Culvert End Section "Closed Taper"?

[SWUPE]

HDS5 Table 12 indicates that an end section with a closed taper in their design can use a Ke of 0.2 rather than 0.5 for sections commonly available from manufacturers. It appears that the pre-cast concrete end sections in this area have the "closed taper". Can anyone give me more info on what they are defining as a closed taper or maybe a link to additional info.

Thanks in advance,

swu

 

[LHA]

If I remember correctly, isn't there a detail in the lower left-hand corner of that table of the taper w/ dimensions?

If so, fax that detail to the precast manufacturer, and ask if they can meet that.

If not, you can get a similar Ke reduction from a bevelled pipe insert into the endsection (versus a square/flush fit). That table does have a detail, because I've added it to CADD details in the past. That way, the contractor will build the bevel.