Pushy Parisian Elbows: Taste for Comfort in Public Transport

Since they change the individuals’ time perception, qualitative aspects of transport are increasingly discussed as factors influencing the choice between individualised and public transport. In this article we investigate, both analytically and empirically, the utility cost of congestion in public transport networks, the congestion being defined as the space available for travelers in trains. First, we propose a simple model integrating a qualitative component into the utility function of commuters. This enables us to underline the effect on the individual welfare, and modal decision, of reduced comfort in trains. For a policy aiming at reducing car usage, this “cross-modal externality†may significantly soften the overall modal switch. Therefore, it appears of major interest to appraise the utility cost of public transport congestion.. Using contingent methodology and survey data from central Paris subway - a relevant case study due to recent evolutions in transportation patterns- we then approximate this discomfort effect. According to answers of 533 line 1 users, this is equivalent to 5.7-8.1 minutes of excess travel, i.e. 29%-42% of average trip duration or 1.01-1.42 euro once translated in monetary terms. With the use of categorical estimates, we show that these figures significantly rise with trip time as well as levels of congestion, while being quite stable across individual characteristics. We conclude with policy implications by approximating the marginal benefit of subway decongestion at 0.25 euro/passenger*kilometer. This new parameter allows us to illustrate how considering comfort in public transport changes the picture when one comes to appraise evolutions in the Parisian transportation patterns. For example, decongestion benefits in undergrounds (3.5 M euros) due to a new tramway in South Paris overpass the time savings induced by this new infrastructure (2.7 M euros). Over 2000-2007, the increase in subway congestion costs may also be estimated at 100 M euros. Therefore, these figures underline the need for an accurate understanding of the perceived costs of travels.

The bias of DLAs at z ~ 2.3: contraining stellar feedback in shallow potential wells

We discuss the recent Baryon Oscillation Spectroscopic Survey measurement of a rather high bias factor for the host galaxies/haloes of Damped Lyman-alpha Absorbers (DLAs), in the context of our previous modelling of the physical properties of DLAs within the $\Lambda$ cold dark matter paradigm. Joint modelling of the column density distribution, the velocity width distribution of associated low ionization metal absorption, and the bias parameter suggests that DLAs are hosted by galaxies with dark matter halo masses in the range $10 < \log M_v < 12$, with a rather sharp cutoff at the lower mass end, corresponding to virial velocities of 35 km/sec. The observed properties of DLAs appear to suggest efficient (stellar) feedback in haloes with masses/virial velocities below the cutoff and a large retained baryon fraction (> 35 %) in haloes above the cutoff.Comment: 10 pages, 9 figures. Published in MNRAS, May 21, 2014. 440 (3): 2313-2321. v3: Corrections in light of errata: MNRAS, 454(1), p. 218. Note, in particular, the changes to Figure 5 and the virial velocity cut-of

Evaluation of Foldable Tractor Roll-Over Protective Structures (ROPS) Clearance

Tractor rollovers are a leading cause of death in the agricultural industry. While rollovers continue to happen, Roll-Over Protective Structures (ROPS) have shown great ability to prevent or reduce the casualties and injuries associated with rollover events. One authority on the subject even goes so far as to claim that “that fatality rates due to tractor overturns could be reduced by a minimum of 71% if all tractors in the U.S. were equipped with ROPS,” (NIOSH, 2009). The potential of this promising statistic has been devalued slightly due to the misapplication of foldable ROPS by leaving the ROPS in the folded down position. Foldable ROPS provide a practical solution to various issues faced by tractor operators. However, a ROPS is not meant to be used in the folded down position, and there are engineering standards that should be used to determine if a folded down ROPS actually offers any protection. This study determined the operator protection provided by ROPS in the extended and the folded positions relative to the applicable engineering standards. To accomplish this, six different sized tractors with different ROPS were analyzed to determine the measurements required to calculate the protection that the tractor and ROPS combination provides in both positions, folded and extended. These calculations yielded results that show consistent trends among all tractors measured. With regards to the engineering standards, all tractors measured provide complete protection when in the upright, extended position and did not provide adequate protection when in the folded position. These results provide useful insights into engineering standards and recommendations