When Lusk et al. submit to the editor a formal list of errata to be attached to their article, I expect they will duly correct all the errors, omissions, and false statements that have been brought to their attention, and not just the three they chose to mention here. This would include amongst other items providing a correct explanation for their choices of particular termination points (rather than the non...
When Lusk et al. submit to the editor a formal list of errata to be attached to their article, I expect they will duly correct all the errors, omissions, and false statements that have been brought to their attention, and not just the three they chose to mention here. This would include amongst other items providing a correct explanation for their choices of particular termination points (rather than the nonsensical one found in footnote 2 to their Table 1), and retracting their false statement that the path and comparison streets have similar cross traffic and numbers of intersections. And as I also already objected, the authors need to explain how they got the usage data for the year 2000 they claim to have for the de Maisonneuve path segment. Considering that no municipality maintains automatic counters there, and that the authors' study was not underway in 2000, contrary to their claim it would seem they do not have data as they describe for that year.
Since I expect the authors will do their duty and correct these faults, I use the space remaining to correct two new errors they have introduced, and to object further.
(1) The path segment they claimed to have studied from 1999 to 2008 but that did not exist for almost the entirety of that period was created in 2007, not 1997.
(2) The corresponding length correction would have been approximately 180 metres, if they had gotten the extra length right to begin with. They did not, and so the correction should be instead approximately 350 metres. The authors are yet to explain how they got their lengths.
(3) The authors tell us not to worry about their selections of comparison streets: these were done "a priori, without knowledge of their safety record, in consultation with local cycling advocates". In fact the biases are so extreme that they are obvious without any measurement. Who were these sight, smell, and hearing impaired local advocates? Their contribution is not identified in either the contributorship statement or the acknowledgements, and the genesis of the study's path and comparison samples remains as mysterious as ever.
(4) The authors say their failures to describe the radical divergences between their path and comparison streets "do not affect the study results." They need to be reminded that without appropriate comparisons, their study lacks validity. Indeed, showing that a comparison is preposterous does not change the results so calculated: instead, it discredits them.
(5) I object to the authors' claim that "not even one comparison pair showed significantly greater risk" for the path. Let us be clear: even with the biased nature of the comparisons, over the near decade of the study period, according to their methods the actual injury rates on the paths were in three cases respectively 21%, 18%, and 1% worse than on the comparison streets. That none of these were found statistically significant is an indictment of the imprecision of the authors' methods, not an endorsement of the paths. I particularly object to this exploitation of the confusion between statistical and public health significance because I already called the authors on it in my previous criticism.
The authors bemoan the fact that on-street path construction has been "hampered" by the AASHTO guidelines, and present their own results as enough against them that it should no longer be discouraged. This summer a cyclist riding on the Christophe Colomb path segment studied by the authors-- a cyclist who did everything right by the rules of the path, and therefore much wrong by the ordinary rules of the road-- was killed by a truck [1] in circumstances exactly as warned about on page 34 of the AASHTO guidelines [2].
References
1. http://www.cbc.ca/news/canada/montreal/story/2012/07/24/montreal-cyclist-hit-24-07-2012.html?cmp=rss, accessed Aug 26 2012.
2. AASHTO Task Force on Geometric Design (1999). Guide for the development of bicycle facilities. Washington, DC: American Association of State Highway and Transportation Officials.
We regret the two errors that Kary identified. "What this study adds"
should read published crash [not injury] rates (the article body states it
correctly), and the Rachel length is 1.7 km [not 3.5]. In Table 1,
correcting for 1.7 doubles Rachel's absolute incident rates; however, it
raises overall crash and injury rates by only 10% to 9.6 and 11.5,
respectively. In Table 2, the relative risk comparison is unaffected sinc...
We regret the two errors that Kary identified. "What this study adds"
should read published crash [not injury] rates (the article body states it
correctly), and the Rachel length is 1.7 km [not 3.5]. In Table 1,
correcting for 1.7 doubles Rachel's absolute incident rates; however, it
raises overall crash and injury rates by only 10% to 9.6 and 11.5,
respectively. In Table 2, the relative risk comparison is unaffected since
the comparison street has the same length as Rachel. Thus, the study
conclusions remain intact.
Exclusion of the 180-m Maisonneuve extension completed in 1997 should
slightly lower its incident rates, and could not raise them by more than
10%, and would therefore not affect the overall results.
Kary's extensive criticisms focus on differences between the cycle
track and comparison streets that do not affect the study results. Readers
may be assured that all comparison segments were selected a priori,
without knowledge of their safety record, in consultation with local
cycling advocates (some of whom prefer mixed traffic over cycle tracks) as
the most similar yet realistic alternative routes. St. Denis, 10 blocks
but only 700 m from Brebeuf, was Brebeuf's comparison because, although
different in geometry, it was the main parallel alternative route for
cyclists crossing the area. Comparisons of MVO injuries demonstrate that
in the aggregate, cycle track and comparison streets revealed similar
environmental danger. Because differences are unavoidable when comparing
streets, we provide results for each comparison pair.
We welcome other studies that better control for the road
environment, including before-after studies. For now, Montreal is North
America's only long-standing, multi-route experiment with cycle tracks.
And while the comparisons in our study are not ideal case-controls, the
findings are strong, as not even one comparison pair showed significantly
greater risk for the cycle track.
1. Rue de Brebeuf Cycle Track vs. Rue St. Denis between Rachel and
Laurier.
These streets are not comparable.
Brebeuf (which has a cycle track) is a narrow 40kph slow-moving one-
way residential street with one traffic lane and one parking lane.
Rue St. Denis (which has no cycle track) is a six-lane (two lanes
often taken up by parking) 50kph limit two-way highway in a commercial
area with lot...
1. Rue de Brebeuf Cycle Track vs. Rue St. Denis between Rachel and
Laurier.
These streets are not comparable.
Brebeuf (which has a cycle track) is a narrow 40kph slow-moving one-
way residential street with one traffic lane and one parking lane.
Rue St. Denis (which has no cycle track) is a six-lane (two lanes
often taken up by parking) 50kph limit two-way highway in a commercial
area with lots of stores and distractions.
It seems to me that more accidents will naturally occur on the six-
lane highway with a faster speed limit. It's unsurprising then that the
study did indeed find a statistically significant advantage in terms of
safety for Rue de Brebeuf. However, I would argue that this has nothing to
do with the safety of the cycle track and everything to do with the very
different nature of the roads compared.
2. Rue Berri Cycle Track vs. Rue St. Denis between Cherrier and
Viger.
These streets are not comparable.
Rue Berri (which has a cycle track) is a 50kph limit divided highway
along 1/3rd of its length with the cycle track removed from busy
intersections by an underpass, so cyclists are naturally removed from the
possibility of intersection accidents.
Along this stretch of Rue St. Denis, the road (which has no cycle
track) is a one-way street with a 50kph speed limit. However it is a much
busier road than Rue Berri in terms of people doing their business
somewhere along that stretch, with a relatively narrow street and lots of
intersections and distractions in the form of little shops and cafes along
the whole route.
Rue Berri showed a statistically significant reduction in injuries
compared with its reference street. However, more accidents are bound to
occur where there are lots of intersections and where drivers are likely
to be distracted. It seems reasonable that the advantage in terms of
reduced injury results on Rue Berri derive from the very different nature
of the roads compared and not from the presence of a cycle track.
3. Boulevard de Maisonneuve Cycle Track vs. Rue Sherbrooke and Rue
Ste. Catherine between Claremont and Wood.
Boulevard de Maisonneuve (which has a cycle track) is a quiet 30kph
one-way two lane residential street along much of its length. The bike
track goes through a park for 1/5th of its length, thus removing any
possibility of intersection conflicts in that area. The presence of the
park effectively reduces the chance of traffic collisions by 20%.
Sherbrooke (which has no cycle track) is a downtown 40kph commercial
street with four lanes of moving traffic and parking on both sides. It has
numerous business distractions along its length. It should be noted that a
recent study found that Sherbrooke is the single most dangerous route in
Montreal for cyclists. Ste. Catherine (which also has no cycle track) is a
similar downtown street, but with a 30kph limit and just two lanes of
moving traffic and a lane for parking on both sides.
The idea that these streets are comparable on anything but the most
superficial level (i.e. they are streets) is a joke. It is ridiculous, in
my view, to attribute a reduction of injuries on Boulevard de Maisonneuve
to the presence of a cycle track, when the streets being compared are not
at all similar - and when the street with the cycle track has obvious and
significant advantages in terms of safety that are unrelated to the
bicycle track itself.
-----------------------
Here we have what seems to me to be a clear case of selection bias.
Note: Even though the three other street comparisons show similar
bias, the remaining street comparisons showed statistically insignificant
results.
The Results of this study are interesting, particularly comparisons
to other countries. I'd be also interested in looking into driver license
test standards. Having worked as an expat in the UK 1999-2005, I knew many
who have tried unsuccessfully to obtain a driver's license because of the
high test standards. You must pass a written test, video response test and
the road test. Only 30% successfully complete all three on t...
The Results of this study are interesting, particularly comparisons
to other countries. I'd be also interested in looking into driver license
test standards. Having worked as an expat in the UK 1999-2005, I knew many
who have tried unsuccessfully to obtain a driver's license because of the
high test standards. You must pass a written test, video response test and
the road test. Only 30% successfully complete all three on the first
attempt. I'm sure the USA pass rate is much higher. It's not unusual for
Brits to repeat the tests 3 or more times and practice intensively
between tries. Several experienced American drivers have had great
difficulty in meeting the test standards, also.
Injury Prevention asks that responses to articles be kept to less than about 300 words. The volume of errors and omissions in this article by Lusk et al. is so excessive that it took me rather more than that-- including photographs of the actual streets-- just to document them. The result is now hosted on John S. Allen's bicycle pages and can be directly found by searching the internet for e.g. these terms:...
Injury Prevention asks that responses to articles be kept to less than about 300 words. The volume of errors and omissions in this article by Lusk et al. is so excessive that it took me rather more than that-- including photographs of the actual streets-- just to document them. The result is now hosted on John S. Allen's bicycle pages and can be directly found by searching the internet for e.g. these terms: compendium errors Lusk.
A very small sample:
-Authors report results for a path section that did not exist for almost the entirety of their claimed study period.
-Errors of up to 100% in the claimed lengths of path segments, and thus corresponding errors in the reported rates of incidents per kilometre.
-Biased selection of comparison streets, such as comparing a path on a one-way, one or two traffic lane, lightly trafficked residential street having a 30 km/hr speed limit, with cycling on a two-way, 4 traffic lane numbered provincial highway having a 50 km/hr speed limit, located in a heavily trafficked commercial district, with numerous alcohol-serving establishments.
The authors went 10 blocks out of the way to find this comparison street, even though the path-adjacent streets are nearly identical in character to the path street.
-False claim of similar numbers of intersections on path and comparison streets.
-Complete reliance on an untested, illogical, ad hoc indicator of danger to cyclists (contrary to the authors' description as if it were routinely used for this purpose), one whose usefulness is refuted by the authors' own data.
-Here and elsewhere, the authors applaud bicycle paths for substantially skewing the character of the user base, from young athletic males to women, children and seniors. Thus even if the authors did their study properly and reported their results correctly-- they did not-- would their conclusion that cycle paths at least do not increase the injury rates really be an endorsement of the cycle paths, or an indictment of them?
Ackery et al (1) show that risk to cyclists in collisions with motor-
vehicles increases with the size of the motor-vehicle. This evidence may
generalize to other types of collisions: consistent with Ackery et al are
studies concerning different sizes of automobile with pedestrians (2,4)
and collisions concerning different sizes of automobiles in general (3).
One can infer that a smaller entity - both in terms of linear d...
Ackery et al (1) show that risk to cyclists in collisions with motor-
vehicles increases with the size of the motor-vehicle. This evidence may
generalize to other types of collisions: consistent with Ackery et al are
studies concerning different sizes of automobile with pedestrians (2,4)
and collisions concerning different sizes of automobiles in general (3).
One can infer that a smaller entity - both in terms of linear dimensions
and mass - will likely come off worse than a larger entity. I use the term
"entity" to refer to the road-user in conjunction where appropriate with
her/his means of conveyance. Thus, the smallest entities are pedestrians
and cyclists: larger entities refer to automobiles, pick-up trucks and
articulated trucks.
The study of visual perception provides a number of factors regarding
size. Time-to-collision is determined from visual expansion of the viewed
entity, supplemented by factors such as physical size and the viewer's
expectations: a smaller entity entails reduced visual expansion, so would
be at risk of overestimated time-to-collision. Also important may be
height in the visual field: for example, the driver's height above the
road will be greater in a SUV than in a small hatchback. Height affects
the upper extent of visual expansion generated by the viewed entity; this
is reduced as height increases, so a SUV presents a greater risk than most
other private automobiles (4,5).
A second issue concerns the potential power of the entity. A major
division follows that for size: the slow speeds and accelerations of self-
powered travel contrast with the speeds and accelerations of motor-powered
travel. One obvious consequence concerns kinetic energy reflecting both
mass and speed: there is a mathematically fourth-power relationship
between speed and survivability (6).
The issues of size and power are hardly rocket-science. Yet they
often have meagre effects in shaping road safety policy. One example from
the UK: any attempts to reduce SUV ownership in urban and suburban areas
where the size and power of SUVs are unnecessary in relation to their
function have been ineffectual, even given the savings that can be made in
a time of increasing fuel prices.
REFERENCES
1. Achery AD, McLellan BA, Redelmeier DA. Bicyclist deaths and
striking vehicles in the USA. Inj Prev 2011; 10.1136/injuryprev-1011-
04066l
2. Simms C, O'Neill D. Sports utility vehicles and older pedestrians.
BMJ 2005;331:787-788.
3. Eberts RE, MacMillan AG. Misperception of small cars. In RE
Eberts, CG Eberts (eds). Trends in Ergonomics/Human Factors II. North
Holland: Elsevier 1985;33-40.
4. Stewart D, Cudworth CJ, Lishman JR. Misperception of time-to-
collision by drivers in pedestrian accidents. Perception 1993:22:1227-
1244.
5. Cavallo V, Berthelon C, Mestre D, et al. Visual information and
perceptual style in time-to-collision estimation. Vision in Vehicles VI.
North Holland: Elsevier 1992;81-89.
I make brief extra comments in response to Lusk et al.
It is difficult comparing the poor cycle-specific facilities that I
find in Northern Ireland with the lack of cycle-specific facilities
typical in the US: neither scenario helps cyclists and any statements
about which is to be preferred may never be more than impressionistic.
However, I would concede that even imperfect cycle-specific
facilities pr...
I make brief extra comments in response to Lusk et al.
It is difficult comparing the poor cycle-specific facilities that I
find in Northern Ireland with the lack of cycle-specific facilities
typical in the US: neither scenario helps cyclists and any statements
about which is to be preferred may never be more than impressionistic.
However, I would concede that even imperfect cycle-specific
facilities provide publicity for the cause of cycle-commuting. Who knows:
if poor facilities lever enough opprobrium among the community, the
appropriate authorities may be pressured into acting to upgrade the
facilites to something genuinely useful for cyclists.
In contrast, I guess the lack of any cycle-specific facilities
typical of the US conveys the impression that urban and suburban cycling
is nothing more than an extreme sport for young macho males - it is
something to be outlawed if at all possible.
Mendivil et al's (1) excellent paper demonstrates the cost-benefits
to be derived from investment in speed cameras. It invokes that remarkable
Achilles-heel accompanying mass motoring: the toleration of levels of
preventable danger that are unacceptable in other transport modes (2).
Attitudes to speed-cameras may reflect the misplaced suspicion that
motorists have long directed to the accuracy of their speedomete...
Mendivil et al's (1) excellent paper demonstrates the cost-benefits
to be derived from investment in speed cameras. It invokes that remarkable
Achilles-heel accompanying mass motoring: the toleration of levels of
preventable danger that are unacceptable in other transport modes (2).
Attitudes to speed-cameras may reflect the misplaced suspicion that
motorists have long directed to the accuracy of their speedometers (3). In
the UK, the initial attitude of a considerable section of the motoring
public towards speed-cameras was hostile: Cameras were deliberately
smashed in the context of a campaign which asserted that speed-cameras
were no more than indirect taxation: a cash-cow for government. It was
further asserted that overt placement of speed-cameras would lead to
erratic speeds which would increase the number and severity of crashes.
This problem could of course be alleviated by covert placing of speed-
cameras, but this solution was no emollient; it would likely bring about
greatly increased detection-rates (4)!
The attitude of the current UK government has unfortunately regressed
during the economic downturn: a shift to local decision-making could lead
to the reduction or elimination of speed-cameras in some areas. Mendivel
et al make it clear that this is not an economically sensible path to
follow.
The story of speed-cameras may come to follow the older story of
breathalysers: the latter have steadily achieved acceptance by most
motorists - but a substantial minority continue stubbornly to misbehave
(5). In the meantime, a side-effect of such toleration of danger may be
that measures to promote less intrusive and healthier modes of travel -
cycling and walking both for full journeys and in conjunction with public
transort - remain less effective than they might be in many jurisdictions.
REFERENCES
1. Mendivil J, Gancia-Altes A, Perez K, et al. Speed cameras in an
urban setting: a cost-benefit analysis. Inj Prev
2011:10.1136/ip.2010.030882.
2. Reinhardt-Rutland A H. Attitudes to SUVs and "slam-door" rolling
stock represent a paradox. BMJ 2005; 331:967.
3. Denton G G. The use made of the speedometer as an aid to driving.
Ergonomics 1969;12:447-454.
4. Reinhardt-Rutland A H. Roadside speed-cameras: arguments for
covert siting. Police J 2001;74:312-315.
5. Gunay R A, Haran I. Face-to-face interviews with motorists who
admit to drink driving in rural Northern Ireland. Traffic Eng Control
2005;46:376-379.
I read with interest Caroline Finch's Online First editorial
describing her recent experience of attending and giving a key note
address at the third World Conference on Prevention of Injury and Illness
in Sport. As someone who also frequently straddles the fields of sports
medicine, injury prevention and, more broadly, health promotion, I would
like to whole heartedly support Professor Finch's call...
I read with interest Caroline Finch's Online First editorial
describing her recent experience of attending and giving a key note
address at the third World Conference on Prevention of Injury and Illness
in Sport. As someone who also frequently straddles the fields of sports
medicine, injury prevention and, more broadly, health promotion, I would
like to whole heartedly support Professor Finch's call for greater
integration and collaboration across these areas. With sports injury
prevention and falls prevention research now on the trail of the holy
grail of translational and implementation research, both have so much they
can learn from each other and from other fields of health and behavioural
science research. Tobacco control is probably the most mature and
sophisticated area of health promotion research so why not see what has
been learnt there and take what is useful for application in injury
prevention. The same applies to physical activity promotion and obesity
prevention. Road traffic safety, falls prevention among the elderly, and
occupational health and safety are three areas of injury prevention
research where so much is already know about what works (and what doesn't)
to change safety behaviours and to translate research evidence into real-
world reductions in injury mortality and morbidity---yet few sports injury
prevention or sports medicine researchers avail themselves of this body of
knowledge.
We agree with Reinhardt-Rutland's concerns1 about Northern Ireland's
poorly designed and policed bicycle facilities but we doubt that the U.S.
traditional model of simply treating bicycles as vehicles is better. What
works is physically separating bicyclists from fast or heavy motor
traffic. Reinhardt-Rutland further suggested that higher fuel costs could
effect change where risk assessments have failed. While waiting fo...
We agree with Reinhardt-Rutland's concerns1 about Northern Ireland's
poorly designed and policed bicycle facilities but we doubt that the U.S.
traditional model of simply treating bicycles as vehicles is better. What
works is physically separating bicyclists from fast or heavy motor
traffic. Reinhardt-Rutland further suggested that higher fuel costs could
effect change where risk assessments have failed. While waiting for
increases in fuel prices, we wanted to underscore the benefits of cycle
tracks, including their lower injury risk.
Cycle tracks, as described and studied in our paper2 are physically-
separated bicycle-exclusive paths along roads as found in the Netherlands.
Cycle tracks can have dividers that prevent cars from parking on them.
Parallel parked cars alongside a cycle track also separate bicyclists from
moving traffic. These cycle tracks by parked cars can also lower exposure
of cyclists to air pollution. Unlike a shared-use segregated path,
pedestrians have a place on their sidewalk and bicyclists on their cycle
track. With cycle tracks, drivers can see a space has been relegated in
the right-of-way for bicyclists, especially when it comes with its own red
and green bicycle signal.
The Montreal case shows that cycle tracks not only have lower injury
risk2 but they may be an effective strategy for promoting cycling3 just by
themselves or combined with other policies (ex. public bicycle share
program, complete streets, etc.). When successful, drivers can witness
women, children, seniors, and parents bicycling instead of mainly young,
adult, male bicyclists in the road.
Reinhardt-Rutland wrote that the Northern Ireland's problematic
bicycle facilities are often ineffective. By definition, non existent
cycle tracks are also ineffective.
1. Reinhardt-Rutland TH. The effectiveness of dedicated cycling
facilities: perceived and objective risk. Inj Prev 2011;17(3):216.
2. Lusk AC, Furth PG, Morency P, Miranda-Moreno LF, Willett WC, Dennerlein
JT. Risk of injury for bicycling on cycle tracks versus in the street. Inj
Prev 2011.
3. Miranda-Moreno LF. Weather or not to cycle: whether or not cyclist
ridership has grown: a look at weather's impact on cycling facilities and
temporal trends in an urban environment. Transportation Research Record in
press.
When Lusk et al. submit to the editor a formal list of errata to be attached to their article, I expect they will duly correct all the errors, omissions, and false statements that have been brought to their attention, and not just the three they chose to mention here. This would include amongst other items providing a correct explanation for their choices of particular termination points (rather than the non...
We regret the two errors that Kary identified. "What this study adds" should read published crash [not injury] rates (the article body states it correctly), and the Rachel length is 1.7 km [not 3.5]. In Table 1, correcting for 1.7 doubles Rachel's absolute incident rates; however, it raises overall crash and injury rates by only 10% to 9.6 and 11.5, respectively. In Table 2, the relative risk comparison is unaffected sinc...
1. Rue de Brebeuf Cycle Track vs. Rue St. Denis between Rachel and Laurier.
These streets are not comparable.
Brebeuf (which has a cycle track) is a narrow 40kph slow-moving one- way residential street with one traffic lane and one parking lane.
Rue St. Denis (which has no cycle track) is a six-lane (two lanes often taken up by parking) 50kph limit two-way highway in a commercial area with lot...
The Results of this study are interesting, particularly comparisons to other countries. I'd be also interested in looking into driver license test standards. Having worked as an expat in the UK 1999-2005, I knew many who have tried unsuccessfully to obtain a driver's license because of the high test standards. You must pass a written test, video response test and the road test. Only 30% successfully complete all three on t...
Injury Prevention asks that responses to articles be kept to less than about 300 words. The volume of errors and omissions in this article by Lusk et al. is so excessive that it took me rather more than that-- including photographs of the actual streets-- just to document them. The result is now hosted on John S. Allen's bicycle pages and can be directly found by searching the internet for e.g. these terms:...
Ackery et al (1) show that risk to cyclists in collisions with motor- vehicles increases with the size of the motor-vehicle. This evidence may generalize to other types of collisions: consistent with Ackery et al are studies concerning different sizes of automobile with pedestrians (2,4) and collisions concerning different sizes of automobiles in general (3). One can infer that a smaller entity - both in terms of linear d...
I make brief extra comments in response to Lusk et al.
It is difficult comparing the poor cycle-specific facilities that I find in Northern Ireland with the lack of cycle-specific facilities typical in the US: neither scenario helps cyclists and any statements about which is to be preferred may never be more than impressionistic.
However, I would concede that even imperfect cycle-specific facilities pr...
Mendivil et al's (1) excellent paper demonstrates the cost-benefits to be derived from investment in speed cameras. It invokes that remarkable Achilles-heel accompanying mass motoring: the toleration of levels of preventable danger that are unacceptable in other transport modes (2).
Attitudes to speed-cameras may reflect the misplaced suspicion that motorists have long directed to the accuracy of their speedomete...
Dear Editor
I read with interest Caroline Finch's Online First editorial describing her recent experience of attending and giving a key note address at the third World Conference on Prevention of Injury and Illness in Sport. As someone who also frequently straddles the fields of sports medicine, injury prevention and, more broadly, health promotion, I would like to whole heartedly support Professor Finch's call...
We agree with Reinhardt-Rutland's concerns1 about Northern Ireland's poorly designed and policed bicycle facilities but we doubt that the U.S. traditional model of simply treating bicycles as vehicles is better. What works is physically separating bicyclists from fast or heavy motor traffic. Reinhardt-Rutland further suggested that higher fuel costs could effect change where risk assessments have failed. While waiting fo...
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