Use of pressure horns by a large number of private and school buses is common on city roads as the traffic police and the transport department have totally failed to ban the pressure horns.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/unchecked-use-pressure-horns-buses-nuisance
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/tribune-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/punjab
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/noise-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/buses
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/noise-rules-2000
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/motor-vehicles-rules-1989
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment