Six minute solutions is the nuts. I studied for a total of 16 hours for the Civil PE/ Transportation exam. 8 hours of that was just doing the sample problems in the six minute solution book. The other 8 hours was the NCEES practice exam with the CERM. I passed the first try.
If you do the problems in the 6 minute solutions, even if you don't quite understand it, during the test most problems are similiar if not identical to the 6 minute solutions.
I really have no use for mine anymore, PM me your address and I'll send it, you can mail me a check for the shipping if you want, its not really a big deal to me.
bta15
*EDIT*: I guess its not really a textbook, but it was by far my most useful study guide