Below we provide mainly some number coming from [1], using a data base; the “registre du Rhone” (Lyon district, France); recording detailed information for 14 478 cyclist victims of road accident in the Rhone county (France). The data under studies have been collected from 1996 to 2007. The level of detail is very high compared to some other data base, and they can help to clarify the helmet debate:

see wikipedia for the AIS and IIS definition and meaning

Injured Body part among cyclists
reported numbers are only for cyclist where the helmeted/unhelmeted status is known

helmeted 1461 unhelmeted 5620 helmeted 1461 unhelmeted 5620
Body region %yes %AIS3+ %yes %AIS3+ yes AIS3+ yes AIS3+
head 16,6% 1,0% 19,5% 2,3% 242 15 1095 128
face 18,3% 0,1% 24,3% 0,2% 268 1 1367 9
neck 3,3% - 2,7% 0,0% 48 0 152 1
Thorax 9,6% 1,8% 6,3% 1,0% 140 26 355 55
abdomen 3,9% 0,1% 3,6% 0,2% 57 2 200 14
spine 7,5% 0,3% 5,0% 0,1% 110 5 281 8
Upper Extremity 53,5% 3,2% 44,7% 3,4% 781 47 2513 189
Lower Extremity 33,7% 1,8% 31,2% 1,9% 493 27 1751 107
skin 17,8% - 15,2% - 260 0 857 0

This table shows that the helmeted cyclist are less often severely injured to the head, less often injured and seevrely injured to the face. But they are more often injured and severely injured to the Thorax and spine, and more often injured to the upper extremity. This suggesthelemeted cyclist get involved in more severe accident. 2 reasons can be advanced for it

    • Helmeted cyclists have a different cyclist practice that non helmeted one (that relate to the infamous MAMIL)

the effect of it is to give an under estimation of the helmet efficiency

    • There is a risk compensation at play along helmeted cyclist

the efficiency of the helmet could be under estimated by those raw number
this annihilate in part the helmet efficeincy

The figure below illustrates the % of head injuries oberved for injuried cyclists with an helmet and without:

The bike helmet seems to have no significant effect at reducing superficial head injuries but it reduces the risk of severe head injury (AIS3+) by 50%. However such severe head injuries represent less than 2% of the total cyclists injuries

So we are looking at a global effect of 1%, but severe head injuries can have long term disabilities consequence, so a reduction by 50% of severe head injuries could be considered a worth endeavour:

Below a more detailled view of the head and face injuries specificities:

Head or face Injuried cyclist: type of lesion according to helmet wearing or not

Helmeted 238 Unhelmeted 1078
lesions N = % N %
Unconsciousness without additional descripted lesion or head trauma without further indication 194 73,5% 668 49,3%
skin lesion 43 16,3% 459 33,9%
brain 21 8,0% 150 11,1%
skull 6 2,3% 65 4,8%
little brain 0 - 4 0,3%
nerves 0 - 4 0,3%
brainstem 0 - 2 0,1%
Destruction skull and brain 0 - 2 0,1%
Total 264 100% 1354 100%

In despite of a pretty huge database, significativity is not reached on many lesions types.

According to [1], Among the 222 cyclists injuried to the skull or its content

  • 30 are dead
  • 42 will have severe heavy brain disabilities (IIS3) – that represents 0.3% of the injuried cyclist
  • 146 will have light brain disabilities – that represents 1% of the injuired cyclist

The effect of the helmet on long term disabilities seems to be measured on a very small cohort:

unhelmeted 35 helmeted 3
fatalities 15 0
%fatalities among total injuried 0,3% -
%fatalities among head injuries 1,4% -
Severe head disabilities (IIS3+) 20 3
% Severe disabilities among total injuried 0,4% 0,2%
% Severe disabilities among head injuried 1,9% 1,3%
% Other severe disabilities in addition of severe head disabilities [10] 19,8% 21,4%

Again, we don’t reach significativity to be able to conclude that a “bike helmet saves life”, but it could well reduce significantly the risk of severe head disabilities. The number could suggests 50%, but again with very little confidence.

In anycase, the effect is measured in tenth of 1% of the total injuries: the absolute number of victim is very small.

How bike injuries compare to other transportation mode?

When involved in an accident, cyclists have the lowest fatailities rate compared to other individual transportation mode. They have also the best chance to survive an accident without long term disabilities. Urban cyclists are even much safer than rural or suburban cyclists:

Cyclists
Injury severities Uurban 6584 Rural 1726 0-10years 3364 Pedestrians 10131 car 53151 Mopette Motorbike 21831
MAIS 1 63,7% 53,7% 72,5% 60,4% 81,6% 61,7%
MAIS 2 28,7% 35,3% 22,4% 24,7% 13,4% 27,0%
MAIS 3 5,8% 7,9% 4,2% 10,0% 2,8% 8,6%
MAIS 4 and 5 0,9% 2,0% 0,3% 2,3% 1,0% 1,5%
fatalities 0,6% 0,8% 0,1% 2,6% 1,2% 1,1%
no disabilities 78,4% 73,8% 88,2% 66,1% 55,3% 73,7%
light diabilities (MIIS1-2) 20,2% 23,8% 11,1% 29,6% 42,8% 23,8%
severe disabilities (MIIS3-6) 0,6% 1,2% 0,2% 1,6% 0,7% 1,3%

When urban cycling is considered alone, helmeted cyclists are observed to have 20% less chance to be severly injured that non helmeted one, whenever involved in an accident, however significativity is not reached [1].

The figures below eventually help to compare the different pattern of injuries, according to transportation mode, and eventually relativize the impact of a bike helmet on the total number of both severe head injuries and severe disabilities.

AIS4plusandTransportationMode

Injuries type according to transportation mode (from [2])

Long term severe disabilities type according to transportation mode (from [2])- head injuries represents ~60% of the long term disabilities fro both pedestrians and cyclists

those figures provide absolute numbers for the Rhone district (1.7Millions) inhabitant for years 2007-2010…
Even if a bike helmet is able to reduce the severe head injuries and disabilities, by 50%, the saving in term of public health could be relatively insignificant but the more generalized economic cost can be real: It has became clear that an helmet legislation is counterproductive, but even promotion campaigns in favor of bike helmet could be counter productive:

  • The money spend on helemet couldn’t justify the health care saving, and could be better invested somewhere else
  • Helmet campaign promotions paint cycling as a dangerous transportation, discouraging people to cycle, conducting to a less healthy population

One could object that a low absolute bike injuries number is due to a relatively low cycle ridership. The dramatic increase in cycle ridership over the last decade, especially in urban area, is well documented, and still the number of total injuries has not increased but is decreasing [2]:

Bike accident evolution in France

Bike accident evolution in France

The more people bike, the more a bike helmet becomes irrelevant…unless you believe pedestrians should wear an helmet too!


More citation to come

[1] Vélo et casque, Journée spécialisée, jeudi 28 mai 2009, Rapport UMRESTTE 0908, May 2009

[2] Bilan 2011 de la sécurité routière en France

[10] doesn’t express it like it, but I am assuming it is due to a typo.

Park Avenue

May 21, 2010

Avenue [ˈævɪˌnjuː] from the old french arrival, has eventually got a different meaning in english, as well as in current french, due to the current usage we give to it nowadays.

Here after is a very simplified history of it:

XVIII century

At the eventual difference of other roads or streets, avenues were usually work of urban planning, and primarly designed as radial promenade at the edge of the city with function to great in a ceremonial way the arriving visitor

Avenue du Mail, Rennes, France. concept plan from the XVIII century. the leisure aspect is the dominant factor, at the expense of the mobility one. credit photo (1)

XIXcentury

Though that not matching to the original vision, the primary promenade function is still well respected.

The same location at the turn of the century. The leisure aspect of the promenade is still well alive

XX century

The advent of the automobile and other social change will involve deep cultural shift:

  • Urban people will eventually prefer spend their free time elsewhere than lingering on the street becoming less pleasant due to the surrounding roaring motors and gas smell (we don’t speak to much pollution those day).
  • the free space is then occupied by the new mobility device

With the advent of the automobile, the promenade change of function! (it is still Avenue du Mail, lately renamed Mail Francois Mitterrand, Rennes France)

XXI century

Another relative cultural shift appears in the 80s, eventually learning of the american experience: it appears very apparent that the adaptation of the European city to the car has no future: and a better use of the scarcely city’s available real estate need to be devised. the LRT, trams in Europe, will be part of the solution, and the large French avenues, will be ideal Right of Way candidate. The vision of the future century is then eventually represented by this artist rendering:

the future Starsbourg tram, line F, riding on what used to be a parking lot...at least in the recent history. credit photo (5)

One will note, it is pretty seldom to see modern tree lined trams, eventually for the following reasons:

  • the tree roots system could compromise the integrity of the trackbed
  • the tree branches could interfere with the overhead wires
  • the falling tree leaves could grease the rails, compromising the acceleration/braking capabilities of the train

In the Strasbourg F-line case, those aspects are mitigated by the integration of the bike path along the tram ROW. the integration of the bike path is an addition to the late LRT project.

Obviously, the vision is a significant progress on the current situation, in the sense it returns to a pleasantly greenish aspect of the avenue.

The park and ride model

Where we should not give more credit to the french than they deserve is here:

  • In most of the case the space allocated to the automobile traffic is not compromised, and the Strasbourg example shown above is basically no exception to the rule: while that the parking space is removed at the benefit of the trams, there is no reduction in automobile traffic lanes benefiting then of a freer flow, since not impeded by car looking for or negotiating parking spot
  • there is no increase of space for pedestrians, and the leisure and social interaction aspect, like lingering on the street, is not part of the picture either

The removal of parking space could be considered as a progress, but usually, a french tram projects barely means reduction of parking space either, but rather relocation of it according to the well known park and ride model.

The picture below feature one P&R in Bordeaux having 603 stalls [6], more than at the Canada line Bridgeport one [7]. Bordeaux has 14 other structures like this along its 3 trams lines…


park and Ride in Bordeaux, france. Notice the state of the track's lawn as soon as you get out of Downtown. credit photo (6)

One can clearly suspects that the motivation to introduce trams in the french cities has not been to challenge the general car centric culture, but was more guided by more pragmatic space constraint requiring a P&R model in order to preserve good vehicular movement on the city arteries and accessibility of the city to an ever greater number of people, including by car.

In that aspect, it has been a more successful model than the US one, eventually due to the greater scarity of

  • downtown parking stall
  • road access

and,

  • the preserved heritage specificity of the European cities could have contributed to maintain the attractiveness of their downtown in despite of access impediment
  • the short length of the European trams line, typically not venturing much farther than 5km from he town center, allow for short trip time, in despite of relatively low average speed [4], the later allowing good integration in the urban fabric

All those factor, in addition of social one going beyond the scope of this post, could have saved the middle size European city to know the fate of their American sister cities, in term of Downtown life.

But, if one considers the public transit market share in 14 french urban areas with LRT; 11% (for weekday trip) [8]; it is hard to speak of a successful strategy, to be emulated.

At the end of the day, the avenue original vision, which cheer size was to provide “park” space for people, devoided to be “park” space for transportation device, has not been restored. Indeed it is now used to “segregate” space according to transportation modes (in a vision where “lingering” is also a “commercialized” activity at the benefit of the sidewalk coffees).

It is a progress on the dictatorship of the automobile reign, and it is possible that the LRT has been an ingenuous tool to legitimate the displacement of the cars toward the outer edge of the city, but is the result the most efficient allocation of the city surface space? or in other term, is it the best we can do?


[1] from archives municipales de Rennes, France

[4] Average speed of european trams is usually below 20km/h, 18.5km/h in the above mentioned case of Bordeaux

[5] from Tram-Train/Tram F, Strasbourg-Bruche-Piémont des Vosges, June 2008

[6] Picture and number from le tram de Bordeaux”

[7] Bridgeport park has 600 stall for Canada line rider according to Translink

[8] Transportation mode share of 14 metropolitan area with tram in France, from “Les deplacements a Nantes metropole Etude N 80, decembre 2009, Insee Pays de Loire, France citing “enquêtes nationales transports et communication 1993-1994, transports et déplacements 2007-2008″, Insee, SOeS and Inrets.

the agency overseeing the “guided transportation systems” in France publishes some numbers worth to be repeated [1]. Though that the sample sizes prevent to draw definitive conclusions: we can still exhibit some trends: not surprisingly multi year studies tend to show that subways [2] are order of magnitude safer than LRTs [3]. This said, it is interesting to probe the source of tram accidents, what is provided by the graphs below.

partition and severity of tram accidents per year function of their location along the lines

Accidents partition per mode, and transportation modal share

It appears, that the bulk of accidents happen at intersections where they involve third parties. If car are responsible of most of the conflict, it is mainly, pedestrians and cyclists whose pay a disproportionate human toll considering the transportation modal sharing [11]. Furthermore, a study of the Belgium institute on road safety shows that while tram/pedestrian conflicts represent 2.1% of the overall pedestrian conflicts in Brussels, they result in more than 6.7% of vehicle/pedestrian conflicts with severe injuries [4] while that pedestrians represent more than 50% of the overall fatalities on the french trams network [1]. However, a non negligible number of accidents happen outside platforms and crossings: most of them involve emergency braking of the trams, which are responsible of most of the passenger casualties. The french agency has further detailed the pattern of crossing accident, and provides statistic per crossing:

yearly number of tram accidents per crossing, according to their severity type

Comparison with the US

It can be interesting to compare the french statistic to the American one, as reported by the Bureau of Transportation Statistics.


Accident rate comparison between USA and France on LRt and subway network

Though that the accident ratio between subway and LRT witnessed in France is also founded in USA, there is a striking difference in the number of casualties per million of trip.

One explanation to it could be the suicide ratio:

  • statistics are not including casualties due to suicide, but suicide characterization can be different according to the country. Thought that casualties due to suicide are not well documented, anecdotal evidences seem to show that the French authorities are more willing than the North American ones to classify an accident as a suicide: Some officious counting report around 70 suicides per year on the Parisian RATP metro alone [5], when this number is of around 30 in New York City [6], and 15 in Toronto [7]. For purpose of a study on the suicides in the Montreal subway, the researchers have requalified fatalities, considered as accident by the coroner, as suicide [8].

That said, the American LRTs still seem more prone to accident than their french counterpart. We can attempt some explanations to it. .

  • LRT accidents are significantly due to third parties, and eventually the measure of accident/trip is unfavorable to the less patronized US LRT vehicle. This explanation can be countered by the fact that busy LRT lines involve busy pedestrians traffic around their route, hence increasing also the chance of accident.
  • Average speed of french LRTs, usually in the 15 to 20km/h range is significantly slower than their american counter part
  • Design of European LRT could be more permissibe too
    • Front design of low floor european LRT seems less prone to drag pedestrian under the railcar
    • All low floor design reduce the chance of fall inside the car in case of emergency braking
  • More frequent LRT could increase the public awareness of their presence
  • Due to the above factor, French LRT seem also less attractive than their US counterpart to suicide candidate


Compared to even recent American design, the European tram design features all low floor train,with “housed” coupler into an all “soft angle” front design, and offers an unobstructed view fro the driver…all these eventually help to prevent or reduce accident consequences (credit photo, Northfolk LRT: LRTA, Brussel tram in Vancouver: Stephen Rees)

Nantes, a real life example

A tramway accident in Nantes (credit photo: Presse Ocean)

To provide some more reality to the statistic, we provide the example of the Nantes Trams network [9]:
it has opened in 85, has 3 lines, totalizing 42km, and carrying an average of 266000 riders /day.

  • One accident every 2 days
  • One accident in 4 involves injuries

Interestingly enough, according to the Nantes transit agency, their BRT records a rate of accident twice less than their trams, though their buses go faster [9]. It is eventually due to a better designed right of way for the bus than for the trams .


[1] see Accidentologie des tramways, Service Technique des Remontées Mécaniques et des Transports Guidés DES TRAMWAYS, 2006 and
Accidentologie des metros, Service Technique des Remontées Mécaniques et des Transports Guidés DES TRAMWAYS, 2006

[2] French subways include also the “VAL” family of subway

[3] French LRTs include also the guided bus systems

[4] Etude des accidents entre un tram et un pieton en region de Bruxelles-capitale

[5] Suicides dans le métro : deux morts par semaine à Paris, France Info, October 30, 2007

[6] Epidemiology of suicide in the New York City subway system, Sandro Galea and al. , APHA 134th Annual meeting and Session, November 4-8, 2006, Boston

[7] More than 150 people killed themselves in subways from 1998-2007, TTC says, National Post, Rob Roberts, November 26, 2009

[8] Qui se tue dans le métro de Montréal?, Brian L. Mishara, UQAM, Dec 1996

[9] Un accident de tramway en moyenne tous les deux jours, October 7, 2008, Presse Ocean, Nantes, France

[10] The rate per million of passengers is not necessarily the most relevant, but it is the only one readily available from the french statistics, which are averaged on the number of available years after 2003 to provide a more relevant sample size. For USA, to increase the sample size, the accident statistics are the average of year 1994 to 2006, as provided by the BTS 2009 report

[11] Transportation mode share of 14 metropolitan area with tram in France, from “Les deplacements a Nantes metropole Etude N 80, decembre 2009, Insee Pays de Loire, France citing “enquêtes nationales transports et communication 1993-1994, transports et déplacements 2007-2008″, Insee, SOeS and Inrets.

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