Development of a Method to Determine Pavement Damage Due to Detours, Project 02-105, Apirl 2005

The research presented in this report provides the basis for the development of a new procedure to be used by the Iowa DOT and cities and counties in the state to deal with detours. Even though the project initially focused on investigating new tools to determine condition and compensation, the focus was shifted to traffic and the gas tax method to set the basis for the new procedure. It was concluded that the condition-based approach, even though accurate and consistent condition evaluations can be achieved, is not feasible or cost effective because of the current practices of data collection (two-year cycle) and also the logistics of the procedure (before and after determination). The gas tax method provides for a simple, easy to implement, and consistent approach to dealing with compensation for use of detours. It removes the subjectivity out of the current procedures and provides for a more realistic (traffic based) approach to the compensation determination.

Freeway Work Zone Lane Capacity, TPF-5(081), 2009

The focus of this report is a capacity analysis of two long-term urban freeway Work Zones. Work Zone #1 tapered four mainline lanes to two, using two separate tapers; Work Zone #2 tapered two mainline lanes to one. Work Zone throughput was analyzed throughout the day over multiple days and traffic operations conditions were analyzed up to a distance of five miles upstream of the Work Zone entrance. Historical data from pavement-embedded detectors were used to analyze traffic conditions. The database consisted of five-minute volume, speed and occupancy data collected from 78 detectors for a total of 50 days. Congestion during each analyzed Work Zone existed for more than fourteen hours each day; Work Zone impacts adversely affected freeway operations over distances of 3.7 to 4.2 miles. Speed and occupancy conditions further upstream were, however, not affected, or even improved due to significant trip diversion. Work Zone capacity was defined based on the maximum traffic flows observed over a one-hour period; throughput values were also compiled over longer periods of time when traffic was within 90% of the maximum observed one-hour flows, as well as over the multi-hour mid-day period. The Highway Capacity Manual freeway capacity definition based on the maximum observed 15-min period was not used, since it would have no practical application in estimating Work Zone throughput when congested conditions prevail for the majority of the hours of the day. Certain noteworthy changes took place for the duration of the analyzed Work Zones: per-lane throughput dropped; morning peak periods started earlier, evening peak periods ended later and lasted longer; mid-day volumes dropped accompanied by the highest occupancies of the day. Trip diversion was evident in lower volumes entering the analyzed freeway corridor, higher volumes using off-ramps and lower volumes using onramps upstream of the Work Zones. The majority of diverted traffic comprised smaller vehicles (vehicles up to 21 feet in length); combination truck volumes increased and their use of the median lane increased, contrary to smaller vehicles that shifted toward a heavier use of the shoulder lane.

Iowa Workforce Development Annual Report Fiscal Year 2013

The past fiscal year brought some improvements in the Iowa economy that should position the state for stronger hiring in the year ahead. The housing market is on solid footing, and hiring is broader in scope, including a number of the service-providing industries that had been on hold for some time. State and local government fiscal conditions have also stabilized due to a rise in tax revenues. This means that government cutbacks will be less of a drag on overall job growth. During FY 2013, Iowa’s non-farm jobs advanced by 19,200 (+1.3 percent) compared to 23,000 (+1.6 percent) for the prior fiscal year. Although manufacturing continued to post the largest over the year job gain at close to 5,600, job growth shifted away from manufacturing to the service providing industries by mid-year. Annual job gains of 2,000 or more were reflected in professional and business services, education and health, leisure and hospitality, retail trade and financial activities. Statewide non-farm employment averaged 1,517,700 in FY 2013, the highest level achieved since the record of 1,524,800 in FY 2008.

Low Modulus Hot Pour Joint Sealant for ACC Pavements, HR-534, 1990

Over the years, the Iowa Department of Transportation has established an outstanding network of connector highways across the state of Iowa. Construction and paving of these primary roadways has essentially been completed. Unfortunately, many of these primary highway pavements are reaching their design life and are in need of rehabilitation. The emphasis, therefore, has shifted from the construction of new highways to the maintenance and rehabilitation of existing highways. The Iowa DOT in recent years has become more concerned with preventing the ingress of surface water into the pavement structure. Crack sealing is receiving greater emphasis. Specifications have been modified to require improved low modulus crack and joint sealing materials.

Pavement Evaluation Using the Road Rater Deflection Dish, MLR-89-2, 1989

In recent years the Iowa Department of Transportation has shifted emphasis from the construction of new roads to the maintenance and preservation of existing highways. A need has developed for evaluating pavements structurally to select the correct rehabilitation strategy and to properly design a pavement overlay if necessary. Road Rater non-destructive testing has fulfilled this need and has been used successfully to evaluate pavement and subgrade conditions and to design asphaltic concrete overlays and portland cement concrete overlays. The Iowa Road Rater Design Method has been simplified so that it may be easily understood and used by various individuals who are involved in pavement restoration and management. Road Rater evaluation techniques have worked well to date and have been verified by pavement coring, soils sampling and testing. Void detection testing has also been performed, and results indicate that the Road Rater can be used to locate pavement voids and that Road Rater evaluation techniques are reasonably accurate. The success of Road Rater research and development has made dynamic deflection test data an important pavement management input.

Performance Based Specifications, TR-403, 1998

The goal in highway construction and operation has shifted from method based specifications to specifications relating desired performance attributes to materials, mix designs, and construction methods. Shifting from method specifications to performance based specifications can work as an incentive or disincentive for the contractor to improve performance or extend pavement life. This literature search was directed at a review of existing portland cement concrete performance specification development, and the criteria that can effectively measure pavement performance. The criteria identified in the literature include concrete strength, slab thickness, air content, initial smoothness, water-cement ratio, unit weight, and slump. A description of each criterion, along with the advantages, disadvantages, and test methods for each are identified. Also included are the results from a survey that was sent out to various state, federal, and trade agencies. The responses indicated that 53% currently use or are developing a performance based specification program. Of the 47% of agencies that do not use a performance based specification program, over 34% indicated that they would consider a similar program. The most commonly measured characteristics include thickness, strength, smoothness, and air content. Lastly recommendations and conclusions are made regarding other factors that affect pavement performance and a proposed second phase of the research is suggested. The research team suggests that a regional expert task group be formed to identify performance levels and criteria. The results of that effort will guide the research team in the development of new or revised specifications.

An Optimum Allocation Approach to Closing or Relocating Highway Maintenance Garages in Iowa, 1981

Highway maintenance engineers and administrators are often confronted with a number of problems related to highway maintenance work programs. One of these problems is concerned with determining the optimum number and locations of highway maintenance garages in a given area. Serious decline in highway revenues and a high inflation rate have made it necessary to examine existing maintenance practices and to allocate reduced financial resources more effectively and efficiently. Searching for and providing of reasonable solutions to these problems is the focus of this research project. The methodology used is to identify and modify for use (if necessary) those models which have already been developed. Models which could give optimum number and locations of highway maintenance garages were found to be too theoretical and/or practically infeasible. Consequently, research focus was shifted from these models to other models that could compare alternatives and select the best among these alternatives. Three such models -- the Alabama model, California model, and Louisiana model, were identified and studied.

Structural Analysis and Overlay Design of Pavements Using the Road Rater, MLR-84-3, 1986

In recent years the Iowa DOT has shifted emphasis from the construction of new roads to the maintenance and preservation of existing highways. A need has developed for analyzing pavements structurally to select the correct rehabilitation strategy and to properly design a pavement overlay if necessary. This need has been fulfilled by Road Rater testing which has been used successfully on all types of pavements to evaluate pavement and subgrade conditions and to design asphaltic concrete overlays. The Iowa Road Rater Design Method has been simplified so that it may be easily understood and used by the widely diverse groups of individuals which may be involved in pavement restoration and management. Road Rater analysis techniques have worked well to date and have been verified by pavement coring, soils sampling and testing, and pavement removal by block sampling. Void detection testing has also been performed experimentally in Iowa, and results indicate that the Road Rater can be used to locate pavement voids and that Road Rater analysis techniques are reasonably accurate. The success of Road Rater research and development has made deflection test data one of the most important pavement management inputs.

Issue review : general fund revenue transfers and appropriations shifts.

This issue review examines how non-general-fund revenue sources have been used to help balance the general fund budget over the last ten years. The report includes examination of non-general-fund appropriations to fund agency operations and programs traditionally funded from the general fund. This document also reviews revenues that have been shifted from a non-general-fund source to the general fund.

Iowa 58 Viking Road Corridor from U.S. 20 to Greenhill Road in Cedar Falls, Iowa, NHSX-U-58-1(91)--8S-07, 2015

The Proposed Action consists of the improvement of Iowa Highway 58 (IA 58) from U.S. Highway 20 (U.S. 20) north to Greenhill Road in Cedar Falls (Black Hawk County, Iowa). The improvement would include limiting at-grade access to IA 58 by adding one or more interchanges to the corridor which would be located at Viking Road, Greenhill Road, and reconfiguring the U.S. 20 interchange (Figure 1). In order to construct these interchanges and associated ramps, the pavement of IA 58 would be reconstructed. In a couple of locations, the alignment of IA 58 would be shifted.