[8] On April 29, 2009, CN announced the company's plan for succession in Harrison's position by appointing Claude Mongeau as his successor effective January 1, 2010.

Bound by a non-competition clause with CN, Harrison maintained a low profile as a director for the Belt Railway of Chicago as well as Dynegy Holdings LLC.

[citation needed] In fall 2011, Harrison was approached by the hedge fund Pershing Square Capital Management led by activist investor Bill Ackman, who was undertaking a proxy battle with the board of directors of CPR.

In the suit, CN's board of directors said it had grounds to believe Harrison may have violated his commitments to CN as part of push by activist shareholder William Ackman and his New York-based hedge fund, Pershing Capital Management LLC, to see Harrison replace Fred Green as CEO of rival CP Ltd.[11] On January 18, 2017, Harrison resigned as CEO of CP Ltd. to join Paul Hilal in another freight rail management restructuring initiative at CSX Corp., a US-based freight rail company.

[14] Harrison died on December 16, 2017, due to severe complications from a recent illness,[15] two days after taking medical leave from CSX.