Where are the dependencies for this? http://www.simtropolis.com/stex/index.cfm?id=17789
You should have asked the creator at STEX for those, but here goes...
You need the Simcity 4 Buildings as Props (file name bldgprop_vol1.dat) which can be downloaded from the official site:
http://simcity.ea.com/coolstuff/loteditor/loteditortool_01.php
Note, that you have to register at that site first.
Well that fixes the mayor statue problem but I still get boxes for the roundabout signs.
Seems like r3b00t has forgotten to include the model of the sign.
There is a SC4Desc file for the sign included in the package, but no SC4Model file.
I would recommend asking r3b00t for the model.