Evaluation of Iowa’s 70 mph Speed Limit — 2.5 Year Update, 2009

On July 1, 2005, the State of Iowa implemented a 70 mile per hour (mph) speed limit on most rural Interstates. This document reports on a study of the safety effect of this change. Changes in speeds, traffic volume on and off the rural Interstate system (diversion), and safety (crashes) for on- and off-system roads were studied. After the change, mean and 85th percentile speeds increased by about 2 mph on rural Interstates, but speeding was reduced (the number of drivers exceeding the speed limit by 10 mph decreased from 20 per cent to about 8 per cent). Daytime and nighttime serious crashes were studied for a period of 14 and a half years prior to the change and 2 and a half years afterwards. Simple descriptive statistics reveal increases in all crash severity categories for the 2 and a half year period following the speed limit increase when compared to the most recent comparable 2 and a half year period prior to the increase. When compared to longer term trends, the increases were less pronounced in some severity levels and types, and for a few severity levels the average crash frequencies were observed to decrease. However, fatal and other serious cross-median crashes increased by relatively larger amounts as compared to expected random variation. The study also analyzed crash frequencies grouped into six-month periods, revealing similar findings.

Road Safety Audit for US 6 from the ECL of Iowa City to the WCL of West Liberty in Johnson and Muscatine Counties, Iowa, 2008

Approximately 13.2 miles of US 6 in eastern Iowa extends from the east corporate limits of Iowa City, Iowa, to the west corporate limits of West Liberty, Iowa. This segment of US 6 is a service level B primary highway, with an annual daily traffic volume varying from 3,480 vehicles per day (vpd) to 5,700 vpd. According to 2001–2007 crash density data from the Iowa Department of Transportation (Iowa DOT), the corridor is currently listed among the top 5% of non-freeway Iowa DOT roads in several crash categories, including crashes involving excessive speed, impaired drivers, single-vehicle run-off-road, and multiple-vehicle crossed centerline. A road safety audit of this corridor was deemed appropriate by the Iowa Department of Transportation’s Office of Traffic and Safety. Staff and officials from the Iowa DOT, Iowa State Patrol, Governor’s Traffic Safety Bureau, Federal Highway Administration, Center for Transportation Research and Education, and several local law enforcement and transportation agencies met to review crash data and discuss potential safety improvements to this segment of US 6. This report outlines the findings and recommendations of the road safety audit team to address the safety concerns on this US 6 corridor and explains several selected mitigation strategies.

Road Safety Audit for the US 61/Harrison Street and West Locust Street Intersection in Davenport-Scott County, Iowa, 2008

On the October 7 and 8, 2008, a road safety audit was conducted for the intersection of US 61/Harrison Street and West Locust Street in Davenport, Iowa. US 61/Harrison Street is a one-way street and a principal arterial route through Davenport, with three southbound lanes. Locust Street is a four-lane, two-way minor arterial running across the city from west to east. The last major improvement at this intersection was implemented approximately 20 years ago. The Iowa Department of Transportation requested a safety audit of this intersection in response to a high incidence of crashes at the location over the past several years, in view of the fact that no major improvements are anticipated for this intersection in the immediate future. The road safety audit team discussed current conditions at the intersection and reviewed the last seven years of crash data. The team also made daytime and nighttime field visits to the intersection to examine field conditions and observe traffic flow and crossing guard operations with younger pedestrians. After discussing key issues, the road safety audit team drew conclusions and suggested possible enforcement, engineering, public information, and educational strategies for mitigation.

Field Evaluation of Elliptical Steel Dowel Performance, 2006

Joints are always a concern in the construction and long-term performance of concrete pavements. Research has shown that we need some type of positive load transfer across transverse joints. The same research has directed pavement designers to use round dowels spaced at regular intervals across the transverse joint to distribute the vehicle loads both longitudinally and transversely across the joint. The goal is to reduce bearing stresses on the dowels and the two pavement slab edges and erosion of the underlying surface, hence improved long-term joint and pavement structure performance. Road salts cause metal corrosion in doweled joints, excessive bearing stresses hollow dowel ends, and construction processes are associated with cracking pavement at the end of dowels. Dowels are also a cost factor in the pavement costs when joint spacing is reduced to control curling and warping distress in pavements. Designers desire to place adequate numbers of dowels spaced at the proper locations to handle the anticipated loads and bearing stresses for the design life of the pavement. This interim report is the second of three reports on the evaluation of elliptical steel dowels. This report consists of an update on the testing and performance of the various shapes and sizes of dowels. It also documents the results of the first series of performance surveys and draws interim conclusions about the performance of various bar shapes, sizes, spacings, and basket configurations. In addition to the study of elliptical steel dowel performance, fiber reinforced polymers (FRP) are also tested as elliptical dowel material (in contrast to steel) on a section of the highway construction north of the elliptical steel test sections.

09032-017 Miller Creek Watershed Final Report

Miller Creek is on the 2006 Section 303d Impaired Waters List and has a 19,926 acre watershed. All indicators, as reported in the Miller Creek assessment, show that the impairment is due to sediment and nutrient delivery from upland runoff which contributes to elevated water temperatures, excessive algae, and low dissolved oxygen levels within the stream. In an effort to control these problems, the Miller Creek Water Quality Project will target areas of 5 tons per acre or greater soil loss or with 0.5 tons per acre or greater sediment delivery rates. The assessment revealed these targeted priority lands make up 32% or 6,395 acres of the Miller Creek watershed. Priority lands include cropland, pasture land, timber, and sensitive riparian areas. It is the goal of this project to reduce sediment delivery by 70% on 60% or 3,837 acres of these priority lands. This will be accomplished through installation of strategically placed structural practices, rotational grazing systems, and buffer strips. These practices will reduce soil loss, reduce sediment delivery, improve water quality, and improve wildlife habitat in the watershed. Utilizing partnerships with NRCS and IDALS-DSC will be important in making this project successful. In addition to using matching funds from EQIP, WHIP, and CRP, the Monroe SWCD is committed to prioritizing local cost share funds through IFIP and REAP for use in the Miller Creek Watershed.

1012-007 Yellow River Headwaters Final Report

The Yellow River Headwaters Watershed (YRHW) drains 26,730 acres of rural land within Winneshiek and Allamakee Counties. While portions of the river have been designated as a High Quality Resource by the State of Iowa, other portions appear on the State's 303(d) List of Impaired Waters due to excessive nutrients, sediment and other water quality issues. The Winneshiek SWCD was fortunate enough to secure WSPF/WPF funds for FY2009 to begin addressing many of the sources of the identified problems, especially along the all-to-critical stream corridor. Initial landowner I producer interest has exceeded expectations and several key BMPs have been installed within the identified critical areas. Yet due to the current budget constraints in the WSPF/WPF programs, we currently have greater landowner I producer interest than we do funds, which is why the District is applying for WIRB funding, to provide supplemental incentives to continue the installation of needed Grade Stabilization Structures, Terraces and Manure Management Systems in identified critical areas. Other funding, currently available to the District, will cover the remaining portions of the project's budget, including staff and our outreach efforts.

1233-015IJ Miller Creek Watershed Final Report

Miller Creek, a 19,926 acre watershed, is listed on the 2008 Section 303d Impaired Waters List. All indicators, as reported in the Miller Creek assessment, show that the impairment is due to nutrient and sediment delivery from upland runoff which contributes to elevated water temperatures, excessive algae, and low dissolved oxygen levels within the stream. The WIRB board provided implementation grant funds in 2010 for a three year project to treat targeted areas of 5 tons per acre or greater soil loss with an estimated reduction of 2,547 tons. As of December 1, 2012, with 95% of the funds allocated, the final results are estimated to provide a sediment delivery reduction of 4,500 tons and an estimated phosphorus reduction of 5,700 lbs per year. These accomplishments and the completion of the three year Miller Creek WIRB project represent "Phase I" of the SWCD's goals to treat the Miller Creek watershed. This application represents "Phase II" or the final phase of the Miller Creek water quality project. The Monroe SWCD plans to reduce sediment delivery by 70% on an additional 245 acres of priority land. This goal will be accomplished through installation of strategically placed structural practices, BMPs, and grazing systems. These practices will reduce soil loss, nutrient runoff, and sediment delivery as well as improve water quality and wildlife habitat in the watershed. Utilization of partnerships with NRCS and IDALS-DSC will continue to be an important part to the success of the project. Project goals will be achieved by utilizing matching funds from EQIP, and the Monroe SWCD has approved the use of District IFIP cost share funds specifically for use in the Miller Creek Watershed.

1011-006 Competine Creek Watershed Final Report

The Competine Creek watershed is a 24,956 acre sub-watershed of Cedar Creek. The creek traverses portions of three counties, slicing through rich and highly productive Southern lowa Drift Plain soils. The watershed is suffering from excessive sediment delivery and frequent flash floods that have been exacerbated by recent high rainfall events. Assessment data reveals soil erosion estimated to be 38,435 tons/year and sediment delivery to the creek at 15,847 tons/year. The Competine Creek Partnership Project is seeking WIRB funds to merge with IDALS-DSC funds and local funds, all targeted for structural Best Management Practices (BMPs) within the 2,760 acres of High Priority Areas (HPAs) identified by the assessment process. The BMPs will include grade stabilization structures, water and sediment basins, tile-outlet terraces, CRP, and urban storm water conservation practices. In addition, Iowa State University Extension-Iowa Learning Farm is investing in the project by facilitating a crop sampling program utilizing fall stalk nitrate, phosphorous index, and soil conditioning index testing. These tests will be used by producers as measures of performance to refine nutrient and soil loss management and to determine effective alternatives to reduce sediment and nutrient delivery to Competine Creek.

07003-001 Clear Lake Watershed Final Report

Clear Lake, Iowa's third largest natural lake, is a premier natural resource and popular recreational destination in north central Iowa. Despite the lake's already strong recreational use, water quality concerns have not allowed the lake to reach its full potential. Clear Lake is listed on Iowa's 2004 303(d) Impaired Waters List due to excessive levels of phosphorus, bacteria, and turbidity. Urban storm water runoff from the 8,600 acre watershed is a significant contributor to Clear Lake's impairment. Local communities have been working towards the goal of making improvements at all 30 storm water outlets that have a drainage area of five acres or more and have a cost effective solution. Many improvements have already been made, and now there are only seven storm water outlet sites remaining that still need protection in order to meet the goal. The storm water improvements have been very effective in reducing contaminants in urban runoff, achieving reduction levels in the 50-80% range. The proposed Clear Lake Storm Water Improvement Project will address the remaining seven outlet sites and take place over three years. The first year will consist of performing engineering and design of storm water best management practices (BMPs) at the seven outlet sites to determine if a cost effective solution exists for each. Years two and three will consist of installing two storm water improvements each year to implement the most cost effective BMPs at a minimum of four of the seven sites. The grant request addresses one of the main priorities of the Iowa Watershed Improvement Grant: storm water runoff.

07032-012 Lake MacBride Watershed Final Report

Lake Macbride is considered to be one of the top four lakes for fishing in the state of Iowa. It is widely used by the public and contributes significant economic benefits to the county. Lake Macbride is situated in the North Corridor which is one of the fastest growing areas in the state. The lake has a surface area of 940 acres and drains 16,205 acres. Lake Macbride is on the Iowa 303(d) list for excessive sediments and nutrients. In 2001, Lake Macbride State Park received over 2.5 million dollars from the Marine Fuel Tax and Fish and Wildlife Trust to install 2 silt basins and stabilize over 12 miles of shoreline in the lake. Also in 2001, the Johnson County SWCD received a WSPF allocation from DSC to address agriculture and urban runoff issues in the watershed. Section 319 funding was received in 2002 to continue watershed efforts to the present. A watershed assessment was completed in 2003 to guide watershed activities. In 2005, a TMDL was completed for the lake. Since 2001, over $645,000 dollars has been spent by landowners and funding partners to install conservation practices in the watershed. Watershed efforts have resulted in the reduction of over 4200 tons of soils from being delivered into Lake Macbride. Nutrient reductions have also occurred from the development of nutrient management plans on 2000 acres. The District is in the process of wrapping up watershed efforts on private land. A series of 13 structures is planned to be installed in the State Park over the next several years. One of the last remaining items that still needs addressed is 1,400 feet of eroding shoreline adjacent to Lake Macbride along Cottage Reserve Road. The road is under the jurisdiction of the Johnson County Board of Supervisors. Both the Board of Supervisors and the IDNR are willing to contribute substantial dollars to address the 250 tons of soil that are being directly delivered to Lake Macbride each year.

05035-012 Clear Lake Watershed Final Report

Clear Lake, Iowa's third largest natural lake, is located in Cerro Gordo County in north-central Iowa. The lake is a premier natural resource and popular recreational destination in north central Iowa, providing more than $40 million dollars annually to the local economy. Despite the lake's already strong recreational use, water quality concerns have not allowed the lake to reach its full recreational potential. Clear Lake is listed on Iowa's 2004 303(d) Impaired Waters List due to excessive levels of phosphorus, bacteria, and turbidity. Urban storm water runoff from the 8,600 acre watershed is a significant contributor to Clear Lake's impairment. There are over 68 storm water outlet points in the Clear Lake watershed that allow untreated urban runoff to empty directly into Clear Lake. Local governments have been very active in installing storm water Best Management Practices (BMPs) at as many of the outlets that current funding allows. To date, 11 of the 68 sites (16%) have been protected. These improvements have been very effective in reducing contaminants in the storm water runoff, but the remaining outlets still need protection. The first phase of this grant request is for an investigation of 10 storm water outlet sites to determine the most cost effective BMP for each site. The second phase of the grant request is to implement the BMPs deemed most cost effective at 5 of the 10 sites investigated. The grant request addresses one of the main priorities of the Iowa Watershed Improvement Grant: storm water runoff.

Assessment of Channelizing Device Effectiveness on High Speed/High Volume Roadways, 2007

Part 6 of the Manual on Uniform Traffic Control Devices (MUTCD) describes several types of channelizing devices that can be used to warn road users and guide them through work zones; these devices include cones, tubular markers, vertical panels, drums, barricades, and temporary raised islands. On higher speed/volume roadways, drums and/or vertical panels have been popular choices in many states, due to their formidable appearance and the enhanced visibility they provide when compared to standard cones. However, due to their larger size, drums also require more effort and storage space to transport, deploy and retrieve. Recent editions of the MUTCD have introduced new devices for channelizing; specifically of interest for this study is a taller (>36 inches) but thinner cone. While this new device does not offer a comparable target value to that of drums, the new devices are significantly larger than standard cones and they offer improved stability as well. In addition, these devices are more easily deployed and stored than drums and they cost less. Further, for applications previously using both drums and tall cones, the use of tall cones only provides the ability for delivery and setup by a single vehicle. An investigation of the effectiveness of the new channelizing devices provides a reference for states to use in selecting appropriate traffic control for high speed, high volume applications, especially for short term or limited duration exposures. This study includes a synthesis of common practices by state DOTs, as well as daytime and nighttime field observations of driver reactions using video detection equipment. The results of this study are promising for the day and night performance of the new tall cones, comparing favorably to the performance of drums when used for channelizing in tapers. The evaluation showed no statistical difference in merge distance and location, shy distance, or operating speed in either daytime or nighttime conditions. The study should provide a valuable resource for state DOTs to utilize in selecting the most effective channelizing device for use on high speed/high volume roadways where timely merging by drivers is critical to safety and mobility.

Fast Track and Fast Track II - Cedar Rapids, Iowa, HR-544, Construction Report, 1989

Two lanes of a major four lane arterial street needed to be reconstructed in Cedar Rapids, Iowa. The traffic volumes and difficulty of detouring the traffic necessitated closure for construction be held to an absolute minimum. Closure of the intersections, even for one day, was not politically feasible. Therefore, Fast Track and Fast Track II was specified for the project. Fast Track concrete paving has been used successfully in Iowa since 1986. The mainline portion of the project was specified to be Fast Track and achieved the opening strength of 400 psi in less than twelve hours. The intersections were allowed to be closed between 6 PM and 6 AM. This could occur twice - once to remove the old pavement and place the base and temporary surface and the second time to pave and cure the new concrete. The contractor was able to meet these restrictions. The Fast Track II used in the intersections achieved the opening strength of 350 psi in six to seven hours. Two test sections were selected in the mainline Fast Track and two intersections were chosen to test the Fast Tract II. Both flexural and compression specimens were tested. Pulse velocity tests were conducted on the pavement and test specimens. Maturity curves were developed through monitoring of the temperatures. Correlations were performed between the maturity and pulse velocity and the flexural strengths. The project was successful in establishing the feasibility of construction at night, with no disruption of traffic in the daytime, using fast Track II. Both the Fast Track II pavements were performing well four years after construction.