How I do so is to create a Railing type with 1x1mm rail at the floor level.
And override the graphics in view of that railing to show as dotted line.
Railing has the properties of the total length even though it is segmented.
There are many reasons one might need to measure the length of multiple lines or walls. Many more than just path of travel. Zoning codes reference the length of walls to determine definition of basements. They also reference percentage of existing non-conforming walls that may continue along a length of encroachment in a yard. Architect's rely on CAD to define these dimensions for approvals.
I don't make this point to correct you but to express to rosskirby that I share the frustration with Revit. Not frustrated by the learning curve, we're way beyond that. It's because the software fails miserably to meet many fundamental capabilities. I can't' return to 2D CAD, and love Revit for that, but I often find it miserable to forge ahead. There should not be Tips and Tricks and third party applications to make it perform as expected.
I don't see your point.
If you want to measure the total length of multiple lines or walls, it can be done easily as explained in message # 3 in this thread.
If you want to measure an egress path, schedule the lengths, tag it, etc, then, you need some other tools, as explained in message # 9 by Ross Kirby, which includes a link to Steve Stafford's blog, who has explained the solution in his blog for several years.
Both needs have a solution, without using any tips and tricks or third-party applications, just using the native Revit tools.
I know this is a liitle late on this reply, I am looking for an answer to totaling the length of multiple lines. I do site development and do feasiblity studies....for way too little feee, and don't want to spend the time redoing my planners less than perfect line work for "phone quote" probable costs. I need to take a subdivision street centerline and total by selecting the all. A very talented programmer....JW.... wrote a LSP for an earlier version and would have expected he pass that along in the new software. I also do preliminary layouts of teh water, saniatary sewer systems, and drainage systems and would like to total those lengths also.
Thanks in advance!