"We will commence transporting and storing rail cars on the tracks in the coming weeks," the letter states.
The letter, on CP letterhead, tells residents not to walk, drive or cycle on or alongside the railway line — which hasn't been used for trains in about 15 years.
"Should you need to cross the tracks, do so only at marked crossings," reads the letter signed by CP's government affairs west director Mike LoVecchio.
Vancouver and CP Rail in long dispute
The City of Vancouver and CPR have been fighting over the future of the corridor, which runs through pricey residential neighbourhoods, for more than a decade.
Vancouver has offered to buy the land off CP Rail, which has owned it for nearly 130 years, but the two sides failed to come to an agreement on the price last year.
After negotiations broke down, CP Rail warned residents last year it intended to use the vacant tracks for train traffic again and began ripping out community gardens along the right of way.
The company admitted at that time the dispute with the city was behind the efforts to reactivate the line.
DOCUMENT: Read CP's letter to residents