Environmental traffic management — The end of the road?

This paper questions some aspects of the technical soundness and public acceptability of environmental traffic management scheme of the kind advocated in the Buchanan report, Traffic in Towns. Practical studies have shown that in inner city areas in particular, and perhaps older built-up areas in general, the concept cannot be adequately defended against a wealth of variety of criticism from those whom it most directly affects, i.e. the public. Participation exercises have revealed public fears that the road closures associated with schemes will ruin the viability of local shops, worsen the environmental conditions along local roads chosen as distributors, cause even greater congestion on the main road network due to displaced traffic, and impede the accessibility of local people to their homes. In the light of these, it is suggested a flexible policy be adopted incorporating changes to the forms of vehicles and the manner in which they are used as well as changes to the physical form of the road network.The opinions expressed in this paper do not necessarily reflect those of the organisations to which the authors are attached.     

Questioning the need for full amortization in PPP contracts for transport Infrastructure

PPP contracts most often have durations of between 20 and 35 years, but in some cases even longer. The main reason for this is the wish of the Public side to minimize its financial contribution, by including in the contract many years of revenue generation by the project to help cover the investment contribution of the private partner. Implicit however is the need to fully amortize the initial investment, which in many countries is even included in the relevant legislation.PPP contracts are normally framed around the delivery of a range of services during the lifetime of the contract, those services requiring the initial construction or recovery of an expensive infrastructure. The specification of the financial clauses of the contract requires the estimation of demand for those services over the period of the contract and this is usually taken as the major incidence of uncertainty in the contract. Indeed, experience shows that demand forecasts often fail substantially, in many cases by more than 20%, mostly by excess, as State side project promoters (and the bidding private partners) tend to be excessively optimistic about the development of such demand.But when we consider the nature of these contracts we should recognize the existence of at least two other very important types of uncertainty: first, the socially desirable scope and specification of the services to be offered as technology and social preferences evolve; and second, the policy guidelines relative to the total quantity and the social distribution of those services, as that quantity may be causing congestion in other parts of the system, or it may become important to (positively or negatively) discriminate some user segments.In both cases, it is almost impossible to foresee at the time of writing the initial contract if, when and in what direction such types of socially beneficial changes in the provision of the services would intervene, but this rigidness may bear a great loss of social welfare in relation to a more adjustable framework. This criticism affects not only PPPs but all kinds of concession contracts with long duration, so it is not the “partnership” element that must be questioned but rather the duration of the contract.An alternative way is relatively straightforward: abandon the assumption that these contracts must provide full amortization of the infrastructure, which allows adoption of contracts with a shorter life, and the use of multiple such contracts over the lifecycle of the infrastructure.The first generation contract would still have to face the full cost of the construction, but the private partner would receive the unamortized part at the end of that contract, to be paid by the State, directly from the public budget if no more private participation is wanted, or indirectly through the acquisition fee for the contract to be paid by the partner to the second life segment. But, crucially, the State recovers the right to re-specify the terms of the service to be provided without the need for any indemnity, and also the uncertainty associated with the evolution of demand in that period will be much smaller, as this will be my then a mature system in operation.This may seem to increase the transaction costs for the State as more contracts (although of a similar type, especially from the second onwards) may have to be negotiated and signed. But if we take into consideration the difficulties of the frequently needed renegotiations of long duration contracts and the conditions of asymmetry of information in which the State normally finds itself in such cases, we will conclude that, besides avoiding the loss of welfare due to the poor fit of the contract after 20 years or so, this solution after all may also reduce the transaction costs associated with negotiations over the duration of the traditional contracts.     

Are we doing it wrong or do we expect too much? Forces that push authorities to become public transport designers

This paper presents a number of reasons that are responsible for the disappointment of authorities in their operators’ efforts to develop public transport (PT) to the advantage of their travellers. The lessons drawn in this paper are based upon the competitive tendering experience of the authors and upon the results of meetings organised with parties involved in competitive tendering and aimed at exchanging lessons. There appears to be three main causes: (1) there is freedom for the operator, but the contract is bad; (2) there is freedom for the operator, there is a good contract, but there is no market; and (3) there is freedom for the operator, but the operator is not able to use it. The paper concludes with a few perspectives for improvement.     

A comprehensive analysis of household transportation expenditures relative to other goods and services: an application to United States consumer expenditure data

This paper proposes a multiple discrete continuous nested extreme value (MDCNEV) model to analyze household expenditures for transportation-related items in relation to a host of other consumption categories. The model system presented in this paper is capable of providing a comprehensive assessment of how household consumption patterns (including savings) would be impacted by increases in fuel prices or any other household expense. The MDCNEV model presented in this paper is estimated on disaggregate consumption data from the 2002 Consumer Expenditure Survey data of the United States. Model estimation results show that a host of household and personal socio-economic, demographic, and location variables affect the proportion of monetary resources that households allocate to various consumption categories. Sensitivity analysis conducted using the model demonstrates the applicability of the model for quantifying consumption adjustment patterns in response to rising fuel prices. It is found that households adjust their food consumption, vehicular purchases, and savings rates in the short run. In the long term, adjustments are also made to housing choices (expenses), calling for the need to ensure that fuel price effects are adequately reflected in integrated microsimulation models of land use and travel.     

Impact of biometric and anthropometric characteristics of passengers on aircraft safety and performance

Demand for commercial air travel has been increasing over the years and recent forecasts indicate similar future trends. New aircraft with enhanced design features are being built and entering the airline service globally. These enhancements aim to ensure continued safety, efficiency, performance and prolonged life serviceability. However, these new enhancements often neglect the impact of the changing anthropometric characteristics of the passenger. Past studies have identified increasing trends in the average weight, height and other anthropometrical and biometrical measures of people at a global scale. However, many are limited to only exploring the ramifications primarily from the perspective of passenger experience. This paper highlights the importance of considering passengers’ anthropometric characteristics from a holistic perspective and identifies gaps for future research.     

Application of Chinese Characters in the Design and Construction of the Badaling Great Wall Station of the Beijing-Zhangjiakou High-Speed Railway北大核心CSCD

The new Badaling tunnel is the longest tunnel on the under-construction Beijing-Zhangjiakou highspeedrailway, with the Badaling Great Wall station to be built in the tunnel. This station, which is under the Badaling Great Wall historic site, is the world’s largest underground high-speed railway station with the most complicated structure and the largest overburden and excavation area. It is therefore a representative project for China’s highspeed railway development strategy, supporting infrastructure facilities for the Beijing Horticultural Expo 2019 and the 2022 Winter Olympics in Beijing, and it is important that it be of high quality and completed safely. In the de-sign and construction of the station, the glyphs of the Chinese characters of "中",”国”,”人”and”品”are used, re-spectively, along the station route, in the rescue and evacuation mode, auxiliary adit and partial excavation, which is a way to successfully integrate the art of Chinese characters into tunnel engineering. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Construction Techniques for the Small-radius Curved Shield Tunnels in Water-rich Fractured Stratum with High Pressure北大核心CSCD

A variety of construction problems, such as bad cutting effects of cutters, unreasonable boring parame- ters and blowout, are often encountered during shield tunnelling under unfavorable geological conditions. Aimed at these construction difficulties of high pressure, abundant underground water, fractured rock stratum, long distance and small-radius curves of Fuzhou metro, the mechanical behaviors of cutting tools were analyzed through theoreti- cal calculations of cutter cutting force, then the reasonable cutter configuration, tunneling parameters and the proper time for cutter replacement were presented. Some measures, such as screw conveyor renovation, mucking control and lowering of groundwater, were adopted for controlling blowout based on practice. The stability of excavation face was analyzed by numerical simulation, and the measures for shield boring and posture control in the long distance and small radius curved tunnels were summarized. The conclusions are as follows: 1) when shield machine is driven in fractured stratum, the effect of lateral impact force produced by spalling rock on cutter will be very large and rein- forcement is needed for cutter; 2) cutter replacement should be taken at proper time based on muck samples in con- ditions of increasing of total shield thrust by 4 000-7 000 kN, cutter torque by 1 000-1 500 kN•m and driving speed smaller than 10 mm/min; 3) adopting screw conveyor device with innovative anti-blowout devices and control measures for ground precipitation and mucking, it controls blowout effectively; 4) the maximum axis offset and the height offset of segment meet the requirements of shield construction specifications during shield construction of long distance small-radius curved tunnel. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Influence of Light Distribution and Installation Style of Luminaires on Power Consumption and Lighting Effect of Tunnel Lighting北大核心CSCD

Light distribution (LD) and installation style of luminaires affect the utilization factor (UF) of luminaires, and the UF affects the luminaire power and road pavement illuminance and further the power consumption of illu- minating system and the luminous effect of road pavement. An UF model of tunnel lighting was established based on the luminaire LD data and installation parameters, in which four LD styles were adopted. For each LD the parame- ters optimization and simulation were conducted regarding four installation styles, e.g. central style, offset-of-vault style, symmetric style and staggered style. The energy-saving and the lighting effects of each LD and luminaire in- stallation style at the tunnel middle zone were studied. The results show that symmetric luminaire installation is the most energy-saving style and has the best lighting effect than the other three luminaire installation styles; the lighting effect of central luminaire installation is the second best; staggered luminaire installation is the most energy-intensive style and has the worst lighting effect except for some special-shaped LD; waterdrop-shaped LD is the most suitable one along transverse direction of tunnel and applicable to the central, offset-of-vault and symmetric luminaire instal- lation styles; symmetric butterfly-shaped LD is the most suitable one along longitudinal direction of tunnel and appli- cable to the central, offset-of-vault, staggered and symmetric luminaire installation styles; with waterdrop-shaped LD along transverse direction and symmetric butterfly-shaped LD along longitudinal direction, they are suitable for the above four luminaire installation styles, and have better energy-saving and lighting effect; as for the LD with symmetric and oblique curve, it’s better for the profile of oblique luminaire distribution to be comply with that along tunnel transverse direction, and it is suitable for the symmetric and offset-of-vault luminaire installation styles. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Temperature Measurements and Tail Brush Replacement using Frozen Liquid Nitrogen for the Nanjing Weisanlu Tunnel北大核心CSCD

A scheme for stopping water by freezing liquid nitrogen and replacing the tail brush is presented in light of the situation encountered at the Nanjing Weisanlu river-crossing tunnel, a long-distance shield driving tunnel characterized by serious water leakage, sand gushing and water inflow at the shield tail brush. The law of the tempera-ture change of the master outlet circuits and each branch circuit when using liquid nitrogen freezing to stop water un-der high water pressures and the temperature change law for the soil body at different depths are analyzed. The re-sults show that: the temperature difference of the liquid nitrogen is large at the inlet and outlet of the freezing pipe,and it reaches around 35℃ after 6 days; the temperature drops fastest in the pebble layer, and the second fastest in the gravel sand layer, with the temperature cooling slowest in the silty fine sand layer; the average velocities at the frontal surface of the frozen soil in the pebble layer, gravel sand layer and silty fine sand layer are 15.5 cm/d, 12.5 cm/d and 8.3 cm/d, respectively, within the range 600 mm away from the frozen pipe; and affected by heat and air convection in the tunnel, the temperature at the junction of the segment and soil is higher than that in the soil layer.A complete frozen wall takes shape after 13 days of liquid nitrogen freezing, and tail brush replacement takes 22 days from freezing. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Adapting to Catch Shares: Perspectives of West Coast Groundfish Trawl Participants

Abstract

Catch share programs are used in fisheries management to meet goals such as species recovery, overcapacity reduction, and economic efficiency. Anticipated impacts include fleet consolidation, infrastructure reduction, and social disruption within communities. The Pacific Coast Groundfish Fishery Social Study (PCGFSS) aims to understand social changes related to the recently implemented West Coast Groundfish Trawl Catch Share Program. In this article, we use a subset of PCGFSS data to explore the ways remaining fishery participants have thus far adapted to catch shares. While some vessels have left the fishery, we found that many participants are adapting to this catch shares program despite challenges. Quota leasing strategies, fishery diversification, gear innovation, and community quota funds are some of the tools participants are using to continue operating under the catch shares program. These early challenges and adaptations to the catch share program are worthy of continued tracking, as researchers, managers, and fishing communities, would benefit by considering first-hand perspectives of the on-the-ground realities of harvesting groundfish in the rationalized fishery.