Improving Portland's grid (taxi, vs., safety)

[impala096]

Originally Posted by hamellr

Actually your major issue is that you're trying to put more cars in Portland when the goal is less cars. You also did not account for the fact that three of the streets in your maps each have one lane dedicated to MAX trains already. While two more have an entire lane dedicated to bikes (which incidentally account for about 25,000 trips per a day within the Downtown core.) Shifting your model a few streets isn't going to work either, because if anything it's smoother and less dense traffic in other areas.

I would be surprised if the volume of vehicles increased in the downtown core after banning vehicles on half the downtown streets. The capacity of many of the existing streets that are currently 2-3 lanes would drop to zero (ie. no cars). The idea that a ban of vehicles on half the downtown streets would somehow lead to more vehicles in downtown is a bit perplexing.

[urbanlife78]

Originally Posted by impala096

I would be surprised if the volume of vehicles increased in the downtown core after banning vehicles on half the downtown streets. The capacity of many of the existing streets that are currently 2-3 lanes would drop to zero (ie. no cars). The idea that a ban of vehicles on half the downtown streets would somehow lead to more vehicles in downtown is a bit perplexing.

Currently all the streets in downtown are below capacity, you currently have a limited number of north/south streets and the east/west streets are designed to be service streets that often times leads to parking garage entrances and trash pick up, and a limited number of east/west streets that lead to bridges.

[EnricoV]

Originally Posted by impala096

You're horrible with Math. 70% isn't half.

If you shut down half the roads to traffic, there's likely to be a reduction in capacity. The latest trend is to convert one-way streets to two-way streets which leads to a similar reduction in capacity, but it's still done.

Ever hear of the "two second rule"? The following distance between vehicles increase as the speeds increase, which explains why the vehicles in the proposed model are spaced further apart. This is intuitive to most people.

No, actually I'm not horrible at math. I'm pretty darn good at it, but I am horrible at trusting the word of fools.

None of your arguments are convincing me that there is any logical reason on earth to use this idiotic plan to change the grid of a city that doesn't need your help.

[bler144]

Originally Posted by hamellr

Bike density would be a good thing though as the bulk of those trips are multi-mile trips. If you want to play urban planner a better idea would be a way to more efficiency dump traffic from I-5 and Barbur Boulevard Downtown, and to remove it via I-405 and I-5. That backup from that makes more of a problem then smoother traffic downtown.

Agree with hamellr and urbanlife. The traffic flow problems that exist downtown have nothing to do with the grid. In and of itself, driving downtown is mostly fine. Even at the heart of rush hour I generally have no problem moving around in downtown (on foot, by bike, by car), it's getting out of downtown by car that's the problem.

The problems that do exist:

-Major thoroughfares are poorly designed for flow (e.g. the mess that is 26 turning from a highway into a meandering wobble past PSU with some bizarre turns before reaching the Ross Island Bridge). If it's not the epitome of inefficient flow, it's close.
-Places where the grid ceases to be a grid entirely. The Pearl/NW run on a traditional N/S/E/W grid. The south half of downtown is askew at roughly a 145 degree angle. The two collide somewhat awkwardly in a manner that's manageable, but still loses efficiency.
-Major streets that allow left hand turns at rush with no protected turn lanes (Burnside in particular)

The OP is solving a problem that, if it exists at all, is waaaay down the list.

[nei]

Originally Posted by impala096

If you shut down half the roads to traffic, there's likely to be a reduction in capacity. The latest trend is to convert one-way streets to two-way streets which leads to a similar reduction in capacity, but it's still done.

If you double the speed of traffic, you move twice as much traffic in the same amount of time so capacity doubles [assuming that the light change would exactly double the average speed]. But you halved road capacity by closing every other street, so the two changes cancel out, led to theoricatlly the same capacity.

[impala096]

Originally Posted by nei

If you double the speed of traffic, you move twice as much traffic in the same amount of time so capacity doubles [assuming that the light change would exactly double the average speed].

This is incorrect. If it was only that easy!

[urbanlife78]

Originally Posted by impala096

This is incorrect. If it was only that easy!

Which streets in Portland would you want to close off to cars?

[bler144]

Originally Posted by impala096

This is incorrect. If it was only that easy!

I agree with you there, but I still think you're looking at Portland wrong if you're focused on the grid at all.

Enough of the city is a grid to fool someone looking quickly at the map (and technically I believe it qualifies as a 'modified grid'), but with the river, bridges, elevation, and curious road layout choices, it's the 'modified' part of that moniker that's the problem almost everywhere in the city, not the 'grid' part.

[SETabor]

As another voice dooming the proposal, if the OP doesn't live here and likely hasn't visited or driven, he likely doesn't understand the local penchant for driving under the speed limit. This occurs whether or not the lights are timed, the traffic is light, the road is clear, etc. It's not everybody but it is enough people to be noticeable. Thus, if you close off half the roads, you're more likely to encounter the slow pokes and the time it would take to cross the city would take even longer.

[impala096]

Originally Posted by urbanlife78

Which streets in Portland would you want to close off to cars?

The proposal was just a general idea, so i really don't have any input on that, and judging by the comments it isn't getting much reception as it is. I just thought it would be interesting to have a grid that services "cars" interlocked with a grid that services "pedestrians/bikes/transit users". Portland seems to have a grid where this could be feasible (since the city has close blocks, and as someone mentioned previously, the current downtown streets are being underutilized).

Portland's block size (that services cars) would be similar to Barcelona: