I know interstates have to be designed to AASHTO standards but what about ramps at interchanges? Is there a grey area along the ramp where the standard changes from AASHTO to the state design manual?
Generally invert changes at sanitary manholes of 2' or greater are done with inside or outside drop manholes but I never really understood what the purpose is. If it's for hydraulic reasons, why not use them for storm manholes as well?
AC, I never have specified high friction aggregate when using normal crown on a curve. To tell you the truth, I've never thought to. I don't think it's necessary but it could help depending on how close to fmax you're getting.
The Green Book contains tables for minimum radius for normal crown road for various design speeds but the radiuses listed are very large since they are based on very low friction factors. An alternative I have used is to use the e + f=v^2/15R equation given in the book and plug in -2% for e...
In the Hydraflow Storm Sewers manual, it says HGL calculations are based on energy-based standard step method. But it notes that it does not compute supercritical flow profiles and that when the energy equation cannot balance, it assumes critical depth. Why would the energy equation not balance...
TerryScan,
Now that I've looked at your hypothetical situation for a bit, based on Brian's definition of a contour, there is no proposed 50 contour since it's flat at 50. There is an existing 50 contour, but no proposed. Am I right Bri?
njpe
TerryScan,
I cracked up when I read your post because we had the EXACT same situation in our office last week which prompted a heated debate. And that is what prompted me to create my original post. I don't have an answer for you but you made my day!
njpe
lha,
I think you are correct about the "merged" contours. Thanks for the insight. However, you mention "break" points for contours occuring at walls. I do not believe contours break at walls. They continue along the wall or curb. This is just another example of the "merged" contour you mention.
There is a common rule that contour lines cannot branch or split. However if there is a v-shaped valley where the bottom is at elev 10, for example, then the 10 contour will be a straight line and then split once the elevation of the bottom of the valley changes. So is this rule just an...
Where should the invert elevation of the pipe into a basin be set at? If its low, as the basin fills up, so will the pipe. Does this matter? Usually pipes are designed to flow full so I'm not saying the pipe can be used as additional storage but what are the considerations when determing the...
