Canada's railways saw 143 accidents involving dangerous goods in 2013, up from 119 a year earlier, according to preliminary data from the Transportation Safety Board.

It’s a slight increase from the average of 133 per year between 2008 and 2012.

Explore the map to see the details and approximate locations of the accidents. The colour coding distinguishes the types of accidents.

Alberta had the highest share of the accidents. The map shows derailments occurred repeatedly in some areas, including neighbourhoods in Winnipeg, Edmonton, Sarnia, and York and Peel regions in the GTA.

Most of the accidents were deemed Class 5, the least serious category. These accidents are recorded by the safety board for archival purposes but not investigated.

The Lac-Mégantic disaster, which killed 47 people in the Quebec town, was categorized as a Class 2 accident, meaning the investigation of it has the potential to significantly improve rail safety.

None of the 143 accidents was categorized as Class 1, which would entail a public inquiry.

“Dangerous goods” are defined by Transport Canada and include varieties of flammable, radioactive and toxic substances.