Old hypothesis that roads are safer than cycle tracks unsupported by data
We acknowledge that we did not control for all of the differences in road geometry and building typologies because there are no ideal matched streets (Re: Cooper). However, alternative research designs also have limitation and feasibility issues. For before and after study designs, some of the Montreal cycle tracks are 20 years old, before injury surveillance and traffic counting data systems were available. Limiting to cycle tracks that were developed after these data were available would limit us to a much smaller number of cycle tracks, thus reducing the statistical power. Utilizing a multivariate analysis to account for other factors such as road geometry, buildings types, pedestrians, trees, etc. would answer a different research question - about the possible independent effect of each factor - and would require many more cycle tracks or another unit of analysis (ex. intersections). Therefore, bicycling on cycle tracks was compared to bicycling on streets without cycle tracks. To select the alternative reference streets without cycle tracks, a few parallel reference streets were considered for each street with a cycle track, The parallel street was then selected because it had, as much as possible, the same cross streets. Recognizing no perfect reference street existed, we also compared relative danger from vehicular traffic by obtaining the injuries to motor vehicle occupants (EMR data). Given these limitations, none of the 6 pairs were found to have a statistically significant higher risk of injury on the cycle tracks. Thus, not one of the comparisons in this research conducted in Montreal supported the old hypothesis that bicycling on cycle tracks posed greater risk than bicycling in the road. In fact the opposite was true as bicycling on the cycle tracks posed less risk.
Conflict of Interest:
Still more errors and omissions
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  in circumstances exactly as warned about on page 34 of the AASHTO guidelines .
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.
Conflict of Interest:
"In Montreal, no greater risk on cycle tracks"
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.
Conflict of Interest:
Flaws in the 2010 Lusk Montreal Study - streets with statistically significant results.
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.
Conflict of Interest:
Compendium of errors and omissions, or: What is not in this article
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?
Conflict of Interest:
Re:Underscoring the Benefits of Cycle Tracks
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.
Conflict of Interest:
Underscoring the Benefits of Cycle Tracks
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.
Conflict of Interest:
Critique of: "Risk of Injury for Bicycling on Cycle Tracks Versus in the Street"
The investigators did not meaningfully compare Relative Bicycling Risk and Relative Traffic Danger for individual pairs. Such a comparison of their data demonstrates that the Apparent Cycle Track Effect was increased Danger to bicyclists at two cycle tracks, Neutrality at two cycle tracks, and increased Safety at two cycle tracks. This contrasts with the investigators' claim that the six cycle tracks had a combined 28% lower injury rate than their eight reference streets.
But are the two cycle tracks that are apparently safer in actuality safer for bicycling than their reference streets? Examination reveals that this is false safety.
The investigators assumed, without testing or providing supporting evidence, that Motor Vehicle Occupant injury counts are a surrogate for traffic danger a bicyclist might face on a given street apart from any treatment. Examination of the street characters of Berri and reference Saint Denis show that MVO injuries are not a suitable surrogate for this pairing. I conclude that after adjustment for its reference street being inherently more dangerous for bicyclists, the Apparent Cycle Track Effect of Safety for Berri is instead Unknown.
The Apparent Cycle Track Effect of Safety for Christophe Colomb can be explained by an artificially low Relative Bicycling Risk compared to reference Saint Hubert, and an artificially high Relative Traffic Danger compared to reference Christoph Colomb non-cycle track section. After adjustments I conclude the Christophe Colomb cycle track has Neutrality with both its reference streets.
The reference streets in pairs 1, 3, and 6 are engineered to be more dangerous with the presence of "faux Door Zone Bike Lanes." Simple re- striping to eliminate this hazard and alert bicyclists to the extent of the door zone, and signage to empower them to use a full traffic lane could reduce bicyclist risk on these streets. This would make the cycle tracks comparatively more dangerous.
For my full critique, see: http://bicyclingmatters.wordpress.com/critiques/montreal-cycle-tracks/
Conflict of Interest:
THE EFFECTIVENESS OF DEDICATED CYCLING FACILITIES: PERCEIVED AND OBJECTIVE RISK
Lusk et al's paper (1) indicates an important subtext regarding travel. Governments wish to make personal mobility as widely available as possible; this inevitably entails promotion of the private automobile, which can provide convenient and comfortable travel for the widest range of individuals, including those for whom disability would otherwise pose severe limitations in participating in society. However, there is a competing agenda concerning congestion, sustainability, pollution and health, along with the risk posed by automobiles for vulnerable road-users such as pedestrians and cyclists.
Authorities must strike a balance. In the case of the US, the balance generally favours the automobile: the insistence that cyclists be treated as "operators of vehicles" (2) underlines that assertion. Canada may be more bicycle-orientated. Lusk et al demonstrate that in Montreal segregated cycle tracks can entail fewer casualties than matched common- user roads: the consequent reduction in perceived and objective risk can sussessfully act to promote cycling.
0However, poorly designed and policed facilities may render the situation for cyclists worse than if the US model is followed. This is arguably the case in Northern Ireland. Cycle lanes at the side of roads are provided. Despite official prohibition, motor-vehicles frequently park or straddle cycle lanes before undertaking manoeuvres: junctions are particularly problematic regarding rights-of-way. Finally, cycle lanes are often well short of any meaningful journey. The official stance is that: "Use of cycle lanes is not compulsory and will depend on your experience and skills" (3). So cyclists are free to use other traffic lanes - but motorists seem unaware of this and often evince hostility towards cyclists exercising this freedom. The cyclist is uncomfortable on any part of the road - hardly a recipe for the development of mass cycle-commuting.
Segregated paths are also provided. These are in fact shared with pedestrians. Pedestrians no doubt provide better fellow travellers for cyclists than do automobiles, but the two groups are nevertheless incompatible regarding speed: cycling through groups of pedestrians or walking through streams of cyclists is not comfortable. Curiously, this is recognised regarding sidewalks, which are solely for pedestrians: cycling and driving are officially outlawed (3).
The above issues may reflect anomalous conceptualisations of risk. Northern Ireland again provides a useful example. The political conflict ("the Troubles") was always perceived to be particularly dangerous - for more so than the roads - as reflected in provision of manpower and resources. In fact, Northern Irish roads were objectively much riskier. Throughout the worst of the Troubles in the 1970s and 1980s, the objective risks of politically-motivated death and injury were about 50% and 12% respectively those for the roads (4). It is perhaps not surprising that strategies for promoting cycling are often ineffectual. With obvious exceptions such as the Netherlands, Denmark and - perhaps - Montreal, this unfortunately may apply in many jurisdictions.
Perhaps the seemingly inexorable increases in fuel cost may achieve real change: personal economics may win where conceptualisations of risk have failed.
1. Lusk A C, Furth P G, Morency P, et al. Risk of injury for bicycling on cycle tracks versus in the street. Inj Prev doi: 10.1136/ip.2010.028696.
2. Forrester J. Effective cycling. Cambridge: MIT Press, 1984.
3. The Highway Code: AA Publishing, 2008.
4. Reinhardt-Rutland A H. Roadside speed-cameras: arguments for covert siting. Police J 2001; 74: 312-315.
Conflict of Interest:
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