Iowa DOT Evaluation of the PASCO Road Survey System, HR-539, 1987

The report compares and contrasts the automated PASCO method of pavement evaluation to the manual procedures used by the Iowa Department of Transportation (DOT) to evaluate pavement condition. Iowa DOT's use of IJK and BPR roadmeters and manual crack and patch surveys are compared to PASCO's use of 35-mm photography, artificial lighting and hairline projection, tracking wheels and lasers to measure ride, cracking and patching, rut depths, and roughness. The Iowa DOT method provides a Present Serviceability Index (PSI) value and PASCO provides a Maintenance Control Index (MCI). Seven sections of Interstate Highway, county roads and city streets, and one shoulder section were tested with different speeds of data collection, surface types and textures, and stop and start conditions. High correlation of results between the two methods in the measurement of roughness (0.93 for the tracking wheel and 0.84 for the laser method) were recorded. Rut depth correlations of 0.61 and cracking of 0.32 are attributed to PASCO's more comprehensive measurement techniques. A cost analysis of the data provided by both systems indicates that PASCO is capable of providing a comparable result with improved accuracy at a cost of $125-$150 or less per two-lane mile depending on survey mileage. Improved data collection speed, accuracy, and reliability, and a visible record of pavement condition for comparable costs are available. The PASCO system's ability to provide the data required in the Highway Pavement Distress Identification Manual, the Pavement Condition Rating Guide, and the Strategic Highway Research Program Long Term Pavement Performance (LTPP) Studies, is also outlined in the report.

Assessing High-Speed Internet Access in the State of Iowa, October 2000

Report for the Iowa Utilities Board and the Iowa Department of Economic Development

Assessing High-Speed Internet Access in the State of Iowa: Second Assessment, February 2002

Report for Iowa Utilities Board

Assessing High-Speed Internet Access in the State of Iowa: Third Assessment, May 2003

Report for the Iowa Utilities Board.

Investigation of A High-Speed Law Enforcement Pursuit involving Toledo Police Department and the Tama County Sheriff's Office, 2002

Investigative report produced by Iowa Citizens' Aide/Ombudsman

Assessing High-Speed Internet Access in the State of Iowa: Fourth Assessment, December 2004

The primary objective of the Fourth Assessment is to evaluate the level of progress in the deployment of high-speed Internet technologies in the State of Iowa.

Technology Transfer of As-Built and Preliminary Surveys Using GPS, Soft Photogrammetry, and Video Logging, 2002

This research involved two studies: one to determine the local geoid to obtain mean sea level elevation from a global positioning system (GPS) to an accuracy of ±2 cm, and the other to determine the location of roadside features such as mile posts and stop signs for safety studies, geographic information systems (GIS), and maintenance applications, from video imageries collected by a van traveling at traffic speed.

Safety Effectiveness of High-Speed Expressway Signals, 2005

The safety benefit of signalizing intersections of high-speed divided expressways is considered. Analyses were conducted on 50 and 55 mph and on 55 mph only intersections, comparing unsignalized and signalized intersections. Results of the 55 mph analysis are included in this report. Matched-pair analysis indicates that generally, signalized intersections have higher crash rate but lower costs per crash. On the other hand, before-and-after analysis (intersections signalized between 1994 and 2001) indicates lower crash rates (~30 percent) and total costs (~10 percent) after signalization. Empirical Bayes (EB) adjusted before-and-after analysis reduces estimates of safety benefit (crash rate) to about 20 percent. The study shows how commonly used analyses can differ in their results, and that there is great variability in the safety performance of individual signalized locations. This variability and the effect of EB adjustment are demonstrated through the use of innovative graphics.

Assessing High-Speed Internet Access in the State of Iowa: Fifth Assessment, May 2006

The primary objective of the Fifth Assessment is to evaluate the level of progress in the deployment of high-speed Internet technologies in the State of Iowa.

Speed Limit Questions? Here’s Your Answer, July 6, 2005

Iowa’s speed regulations are based on the same basic speed law that is used in all 50 states: “Any person driving a motor vehicle on a highway shall drive the same at a careful and prudent speed not greater than nor less than is reasonable and proper, having due regard to the traffic, surface, and width of the highway and of any other conditions then existing, and no person shall drive any vehicle upon a highway at a speed greater than will permit the person to bring it to a stop within the assured clear distance ahead, such driver having the right to assume, however, that all persons using said highway will observe the law.” Statutory limits are based on the concept that uniform categories of highways can be traveled safely at certain preset maximum speeds under ideal conditions. Whether the speed limit is posted or unposted, drivers should reduce their speed below these values in poor weather, heavy traffic, and under other potentially hazardous conditions.

Assessing High-Speed Internet Access in the State of Iowa: Sixth Assessment, January 2008

This Assessment gauges the availability of highspeed Internet access to both rural and non-rural Iowans. The Board continues to evaluate the progress in the deployment of high-speed Internet access through this Sixth Assessment, including information related to Internet speeds available to consumers and pricing of high-speed Internet services. Comparison of this Assessment with the earlier efforts is critical if a clear perspective on the developing availability of high-speed Internet access to all residents of the State of Iowa is desired.

Speed Limit Questions? Here’s Your Answer, February 8, 2010

Iowa’s speed regulations are based on the same basic speed law that is used in all 50 states: “Any person driving a motor vehicle on a highway shall drive the same at a careful and prudent speed not greater than nor less than is reasonable and proper, having due regard to the traffic, surface, and width of the highway and of any other conditions then existing, and no person shall drive any vehicle upon a highway at a speed greater than will permit the person to bring it to a stop within the assured clear distance ahead, such driver having the right to assume, however, that all persons using said highway will observe the law.” Statutory limits are based on the concept that uniform categories of highways can be traveled safely at certain preset maximum speeds under ideal conditions. Whether the speed limit is posted or unposted, drivers should reduce their speed below these values in poor weather, heavy traffic, and under other potentially hazardous conditions.

Evaluation of Electronic Speed Limit Signs on US 30, September, 2011

This study documents the speed reduction impacts of two dynamic, electronic school zone speed limit signs at United Community Schools between Ames and Boone, Iowa. The school facility is situated along US Highway 30, a rural four-lane divided expressway. Due to concerns about high speeds in the area, the Iowa Department of Transportation (DOT) decided to replace the original static school zone speed limit signs, which had flashing beacons during school start and dismissal times (Figure 1), with electronic speed signs that only display the reduced school speed limit of 55 mph during school arrival and dismissal times (Figure 2). The Center for Transportation Research and Education (CTRE) at Iowa State University (ISU) conducted a speed evaluation study one week before and 1 month, 7 months, and 14 or 15 months after the new signs were installed. Overall, the new dynamic school zone speed limit signs were more effective in reducing speeds than the original static signs with flashing beacons in the 1 month after period. During the 7 and 14 month after period, speeds increased slightly for the eastbound direction of traffic. However, the increases were consistent with overall speed increases that occurred independent of the signs. The dynamic, electronic signs were effective for the westbound direction of traffic for all time periods and for both start and dismissal times. Even though only modest changes in mean and 85th percentile speeds occurred, with the speed decreases, the number of vehicles exceeding the school speed limit decreased significantly, indicating the signs had a significant impact on high-end speeders.

Relationship between Speed and Lateral Position on Curves, September 2012

Excessive speed is often cited as a primary driver factor in crashes, particularly rural two-lane crashes. It has also been suggested that speed plays a significant role in crashes on curves. However, the relationship between speed and crashes on curves is not well documented because it is difficult to determine driver speed after the fact when investigating a crash. One method to begin documenting this relationship is to explore the relationship between lateral position and speed as a crash surrogate. For this study, the researchers collected speed and lateral position data for three rural two-lane curves. The relationship between lateral position and speed was assessed by comparing the odds of a near-lane crossing for vehicles traveling 5 or more mph over the advisory speed to those for vehicles traveling below that threshold.

Improving the Accuracy and Usability of Iowa Falling Weight Deflectometer Data, May 2013

This study aims to improve the accuracy and usability of Iowa Falling Weight Deflectometer (FWD) data by incorporating significant enhancements into the fully-automated software system for rapid processing of the FWD data. These enhancements include: (1) refined prediction of backcalculated pavement layer modulus through deflection basin matching/optimization, (2) temperature correction of backcalculated Hot-Mix Asphalt (HMA) layer modulus, (3) computation of 1993 AASHTO design guide related effective SN (SNeff) and effective k-value (keff ), (4) computation of Iowa DOT asphalt concrete (AC) overlay design related Structural Rating (SR) and kvalue (k), and (5) enhancement of user-friendliness of input and output from the software tool. A high-quality, easy-to-use backcalculation software package, referred to as, I-BACK: the Iowa Pavement Backcalculation Software, was developed to achieve the project goals and requirements. This report presents theoretical background behind the incorporated enhancements as well as guidance on the use of I-BACK developed in this study. The developed tool, I-BACK, provides more fine-tuned ANN pavement backcalculation results by implementation of deflection basin matching optimizer for conventional flexible, full-depth, rigid, and composite pavements. Implementation of this tool within Iowa DOT will facilitate accurate pavement structural evaluation and rehabilitation designs for pavement/asset management purposes. This research has also set the framework for the development of a simplified FWD deflection based HMA overlay design procedure which is one of the recommended areas for future research.