Problem was reported at here.
http://forum.simutrans.com/index.php?topic=1904.msg19724#msg19724
Code is written in ****ert, this will not exec in release version.
ai_goods.cc:620-
// connect to track
ribi1 = ribi_typ(diff1);
****ert( welt->lookup_kartenboden(platz1+size1-diff1)->weg_erweitern(track_wt, ribi1) );
ribi1 = ribi_t::rueckwaerts(ribi1);
****ert( welt->lookup_kartenboden(platz1+size1)->weg_erweitern(track_wt, ribi1) );
ribi2 = ribi_typ(diff2);
****ert( welt->lookup_kartenboden(platz2+size2-diff2)->weg_erweitern(track_wt, ribi2) );
ribi2 = ribi_t::rueckwaerts(ribi2);
****ert( welt->lookup_kartenboden(platz2+size2)->weg_erweitern(track_wt, ribi2) );
return true;
Patch attached. However, weg_erweitern shouldn't fail in this situation.