RESEARCH BMJ: first published as 10.1136/bmj.c2884 on 6 July 2010. Downloaded from Effect of a barrier at Bloor Street Viaduct on suicide rates in Toronto: natural experiment Mark Sinyor, resident physician,1,2 Anthony J Levitt, psychiatrist in chief2 1Department of Psychiatry, ABSTRACT related suicides decreased after the introduction of leg- University of Toronto, ON, Canada Objective To determine whether rates of suicide changed islation for gun control,67although some evidence sug- 2 Department of Psychiatry, in Toronto after a barrier was erected at Bloor Street Sunnybrook Health Sciences gests that these reductions were matched by increases 89 Centre and Women’s College Viaduct, the bridge with the world’s second highest in suicides by other means, such as jumping. Hospital. 2075 Bayview Avenue, annual rate of suicide by jumping after Golden Gate Barriers to prevent jumping have been established at Toronto, ON, Canada M4N 3M5 Bridge in San Francisco. the Empire State Building, the Eiffel Tower, and sev- Correspondence to: M Sinyor 10 11 [email protected] Design Natural experiment. eral bridges worldwide. Recent arguments in Setting City of Toronto and province of Ontario, Canada; favour of barriers on bridges used for suicide stem Cite this as: BMJ 2010;341:c2884 records at the chief coroner’s office of Ontario 1993-2001 doi:10.1136/bmj.c2884 from studies in the 1970s that assessed the survivors (nine years before the barrier) and July 2003-June 2007 of suicide attempts at Golden Gate Bridge in San Fran- (four years after the barrier). cisco, the bridge with the world’s highest annual rate of Participants 14 789 people who completed suicide in the suicide by jumping.10 In one study, four of six survivors city of Toronto and in Ontario. said that they would not have attempted suicide at any Main outcome measure Changes in yearly rates of suicide location other than Golden Gate Bridge and all six by jumping at Bloor Street Viaduct, other bridges, and favoured the construction of a barrier at the bridge.12 buildings, and by other means. In another study, only 6% of 515 people who had been http://www.bmj.com/ Results Yearly rates of suicide by jumping in Toronto prevented from jumping off Golden Gate Bridge had remained unchanged between the periods before and subsequently completed suicide.13 Despite this evi- after the construction of a barrier at Bloor Street Viaduct dence, 74% of respondents to a US telephone survey (56.4 v 56.6, P=0.95). A mean of 9.3 suicides occurred believed that most or all people prevented from jump- annually at Bloor Street Viaduct before the barrier and ing off Golden Gate Bridge by a barrier would find none after the barrier (P<0.01). Yearly rates of suicide by another way to complete suicide.14 Studies examining jumping from other bridges and buildings were higher in the introduction of suicide barriers at Memorial Bridge on 3 October 2021 by guest. Protected copyright. the period after the barrier although only significant for in Augusta, Maine15 and Clifton Suspension Bridge in other bridges (other bridges: 8.7 v 14.2, P=0.01; Bristol, England16 as well as the introduction of a safety buildings: 38.5 v 42.7, P=0.32). net at Muenster Terrace in Bern, Switzerland17 showed Conclusions Although the barrier prevented suicides at reductions in mean numbers of suicides of 0.6, 4.2, and Bloor Street Viaduct, the rate of suicide by jumping in 2.5 persons per year respectively at each location. Each Toronto remained unchanged. This lack of change might article examined the change in rates of suicides by have been due to a reciprocal increase in suicides from jumping from nearby bridges or buildings and con- other bridges and buildings. This finding suggests that cluded that little, if any, substitution of location Bloor Street Viaduct may not have been a uniquely occurred. However, these studies lacked statistical attractive location for suicide and that barriers on bridges power because of the relatively small yearly decreases may not alter absolute rates of suicide by jumping when in numbers of suicides at each bridge as well as low comparable bridges are nearby. rates of suicide in general. No study of a suicide pre- vention barrier has shown a statistically significant INTRODUCTION drop in overall rates of suicide in the vicinity. It is well recognised that restricting access to a means of For more than a decade it has been debated whether suicide may delay or even prevent suicide among a barrier at Bloor Street Viaduct would be effective at vulnerable people.1 This principle has been shown preventing suicides in Toronto, Canada. Since the con- successfully in the United Kingdom with the imple- struction of the viaduct in downtown Toronto in 1918, mentation of relatively simple strategies such as switch- at least 400 people have jumped to their deaths from ing to carbon monoxide-free sources of gas,2 restricting the bridge.18 The 40 m high viaduct spans two major pack sizes of paracetamol (acetaminophen) and roads, is 490 m long, is double decked, and has an salicylates,34 and fitting cars with catalytic arched design with five lanes of traffic above a converters.5 In both Canada and New Zealand firearm subway.19 With about 10 suicides annually from 1993 BMJ | ONLINE FIRST | bmj.com page 1 of 6 RESEARCH to 2002 (baseline data from this study), Bloor Street 1996-2001 and 2001-6. We estimated population Viaduct had the dubious distinction of being the sec- growth by extrapolating backwards from 1993-6 and ond most popular bridge for suicide studied in the forwards from 2006 to June 2007. BMJ: first published as 10.1136/bmj.c2884 on 6 July 2010. Downloaded from world after Golden Gate Bridge.10 The barrier at Bloor Street Viaduct, named the “luminous veil,” was Statistical analysis constructed between April 2002 and June 2003. The To examine differences between suicide rates before barrier is about 5 m high and consists of thousands of and after the barrier we carried out Poisson regression thin steel rods spaced closely together and supported analyses. We analysed demographic data using two externally by an angled steel frame.20 It is not known tailed, independent sample t tests for continuous vari- whether the barrier has had any impact on Toronto’s ables and two sided χ2 tests for categorical variables. overall rate of suicides and on the rate of suicides by Data on postal codes were analysed using a one sided jumping. We examined coroner’s data before and after χ2 test under the assumption that more people would the construction of the barrier, to determine if suicide travel from outside the city to complete suicide at Bloor rates had changed and whether or not people substi- Street Viaduct (before the barrier) than at other bridges tuted Bloor Street Viaduct for different locations or in the period after the barrier. We considered a P value means of suicide. less than 0.05 to be statistically significant. METHODS RESULTS We examined records at the chief coroner’s office of Annual rates of suicide by jumping in Toronto Ontario covering all suicides in Ontario from 1 Janu- remained unchanged before and after the construction ary 1993 to 30 June 2007. To be included in the data of the barrier at Bloor Street Viaduct (56.4 v 56.6, collection the death had to be ruled a suicide by the P=0.95; table 1, fig 1). A mean of 9.3 suicides took coroner’s office according to the standard of a high place annually before the barrier and none after the degree of probability. Given the large number of barrier (P<0.01; fig 2). After the barrier the annual charts, it was not possible to examine deaths classified rate of suicides by jumping from bridges other than under different categories such as accident, homicide, Bloor Street Viaduct increased significantly (8.7 v. or undetermined cause of death. Staff at the coroner’s 14.2, P=0.01) and from buildings increased non-signif- office provided a spreadsheet listing all the cases coded icantly (38.5 v 42.7, P=0.32). In 2002, the year when as suicides in Ontario for each year in the study. As it construction of the barrier commenced (but was not takes about two years for a case to be closed, complete complete), 63 suicides by jumping occurred in Toronto http://www.bmj.com/ data for 2007 were available only in 2009. The follow- of which 30 were from bridges and 19 from the Bloor ing information was included in the spreadsheet: date Street Viaduct. of suicide, age, sex, region, municipality, and cause of Both the overall rate of suicides in Toronto and the death, such as a fall or jump from a height, hanging, or rate of suicides by means other than jumping decreased shooting. We grouped the suicides into four categories: by 28 suicides per year in the period after the barrier (all all suicides in Ontario (excluding Toronto), all suicides Toronto suicides per year: 253.4 v 225.4, P=0.05; Tor- in Toronto, suicides in Toronto by jumping (where v onto suicides per year by other means: 197.0 168.8, on 3 October 2021 by guest. Protected copyright. jumping implied from a height, therefore people who P=0.04). The decrease in overall rate of suicide in Tor- jumped in subways were excluded), and suicides in onto bordered on statistical significance whereas the Toronto by means other than jumping.