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Project Details
STATUS

Completed

START DATE

04/01/16

END DATE

06/29/18

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, MTC
SPONSORS

Deep Foundations Institute
Midwest Transportation Center
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Andrew Boeckmann

University of Missouri - Columbia

Co-Principal Investigator
J. Erik Loehr

About the research

A-walls are retaining structures composed of regularly spaced deep foundation elements battered in opposing directions and connected through a grade beam to mitigate movements of a slope or embankment. Analysis of A-walls for slope stabilization applications is challenging because of complex interactions between deep foundation elements and moving soils. A previous method was successful in modeling A-walls with consideration of both lateral and axial load transfer, but interaction between upslope and downslope A-wall elements through the capping beam is neglected in the “uncoupled” analysis. To evaluate the effect of coupling, the research team analyzed slopes stabilized with A-walls using finite element models with upslope and downslope piles connected at the pile heads. Results of the analyses were compared to those of uncoupled lateral and axial analyses utilizing the p-y and t-z methods. Load transfer parameters for the analyses were calibrated to field measurements of load transfer in A-walls to demonstrate viability of the revised methodology. Results of the coupled analyses were then compared to results from uncoupled analyses to evaluate the effect of interaction between upslope and downslope piles.

Coupled analyses produced bending moment and axial force profiles in reasonable agreement with measured values. Calibration of p-y and t-z curves to achieve predictions consistent with field measurements required significant softening of ultimate lateral and axial resistance values, but the softening was less than that required for calibration of uncoupled analyses. Modeling of interaction through the capping beam resulted in more reasonable calibrated values of lateral and axial soil resistance, better agreement with measured axial force profiles, and better agreement with measured bending moments and axial forces at shallow depths. The results indicate that interaction facilitated by the capping beam has a significant effect on development of forces within the A-wall elements. For deep sliding, reasonable predictions of pile resistance can be achieved using uncoupled models. However, for shallower sliding, the capping beam is likely more consequential and a coupled analysis is prudent. Coupled analysis is also beneficial for structural design of the capping beam.

Both calibration case histories involved relatively deep sliding and relatively small values of total soil movement. Additional analyses with new datasets from A-wall applications for shallower slides and greater movement are recommended.


Funding Sources:
Deep Foundations Institute ($18,700.00)
Midwest Transportation Center
University of Missouri – Columbia ($6,100.00)
USDOT/OST-R ($20,000.00)
Total: $44,800.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

In-Progress

START DATE

04/01/16

END DATE

12/31/16

RESEARCH CENTERS InTrans
SPONSORS

Deep Foundations Institute
Midwest Transportation Center
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Andrew Boeckmann

University of Missouri - Columbia

Co-Principal Investigator
J. Erik Loehr

About the research

A-walls are a slope stabilization technique involving a series of deep foundation elements installed in a failing or marginally stable slope using an A-shaped pattern of alternating inclinations. A-walls have been used to successfully stabilize several noteworthy slopes, but analysis of the walls is complicated by several complex load-transfer mechanisms. These complications have dissuaded engineers from using the promising approach.

The Deep Foundations Institute (DFI) has funded a study by the University of Missouri to improve analysis techniques for A-walls using computer code developed by the university. The MTC effort will be used to develop improved design practices for A-walls, which will be valuable for transportation agencies that face significant risks and costs associated with slope instability. The objective of this project is to develop improved design guidance for A-walls, which will be a valuable tool for departments of transportation (DOTs).

Project Details
STATUS

In-Progress

PROJECT NUMBER

DTFH611600001

START DATE

11/17/15

END DATE

05/16/17

RESEARCH CENTERS InTrans, CTRE
SPONSORS

U.S. Department of Transportation
University of Missouri - Columbia

Researchers
Principal Investigator
Praveen Edara

University of Missouri-Columbia

Co-Principal Investigator
Omar Smadi

Director, CTRE

About the research

CTRE is a subcontractor to the University of Missouri – Columbia on the project: Research Utilizing the SHRP 2 Safety Data to Support Highway Safety.

Project Details
STATUS

Completed

START DATE

02/01/14

END DATE

10/30/17

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, MTC
SPONSORS

Midwest Transportation Center
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
John Bowders

University of Missouri - Columbia

Principal Investigator
Andrew Boeckmann

University of Missouri - Columbia

About the research

The Federal Highway Administration (FHWA) has developed and promoted geosynthetic reinforced soil-integrated bridge system (GRS-IBS) technology to deliver accelerated bridge construction economically, primarily for relatively small bridges. The technology harnesses the stiffness of GRS to eliminate the need for piling or other conventional foundation systems. Eliminating piling typically results in cost and schedule benefits.

Despite the cost and time savings and performance benefits associated with GRS-IBS technology, it has not experienced widespread implementation. Use of the technology is likely becoming more common and widespread, particularly with several agencies deploying GRS-IBS on numerous occasions. However, other agencies have likely not implemented GRS-IBS because of a lack of familiarity with the technology and its implementation benefits.

To help overcome this lack of familiarity, the research team documented recent implementations focusing on technical performance and practical lessons from agency experiences in contracting and constructing these types of bridges. These GRS-IBS experiences were culled from a literature review, interviews with agency and contractor personnel, and the research team’s experience with construction and performance observations of the Rustic Road GRS-IBS project in Boone County, Missouri.

The final report, tech transfer summary, and implementation aid that were developed as a result of this work are for two Midwest Transportation Center research projects: Advancing Implementation of Geosynthetic Reinforced Soil-Integrated Bridge Systems (GRS-IBS) and Implementation Evaluation of the Rustic Road Geosynthetic Reinforced Soil-Integrated Bridge System.


Funding Sources:
Midwest Transportation Center
University of Missouri – Columbia ($44,999.00)
USDOT/OST-R ($71,349.00)
Total: $116,348.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

In-Progress

START DATE

10/01/14

END DATE

09/30/17

RESEARCH CENTERS InTrans, BEC, CTRE, MTC
SPONSORS

Midwest Transportation Center
Missouri Department of Transportation
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Glenn Washer

University of Missouri - Columbia

About the research

The objective of this project is to develop new nondestructive evaluation (NDE) technology for the condition assessment of post-tensioned bridge components.


Funding Sources:
Midwest Transportation Center
Missouri Department of Transportation ($50,593.00)
University of Missouri – Columbia ($9,407.00)
USDOT/OST-R ($60,000.00)
Total: $120,000.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

Completed

START DATE

09/05/15

END DATE

08/08/17

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE, MTC
SPONSORS

Midwest Transportation Center
Smart Work Zone Deployment Initiative
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Praveen Edara

University of Missouri-Columbia

Principal Investigator
Madhav Chitturi

University of Wisconsin, Madison

Co-Principal Investigator
John Shaw

Researcher, CTRE

Co-Principal Investigator
Carlos Sun
Student Researcher(s)
Zhu Qing

About the research

Many work zones require lane closures, and road users need to be notified of these closures through appropriate upstream signage. A literature review prepared for this study found several previous investigations indicating insufficient comprehension of the U.S. standard lane closure sign (designated in the Manual on Uniform Traffic Control Devices for Streets and Highways [MUTCD] as W4-2) and similar signs used internationally. The W4-2 sign is also unsuitable for signing interior lane closures on roadways with three or more lanes.

Driver comprehension of several alternative sign faces was tested through a survey using the ANSI Z535.3 process and was followed by a driving simulator study. The driver comprehension survey suggests that an Upward Drop Arrow design is a promising alternative to the existing W4-2 sign for sites where two upstream lanes are reduced to one lane in the work zone. In addition, one-arrow-per-lane signs developed as Americanized versions of the Vienna Convention G12a sign template are a promising option for interior lane closures on multi-lane roadway segments.

A driving simulator study compared the W4-2, a MERGE text sign with a horizontal arrow, and an Americanized version of the Vienna Convention G12a sign. In terms of sign comprehension, the W4-2 was the least understood of the three signs. The W4-2 resulted in more late merge maneuvers than the other two signs. Field evaluation of the Upward Drop Arrow and Americanized G12a signs is recommended as a follow-up to this study.


Funding Sources:
Midwest Transportation Center
Smart Work Zone Deployment Initiative ($23,714.00)
University of Missouri – Columbia ($13,984.00)
USDOT/OST-R ($74,022.00)
Total: $111,720.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

In-Progress

START DATE

09/30/13

END DATE

08/31/17

RESEARCH CENTERS InTrans, CTRE, MTC
SPONSORS

Midwest Transportation Center
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Glenn Washer

University of Missouri - Columbia

About the research

This research is exploring risk-based inspection (RBI) approaches to bridge inspection planning to better match requirements to inspection needs through engineering analysis.


Funding Sources:
Midwest Transportation Center
University of Missouri – Columbia ($87,544.00)
USDOT/OST-R ($78,992.00)
Total: $166,536.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

Completed

START DATE

09/01/15

END DATE

08/31/17

RESEARCH CENTERS InTrans, CTRE, MTC, SWZDI
SPONSORS

Midwest Transportation Center
Smart Work Zone Deployment Initiative
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Praveen Edara

University of Missouri-Columbia

Co-Principal Investigator
Henry Brown

University of Missouri - Columbia

Co-Principal Investigator
Carlos Sun
Student Researcher(s)
Yohan Chang

About the research

Traditionally, traffic impacts of work zones have been assessed using planning software such as Quick Zone, custom spreadsheets, and others. These software programs generate delay, queuing, and other mobility measures but are difficult to validate due to the lack of field data necessary for validation. One alternative approach for assessing the travel time impacts of a work zone is through data mining. Historical data of travel times observed during work zones and normal conditions can be used for work zone planning and scheduling.

This project developed a prototype tool using historical data for work zones in the St. Louis region in Missouri. Data from 782 work zones on I-70, I-270, and MO 141 that occurred between January 2014 and October 2015 were used. Several data sources were utilized in this project. These included electronic alerts of work zone information such as start and end times, location, lane closure information, and travel times. Spatially, the data included the work zone segment, two upstream segments, and all segments within a 2-mile radius of the work zone. Two delay measures were used for quantifying impact of work zones on freeway segments: travel time delay based on historical average travel times for the segment and travel time delay based on historical 15th percentile travel time values.

A model was developed to estimate travel times for planned work zones at sites that may not have sufficient historical work zone data. The Random Forests technique was used to develop the model. Separate models were developed for interstate and arterial work zones using historical travel times and speed profiles, work zone and upstream segment lengths, lane closure information, and work zone schedule. The predicted travel times were then utilized to compute delays. A prototype of the data-driven traffic assessment tool was developed. The predicted travel times for both interstate and arterial work zones were within 5% error.

For demonstration purposes, the scope of the prototype was limited to two interstate corridors and one arterial corridor. The tool uses four types of input information: work zone location, roadway direction, work zone duration, and work zone type and lane closure information. The tool then uses this information to mine the historical data to identify any work zones that occurred at the same location in the past. If a match is found, the historical data is utilized to generate the expected delay measures. If a match is not found, the Random Forests prediction model is used to generate the expected delay measures.


Funding Sources:
Midwest Transportation Center
Smart Work Zone Deployment Initiative ($50,003.00)
University of Missouri – Columbia ($13,374.00)
USDOT/OST-R ($84,158.00)
Total: $147,535.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

In-Progress

START DATE

09/30/13

END DATE

08/31/17

RESEARCH CENTERS InTrans, CTRE, MTC
SPONSORS

Midwest Transportation Center
Missouri Department of Transportation
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Glenn Washer

University of Missouri - Columbia

About the research

This research studies a bridge in Kansas City, Missouri that was constructed in 1959 but never opened to traffic to assess its deterioration and compare results from different nondestructive testing methods.


Funding Sources:
Midwest Transportation Center
Missouri Department of Transportation ($58,271.00)
University of Missouri – Columbia ($12,988.00)
USDOT/OST-R ($83,009.00)
Total: $154,268.00

Contract Number: DTRT13-G-UTC37

Project Details
STATUS

Completed

START DATE

09/01/14

END DATE

12/31/16

RESEARCH CENTERS InTrans, CTRE, MTC
SPONSORS

Midwest Transportation Center
Missouri Department of Transportation
University of Missouri - Columbia
USDOT/OST-R

Researchers
Principal Investigator
Carlos Sun
Co-Principal Investigator
Praveen Edara

University of Missouri-Columbia

Co-Principal Investigator
Charles Nemmers

MTC Lead, University of Missouri - Columbia

Co-Principal Investigator
Bimal Balakrishnan

About the research

The J-turn, also known as restricted crossing U-turn (RCUT) or superstreet, is an innovative geometric design that can improve intersection safety. Even though this design has been in use in several states for many years, there is very little research-based guidance for several design parameters.

A driving simulator study was conducted to analyze the parameters of lane configuration, U-turn spacing, and signage. Two lane configurations were examined: 1) acceleration/deceleration configuration where acceleration and deceleration lanes are provided and 2) deceleration only configuration where only deceleration lanes are provided.

Lane configuration was found to be the most important parameter affecting J-turn safety based on speed differentials. The only significant interaction effect among parameters was between lane configuration and U-turn spacing. The acceleration/deceleration configuration performed better than the deceleration only configuration with 66.3 percent fewer safety critical events. Vehicle trajectories and average lane-change locations showed that U-turn spacing impacted significantly the acceleration/deceleration configuration (i.e., average merge locations changed by 96 to 101 percent), but not the deceleration only configuration. No strong preference was demonstrated by the study subjects for either the directional or the diagrammatic signage style.

This project represents the first human factors study of the J-turn focused on developing design guidance. This human factors approach complements other traditional approaches such as crash analysis and micro-simulation.


Funding Sources:
Midwest Transportation Center
Missouri Department of Transportation ($99,207.00)
University of Missouri – Columbia ($69,272.00)
USDOT/OST-R ($99,965.00)
Total: $268,444.00

Contract Number: DTRT13-G-UTC37

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