Diverging Diamond Interchanges

[jakeroot]

But it's probably not as questionable as the planned DDI for US 20 at IL 390 (Link to meeting handout with exhbit)

That is indeed ridiculously questionable. The only traffic that needs to crossover is traffic turning left onto 390. Southbound through traffic should just stay right as a free-flow movement. Of course at that point, you may as well design a CFI or regular left turn...which are arguably easier and just as safe.

I don't know what agencies are smoking these days. DDIs still require traffic to cross over oncoming lanes of traffic. If anything, this proposed DDI creates more conflict points than a regular left turn would have.

[Great Lakes Roads]

Random question, but has there been a DDI that had to be rebuilt to accommodate a wider freeway?

I'm asking because TxDOT is planning to rebuild and widen I-35 between Georgetown and Round Rock to add two non-managed lanes in each direction.

[jakeroot]

Random question, but has there been a DDI that had to be rebuilt to accommodate a wider freeway?

I'm asking because TxDOT is planning to rebuild and widen I-35 between Georgetown and Round Rock to add two non-managed lanes in each direction.

I can't answer the first question (my gut says...probably), but as to the DDI at I-35/University in Round Rock, I think the support columns will support the planned widening through there. Unless the widening is more dramatic than I realize.

[ET21]

But it's probably not as questionable as the planned DDI for US 20 at IL 390 (Link to meeting handout with exhbit)

That is indeed ridiculously questionable. The only traffic that needs to crossover is traffic turning left onto 390. Southbound through traffic should just stay right as a free-flow movement. Of course at that point, you may as well design a CFI or regular left turn...which are arguably easier and just as safe.

I don't know what agencies are smoking these days. DDIs still require traffic to cross over oncoming lanes of traffic. If anything, this proposed DDI creates more conflict points than a regular left turn would have.

Yeah we also really don't need that for a 1/2 mile or mile extension of a highway where traffic is already pretty low. Plus your highway the DDI is going over dead ends at the neighboring street which you can also access pretty easily on either Greenbrook Blvd to the south or by just going north on US 20 two stoplights lol