The Southern 100 racing club says new safety fencing on the Castletown bypass will remain in place until July.
The club says the new specialist fencing was installed for the Pre-TT Classic Road Races on the bypass as well as the start and finish line.
The plastic water-filled barriers have debris fencing placed on top.
The club says it's grateful for people's understanding as the barriers will be emptied at the end of the Southern 100 in July and removed by course contractors.
Will ring doorbell users need to register for data protection?
Major reservoir safety projects finished
Second weather warning this weekend
Does government plan to press ahead with min wage rise?
Where has government found £11m in savings?
Is there border security for Irish sailings?
Emergency powers used to fell trees
Busy road in West to close next week