The decision to reintroduce the odd-even scheme from April 15 to 30 was based on responses from a little over four lakh people.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/80-delhiites-want-it-back-govt-survey
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/odd-even-numbered-cars
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/two-wheelers
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cars-and-congestion
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/public-transport