overall pavement condition index, PCI-2, that combines individual indices using weighting factors. The different indices cover cracking, ride, rutting, faulting, and friction. The Cracking Index is formed by combining cracking data (transverse, longitudinal, wheel-path, and alligator cracking indices). Ride, rutting, and faulting indices utilize the International Roughness Index (IRI), rut depth, and fault height, respectively

Implementation of HERS-ST in Iowa and Development / Refinement of a National Training Program

The Highway Economic Requirements System (HERS) is an economic model that uses highway performance monitoring system (HPMS) data to project future highway conditions and requirements. HERS is a highly complex model that, at the national level, uses samples of the highway network taken from the HPMS data. As a result, at the national level it is only used for aggregate network-level analysis (planning-level analysis). When the Federal Highway Administration’s Office of Asset Management was established in 1999, the office began developing the state version of HERS, or HERS-ST. HERS-ST has since evolved into a model that is specifically crafted for states. A DOS version of HERS-ST was demonstrated at a workshop attended by representatives of several state transportation agencies in 2001. Since then, several improvements have been made to the software, including updates for a Windows environment and the addition of GIS capabilities. The current project will yield a HERS-ST specifically for Iowa, but one that can be used as a model for other states

Toolbox of Countermeasures for Rural Two-Lane Curves

The Federal Highway Administration (FHWA) estimates that 58 percent of roadway fatalities are lane departures, while 40 percent of fatalities are single-vehicle run-off-road (SVROR) crashes. Addressing lane-departure crashes is therefore a priority for national, state, and local roadway agencies. Horizontal curves are of particular interest because they have been correlated with increased crash occurrence. This toolbox was developed to assist agencies address crashes at rural curves. The main objective of this toolbox is to summarize the effectiveness of various known curve countermeasures. While education, enforcement, and policy countermeasures should also be considered, they were not included given the toolbox focuses on roadway-based countermeasures. Furthermore, the toolbox is geared toward rural two-lane curves. The research team identified countermeasures based on their own research, through a survey of the literature, and through discussions with other professionals. Coverage of curve countermeasures in this toolbox is not necessarily comprehensive. For each countermeasure covered, this toolbox includes the following information: description, application, effectiveness, advantages, and disadvantages. Countermeasures covered are as follows: speed signs, chevrons, widening/adding paved shoulders, reflective barriers, high-friction treatments, raised pavement markers, edge lines, transverse pavement markings, vertical delineation, rumble strips, rumble stripes, on-pavement curve signing, flashing beacons, dynamic curve warning systems, and pavement inset lights

Evaluation of the TAPCO Sequential Dynamic Curve Warning System

Implementing safety countermeasures on rural horizontal curves to address speeding can improve the safety performance for those locations. State safety and traffic engineers are faced with making decisions on what type of technology to use and which sites to use the technology on in a fiscally constrained environment. The research conducted for this project will evaluate a Sequential Dynamic Curve Warning System (SDCWS) that could be an additional tool for these engineers to use either separately or in combination with other countermeasures to address horizontal curve locations with a history of safety concerns

Evaluation, Selection and Planning the Implementation of a Pavement Management Optimization Model: Phase II Report

The purpose of this report is to briefly document the activities and accomplishment of Phase II. A comprehensive report will be completed at the end of the third phase. Because the work is exploratory in nature, it is being conducted utilizing a close working relationship between the Iowa DOT and the Iowa Transportation Center at Iowa State University (ITC/ISU). The connection between the two organizations is being maintained through an Iowa DOT employee Pavement Management Optimization Steering Committee. The committee members and the ITC/ISU researchers meet informally on a regular basis but formally meet at least once per month. The work and the direction for the research is recursive, with each task being guided by information determined in the prior task

Use of functional silos to optimize agency decision making

101 p.The purpose of the project was to document how agencies make positive use of functional silos and then efficiently allocate resources across them. Functional silos are considered to be any group of expertise within a transportation organization that focuses on one area of expertise. Often, different functional silos compete for agency resources. Functional silos impact their agency positively by allowing members to accumulate expertise in the area of the silo. On the other hand, silos can have a negative impact on resource allocation. The solution to efficient resource allocation is bridging the silos and making overall decisions that offer the most satisfactory solutions globally. Case studies are presented for the Maryland Department of Transportation, Ohio Department of Transportation, and Florida Department of Transportation

Evaluating All-Weather Pavement Markings in Illinois: Volume 1

Pavement markings provide critical guidance to motorists, especially under dark (non-lighted) conditions. However, the ability to see these pavement markings on a wet, rainy night is problematic given that the presence of water considerably decreases pavement marking retroreflectivity. This project evaluated the performance of several allweather pavement marking products in an effort to provide guidance on their use on Illinois Department of Transportation (IDOT) roadways. In addition, a laboratory evaluation was completed in an effort to simulate degradation mechanisms of these pavement markings so that future all-weather materials can be evaluated in a timely manner within the lab versus public roadway. The study found that only 15% of the all-weather products provided a retroreflectivity of 50 millicandelas per meter squared per lux (mcd/m²/lux), which is noted as (mcd) within this report, under continuous wetting conditions. The lab evaluation showed some promise for the dry retroreflectivity performance given that data variability was low and there was good correlation initially with the field data. The correlation was not as good, however, as the markings aged, and correlation in the wet conditions was not good.Illinois Department of Transportation, R27-120Ope