1. Professor, Dept. of Civil Systems Engineering, Technische Universitat Berlin, TIB 1-B13, Gustav-Mayer-Allee 25, 13355 Berlin, Germany (corresponding author).
2. Professor, Dept. of Computer Science, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
3. Owner, Prairie Sky Consulting, 1104 Parkview Dr., Mahomet, IL 61853.