a different manufacturer, Alstom, in its stations. Considered a novelty at the time of its installation, platform screen doors were introduced primarily to minimise hefty air-conditioning costs, especially since elevated stations are not air-conditioned and are much more economical to run in comparison. Since then the safety aspects of these doors have become more important, as highlighted by a series of high-profile incidents where individuals were injured or killed by oncoming trains since the year 2002—all occurring on elevated stations with no screen doors. Intrusions onto the tracks at elevated stations have fallen since the installation of half-height platform screen doors. Initially, all elevated stations did not have half-height platform screen doors (HHPSDs) installed. The government had not supported the retrofitting of these gates at elevated platforms due to prohibitively high costs. Costs have since fallen due to the popularity of such gates worldwide, making such a project now feasible, and in a speech by the Minister for Transport Raymond Lim on 25 January 2008, the government announced plans for the retrofitting of HHPSDs on platforms at all elevated stations by 2012. Pasir Ris was the first elevated station to have platform screen gates and Kranji was the last elevated station to have platform screen gates. By 2011, all elevated East West Line stations have the platform screen doors installed and by 2012, all elevated North South Line stations have the platform screen doors installed. HHPSDs installed through this period were installed by ST Electronics. Newer half-height platform screen doors on the Tuas West Extension which opened in 2017 were installed by Fangda of China. All platform screen doors of both types on the MRT system have emergency door handles. References Mass Rapid Transit (Singapore) Railway safety