Institute for Transportation

About the research

Static soil shear strength parameters in the form of friction angle and cohesion are required inputs for the safe design of foundations and earth retaining structures for virtually all transportation infrastructure including bridges, buildings, railways, wharves, piers, ports, tunnels, and pavements. Additionally, measuring the dynamic and cyclic behavior of soil in terms of stress-strain hysteresis loops as well as the associated evolution of pore water pressure is important for obtaining modulus and damping parameters for seismic design, determining post-cyclic strength, and liquefaction susceptibility analysis. These soil parameters are typically obtained by retrieving soil samples and testing them in the laboratory, which is time-consuming, expensive, and the results are sensitive to sample disturbance. Alternatively, the shear strength parameters may be estimated using empirical correlations to in situ penetration tests such as the Standard Penetration Test (SPT) or Cone Penetration Test (CPT). However, neither of these tests directly measure the shear strength of soil and instead rely upon empirical correlations that can be imprecise due to large statistical variability. Furthermore, the SPT and CPT do not subject the soil to repeated continuous cyclic loading conditions like those imposed by earthquakes or vibration sources. The goal of this project was to develop a new in situ testing device that could measure static and dynamic soil properties in the soil’s natural setting, with less sample disturbance and requiring less time than laboratory tests.

In this project, a Cyclic Borehole Shear Test (CBST) device was developed to enable the rapid in situ measurement of cyclic behavior and monotonic shear strength properties of soil. Based on the results of several field testing trials, numerous refinements and modifications were made to the system including the physical testing apparatus inserted into the borehole, the electronic and pneumatic measurement and control system, and the software control program. Comparisons of field test results to those of conventional laboratory tests demonstrated that the device can measure meaningful cyclic behavior of soil in situ. Further research will be pursued to more rigorously relate the measured displacements from the device to shear strains in the soil surrounding the borehole, and to study applications of the device to in situ measurement of the liquefaction behavior of soils. With further research, the device thus has the potential to fundamentally transform the presently empirical techniques used in practice for assessment of soil liquefaction resistance into a more mechanistic physics-based framework.

About the research

The objective of this research was to identify best practices and prepare guidelines for state departments of transportation (DOTs) on how to evaluate and charge for the accommodation of utility and communication installations on public right-of-way (ROW). The guidelines include a comparison of fees, leasing, and in-kind trading used by a majority of state DOTs. Reasons for the variance in fees, valuation methods, and other factors were analyzed to explain the variation in approaches taken by state DOTs and standardized and normalized so that the comparisons are evaluated in like terms. The guidance should provide state DOTs the means and approaches necessary to execute a fee or leasing schedule for occupancy both for general utilities and for telecommunications facilities.

About the research

The determination of the level-of-service (LOS) at signalized intersections is an important activity for decision-making in the allocation of resources for managing public roads, estimating the impact of new developments, and designing signal timing plans. The Highway Capacity Manual (HCM) methodology for signalized intersections is the most widely used method of estimating the LOS. The core of this methodology is a delay equation that takes as its inputs the demand volumes for various movements at an intersection, the signal timing, and other parameters related to the configuration of the intersection.

For right-turn movements, the current HCM methodology instructs users to obtain field measurements of the right-turn-on-red (RTOR) flow rate or else to assume that all of the right-turning vehicles execute the movement during the green interval. A consequence of this is that the estimated delay for the right-turn movement is likely overestimated. Other estimated quantities related to characteristics of the right-turn movement, such as the pedestrian delay, are also likely to be inaccurate. Furthermore, the scenario of dual right-turn lanes has not received much attention in previous studies.

The main products of this research are the models, which are documented in the report and in this summary. In addition, a practitioner guide was developed that contains documentation of the models along with a spreadsheet tool to provide sample calculations. Additionally, the RTOR volume calculations have been integrated into the HCM Computational Engine. The practitioner guide also includes a synthesis of guidance on whether to permit RTOR at a given location. In addition, during the course of this research a survey was distributed to develop an understanding of current practice with regard to RTOR. The survey results are presented in this report.

About the research

Connected and autonomous vehicle (CAV) technologies hold the potential to produce a number of safety, mobility, and environmental benefits for the users and operators of the nation’s surface transportation system. The benefits of connected vehicle technologies are expected to be wideranging and apply not only to roadway users but also transportation agencies. These benefits include reduced crashes, improved mobility, lower emissions, a reduced need to construct roadway infrastructure (fostered by mobility improvements), among others. However, the advent of a fully-integrated CAV system is not expected to come online for at least 20 years due to turnover in the existing vehicle fleet. As a result, infrastructure will need to be maintained for human drivers as well as CAVs for some time. Additionally autonomous vehicle (AV) technology is being developed by private industry regardless of the state of current infrastructure. As such, AV technology is heavily based on 360 degree awareness in close proximity of the vehicle and not heavily integrated with the provided infrastructure. Yet, demonstrations by the U.S. Department of Transportation (USDOT) and others have shown that significant benefits to safety will require that AV technology operate with connectivity between vehicles, based on the basic safety message (BSM), and communications with roadside infrastructure.

The USDOT publication and outreach in deploying Preparing for the Future of Transportation: Automated Vehicle 3.0 makes it very clear that the federal government’s role will focus on vehicle safety and will not employ blanket regulation, which makes the likely progression of vehicle technology driven by cost of vehicle turnover for private owners and market forces for shared vehicle owners/operators.

The need to maintain a dual system that serves regular drivers and CAVs for some time to an acceptable level of service coupled with uncertainty in the direction of CAV technology creates an additional maintenance burden for agencies who already have constrained workforces and budgets. Compounding this is that changing maintenance needs will require a different set of workforce skills than is currently available in most transportation agencies.

About the research

Construction Manager/General Contractor (CMGC) project delivery is an integrated team approach to the planning, design, and construction of a highway project, to control schedule and budget, and to assure quality for the project owner. The team consists of the owner, the designer, which might be an in-house engineer, and the at-risk construction manager. The aim of this project delivery method is to engage at-risk construction expertise early in the design process to enhance constructability, manage risk, and facilitate concurrent execution of design and construction without the owner giving up control over the details of design as it would in a design-build project. The objective of this research is to address the needs for CMGC guidance for evolving alternative project delivery methods. The research documents the results of a survey of state DOTs (response rate of 84 percent), a content analysis of 50 CMGC solicitation documents, and 10 case studies of CMGC projects. The research yielded a set of CMGC delivery models that are specifically adapted for DOT projects, not a regurgitation of the models in use in vertical construction. The models are described in a Guidebook for initiating and implementing a CMGC project delivery system for highway projects at transportation agencies.

About the research

About the research

The objective of this research is to develop a guide for transportation practitioners that describes and evaluates the safety benefits, as shown by driver performance or other methods, of retroreflective pavement markers (RPMs), both raised and recessed, for nighttime driving, particularly during wet weather.

See the NCHRP project page for more information.

About the research

The objective of this research is to develop guidelines to improve the quality of element-level data collection for bridges on the National Highway System (NHS) in reference to the AASHTO Manual for Bridge Element Inspection.

Funding Sources:
Midwest Transportation Center
National Cooperative Highway Research Program (NCHRP) ($120,000.00)
USDOT/OST-R ($120,000.00)
Total: $240,000.00

Contract Number: DTRT13-G-UTC37

About the research

Many state and local agencies collect downward pavement imagery using highway-speed data collection vehicles. The images are subsequently processed using proprietary semi- or fully-automated crack detection and classification software to identify pavement cracking for use in asset management systems. There are multiple methods and software for defining, classifying, and reporting cracking data. In addition, these methods and the cracking data they produce are not always comparable between states, even if similar data collection and detection technologies are used. One outcome of this situation is that vendors must customize the cracking definitions for each client they serve.

In order to unify data reporting, sharing, and evaluation, standardization of pavement cracking definitions is needed. Research is needed to define cracking measurement terms for uniformity and potential standardization, building upon work done in the American Association of State Highway and Transportation Officials (AASHTO) provisional protocol (PP) 67 and 68. Additionally, research is needed to produce user and system requirements to aid in the future development of production-grade evaluation software for classifying cracking type, extent, and severity. The standard definitions will aid in sharing information among agencies and vendors as well as reporting to the Federal Highway Administration (FHWA) and setting national, state, and local performance goals.

The objective of this research is to develop standard, discrete definitions for common cracking types in flexible, rigid, and composite pavements. The definitions shall classify cracking type, extent, and severity based on information from images collected by highway-speed data collection vehicles, including orientation, length, density, displacement, location, and other relevant factors. The standard definitions shall be used to facilitate comparable measurement and interpretation of pavement cracking in the highway community. The definitions shall be of sufficient detail to serve as the basis for user and system requirements for cracking evaluation software for automated data collection. Application to both existing and emerging image-based data collection technologies shall be considered.

About the research

Implementation of geotechnical asset management (GAM) offers a significant opportunity to improve the general geotechnical practice through the development of design and management approaches that require consideration of the tradeoffs between least risk and life-cycle costs. The product from this work must be an adaptable implementation manual with the necessary template tools for an agency to recognize the benefits of GAM.

The InTrans researchers are subject matter experts on this projects.

See the National Cooperative Highway Research Program (NCHRP) project page for additional information on this project.