bypass links and hydrodynamic routing

[tmcintosh10]

How are people modeling curb inlet bypass flow?  When I first got into using SSA, I looked on-line through some AU handouts and blogs etc.  I learned to model on-grade inlets using direct bypass links. I would create one that linked upstream and downstream inlets. It appears that hydrodynamic routing is the preferred option for modeling pipe networks with storage nodes, and the direct links don't work due to error 134.  It would seem that the logical fix for this is to model all gutter bypass as user defined open channel and create a channel section that matches the road and gutter section.  Is that correct? Also, how does the software view a direct link versus open channel?

Thanks,

Toby

[Matt.Anderson · Accepted solution]

Toby;

Yes, the surface links are meant to be channels.  If you insert a Civil 3D drawing that has on-grade inlets, SSA will automatically build a channel based on the applications default values for gutter, and road slopes and apply it to the inlet.

Hydraulically - the water that bypasses an inlet - gets routed down the gutter.  A direct link would not include any routing along the curb.  It would mean the Qpeak at time X is directly sent down to the next inlet at time step X+1. (Qin = Qout)

[tmcintosh10]

Matt,

Thanks for the quick reply.  I figured that is how the direct link worked.  As for the channel that SSA builds, it appears those conveyances are named 'XS-L-Pipe...' and are what connect the 'extra outfalls' to the structures upon import.  I guess instead of deleting the outfalls initially, I should modify the conveyance to link the inlets first.  Hindsight is always 20-20.

Thanks,
Toby 

[tmcintosh10]

Matt,

As I was working through my model and updating my bypass links, I was curious if you could explain how or what is used to create the open channel links when importing to SSA?  They appear to follow the curb and road lane profile, but seem a little bit different.  Also, they stop at station 7, while spreads could exceed that value.

Thanks,

Toby

[Matt.Anderson]

Toby -

The only data we have available is the gutter spread warning value.  It however, helps get you started.

[tmcintosh10]

Ok, thanks for your help.

Toby