Search results

The fatigue problems of the carriageway slabs of reinforced concrete rib-beam bridges were studied. The analysis of the carriageway slabs could not achieve the actual stress state.

Based on this characteristic, the reinforced concrete T-beam group structure system was taken as the research object. Four scale models of the carriageway slabs of reinforced concrete ribbed bridges were designed. The fatigue failure modes and actual fatigue resistance of the carriageway slabs with different length-to-side ratios were systematically studied through static load and fatigue experiments. Based on this, the concrete damage plasticity model (CDP model) was combined with numerical simulation analysis to study the influence of the length-to-short-side ratio of the carriageway slab on the fatigue performance and the remaining bearing capacity.

The results show that the fatigue failure of the carriageway slab is a three-stage failure; the ratio of the long and short sides has a significant effect on the fatigue performance of the carriageway slab. Under the same fatigue load level, the smaller the ratio of the long and short sides of the carriageway slab.

The fatigue resistance of the unidirectional board is significantly lower than that of the bidirectional board. It is recommended to use the bidirectional board in actual engineering design.

The effects of fatigue load level and plate thickness on the fatigue performance of reinforced concrete T-beam bridges.

Fatigue load tests were performed based on the fatigue damage theory of reinforced concrete, combined with finite element model analysis. The other conditions are controlled separately, and the fatigue performance of the T-beam bridge carriageway slab under different fatigue load levels and different plate thicknesses is studied.

The fatigue process of the carriageway slab of a reinforced concrete T-beam bridge is divided into three stages: fatigue damage generation, fatigue damage development and fatigue failure. Under certain other conditions, as the fatigue load level increases, the fatigue damage of the carriageway slab accelerates; as the thickness of the carriageway slab increases, the fatigue resistance of the carriageway slab improves.

Tests and simulations have been carried out, but have not been applied to actual engineering for the time being.

Increasing the thickness of the carriageway slab in actual engineering is conducive to improving the fatigue performance of the bridge, and heavy-duty traffic has a greater impact on the durability of the bridge.

It has certain reference value for bridge design, inspection and subsequent maintenance and reinforcement.

The originality of this article lies in designing and carrying out static and cyclic load tests separately, while introducing material damage models based on a large number of references and combining finite element analysis to consider the impact of a specific factor on fatigue performance. The test and analysis results can provide reference for bridge design and inspection.

Automated condition surveys have been recently introduced for condition assessment of highway infrastructures worldwide. Accurate predictions of the current state, median life (ML) and future state of highway infrastructures are crucial for developing appropriate inspection and maintenance strategies for newly created as well as existing aging highway infrastructures. The paper aims to discuss these issues.

This paper proposes Markov Chain based deterioration modelling using a linear transition probability (LTP) matrix method and a median life expectancy (MLE) algorithm. The proposed method is applied and evaluated using condition improvement between the two successive inspections from the Surface Condition Assessment of National Network of Roads survey of the UK Pavement Management System.

The proposed LTP matrix model utilises better insight than the generic or decoupling linear approach used in estimating transition probabilities formulated in the past. The simulated LTP predicted conditions are portrayed in a deterioration profile and a pairwise correlation. The MLs are computed statistically with a cumulative distribution function plot.

The paper concludes that MLE is ideal for projecting half asset life, and the LTP matrix approach presents a feasible approach for new maintenance regime when more certain deterioration data become available.

Purpose – Measures aimed at reducing intersection crashes have high potential to be cost effective since intersections constitute only a small part of the overall highway system but intersection-related crashes constitute more than 50% of all crashes in urban areas and over 30% in rural areas. Roundabouts are a proven safety countermeasure, but several issues that significantly affect both crash frequency and severity have been observed at both existing and new roundabouts. This chapter aims to provide guidance on roundabout selection and design criteria.

Methodology – The chapter first describes the most relevant criteria to be considered for choosing a roundabout. Then, after the explanation of the roundabout design process and a clear description of the roundabout classification, the chapter provides recommendations for all the steps of the geometric design, highlighting the main design features that contribute to the best safety performances, including speed control and sight distance checks. Finally, the chapter explains traffic control devices and facilities for pedestrians and cyclists.

Findings – Roundabout design needs to balance opposing demands and it is important to adopt a performance-based design approach within an iterative process. The most important performance check is the analysis of vehicle speeds through the roundabout, since achieving appropriate vehicular speeds has a very positive safety effect.

The paper considers the application of neural networks to model driver decisions to change lane on a dual carriageway road. The lane changing process is treated as consisting of two decisions, namely motivation and opportunity. Separate backpropagation neural networks are applied to represent each of the two decisions. The trained motivation and opportunity neural network models are linked to produce a layered network which represents the complete lane changing process. Separate models are developed to represent the nearside to offside lane changing decision, and the offside to nearside lane changing decision. This paper describes the development of the model of the nearside to offside lane changing decision.

For model development, data were collected from several subject vehicle drivers. The results are presented and the implications considered. Selected data were applied to train the neural networks and then an independent subset of data were used to assess performance. When the complete nearside lane changing neural network model was presented with the unseen test examples, 93.3% of the examples were correctly predicted as a lane change or no lane change. These results are shown to be a considerable improvement on those obtained previously.

February 10, 1969 Master and Servant — Negligence — Safe system of work — Roadworks — Workman in gang resurfacing carriageway injured by lorry driving too fast — Warning signs in position — Whether employers negligent in not erecting barriers against passing traffic — No evidence of common practice of erecting barriers — Effect of suggested barriers to reduce traffic to one lane — Need to balance public interest against risk to workers on carriageway — Whether lorry wholly to blame.

The purpose of this paper is to propose PlaceMaker as a method of urban analysis and design which both detects elements that do not feature in traditional mapping and which constitute the contemporary identity of the places, and identifies appropriate project interventions. In order to illustrate the method's potential, the final results of experimentation carried out in the Ramblas in Barcelona are presented.

The proposed method gathers, processes and reconstructs the data deriving from nominal, perceptual, graphic, photographic and video surveys, and compares these data with those provided by an analysis of expectations, an analysis of traditional cartography and two questionnaires administered to local inhabitants. The information collected during the phases of analysis constitutes the basis for constructing guidelines for sustainable design and planning. Two final complex maps – the first of analysis and the second of design – respectively, represent the identity of places and project interventions.

The design orientations took into account liveability, place identity, safety of this place and user preferences in order to mitigate the impact of globalization and achieve sustainable urban development. The experiment shows that the urban identity emerging in the analysis phases is not entirely sustainable: many factors are contributing to transforming it not only through changes in places, but also in habits and perceptions of the huge flow of people who use the Ramblas. The actions proposed are thus designed to enhance the identity of places, albeit not crystallizing it.

PlaceMaker is an original method which is intended for use as a support tool in integrated sustainable project design targeting place identity and as a tool for dynamic and complex place knowledge. The main potential beneficiaries are administrators, urban planners and designers and, in simplified form, citizens, tourists and place users.

Purpose – This chapter reviews planning and design approaches for cycle traffic in order to direct future thinking towards the critical aspects of network design that will have a beneficial impact on the utility and nature of the environment for cycling.

Approach – This chapter provides a critique of the approach of adopting a so-called hierarchy of solutions frequently adopted in western countries with low levels of cycling use.

Findings – The guiding principle for designing routes for cycle traffic is that the bicycle is a vehicle capable of speed and, as a consequence, links and junctions need to be designed according to appropriate geometric design standards. In addition, owing to the nature of the cycle and rider combination, the oft repeated Dutch characteristics for good design for cycle traffic of coherence, directness, attractiveness, safety and comfort remain firm.

Practical implications – The practical implications of the outcomes from the chapter are a method of approach for planning infrastructure for cycle traffic which starts with an analysis of demand and works through to the creation of suitable networks for cycle traffic which are grounded in, and extended from, suitably regulated existing highway networks.

Social implications – An extensive transport system suitable in nature for cycle traffic will attract a wide base of users and consequently allow for the benefits of cycling to be captured.

Value of chapter – The value of the chapter rests in its emphasis on the need to treat cycling as a distinct transport mode and, consequentially, planning and engineering needs to be undertaken in a way conducive to providing the basic necessary infrastructure for such a distinct mode.

The purpose of this paper is to propose and confer a strategic cost model as a concept for good decision making for highway asset treatment in the transport industry.

The paper is based on asset performance condition and treatment renewals using a five-point performance for developing prospective treatment strategies. The strategic cost model is presented in the similitude of picturesque and its outcomes via an exploratory data analysis.

The results articulate the best maintenance plan for the forthcoming and future years. The strategic cost model uses the combination of the current condition band, the sample area and likely treatment cost for proposing the optimal treatment solution based on consideration of desired treatment level.

The strategic cost model is suitable for outlining the asset performance condition, treatment renewals and analytical cost optimisation. The formulated analytical cost model and developed prospective strategies enable good decision making, long-term contract negotiations and whole life cost maintenance and management.

Embracing eminent performance condition from the research area of lifecycle planning and deterioration models of a physical asset, a prospective cost strategy for asset maintenance is proposed in the study. The resultant treatment strategies using the analytical approach portray the ability that enables the adaptation of expected outcomes.