Passenger transmission and productiveness of transit lines with high loads

Deterministic transit capacity analysis applies to planning, design and operational management of urban transit systems. The Transit Capacity and Quality of Service Manual (1) and Vuchic (2, 3) enable transit performance to be quantified and assessed using transit capacity and productive capacity. This paper further defines important productive performance measures of an individual transit service and transit line. Transit work (p-km) captures the transit task performed over distance. Passenger transmission (p-km/h) captures the passenger task delivered by service at speed. Transit productiveness (p-km/h) captures transit work performed over time. These measures are useful to operators in understanding their services’ or systems’ capabilities and passenger quality of service. This paper accounts for variability in utilized demand by passengers along a line and high passenger load conditions where passenger pass-up delay occurs. A hypothetical case study of an individual bus service’s operation demonstrates the usefulness of passenger transmission in comparing existing and growth scenarios. A hypothetical case study of a bus line’s operation during a peak hour window demonstrates the theory’s usefulness in examining the contribution of individual services to line productive performance. Scenarios may be assessed using this theory to benchmark or compare lines and segments, conditions, or consider improvements

Effects of countdown displays in public transport route choice under severe overcrowding

The paper presents a route choice model for dynamic assignment in congested, i.e. overcrowded, transit networks where it is assumed that passengers are supported with real-time information on carrier arrivals at stops. If the stop layout is such that passenger congestion results in First-In-First-Out (FIFO) queues, a new formulation is devised for calculating waiting times, total travel times and route splits. Numerical results for a simple example network show the effect of information on route choice when heavy congestion is observed. While the provision of information does not lead to a remarkable decrease in total travel time, with the exception of some particular instances, it changes the travel behaviour of passengers that seem to be more averse to queuing at later stages of their journey and, thus, prefer to interchange at less congested stations

Involvement of (pro)renin receptor in the glomerular filtration barrier

(Pro)renin receptor-bound prorenin not only causes the generation of angiotensin II via the nonproteolytic activation of prorenin, it also activates the receptor’s own intracellular signaling pathways independent of the generated angiotensin II. Within the kidneys, the (pro)renin receptor is not only present in the glomerular mesangium, it is also abundant in podocytes, which play an important role in the maintenance of the glomerular filtration barrier. Recent in vivo studies have demonstrated that the overexpression of the (pro)renin receptor to a degree similar to that observed in hypertensive rat kidneys leads to slowly progressive nephropathy with proteinuria. In addition, the handle region peptide, which acts as a decoy peptide and competitively inhibits the binding of prorenin to the receptor, is more beneficial than an angiotensin-converting enzyme inhibitor with regard to alleviating proteinuria and glomerulosclerosis in experimental animal models of diabetes and essential hypertension. Thus, the (pro)renin receptor may be upregulated in podocytes under hypertensive conditions and may contribute to the breakdown of the glomerular filtration barrier

Failure mechanisms in alloy of polyamide 6,6/polyphenylene oxide under severe conditions

Toughening mechanisms of a polyamide 6,6/polyphenylene oxide alloy containing an elastomer tested under a slow rate, an impact rate, and a low temperature have been investigated using various microscopy techniques. It is found that the toughening mechanisms of the alloy may change from crazing/shear yielding, to crack bridging/crazing, and to transparticle failure, depending on the testing conditions. Except for the low temperature high strain rate testing condition and in the plane stress region of the crack, the crazing mechanism has been observed in all the conditions we studied. When the testing rate is high, the shear yielding mechanism is suppressed; multiple crazing and particle bridging mechanisms appear to dominate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44700/1/10853_2004_Article_BF00557130.pd

Mechanical modeling of initiation of localized yielding under plane stress conditions in rigid-rigid polymer alloys

Two-dimensional Finite Element Method simulations, which involve consideration of the nonlinearity of a material, have been conducted to gain understanding about the rigid-rigid polymer toughening concept we proposed. The simulation results for the plane stress condition indicate that as long as the inclusion phase possesses (i) a 60% difference in the tangent modulus from that of the matrix at any given strain level prior to failure or (ii) smaller yield or craze stain than the yield strain of the matrix, then, localized shear yielding will occur around the inclusion. A toughened rigid-rigid polymer alloy system can then be obtained. The plain strain case is also discussed with an implementation of the rigid-rigid polymer toughening concept.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38110/1/760311106_ftp.pd

The effect of a new intercity expressway based on travel time reliability using electronic toll collection data

This study describes a method of evaluating the level of service of road networks, based on the average travel time and travel time reliability using electronic toll collection (ETC) data. The authors focused on the variance in travel time under normal circumstances, thus, traffic accidents were removed from the database, and any effect of individual vehicle preference was excluded. They evaluated the travel time distribution based on the average travel time from ETC data for each 15-min interval. The level of service in an actual intercity highway network was analysed using the proposed method. This analysis showed that the level of service fluctuated according to the road section analysed, the month and the time of day. These findings were confirmed by the shape of the cumulative distribution and indices of average travel time and travel time reliability. Using the evaluation method described here, the analysis also confirmed the change in travel time distribution between major interchanges after the opening of a new intercity highway route. As a great change in the traffic conditions occurred, the authors analysed the relationship between traffic demand and the level of service using detector data

High load transit line passenger transmission and productiveness efficiencies

Performance of urban transit systems may be quantified and assessed using transit capacity and productive capacity in planning, design and operational management activities. Bunker (4) defines important productive performance measures of an individual transit service and transit line, which are extended in this paper to quantify efficiency and operating fashion of transit services and lines. Comparison of a hypothetical bus line’s operation during a morning peak hour and daytime hour demonstrates the usefulness of productiveness efficiency and passenger transmission efficiency, passenger churn and average proportion line length traveled to the operator in understanding their services’ and lines’ productive performance, operating characteristics, and quality of service. Productiveness efficiency can flag potential pass-up activity under high load conditions, as well as ineffective resource deployment. Proportion line length traveled can directly measure operating fashion. These measures can be used to compare between lines/routes and, within a given line, various operating scenarios and time horizons to target improvements. The next research stage is investigating within-line variation using smart card passenger data and field observation of pass-ups. Insights will be used to further develop practical guidance to operators

Absorbing Markov Chain approach to modelling disruptions in supply chain networks

Recent developments in the area of network science has encouraged researchers to adopt a topological perspective in modelling Supply Chain Networks (SCNs). While topological models can provide macro level insights into the properties of SCN systems, the lack of specificity due to high level of abstraction in these models limit their real-world applicability, especially in relation to assessing the impact on SCNs arising due to individual firm or supply channel level disruptions. In particular, beyond the topological structure, a more comprehensive method should also incorporate the heterogeneity of various components (i.e. firms and inter-firm links) which together form the SCN. To fill the above gap, this work proposes using the idea of absorbing Markov chains to model disruption impacts on SCNs. Since this method does not require path enumeration to identify the number of supply chains which form the SCN, it is deemed more efficient compared to the other traditional methods