[dc-critmass-list] Study in Lyon FR says cars are slow in the city

[michael turner]

http://arxiv.org/ftp/arxiv/papers/1011/1011.6266.pdf

Characterizing the speed and paths of shared
bicycles in Lyon
Pablo Jensen (a,c), Jean-Baptiste Rouquier (b), Nicolas Ovtracht (c)
and Céline Robardet (d)
(a) Institut des Systèmes Complexes Rhône-Alpes (IXXI) ; Laboratoire de 
Physique, École Normale
Supérieure de Lyon, 69007 Lyon, France
(b) ISC PIF (CNRS and CRÉA, École Polytechnique, Paris, France
(c) Laboratoire d’Économie des Transports, Université Lyon-2, Lyon, France;
(d) Université de Lyon, INSA-Lyon, CNRS, LIRIS UMR5205, F-69621 France
Abstract :
Thanks to numerical data gathered by Lyon's shared bicycling system Vélo'v, we
are able to analyze 11.6 millions bicycle trips, leading to the first robust
characterization of urban bikers' behaviors. We show that bicycles outstrip cars 
in
downtown Lyon, by combining high speed and short paths.These data also allows us
to calculate Vélo'v fluxes on all streets, pointing to interesting locations for 
bike
paths.
Lyon's Vélo'v started in May 2005 and represented the first massive shared
bicycling system. Today, 4000 bikes can be taken in one of the 343 stations 
spread
across the city (Figure 1). On average, some 16 000 journeys per day are 
completed,
but when public transportation is on strike, this number doubles. Our dataset, 
kindly
provided by Vélo'v operator JC Decaux [Decaux, 2010], contains all the trips 
that
occurred between May 25
th
2005 and December 12
th
2007. Each record contains the
location and time of the beginning and the end of the trip, as well as the 
precise trip
distance provided by a counter on the bike. The average trip distance is 2.49 km 
and
the average trip time 14.7 min.
Speed is an essential feature to determine the efficiency of transportation 
systems.
Figure 2a shows that bikers' average speed reaches a peak of 14.5 km/h in the 
early
weekday mornings, when there is almost no hindrance by cars or traffic lights.
Interestingly, this early morning peak is the only moment when average summer 
and
winter speeds (not shown) are identical, pointing to an intrinsic limit of the 
system.
For any other moment of the day, winter speeds are higher (up to 9\% in the 
evening).
However, experienced or hurried bikers can go much faster : the top 10\% (black
curve in Figure 2a) reach 20 km/h. Lower speeds can be explained by traffic
conditions or lack of hurry. The former explain the morning speed decrease, even 
if
bikers may speed up if needed, as shown by the increase of average speed at rush
hours (especially 8:45) all five working days (Figure 2a, inset) and the clear 
peaks in
the fastest bikers' speed (7:45 and the plateau 8:45 to 9:45). When there is no 
need to
hurry, average speed falls to 10 km/h, as in weekends afternoons. Intriguingly,
wednesday morning speeds (upper curve in the inset) are systematically higher 
than
other weekdays. Since car traffic does not decrease on wednesdays, we speculate 
that
this higher speed might be related to a higher proportion of (faster) masculine 
bikers,
since a significant fraction of women stay home to care for children on 
wednesdays
[Bel, 2008].
The data allows us to compare the Vélo'v real trip distances between stations to
car and pedestrian distances. Figure 2b shows that bike's paths are much closer 
to
pedestrians'. Actually, when there exists a shortcut, 68.2\% of bike's trips are 
shorter
than car's (left of the vertical line in Figure 2b), the average distance 
reduction being
13\%. The proportion is slightly weaker (61.3\% out of 3,506,294 trips) if all
weekday hours are taken into account. In both cases, to avoid artifacts, we only 
keep
trips longer than 500m between a couple of stations where car distance is
significantly longer than pedestrians' (at least 200m). This suggests that, as 
specific
bicycle tracks were virtually unknown in Lyon at that time, most bikers use
sidewalks, drive the wrong way up one-way streets or use the bus / tramway 
lanes.
Finally, using data on the fluxes between couples of stations and assuming that 
bikers
follow pedestrian paths, we can calculate Vélo'v fluxes on all streets (Figure 
1).
Knowing these fluxes should help town authorities in creating bike paths where 
they
are most needed.
Our analysis shows that in morning rush hours, bike's average speed - in real
conditions and for average users - is 13.5 km/h. Adding the effect of shorter 
bike's
trips (Figure 2b) leads to an effective speed close to 15 km/h. This speed 
should be
compared to car's average speeds in downtown European cities, which vary from 10
km/h to 15 km/h [Paris, 2010; Prudhomme and Bocarejo, 2005]. Therefore, even
when considering bare speeds, bikes are faster than cars in downtowns. This
advantage is not cancelled by including in the speed calculations the average 
time
needed to reach the car or the bike. Indeed, even if walking distance to car's 
parking
is difficult to estimate, it is of order 200m in downtown Lyon, which is similar 
to the
distance to the closest Vélo'v station. On the other hand, finding a parking 
slot is
generally more difficult than an empty Vélo'v slot in downtown areas. The
combination of these elements may explain why, after Vélo'v gave a modern look 
to
cycling in 2005, the number of bikers has almost doubled in Lyon [Grand Lyon,
2010].
References
Bel G., 2008,
Les femmes face au travail à temps partiel, Rapport du Conseil économique et 
social,
available at http://www.conseil-economique-etsocial.
fr/rapport/doclon/08261005.pdf
Decaux, 2010, http://www.jcdecaux.com/
Grand Lyon 2010, Prospective on green transports, Grand Lyon
http://www.grandlyon.com/fileadmin/user_upload/Pdf/ac
tivites/deplacements/plan_modesdoux_2009-2020.pdf
Paris, 2010, Moving in Paris, Mairie de Paris
http://www.nxtbook.fr/newpress/Mairie-de-paris-directionvoiri
e deplacements/Bilan_des_deplacements_en_2007_Paris/index.php#/2 4
Prudhomme R. and JP Bocarejo, 2005, The London congestion charge : a tentative
economic appraisal, Transport Policy, 12 279
FIG. 1: Map of Vélo'v stations and daily average fluxes on Lyon's streets. The 
map was
obtained thanks to the MOSART modelling platform (http://mosart.let.fr/)
(a)
(b)
FIG. 2: (a) Average speed vs hour in weekdays and weekends. Bars give the 95\%
confidence interval. (b) Histogram of (velov - pedestrian) / (car - pedestrian) 
distances for the
375,165 morning (7 to 9am) weekday trips, when bikers are likely to have time 
constraints.



      
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