An attacking block, similar in principle to the huff
, used to fend off players attempting to defend an attacking move. Whilst on the same line as the defender, and with the latter on an interchange, the attacking player shunts to the interchange and switches lines, then blocks the station immediately after the interchange. The defender can not pass the attacker to prevent any combination up the newly held line, and must resort to straddling
. On interchanges near the end of lines, this can be horribly effective.