A bridge is just a technique used to stretch a sector.
To make a sector stretch

1) Give the sector a Lotag of 27.  Hit T in the sector.

2) Insert a sprite and change it to SectorEffector.

3) Point the sector effector ". and ," towards the Direction to stretches.

4) Give the Sector Effector a lotag of 20. Hit alt+T on the SE.

5) Insert a Speed sprite in the sector.

6) Give the speed sprite a lotag.  It will determine how long it streches.
