Does the installation of blue Lights on train platforms shift suicide to another station?: Evidence from Japan

Abstract

Background

Installing physical barriers at suicide hotspots is known as an effective strategy for suicide prevention. However, the effectiveness of physical barriers may be nullified by the substitution phenomenon, i.e., that restricting access to a particular place induces people at risk to look for a nearby place for suicide.

Methods

This study tests whether the substitution phenomenon exists in the case of railway and metro suicides. We focused on the prevention effort by a Japanese railway company that installed blue light-emitting-diode (LED) lamps on railway platforms to prevent people from diving to a running train. Using panel data of 71 train stations between 2000 and 2013, we compared the number of suicides before and after the installation of the blue lights at 14 stations where the lights were installed and at neighboring five stations on the same railway line, using the number of suicides at all other stations without the intervention as a control group.

Findings

Our regression analysis shows that the introduction of blue lights decreased the number suicides by 74% (CI: 48–87%) at stations where the blue lights were installed, while it did not result in a systematic increase in the number of suicides at the neighboring stations.

Interpretation

The installation of blue lights generated no systematic substitution phenomenon at nearby stations.

Introduction

Restricting access to suicide hotspots is known as an effective strategy for suicide prevention (Florentine and Crane, 2010, Yip et al., 2012). This is typically implemented by creating physical barriers at high sites (e.g., bridges) from which people jump or at train platforms where people jump in front of trains. A recent article by Cox et al. (2013) reviewed 9 articles and found consistent evidence that the presence of barriers at these hotspots was associated with reduction in the number of suicides.

Nevertheless, the effectiveness of physical barriers at hotspots may be nullified by the substitution phenomenon, i.e., that restricting access to a particular place induces people at risk to look for a nearby place for suicide, resulting in no major reduction in the overall number of suicides after implementation. This possibility has been widely studied in the case of suicide by jumping from high sites (e.g., Law et al., 2014). After reviewing related studies, Pirkis et al. (2013) concluded that the physical barriers to prevent jumping from bridges or cliffs increased suicides at nearby sites by 44%, while the prevention effort generated an overall reduction in suicides by 28% at the study cites.

Less is known about the possibility of the substitution phenomenon in the case of railway and metro suicides. Despite increasing efforts to install physical barriers to prevent railway and metro suicides (Ladwig et al., 2009, Law and Yip, 2011, Mishara, 2007), only a single study has examined whether the installation of physical barriers generates the substitution phenomenon. Law et al. (2009) showed that the installation of platform screen doors prevented suicide with no substitution phenomenon in the subway system of Hong Kong.

This study offers another test for the possibility of the substitution phenomenon in the case of railway suicides. We focused on the prevention effort by a Japanese railway company that installed blue light-emitting-diode (LED) lamps on railway platforms to prevent people from diving in front of a running train. This company, whose service is provided in the metropolitan area in Japan, installed blue lamps on platforms at some, but not all, of its stations and railways crossings in the last several years with the expectation that they have a calming effect on people who are agitated and ultimately stop them from jumping in front of trains. Matsubayashi et al. (2013) evaluated the effect of these blue lights on the number of suicides by using panel data of 71 train stations between 2000 and 2010. It found that the introduction of blue lights resulted in a decrease in suicides by 83% (CI: 14–97%) at stations where blue lights were installed.

Using an updated data set from the period of 2000 to 2013, we examined the possibility that the installation of blue lights at a particular station shifted the incidents of suicide to its neighboring stations. We compared the number of suicides before and after the intervention with the blue light at 14 stations where the lights were installed and at the neighboring five stations on the same railway line, using the number of suicides at all other stations without the intervention as a control group.