How to properly transition a road corridor based off an alignment going from a normal 2% crown into a 2% super? This particular job transitions from the crown in a Y. Any tips or videos would be great. Thanks
1 Like
Chris
There are two ways to handle this - one uses slope tables in an instruction of the corridor, the other uses a Superelevation instruction which requires the superelevation detail to be set up on the alignment.
Slope Tables
In your corridor you create a Template. In the template you have an instruction that is eg the Pavement Surface instruction on the right side of the crown - that says eg the road is 12’ wide at a -2% cross slope. Where you enter the cross slope, you can change the input by pulling down the list of options and select Table. This then allows you to enter the Station and Cross Slope table for the right side of the road. ie you enter something like this
Station = 0 Slope = -2%
Station = 500 Slope = -2%
Station = 680 Slope = +2%
Station = 1080 Slope = +2%
Station = 1260 Slope = -2%
etc. This will cause the pavement surface to start to super at station 500 and be at full super at station 680, stay at full super through the curve (a Left hand curve) and then start to de super at station 1080 and be back at normal cross slope at station 1260 onwards.
I often go through the plans and tabulate the slope for Left and Right side changes in Excel - then you can copy the Station / Slope values from Excel and paste them into the slope table.
https://myrockpile.retrieve.com/g/HE9RHAFX#/content/90927 at minute 124 we cover slope tables
https://myrockpile.retrieve.com/g/UTG6WQXB#/content/101090 at minute 159:20 we cover slope tables
The above approach works for simple cross slope variations, however if you are doing multilane highways, or super elevations that are not pivoting around the crown point, then you need to use the super elevation method of defining all this. That takes into account the design Runoff and runout values for the road. This is tricky to explain in a short post - we have videos on this in our Corridor Training Class on the Rockpile Library - Try these videos
https://myrockpile.retrieve.com/g/ML96PUX8#/content/101200 at minute 08:30 through minute 106:05 we cover superelevations in detail
Hope these help - if not let me know
Alan
2 Likes