Dynamics and Processes in Operations Control Centers in Urban Public Transport: Potentials for Improvement

Disruptions in public transport operations occur every day. Thus, providing a reliable system is a challenge for operations and planning. This paper gives insights into the dynamics and processes of operations control centers in public transport to reveal potentials for further improvement in reliability. Therefore, directors were interviewed, dispatchers observed, and operations documentation was studied. It has become obvious that the process of dispatching has four different types of call signals (assault, accident, missing replacement, and wish-to-talk) corresponding to different kinds of incidents. The drivers use those call signals to contact the operations control center and initialize different procedures of communication between the dispatchers, drivers, and other involved parties. As the communication is mostly conducted via phone or radio, several improvements are possible, such as training in communications and increased use of information technology in operations. In planning tools, the handling of incidents is marginally supported. As all kinds of incidents can affect the service, they should be represented in planning tools to design more reliable public transport systems. However, they do not need to be represented in full detail. Verbal communication could mostly be reduced to single decisions. Accidents, for example, influence the operation by delayed vehicles and blocked ways. The findings of this work allow a better understanding of operations control centers and reveal their potentials for improvement

Simulative Wirkungsuntersuchung eines Kolonnenassistenten auf die Kapazität der Fernstraßeninfrastruktur

Der Kolonnenassistent ist ein sich in der Entwicklung befindliches Fahrerassistenzsystem. Neben Einsparungen von Kraftstoff und Emissionen, sowie einer gesteigerten Verkehrssicherheit, wird sich auch eine Steigerung der Kapazität auf Fernstraßen erhofft. Die vorliegende Masterarbeit beschäftigt sich mit dieser Kapazitätssteigerung und untersucht diese durch entsprechende Verkehrssimulationen

State of the art of passenger redirection during incidents in public transport systems, considering capacity constraints

This paper gives a comprehensive insight into the investigations done in passenger redirection during incidents in public transport systems. In public transport operations, incidents such as traffic accidents, deployment of emergency forces, or technical failures happen every day and disrupt the service. Most of the investigations done in the field of incident management focus on the readjustment of the supply towards the incident situation and are therefore referred to as supply-centric part of incident management. However, especially in recent years, more and more investigations have also been done on the passenger-centric part of incident management. These rather focus on the effects of incidents on passengers or even include them in the solution of the incident situation, either by informing them adequately about the given situation (passive redirection) or by providing them with concrete path advice (active redirection). The results show that adequate passenger information during incidents can reduce the average delay of affected passengers and support the recovery of the public transport system. This improves the reliability of a public transport system and boosts its attractiveness

Transport and emissions of gaseous air pollutants in a high-traffic urban street canyon 

&amp;lt;p&amp;gt;Urban air quality directly determines urban quality of life. To improve it, we need to know about local emissions, chemical transformations, and transport processes of the energy-containing vortices in the air. The combination of high-resolution ultrasonic anemometers and state-of-the-art vortex-resolving Large Eddy Simulation (LES) technique is a powerful key tool enabling this understanding. Here, we investigated the dynamics and transport of air with particular focus on nitrogen dioxide (NO&amp;lt;sub&amp;gt;2)&amp;lt;/sub&amp;gt; in a highest-traffic street canyon with eight driving lanes in the urban setting of the city of Munich, Germany. Using spatially distributed observations and results from flow-resolving simulations, temporally and spatially resolved patterns and trends of airflow and pollutant concentrations are presented. The airflow conditions in the wide (approx. 80m) urban street canyon are largely decoupled from the synoptic flow over the city. The street is mostly characterized by a channeled, northerly current and weak wind speeds and turbulence kinetic energy (TKE) during the day, independent of prevailing synoptic forcing conditions. At night, the channeled current shifts to southern flow and reverses back to northerly winds in the early morning transition. One exception to this rule are infrequent synoptic easterly flows perpendicular to the street canyon orientation, which lead to a deflection of the flow by the building fronts and a flow reversal to westerly flows at the street level. In this case, TKE is strongly enhanced, and pollutant concentrations are low due to enhanced mixing and inflow of less polluted above-city air. Emission coefficients from the Handbook for Emission Factors for Road Transport (HBEFA) have been used in combination with traffic demand data from loop detectors to compute the respective NO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emissions. These emissions show daily peaks in the morning and afternoon hours, and a significant differentiation between weekday, Saturday, and Sundays with less traffic. The individual lanes also differentiate in amount of emission. Linking the results from the point turbulence and NO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; measurements with the LES approach helps to understand the turbulent air transport and NO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; in parts of the street canyon where no observations exist. The first results from an LES run in a twofold nested domain with a spatial resolution of &amp;amp;#916;x,y,z = 1m for the street canyon and buildings show promising similarities in airflow patterns and dynamics compared to the observations and are currently undergoing further validation. This study is financed by the Bavarian Ministry of the Environment and Consumer Protection.&amp;lt;/p&amp;gt;</jats:p

Holocene collapse of Socompa volcano and pre- and post-collapse growth rates constrained by multi-system geochronology

International audienceVolcano sector collapses are catastrophic events that can mobilize huge volumes of material and cause changes in the magmatic plumbing system, leading to variations in growth rate and/or composition. Dating pre-historic volcanic debris avalanche deposits is challenging. Geological materials directly recording avalanche formation and amenable to radiometric dating are rare, and, in the case of Holocene events, the applicable radiometric dating techniques are scarce. Socompa volcano suffered the largest collapse event in the Central Volcanic Zone of the Andes, producing one of Earth's most spectacular and best-preserved volcano avalanche deposits. We apply multiple dating techniques to unravel the timing of Socompa's collapse and gain insights into its pre- and post-collapse eruptive history. The age of the collapse event is constrained by a 14C age of 6,200-6,400 BP of a paleosol buried by the avalanche, and by a post-collapse lava flow dated at 5.91 ± 0.43 ka by zircon double-dating. Bayesian age sequence modeling integrating these ages determines that the collapse occurred at 6.18-0.64+0.28 ka. Four zircon eruption dates and one unspiked K-Ar age between 69.2 ± 6.0 and 22.1 ± 1.9 ka constrain the age of the youngest stage of activity before the collapse. The ages, together with paleosurface modeling and volume calculations, allow estimating growth rates for the young pre-collapse and post-collapse stages of ~ 0.2-0.3 km3/kyr and ~ 0.5-2 km3/kyr, respectively, indicating a significant increase in activity after the collapse event. The collapse may have triggered a new growth phase or accelerated an ongoing one and was likely associated with a Plinian eruption that produced widespread pumice fallout. The pre- and post-collapse lavas have similar compositions and zircon crystallization age distributions, suggesting that the same or a similar magma reservoir was tapped before and after the collapse. Thus, huge collapses such as Socompa's event can promote increased volcanic activity as a consequence of the unloading effect, but the overall plumbing system may not be affected enough to show significant variations in erupted compositions, at least transiently. Our results highlight the efficacy of the zircon double-dating method for dating very young felsic lavas and for constraining the age of debris avalanche deposits. This is particularly relevant in the Andean Central Volcanic Zone and other regions with arid climates, where organic material is rare and hence 14C dating is often unfeasible. Furthermore, the post-collapse zircon eruption age of 5.91 ± 0.43 ka is the youngest radiometric age yet obtained for a lava flow in the southern Central Volcanic Zone, highlighting the youth of volcanic activity at Socompa, and confirming its status as a Holocene active volcano