Abstract: A shuttle member for a horizontal lifeline system having at least one elongate line attached between at least two anchorage points. The shuttle member includes: a body having: (i) an upper portion configured for attachment to the line by at least partially surrounding the line; (i) an intermediate portion that, together with the upper portion, defines at least one passage slit that is sized such that the elongate line cannot pass therethrough; and (iii) an attachment portion configured for attachment of at least a portion of a lanyard. A shuttle member arrangement and a passing method are also disclosed.