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Project Details
STATUS

Completed

START DATE

03/01/14

END DATE

12/31/15

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
Jing Dong

Transportation Engineer, CTRE

Co-Principal Investigator
Neal Hawkins

Associate Director, InTrans

About the research

In urban areas, interchange spacing and the adequacy of design for weaving, merge, and diverge areas can significantly influence available capacity. Traffic microsimulation tools allow detailed analyses of these critical areas in complex locations that often yield results that differ from the generalized approach of the Highway Capacity Manual. In order to obtain valid results, various inputs should be calibrated to local conditions. This project investigated basic calibration factors for the simulation of traffic conditions within an urban freeway merge/diverge environment.

By collecting and analyzing urban freeway traffic data from multiple sources, specific Iowa-based calibration factors for use in VISSIM were developed. In particular, a repeatable methodology for collecting standstill distance and headway/time gap data on urban freeways was applied to locations throughout the state of Iowa. This collection process relies on the manual processing of video for standstill distances and individual vehicle data from radar detectors to measure the headways/time gaps. By comparing the data collected from different locations, it was found that standstill distances vary by location and lead-follow vehicle types. Headways and time gaps were found to be consistent within the same driver population and across different driver populations when the conditions were similar. Both standstill distance and headway/time gap were found to follow fairly dispersed and skewed distributions. Therefore, it is recommended that microsimulation models be modified to include the option for standstill distance and headway/time gap to follow distributions as well as be set separately for different vehicle classes.

In addition, for the driving behavior parameters that cannot be easily collected, a sensitivity analysis was conducted to examine the impact of these parameters on the capacity of the facility. The sensitivity analysis results can be used as a reference to manually adjust parameters to match the simulation results to the observed traffic conditions. A well-calibrated microsimulation model can enable a higher level of fidelity in modeling traffic behavior and serve to improve decision making in balancing need with investment.

 

 

Project Details
STATUS

In-Progress

START DATE

12/10/13

END DATE

05/31/15

RESEARCH CENTERS InTrans
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
Gene Takle

About the research

Frost on roads and bridges in Iowa represents a potential hazard to the motoring public (Takle, 1990). Iowa Department of Transportation (DOT) contracts with a private agency for daily forecasts of bridge and roadway frost for guidance on mitigation and amelioration of frost conditions of traveled surfaces but seeks a supplemental forecast to assist in determining uncertainty at times when forecast skill is low. The Agronomy Department runs a legacy weather forecast model (MMS) in real time that can be used for creating forecast variables needed to drive bridge and roadway forecast models. Takle (1990) provided an overview of frost occurrence on roads and bridges in Iowa, documenting the spatial and temporal occurrences. Greenfield and Takle (2006) developed a bridge frost prediction model (BridgeT) that can be applied to Iowa bridges, and Knollhoff et al. (2003) provided estimates of the amount of frost accumulation required to be observable by standard IDOT methods of detection. Environment Canada (2013) has created a model, METRo (Model ofthe Environment and Temperature of Roads), for forecasting frost on both roads and bridges. METRo uses observations provided by a road weather station (road weather information system, RWIS) and the atmospheric forecast model, to predict the roads conditions such as freezing rain, accumulation of snow, frost and thaw for a specific location. METRo is written in python and fortran 90 and performs a 48-h forecast on a standard desktop computer in less than 2 seconds. The project proposes to run the MMS forecast model on a daily basis to produce 72-h forecasts of temperature, dew-point temperature, precipitation, wind speed and solar radiation at the standard observing level as well as skin temperature for all model grid points in Iowa at 12-km resolution. These output data will be used to drive BridgeT and METRo on a daily basis for all MMS grid points in Iowa to provide frost and temperature forecasts for roads and bridges in Iowa. The forecast model will be initialized with the 00 UTC (6 PM local standard time) and 12 UTC (6 AM local standard time) data and will provide output by 09 UTC and 21 UTC, respectively, to run the frost models. Surface temperature and output of the frost models will be available online at 12 UTC (6 AM) and 00 UTC (6 PM), respectively, for indicating surface temperature and frost occurrence for the following 30 hours and surface temperature and frost outlook for the subsequent 36 hours. Forecasts will be issued with twice daily valid times for the period of 26 November 2013 through 15 April2014. Frost forecast probability will be indicated by a color scheme indicating HIGH, MEDIUM, and LOW probability of frost for each county. These probabilities will be determined by use of frost accumulation results of Knollhoff (2003). Twice daily maps of surface temperature and frost occurrence on roads and bridges in all Iowa counties. A comparison of surface temperatures at validation time will be compared with observed values as measured by the road weather information system (RWIS) network. All of this information will be archived and provided as necessary to support analyses of this modeling approach.

 

 

Project Details
STATUS

Completed

START DATE

03/11/15

END DATE

03/31/17

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
Jing Dong

Transportation Engineer, CTRE

About the research

Winter road maintenance operations involve complex operational strategies and long-term planning decisions. The objective of this project was to develop an optimization-based approach to sustainable replacement, improvement, and relocation of maintenance garages. In particular, an arc routing problem was formulated to design efficient routes for salting, pre-wetting, and plowing, considering the operational characteristics of winter road maintenance.

The researchers conducted two case studies—for the Muscatine and Dubuque areas in Iowa. In both case studies, heuristic solution algorithms were developed to find the optimal snow routes that satisfy maintenance service level requirements.

Alternative garage locations were compared in terms of number of snow routes, deadhead times, and distances. New garage locations were recommended to replace the existing Muscatine and Dubuque garages.

Project Details
STATUS

In-Progress

PROJECT NUMBER

SPR-P1(14) M007

START DATE

07/01/13

END DATE

12/31/15

RESEARCH CENTERS InTrans, CTRE, REACTOR
SPONSORS

Federal Highway Administration State Planning and Research Funding
Nebraska Department of Roads

Researchers
Principal Investigator
Anuj Sharma

Research Scientist and Leader, REACTOR

About the research

This study developed a systematic approach for using data from multiple sources to provide active traffic management solutions. The feasibility of two active traffic management solutions were analyzed: ramp-metering and real-time crash risk estimation and prediction. Using a combined dataset containing traffic, weather, and crash data, this study assessed crash likelihood on urban freeways and evaluated the economic feasibility of providing a ramp metering solution.

A case study of freeway segments in Omaha, Nebraska, was conducted. The impact of rain, snow, congestion, and other factors on crash risk was analyzed using a binary probit model, and one of the major findings from the sensitivity analysis was that a one-mile-per-hour increase in speed is associated with a 7.5% decrease in crash risk.

FREEVAL was used to analyze the economic feasibility of the ramp metering implementation strategy. A case study of a 6.3 mile segment on I-80 near downtown Omaha showed that, after applying ramp metering, travel time decreased from 9.3 minutes to 8.1 minutes and crash risk decreased by 37.5% during the rush hours. The benefits of reducing travel time and crash cost can easily offset the cost of implementing ramp metering for this road section.

The results from the real-time crash risk prediction models developed for the studied road section are promising. A sensitivity analysis was conducted on different models and different temporal and spatial windows to estimate/predict crash risk. An adaptive boosting (AdaBoost) model using a 10 minute historical window of speeds obtained from 0.25 miles downstream and 0.75 miles upstream was found to be the most accurate estimator of crash risk.

Project Details
STATUS

Completed

PROJECT NUMBER

14-509

START DATE

08/01/14

END DATE

02/28/18

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, MTC
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation
Midwest Transportation Center
USDOT/OST-R

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

About the research

Lane departure crashes make up a large percentage of rural crashes for states in the midwest. Since agencies have limited resources, they rely on studies that demonstrate the effectiveness of a particular countermeasure in order to make decisions about which countermeasures should be selected. Most agencies prefer countermeasure effectiveness to be stated in terms of crash modification factors (CMFs) since they are easily understood and commonly used by agencies. Developing data driven performance measures for safety is one of the main Midwest Transportation Center (MTC) themes and robust CMFs have not been developed for a number of lane departure countermeasures.

The objective of this research is to develop CMFs for several lane departure countermeasures that have been used in Iowa. The research includes selecting sites where the countermeasures have been installed, identifying control sites, extracting site characteristics, reducing crash data, conducting analyses, and summarizing results. The team developed tech briefs for the following lane departure countermeasures as determined by the technical advisory committee:

  • Safety Edge
  • Chevrons
  • Destination lighting at stop-controlled intersections
  • Stop-sign beacons

Funding Sources:
Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation ($98,448.00)
Midwest Transportation Center
USDOT/OST-R ($72,182.00)
Total: $170,630.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

Completed

START DATE

04/21/15

END DATE

10/31/18

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
David Eisenmann

About the research

The use of nondestructive evaluation (NDE) to evaluate the structural worthiness of civil structures was continued in this Phase II research project. This aim of the project was to validate the use of two NDE methodologies, ground penetrating radar (GPR) and magnetic flux leakage (MFL), to detect material loss in reinforcing steel of a barrier rail on a bridge located in central Iowa. Controlled samples were used in laboratory experimental work to look at factors that might affect a response from reinforcing steel on the measurements collected with GPR and a MFL system. The GPR work involved measurements taken both in the air and with a “phantom concrete,” which mimicked the response expected from concrete. Data collected from the field were compared to data collected five years previously. Laboratory data collections were also performed with MFL with positive results. Due to the nature of the MFL system, no usable data were collected from field work. Data were collected from sections of reinforcing steel taken from a barrier rail on the bridge, but complications prohibited the comparison of these data to actual inspected sections of the barrier rail. Ultimately, the research provided positive insights into the use of NDE methodologies in a non-traditional manner for the detection of corrosion in reinforcing steel.

Project Details
STATUS

Completed

PROJECT NUMBER

13-468, TR-656, SPR 90-00-0646-000

START DATE

05/09/13

END DATE

12/13/19

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, PROSPER
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation
Iowa Highway Research Board

PARTNERS

Stine Seed Company of Iowa
PLET (Canada)

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Sunghwan Kim

Associate Director, PROSPER

About the research

Rapid advancements in bioenergy-based industry have not only reduced our dependency on fossil resources but also brought about sustainable development for human society. The production of biofuel derived from biomass also produces co-products containing lignin. Biofuel co-products (BCPs) containing sulfur-free lignin were investigated in this research study to gain further insight into their benefits in stabilizing pavement subgrade soil. Four different types of co-products were tested: (1) an oily liquid type with medium lignin content (BCP A), (2) a powder type with low lignin content (BCP B), (3) another oily liquid type with high lignin content (BCP C), and (4) an oily liquid type of lignin derived from paper pulp production (lignosulfonate). The laboratory tests focused on engineering properties, including unconfined compressive strength (UCS), shear strength, freeze-thaw durability, and moisture sustainability of BCPs-treated soils. Four types of Iowa soil were mixed with BCPs and lignosulfonate for testing, and the results indicated that BCPs are more promising additives for soil stabilization in Iowa because of their beneficial effects in improving soil engineering properties, strength properties, durability, and resistance to moisture degradation. Scanning electron microscope (SEM) and x-ray diffraction (XRD) analyses were also performed to identify mechanisms of lignin-based soil stabilization. A microstructural analysis showed that lignin materials could coat and bind soil grains and thereby form a strong soil structure.

Five soil stabilizers (cement, lignosulfonate, chlorides, Claycrete, and Base One) were sprayed on a gravel road subgrade for the field demonstration. In situ tests including light weight deflectometer (LWD) and dynamic cone penetration (DCP) were performed before, one week after, and one year after the construction to monitor the performance of the stabilized sections and to draw the lessons learned from the practice. The construction process was documented both visually and in written form. Some critical lessons were learned, which provide recommendations for future studies and benefit relevant practitioners. Based on this study’s findings, the application of BCPs in soil stabilization appears to benefit both the bioenergy industry and the pavement construction industry.

Project Details
STATUS

Completed

PROJECT NUMBER

15-560, SPR RB12-016

START DATE

12/01/15

END DATE

05/31/18

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Co-Principal Investigator
Yaohua "Jimmy" Deng

Research Engineer

About the research

The electrochemical fatigue sensor (EFS) was developed to detect very small fatigue cracks that are actively growing. To evaluate the fatigue crack capabilities and gain a better of understanding of implementation needs, a laboratory test and a field monitoring program were developed to evaluate the EFS system using the CrackChek and FatigueWatch sensors, respectively.

The laboratory test program consisted of evaluating the adequacy of CrackChek sensors for crack detection. The CrackChek sensors were installed on a standard steel plate specimen. An electrical discharge machining (EDM) notch was induced in the mid-length of the steel plate and a pair of sensors (i.e., crack and reference sensors) were installed adjacent to the notch tip.

The field monitoring program consisted of evaluating the adequacy of the FatigueWatch sensors for crack detection and the general capabilities of the system for use in field applications. The sensors were installed on the Cherry Creek Bridge near Newton, Iowa, on a sacrificial specimen and on a bridge girder web in a known fatigue-sensitive location. The sacrificial specimen was a standard steel plate exactly the same as the one used for evaluating the CrackChek sensors. The EDM notch was also generated in the edge and mid-length of the specimen and a pair of sensors were installed near the notch tip. After a 13-month data collection and analysis period, no crack formed in either the sacrificial specimen or the bridge girder web where the sensors were installed.

In summary, the CrackChek and FatigueWatch sensors perform well for crack detection.

Project Details
STATUS

In-Progress

START DATE

05/01/15

END DATE

07/31/17

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, CTRE, MTC
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation
Iowa Highway Research Board
Midwest Transportation Center
USDOT/OST-R

Researchers
Principal Investigator
Jeramy Ashlock

Faculty Affiliate

Co-Principal Investigator
Sri Sritharan

Faculty Affiliate

About the research

In recent years, the Iowa Department of Transportation (DOT) as well as several other state DOTs have made increasing use of drilled shaft foundations on bridge projects. Due to soil variability and the lack of redundancy, the Iowa DOT typically requires that a bi-directional Osterberg cell (O-cell) load test be performed on a demonstration shaft at each new bridge project. The load test results are then used to verify the predicted capacity, and often to adjust the values of geotechnical shaft resistances used in designing the shafts for the entire bridge. However, O-cell tests are very costly (around $100k per test), and often provide inconclusive results, as only the upper or lower portion of the shaft (or neither) actually reach failure. As a result, extrapolation is commonly necessary to estimate the expected load-displacement behavior of the bridge foundations under the actual top-down loading conditions.

To address these shortcomings, this research investigates the use of top-down load tests on reduced-scale drilled shafts and develops scaling relations to predict the load-displacement curves of the full-scale shafts. Test results from the reduced-scale shafts will be compared to those from a planned full-scale O-cell test at an Iowa DOT bridge project site.

The research will contribute to the Midwest Transportation Center (MTC) theme of Data Driven Performance Measures for Enhanced Infrastructure Condition, Safety, and Project Delivery. Specifically, the project will contribute load-test data for the DSHAFT load and resistance factor design (LRFD) calibration database for drilled shafts, while enhancing the safety of the infrastructure system through more accurate and reliable design methods for drilled shaft foundations. The final products of this research will include design guides and tech-transfer materials for immediate use of the technology by the practicing engineers.


Funding Sources:
Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation
Iowa Highway Research Board ($100,000.00)
Midwest Transportation Center
USDOT/OST-R ($100,000.00)
Total: $200,000.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

Completed

PROJECT NUMBER

17-626

START DATE

07/15/17

END DATE

02/06/20

SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
Jing Dong

Transportation Engineer, CTRE

Co-Principal Investigator
Neal Hawkins

Associate Director, InTrans

About the research

During winter road maintenance operations, the Iowa Department of Transportation (DOT) is responsible for servicing 24,000 lane miles of roadways, including Interstates, US highways, and Iowa roads. This project focused on operations for District 3, located in northwest Iowa, which services about 4,000 lane miles from 20 depots.

Two optimization problems were solved to determine the optimal snowplow routes in this district. The first problem was to design winter maintenance truck routes for single depots under the district’s current responsibility maps. The second problem was to design routes for multiple depots with intermediate facilities, with the service boundaries among the depots able to be redesigned. Both optimization problems were solved as capacitated arc routing problems (CARPs) using a memetic algorithm (MA) and considering the constraints of road segment service cycle time, heterogeneous vehicle capacities, fleet size, road-vehicle dependency, and work duration.

The results from solving the single-depot optimization problem show a 13.2% reduction in deadhead distance compared to current operations. The deadhead savings could be even larger because while the optimized routes strictly satisfy all constraints, the current operations might not. For the multiple-depot optimization problem, due to the network structure and current depot locations, the difference between the optimized routes based on a multiple-depot configuration and those based on a single-depot configuration is insignificant.

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