Effects of Permafrost and Seasonally Frozen Ground on the Seismic Response of Transportation Infrastructure Sites

INE/AUTC 11.0

Right-turn Traffic Volume Adjustment in Traffic Signal Warrant Analysis

An intersection with heavy right-turn volumes, without any reduction, might mislead a signal warrant analysis, and a different conclusion may be reached on whether a signal is warranted. Previous right-turn volume reduction methods based mostly on engineering judgment lack specific theoretical backgrounds. Therefore, this paper proposes a new method with theoretical justification. The method focuses on traffic operation principles centered on finding the delay equivalent relationship between right-turn and through traffic, that is, to equate the right-turn volume to through vehicles to produce the same control delay on a minor street. Equivalent factor tables were constructed on the basis of four geometric configurations. Combining with the various traffic volume distributions, more than 12,000 scenarios were analyzed. The volume ratio in the two directions of the main street was especially considered. The analysis showed that the uneven volume distribution in the main street had a greater effect on the minor-street right-turn movement. To use the equivalent factors efficiently, statistical regression models were developed. Last, the proposed method was applied to one signal warrant case and demonstrated promising results for its practical application in traffic signal warrant analysis

Seismic analysis of motorway bridges accounting for key structural components and nonlinear soil-structure interaction

The paper introduces an efficient methodology to analyze the seismic performance of motorway bridges. Rigorous 3D models of a typical overpass bridge are developed and used to assess the efficiency of the proposed method. Fixed-base conditions are initially considered to focus on the effect of key structural components. The proposed simplified model is composed of a SDOF system of a pier with lateral and rotational springs and dashpots connected at the top, representing the deck and the abutment bearings. Its definition requires section analysis of the pier, and computation of spring and dashpot coefficients using simple formulas. It is shown that the lateral and rotational restraint provided by the deck and the abutment bearings is not at all negligible and should be taken into account. The simplified model is extended to account for nonlinear soil-structure interaction, replacing the soil-foundation system with horizontal, vertical, and rotational springs and dashpots. While the horizontal and vertical springs and dashpots are assumed elastic, the nonlinear rotational spring is defined on the basis of non-dimensional moment-rotation relations. The simplified model compares well with the full 3D model of the bridge-abutment-foundation-soil system, and is therefore considered a reasonable approximation.</p

The effect of cycle lanes on the proximity between motor traffic and cycle traffic

An experiment collected proximity data of motor traffic overtaking cycle traffic on roads with and without cycle lanes using an instrumented bicycle. The work enhances previous research which has considered the riding position of the cyclist and whether or not the cyclist was helmeted, while controlling for vehicle type. The analysis shows that significantly wider passing distances are adopted by motorists in the condition without a 1.45 metre cycle lane, with posted speed limits of 40mph and 50mph with a 9.5 metre wide carriageway. These findings were not replicated for a similar width road with a posted speed limit of 30mph and a 1.3 metre cycle lane. The results suggest that in the presence of a cycle lane, drivers may be driving within the confines of their own marked lane with less recognition being given to the need to provide a comfortable passing distance to cycle traffic in the adjacent cycle lane

Performance-Based Seismic Design and Assessment of Bridges

Current trends in the seismic design and assessment of bridges are discussed, with emphasis on two procedures that merit some particular attention, displacement-based procedures and deformation-based procedures. The available performance-based methods for bridges are critically reviewed and a number of critical issues are identified, which arise in all procedures. Then two recently proposed methods are presented in some detail, one based on the direct displacement-based design approach, using equivalent elastic analysis and properly reduced displacement spectra, and one based on the deformation-based approach, which involves a type of partially inelastic response-history analysis for a set of ground motions and wherein pier ductility is included as a design parameter, along with displacement criteria. The current trends in seismic assessment of bridges are then summarised and the more rigorous assessment procedure, i.e. nonlinear dynamic response-history analysis, is used to assess the performance of bridges designed to the previously described procedures. Finally some comments are offered on the feasibility of including such methods in the new generation of bridge codes

A Trialectic Framework for Large Group Processes in Educational Action Research: The Case of Academic Development for Syrian Academics in Exile

The term ‘large group process’ (LGP) refers to a range of participatory approaches to community engagement, geared towards exploring and/or identifying solutions to shared issues and problems, and planning change. Primarily used for applied purposes, they can be also used as a method of inductive inquiry in social research, particularly within action research projects. In this methodological paper I outline and critically evaluate an LGP design implemented within an action research project focused on the needs of Syrian academics in exile. The LGP elicited multi-level data from a geographically-dispersed community, while simultaneously constituting a relational learning experience and community action event for the participant population, and therefore aligned with the threefold aims of educational action research. The paper makes three significant contributions: a model for LGP design that elicits participants’ collective and individual meaning frames; a trialectic framework for ensuring that the research, action and learning aspects of educational action research projects are mutually-supporting; and an accompanying orientation to researcher-participant relationships that may help to enhance the epistemological validity, catalytic validity and ethical foundations of projects

DESIGNING PORT INFRASTRUCTURE FOR SEA LEVEL CHANGE: A SURVEY OF U.S. ENGINEERS

Seaports are particularly vulnerable to the impacts of climate change due to their coastal location. With the potential threat of up to 2.5m in sea level rise by 2100, resilient port infrastructure is vital for the continued operation of ports. There are strong economic and social incentives for seaports to provide long-term resilience against climate conditions. For example, service disruptions can cost billions of dollars and impact the livelihoods of those who depend on the port. Engineers play a pivotal role in improving the resilience of ports, as they are responsible for designing port infrastructure that will be adequately prepared for future sea level change (SLC). However, incorporating SLC is a challenging task due to the uncertainty of SLC projections, the long service lives of port infrastructure, and the differing guidelines and recommendations for managing SLC. Through an online survey of 85 U.S. port and marine infrastructure engineers, this research explores the engineering community’s attitude and approach to planning for SLC for large-scale maritime infrastructure projects. Survey findings highlight the extent that projects incorporate SLC, the wide range of factors that drive the inclusion of SLC, and the numerous barriers that prevent engineers from incorporating SLC into design. This research emphasizes that traditional engineering practices may no longer be appropriate for dealing with climate change design variables and their associated uncertainties. Furthermore, results call for collaboration among engineers, port authorities, and policy makers to develop design standards and practical design methods for designing resilient port infrastructure

The mortality impact of bicycle paths and lanes related to physical activity, air pollution exposure and road safety

© 2015 Elsevier Ltd. Objective: Guidelines for bicycle infrastructure design tend to consider safety issues but not wider health issues. This paper explores the overall health impact of bicycle infrastructure provision, including not just road safety impacts, but also the population health impacts stemming from physical activity as well as cyclists' exposure to air pollution. Data and methods: We have summarised key publications on how bicycle paths and lanes affect cyclists' exposure to physical activity, air pollution, and road safety. The health impact is modelled using all-cause mortality as a metric for a scenario with new bicycle lanes and paths in a hypothetical city. Results: The outcomes of the study suggest that, based on currently available research, a reduction of all-cause mortality is to be expected from building bicycle lanes and paths along busy roads with mixed traffic. Increased physical activity through more time spent cycling is the major contribution, but is also the most uncertain aspect. Effects related to air pollution and cycling safety are likely to reduce mortality but are small. The overall benefits are large enough to achieve a high benefit-cost ratio for bicycle infrastructure. Conclusions: The introduction of bicycle paths and lanes is likely to be associated with health benefits, primarily due to increased physical activity. More research is needed to estimate the absolute size of the health benefits. In particular, evaluations of the effects of bicycle infrastructure on time spent cycling are limited or of insufficient quality to infer causality. We recommend before-after studies measuring the effects of different interventions and in areas representing a wide range of base levels of cycling participation