Projects that Moved the Traffic Problem Downstream

[DJ Particle]

^ MnDOT was already breaking the bank as it was on the Crosstown project.  To properly address the issue would have required extending the project limit to Cedar, replacing the Portland bridge, filling in some wetlands on the north side of Legion Lake, addressing both the frontage roads and the Bloomington ramps, and all in all would have added several tens-of-millions of dollars to the price tag....easily $30 million, probably more.

On the other hand, the way the concrete was laid down suggests that it's still coming in the indeterminate future.  Same with a future third thru lane for MN-62 west of the Commons.  So at least in that case, more improvements are in the long-term plans.

[webny99]

Another example has developed on Rochester's west side with the completion of the I-490/I-390/NY 390/NY 31 interchange reconstruction. This interchange used to be congested on the southbound approach. Now, southbound traffic flows freely through the interchange - and even has multiple options to pass through the interchange with the old roadway left in place for the NY 31 to I-390 SB movement.

Which is great, except that morning traffic now overwhelms I-390 SB approaching the employment hubs at Exit 16, often slowing things up from the Exit 17 merge all the way back to I-490. And the fact that ROC airport is busiest in the early morning doesn't help things at the 17 and 18 merge points. So although a full widening isn't necessarily justified, an auxiliary lane from Exit 18 to 17 is definitely needed as a direct result of the aforementioned project.

[zzcarp]

CDOT's extension of the I-25 HOT lanes north from US 36 to 120th Ave and beyond has caused this. Before, the southbound lanes north of 84th Avenue was the natural bottleneck. With the HOT relief valve, there is a lot more congestion at US 36 EB to I-25 SB now in the morning and often even on weekend evenings as well.

Another move was the US 6/I-25 interchange reconstruction. All WB US 6 traffic from I-25 narrows from three lanes to 1 to merge onto the 6th Avenue Freeway mainline. It moved the congestion from the I-25 to US 6 merge out to west of Federal Blvd.

Another I-25 improvement at US 85/Santa Fe moved the congestion. Prior to reconstruction, US 85 NB had a free-flowing left entrance that became the left lane of the I-25 mainline NB. The I-25 NB mainline necked down to 3 lanes, so congested started southeast. The reconstruction made a full 4-lane cross-section on I-25 NB and US 85 NB now has a two-lane flyover ramp that merges on the right-hand side of I-25. This improvement moved the I-25 congestion point downstream about a half mile to the new flyover merge point, and it created nearly constant daily US 85 NB congestion on the flyover ramp even outside of rush hour times.

[vdeane]

I feel like the I-87/Northway project at exit 4 adding the aux lane to exit 5 is this.  It used to be that there was a backup at exit 4, then things moved, then there was a backup at 6-7.  Now, the backup at exit 4 is considerably lessoned, but there's a noticeable slowing of traffic at exit 5 now that didn't exist before.

[RoadWarrior56]

Almost any freeway or interchange project in Metro Atlanta has or would do little more than moving traffic problems downstream.  There is just not enough capacity on most of the existing freeway system to accommodate traffic demand.  Fixing interchanges may improve safety and localized operations, but at some point all of the traffic will have to squeeze back into the existing lane configurations.

I am figuring the ongoing reconstruction that has been going on for years centered on the I-285/SR 400 interchange will primarily just relocate most of the existing congestion. 

[Big John]

^^ A major component of Atlanta's traffic problems is they use a funnel system instead of a grid system.

[ET21]

Does the Hillside Strangler count here?

I'd say it's the quintessential project for this thread.  IDOT moves the merge point east of Mannheim, traffic issue is the same as before.

Runner up will be the Kennedy from Harlem eastward inbound once they finish the extra lane expansion

Can confirm, this does back up frequently during rush hour now

[epzik8]

This is basically just every extension of the I-95 HOV lanes in Virginia

[Gnutella]

^^ A major component of Atlanta's traffic problems is they use a funnel system instead of a grid system.

That, and the fact that Atlanta is a 6,000,000 metropolitan area with the highway network of a 2,000,000 metropolitan area.

[US 89]

What kills Atlanta is that the surface arterials suck. A big chunk of the surface roads are winding two-lane roads or four lane roads without left turn lanes. Even the bigger ones that do exist are usually stoplight hell. They simply aren't that useful, which pushes more traffic onto the interstates.

Contrast that to a place like Denver, where there is a huge grid network of high-quality arterials that can serve as an effective alternate to the freeways through town, which lightens the demand on them some. Like any big city, the freeways will still get congested especially at peak hours, but anyone who's spent significant time in both cities will tell you Atlanta is worse.

[ran4sh]

Yeah I've always wondered why the agencies in Georgia/Atlanta that determine the traffic light timing won't at least coordinate the lights.

[webny99]

What kills Atlanta is that the surface arterials suck. A big chunk of the surface roads are winding two-lane roads or four lane roads without left turn lanes. Even the bigger ones that do exist are usually stoplight hell. They simply aren't that useful, which pushes more traffic onto the interstates.

This actually sounds a lot like the mainland portions of the NYC metro area.

[Avalanchez71]

The right lane runners ruin it every time.  The I-65 choke point in Williamson County, TN was around exit 65 until a few years ago.  They added lanes between exit 65 and exit 59 and the choke point is now there.  However, the traffic still gets backed-up around Exit 65 anyway.  So now the additional lanes do nothing.  Then the folks that know that the lane is going to end run the right lane to the last minute and choke off traffic behind them.  If they would have merged earlier and stayed in their lane, the traffic would flow.

[Rothman]

The right lane runners ruin it every time.  The I-65 choke point in Williamson County, TN was around exit 65 until a few years ago.  They added lanes between exit 65 and exit 59 and the choke point is now there.  However, the traffic still gets backed-up around Exit 65 anyway.  So now the additional lanes do nothing.  Then the folks that know that the lane is going to end run the right lane to the last minute and choke off traffic behind them.  If they would have merged earlier and stayed in their lane, the traffic would flow.

No.  Zipper merge at the merge point is more efficient.

[Brandon]

The right lane runners ruin it every time.  The I-65 choke point in Williamson County, TN was around exit 65 until a few years ago.  They added lanes between exit 65 and exit 59 and the choke point is now there.  However, the traffic still gets backed-up around Exit 65 anyway.  So now the additional lanes do nothing.  Then the folks that know that the lane is going to end run the right lane to the last minute and choke off traffic behind them.  If they would have merged earlier and stayed in their lane, the traffic would flow.

Looks like it's because the freeway goes from 4 lanes + HOV to 3 lanes + HOV at that point.  TnDOT would probably be better off extending the right lane further south.

[1995hoo]

The right lane runners ruin it every time.  The I-65 choke point in Williamson County, TN was around exit 65 until a few years ago.  They added lanes between exit 65 and exit 59 and the choke point is now there.  However, the traffic still gets backed-up around Exit 65 anyway.  So now the additional lanes do nothing.  Then the folks that know that the lane is going to end run the right lane to the last minute and choke off traffic behind them.  If they would have merged earlier and stayed in their lane, the traffic would flow.

Why build the lane at all, then? Actually, why not take it a step further? Because the "merge early" crowd cannot agree when anyone is supposed to merge beyond the general principle that "nobody should get over any later than I do," obviously all roads must have only a single lane in each direction in order to pacify the early-mergers.

[mgk920]

What kills Atlanta is that the surface arterials suck. A big chunk of the surface roads are winding two-lane roads or four lane roads without left turn lanes. Even the bigger ones that do exist are usually stoplight hell. They simply aren't that useful, which pushes more traffic onto the interstates.

Contrast that to a place like Denver, where there is a huge grid network of high-quality arterials that can serve as an effective alternate to the freeways through town, which lightens the demand on them some. Like any big city, the freeways will still get congested especially at peak hours, but anyone who's spent significant time in both cities will tell you Atlanta is worse.

The Atlanta area was established looooong before cars were in anyones' wildest dreams, so the transport network reflected that time's reality.  OTOH, Denver was developed in a different era under the Northwest Ordinance grid.

Mike

[jeffandnicole]

The right lane runners ruin it every time.  The I-65 choke point in Williamson County, TN was around exit 65 until a few years ago.  They added lanes between exit 65 and exit 59 and the choke point is now there.  However, the traffic still gets backed-up around Exit 65 anyway.  So now the additional lanes do nothing.  Then the folks that know that the lane is going to end run the right lane to the last minute and choke off traffic behind them.  If they would have merged earlier and stayed in their lane, the traffic would flow.

Like every other time this is pointed out, it doesn't matter where they merge over, traffic would slow down at that point. 

[webny99]

The right lane runners ruin it every time.  The I-65 choke point in Williamson County, TN was around exit 65 until a few years ago.  They added lanes between exit 65 and exit 59 and the choke point is now there.  However, the traffic still gets backed-up around Exit 65 anyway.  So now the additional lanes do nothing.  Then the folks that know that the lane is going to end run the right lane to the last minute and choke off traffic behind them.  If they would have merged earlier and stayed in their lane, the traffic would flow.

I will pile on and say that right lane runners is a misnomer to begin with, BUT this also seems like a flawed design because it should be the left lane that ends instead of the right lane. The HOV lane complicates things somewhat, but it could still be done.

[SilverMustang2011]

What kills Atlanta is that the surface arterials suck. A big chunk of the surface roads are winding two-lane roads or four lane roads without left turn lanes. Even the bigger ones that do exist are usually stoplight hell. They simply aren't that useful, which pushes more traffic onto the interstates.

Contrast that to a place like Denver, where there is a huge grid network of high-quality arterials that can serve as an effective alternate to the freeways through town, which lightens the demand on them some. Like any big city, the freeways will still get congested especially at peak hours, but anyone who's spent significant time in both cities will tell you Atlanta is worse.

The area southwest of Atlanta is brutal for this, and a great example of how to not fix a traffic problem. GDOT added express lanes to 75 from McDonough to I-675, but made them reversible due to space constraints, so now one direction lacks express lane access half the day, so its not uncommon for NB traffic to back up to Locust Grove as an example. It also shifted the SB bottleneck from the SB 75/675 merge when the lanes are open to when they end and traffic has to merge left back into the mainline. And, unlike the express lanes on the north side of Atlanta where 75 is significantly wider, 75 is only 6 lanes South of 675, so congestion is a lot more common. To make the issue even worse, most of the surface roads in Henry County are 2 lanes like you mentioned despite all the subdivision growth, there's no reliable route for local traffic to take.