I'm using the AASHTO superelevation wizard, and after creating a superelelvation section, Inroads calculates the runoff length incorrectly. In this example, for a 6.4% superelevation, it thinks the runoff should be 34.56 m. I want it to be 79 m, which is the length given in the 2004 Greenbook for 6.4%, 100kph design speed, 2 lanes rotated.
Is there a place to tell inroads what the design speed is, or does it pull from the rate calculator in the first step of the wizard?
Yes, the Rate and Speed come from the Rate Calculator which are stored in the geometry project and on an individual curve. This is the information used in the intital step of the wizard.
I would need to see all the settings prior to this step in the wizard to assist in determining how the values are being calculated. There are a lot of options which can impact the length calculations.
HTH
Thomas
Here's my workflow up to this point:
Try setting the spiral to tangent point to normal crown and check the results. There is also the setting of the % runoff or % total toggle that affects the location of the critical stations.
Also, I am curious as to why you would not use insdie pivot and then define the LEP and REP as range the then the CL (pavement) as the crown point?
Finally, I do not think you need to run the Rate calculator each time. I am fairly certain that once it is run, the values then come directly from the alg.
HTH and let me know if changing the setting changes your STL values.
Thanks for your time helping me with this Thomas,
I figured out that setting the Maximum Delta G value is essential. This value should come from AASHTO2004 table 3-30, and is 0.44 for my road, not 1.0. I had disregarded it because I wasn't sure what it meant.
I'm using the inside edge of pavement as the crown point because that was how Kevin McDonald did it in the workflow he gave me for this nightmare section. I don't honestly understand why it's done this way. Maybe he can explain:
http://communities.bentley.com/Products/Road___Site_Design/w/Road_and_Site_Design__Wiki/super-rollover-on-inside-median.aspx
I think you're right about not having to run the rate calculator each time - I just wanted all the dialogs to show up in the video.
Tim,
I'm glad that you figured it out. Just to let you know, the AASHTO Runoff rates are calculated using AASHTO equation 3-25, so that is why having the correct Delta G is essential.