TransCanada is offering the lower toll costs to help fill its underutilized Canadian Mainline natural gas pipeline system from a centre in Alberta to a hub in southern Ontario.

The Calgary-based energy transport company is inviting shippers to sign long-term binding commitments by March 9 to move gas on its underutilized Canadian Mainline system from a shipping centre in Alberta to a hub in southern Ontario.

The Calgary-based company says its proposal for a new round of binding commitments doesn't affect current contracts that are already in place for the system.