MMORPG.com City of Heroes Correspondent H. Hussk writes this dissection of travel powers in the City of Heroes franchise, and how it has affected PvP combat.

The Artificial Response Mechanic "Travel Suppression" is the system that is used by CoX to handle balance to the pervasive use of travel powers as a means to attack and escape combat. It is not believed that travel powers were originally meant to be used as a means of combat; instead, they were only meant as a method of arriving at the fight destinations.

Although this is speculation: what ensued appears to be less than intended. Early on in their release, characters were performing "drive-by" attacks through the forms of travel and removing themselves from commitment of combat before any actual confrontation took place.

Travel Suppression, although artificial, is designed to counteract such an action. Through the use of arbitrary timers which can be raised or lowered, you are forced to move at walking speed levels if you are attacked or attack. While it can objectively be argued whether this system is working, it is noteworthy that all forms of PVP are going through changes at this time, which keep the characters in a state of change. It is not uncommon for the developers to allow "respecification" tokens, where a character can change his power choices, after they make they make such changes.

Read Movement Powers and PvP