Truss road bridge
This is a non-spline bridge with attached abutments; it can be found under the building menu in surveyor.
Because this bridge is so narrow (only one lane) I didn't enable it for traffic.
If you need traffic support, you can probably lay an invisible single-lane road across the bridge in the direction you wish for travel.
3 levels of detail; 1189 / 780 / 489 polygons
Revision 1: fixed broken LoD