TORONTO -- Hydro One says it will have invested more than $845 million to improve electricity reliability in Toronto and the GTA by the end of 2018.

Hydro One says it has already completed more than $157 million in upgrades through 10 transmission station projects to improve reliability and replace aging infrastructure.

In addition, the utility says it plans to complete more than $688 million in improvements and replacements by the end of 2018.

Hydro One COO Sandy Struthers says the work is designed to improve electricity reliability in Toronto and the GTA.

Hydro One owns and operates Ontario's 29,000-kilometre high-voltage transmission network that delivers electricity to large industrial customers and municipal utilities.