Superelevation lanes and median

[troma]

The superelevation wizard doesn't ask for the median width. Does this change anything? By this diagram it looks like I should just ignore the median width.

Also does it make a difference if I tell C3D that I have just one lane, 8.80m wide, or that I have two lanes at 4.40m wide each?

Does this actually change anything in the calculation?

Or is there a way to actually tell it that I have two lanes at 3.50m wide each plus a bike lane at 1.80m wide? Maybe use the shoulder setting for the bike lane?

Thanks. Bit of a newbie at this stuff.

Civil 3D 2013, SP2, 64 bit

[sboon]

The superelevation transition calculations can use two methods.  The common method (at least around here) is to read the values from a table.  The other method uses the lane/shoulder width and a transition rate to calculate it.

Which method are you using?

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[troma]

I wasn't really sure how to do it, but I figured since I wasn't in USA I shouldn't use AASHTO. I didn't see any options for Canada specifically, so I decided to just use the formula.

The 60% number is the one thing I in this box that I set with any confidence. 60/40 split is shown in the Design Guide for Canadian Roads.

I did change the lanes from originally 1 @ 11.30m to then more correct 1 @ 8.80m and then to 2 @ 4.40m. It didn't change any of the calculated results. (I mean the rate of full superelevation and the station of all of the superelevation critical points was the same whichever way I did it.)

Is there somewhere where it tells you what formula it is using? I was told to use a design speed of 70km/h and a superelevation of 4.80%. Well, when I ran the numbers C3D assigned a superelvation of 5.00%. I played with the design speed a bit, and when I set it to 69km/h then it calculated a superelevation of 4.80%, so I'm going with that right now but I don't know if all the transition lengths are matching my design standards.

I think I need to figure out how to add my own table of values.

[troma]

I did find some formulae (attached).

[For some reason I can't insert an image.]

The difficult thing has been trying to decipher the Design Guide for Canadian Roads. I did end up entering values from the book into a superelevation table to use, but I put some of the values in wrong. The table doesn't include the transition length; the number I thought was that was actually the spiral parameter 'A'. The superelevation transition length needs to be calculated from the spiral parameter, even if there is no spiral in the alignment (as is the case in this situation).