Elevations are not necessary to create a network dataset.
The most basic way to create a network dataset in Catalog is to right-click on the lines shapefile and choose New Network Dataset. Then Next through the wizard taking all defaults and then click Finish. That should create a network dataset.
Can you also check if there is an existing network dataset based on the same lines shapefile in that folder? A shapefile can only participate in one network dataset at a time.
Robert - that isn't true. Creating a network dataset—Help | ArcGIS Desktop
Network datasets can be created from shapefiles. This may require some troubleshooting.
David, is that the only error? "could not create network dataset"
What is the path of the Windows folder where the shapefile sits? Can you check the security/permissions of that folder - do you have write access?
I don't see any other error. The path is "D:\Dropbox\growth_shadow\cross_sections\RAILROADS\RR1826-1911Modified050916.shp". I am not sure what you mean... Do I need a permission yto access my Dropboox from ArcCatalog or ArcDesktop...
In another message I mentioned that I don't have elevation measures. Shall I try to create them? Also... these are railroads and I would like to map them on a county map. So I do have a county shapefile besides the railroads shapefiles. Perhaps the thing is that they should be both in a folder?
Kory, what do you mean by "Network datasets can be created from shapefiles. This may require some troubleshooting." What kind of troubleshooting? I think this may be the problem I am facing...
Just to rule out the issue of a dropbox, can you copy the shapefile to a new folder on your local disk drive and try again?
Also, what version of the software are you using?
I did that but still no success. Do you think the fact that my data does not have elevation may be causing this? Can you point me to some online tutorial where a SHAPEFILE is transformed into a NETWORK DATASET?