In's and Out's of 'Abandon Bridge' ?

[Steel God]

The manual doesn't get too detailed on the details of 'Abandon Bridge', but it seems fairly straight forward.  However, I'm assuming that if you abandon the bridge it allows the unit to move along but the bridge stays intact.  Is that a correct assumption?

No sir, the exact opposite.  Engineering bridges of the era are not self maintaining things, they must be manned to keep the current from sweeping them away.  If your engineer “abandons” his bridge he is cutting it loose and letting it go.  You may move the engineer but having abandoned his equipment he’ll never build another one.