HO-HO-HO! This is gonna be FUN-FUN-FUN! (I-405 closure in CA)

[Revive 755]

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic.

Really?  I can think of at least one corridor that was widened and flows great during rush hour.

My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

Maybe your CA 91 didn't get enough new lanes, or there is some other problem such as a bad merge, sharp curve, or steep grade that messes up traffic and needed to be dealt with when the lane was added.

[roadfro]

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic. My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

I suppose we can keep going back and forth on this...

If adding a general purpose lane doesn't help congestion, how will adding another HOV lane help? Unless you've got a major incentive to get more people to carpool (i.e. some kind of employer incentive, toll breaks, or something else that will give drivers a tangible monetary benefit), it's highly unlikely that an additional HOV lane is going to help much. True, the capacity is there to move more people per hour, but the addition of another HOV lane alone is not going to be the way to actually move more people per hour.

[Scott5114]

The "induced traffic" theory makes no sense. People are going to suddenly decide they need to drive to more places because CA-91 has a new lane? Sure...

[Riverside Frwy]

Where are the multi-lane HOV's in SoCal? I know there are a few.

I-110 between I-105 and Adams Blvd, just south of I-10.

CA-91 also has a brief Multi-Lane HOV just west of CA-71, but this multi-lane HOV is more of a consequence of the fact that it is a continuation of the 91 express lanes that end at the County line.

[Riverside Frwy]

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic.

Really?  I can think of at least one corridor that was widened and flows great during rush hour.

My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

Maybe your CA 91 didn't get enough new lanes, or there is some other problem such as a bad merge, sharp curve, or steep grade that messes up traffic and needed to be dealt with when the lane was added.

There is already 7 lanes going eastbound from the new lane.  You can only make a freeway so wide.(especially since it's already situated against the mountain) And yes, there are cases where adding lanes helps, but in the case I-405 which is what this thread is about, it will do nothing.

The "induced traffic" theory makes no sense. People are going to suddenly decide they need to drive to more places because CA-91 has a new lane? Sure...

Actually, yes. New lane infers that traffic will flow better, so many people who tried to avoid CA-91 because of it's traffic now thinks it's ok drive, only screwing up the freeway again.

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic. My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

I suppose we can keep going back and forth on this...

If adding a general purpose lane doesn't help congestion, how will adding another HOV lane help? Unless you've got a major incentive to get more people to carpool (i.e. some kind of employer incentive, toll breaks, or something else that will give drivers a tangible monetary benefit), it's highly unlikely that an additional HOV lane is going to help much. True, the capacity is there to move more people per hour, but the addition of another HOV lane alone is not going to be the way to actually move more people per hour.

As I said in a previous post, You are going to be sitting in traffic either way. Adding More and more general purpose lanes aren't going to help I-405. I figure, if the freeway is going to be jacked up either way, you might as well be moving more people per hour to their destination.

EDIT: I don't really see how it's NOT going to move more people per hour.

[Scott5114]

That may be so for CA-91 individually, but if they are now driving CA-91 it means they are not driving whatever route they were using before. The overall capacity of the highway system is still increased. You have to look at effects like this.

[Interstate Trav]

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic.

Really?  I can think of at least one corridor that was widened and flows great during rush hour.

My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

Maybe your CA 91 didn't get enough new lanes, or there is some other problem such as a bad merge, sharp curve, or steep grade that messes up traffic and needed to be dealt with when the lane was added.

The problem with the lane added to the 91 is that the 91 still narrows after the 71 and it causes a huge delay.  If a lane eachway was added from the County Line to the 15 then traffic would flow smoother, you could had 10 lanes to 91 east, at Green River, but inless it syas wider after the the 71 then it's going to be the same problem.

[roadfro]

The "induced traffic" theory makes no sense. People are going to suddenly decide they need to drive to more places because CA-91 has a new lane? Sure...

Actually, yes. New lane infers that traffic will flow better, so many people who tried to avoid CA-91 because of it's traffic now thinks it's ok drive, only screwing up the freeway again.

That may be so for CA-91 individually, but if they are now driving CA-91 it means they are not driving whatever route they were using before. The overall capacity of the highway system is still increased. You have to look at effects like this.

This is really a double-edged sword. Let's assume that it is well known and publicized that a new lane has been added. It is possible that people who have been avoiding driving the highway due to chronic congestion may start trying the route again now that additional capacity is added. If enough people make that leap, it may have a negative affect on the flow of the freeway. This might induce those drivers to go back to their old routes avoiding the highway. It can be an endless cycle, but the overall result is that the transportation network as a whole still has added capacity.

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic. My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

If adding a general purpose lane doesn't help congestion, how will adding another HOV lane help? Unless you've got a major incentive to get more people to carpool (i.e. some kind of employer incentive, toll breaks, or something else that will give drivers a tangible monetary benefit), it's highly unlikely that an additional HOV lane is going to help much. True, the capacity is there to move more people per hour, but the addition of another HOV lane alone is not going to be the way to actually move more people per hour.

As I said in a previous post, You are going to be sitting in traffic either way. Adding More and more general purpose lanes aren't going to help I-405. I figure, if the freeway is going to be jacked up either way, you might as well be moving more people per hour to their destination.

EDIT: I don't really see how it's NOT going to move more people per hour.

The underlying assumption that I believe you're making is that more HOV vehicles are going to start using that route simply because there's an additional HOV lane. I dispute that--I believe there would not automatically be an increase in HOV traffic by simply adding an HOV lane, as I don't think many people would make the switch to carpooling just because there's another HOV lane, due to the fairly rigid SOV mindset that exists. So in my view, adding an additional general purpose lane would be more effective in moving more people per hour, because there are more SOV/general purpose vehicles.

We might have to agree to disagree on this...

[Zmapper]

Perhaps some sort of slugging/ casual carpool/ Avego type system could be used to fill the empty seats in the SOVs. The challenge is ensuring a critical mass of users that vehicles show up within a reasonable waiting time and there are passengers to fill the extra seats.

[Brandon]

The "induced traffic" theory makes no sense. People are going to suddenly decide they need to drive to more places because CA-91 has a new lane? Sure...

Agreed.  ISTHA added a lane each way on I-355 between I-88 and 75th Street a couple of years ago.  The backups were legendary.  Now, they're mostly gone but for some weaving at I-88 in the morning and 63rd Street in the afternoon.  Ditto for IDOT adding a lane on I-55 between I-80 and Weber Road.  The backups disappeared.  Turned out that they were caused by merging traffic having nowhere to go coming on at IL-126 in the morning and the lost lane at Weber in the afternoon.  It's not so much adding a lane that helps as having a consistent width for the road.

[Zmapper]

Wait 10 years. Then tell us if the backups are still gone.

[Scott5114]

That has little to do with the number of lanes on the highway–in ten years the number of people in I-355's "watershed" area will undoubtedly have increased, so more people will be driving whether or not I-355 had been widened.

[Brandon]

Wait 10 years. Then tell us if the backups are still gone.

It's more about improving flow, not just about lanes.  The worst bottlenecks around here have more to do with merging and exiting trucks than anything to do with cars.  One of them, Arsenal Road at I-55, is getting a new interchange to fix this exact problem.  The old one has some loops that require trucks to slow to 15-20mph to enter I-55, and causes truck backups onto I-55.

[Riverside Frwy]

The "induced traffic" theory makes no sense. People are going to suddenly decide they need to drive to more places because CA-91 has a new lane? Sure...

Actually, yes. New lane infers that traffic will flow better, so many people who tried to avoid CA-91 because of it's traffic now thinks it's ok drive, only screwing up the freeway again.

That may be so for CA-91 individually, but if they are now driving CA-91 it means they are not driving whatever route they were using before. The overall capacity of the highway system is still increased. You have to look at effects like this.

This is really a double-edged sword. Let's assume that it is well known and publicized that a new lane has been added. It is possible that people who have been avoiding driving the highway due to chronic congestion may start trying the route again now that additional capacity is added. If enough people make that leap, it may have a negative affect on the flow of the freeway. This might induce those drivers to go back to their old routes avoiding the highway. It can be an endless cycle, but the overall result is that the transportation network as a whole still has added capacity.

Wait, wait, wait, aren't you sitting in traffic anyway? The 405 is going to be jacked up no matter what, we all know that adding general lanes doesn't do ANYTHING to traffic. My CA-91 got a new lane and it's STILL jacked up. The new lane just brought a whole new ton of cars with it. So with that said, you might as well be moving more people per mile/hour. So in the case of the 405, you'll be sitting in traffic no matter you do regardless, making your point moot.

If adding a general purpose lane doesn't help congestion, how will adding another HOV lane help? Unless you've got a major incentive to get more people to carpool (i.e. some kind of employer incentive, toll breaks, or something else that will give drivers a tangible monetary benefit), it's highly unlikely that an additional HOV lane is going to help much. True, the capacity is there to move more people per hour, but the addition of another HOV lane alone is not going to be the way to actually move more people per hour.

As I said in a previous post, You are going to be sitting in traffic either way. Adding More and more general purpose lanes aren't going to help I-405. I figure, if the freeway is going to be jacked up either way, you might as well be moving more people per hour to their destination.

EDIT: I don't really see how it's NOT going to move more people per hour.

The underlying assumption that I believe you're making is that more HOV vehicles are going to start using that route simply because there's an additional HOV lane. I dispute that--I believe there would not automatically be an increase in HOV traffic by simply adding an HOV lane, as I don't think many people would make the switch to carpooling just because there's another HOV lane, due to the fairly rigid SOV mindset that exists. So in my view, adding an additional general purpose lane would be more effective in moving more people per hour, because there are more SOV/general purpose vehicles.

We might have to agree to disagree on this...

I think you guys are misunderstanding my post. I'm not disputing that overall capacity for the SYSTEM has increased, I'm saying that for individual freeways themselves, I think turn current General lanes to HOV would be a cost effective way in improving capacity without spending billions on tearing down perfectly good bridges, realigning perfectly good interchanges, and so on...

However, some of you have mentality that we can just keep adding lanes forever. What are we going to have? 20-30 lane freeways crisscrossing LA? We have to look for better options besides just adding lanes.

As I said before Roadfro: The only reason people are so set SOVs is that most of the freeway is made for them. As I said, make the freeways 50% HOV and see more people actually making an effort to get people to ride with.

Agreeing to disagree gets us no where. Infact I hate that phrase, and I think it's something said when the person is afraid of being proven wrong.(I'm not saying you are, I'm just saying from experience)

[Scott5114]

The only reason people are so set on SOVs is because don't consider HOVs a viable option. Why this is will vary from person to person. Really, outside of "slugging", HOVs are only going to work if you have a bunch of people commuting from a cluster of locations around Point A to a cluster of locations around Point B. Otherwise the time savings gained by being able to use HOV lanes will be offset by the added amount of time picking up and dropping off passengers. Everyone in the car is going to have to be neighbors who work somewhat close to one another. Another thing to consider is that many people find it socially awkward to host someone they barely know in their car, as well.

If adding freeway lanes doesn't help with congestion there is usually a reason for that. Usually that freeway is too overburdened because one of the freeways that was supposed to support it got cancelled. So all the traffic that would have taken that freeway instead is now forced onto one of the freeways that was built. If you look at a metro like Oklahoma City or Kansas City which had all of its freeways built you'll see that traffic flows quite smoothly and in the cases where it doesn't adding lanes is usually enough to sort the problem.

[roadfro]

I think you guys are misunderstanding my post. I'm not disputing that overall capacity for the SYSTEM has increased, I'm saying that for individual freeways themselves, I think turn current General lanes to HOV would be a cost effective way in improving capacity without spending billions on tearing down perfectly good bridges, realigning perfectly good interchanges, and so on...

However, some of you have mentality that we can just keep adding lanes forever. What are we going to have? 20-30 lane freeways crisscrossing LA? We have to look for better options besides just adding lanes.

As I said before Roadfro: The only reason people are so set SOVs is that most of the freeway is made for them. As I said, make the freeways 50% HOV and see more people actually making an effort to get people to ride with.

Agreeing to disagree gets us no where. Infact I hate that phrase, and I think it's something said when the person is afraid of being proven wrong.(I'm not saying you are, I'm just saying from experience)

Riverside Frwy: I don't believe I'm misunderstanding your posts--I'm still just disagreeing with your premise. I will concede the point that converting an existing lane to a carpool lane is a way to increase capacity in terms of throughput of people per hour. (I feel obligated to point out, however, that people per hour is not a measurement used in traffic engineering as it is something not easily quantifiable [without sophisticated equipment and expense] as opposed to the standard measurement of vehicles per hour.)

Carpooling works much more efficiently in areas where residential communities are denser and closer together, and employment centers are also clustered more closely. In this kind of developed community, it is much easier and convenient for people to establish carpools, as they are more likely to live and/or work much closer together. When looking at an area like Los Angeles, there is much more suburban sprawl, such that homes and businesses can really be anywhere. The growth of the suburb and the rise in availability and affordability of the automobile were closely connected (and still are), thus lending to the single occupant vehicle mindset that is so ingrained in the culture.

All this leads to the point that Scott5114 made above: Is it viable to make a carpool when the members of said carpool live/work so spread out? One has to weigh whether the time saved by using HOV lanes is greater than the time spent picking up/dropping off carpool members at two or more locations. I contend that for most people in most cases, the time saved in the HOV lanes is not worth the extra passenger drop off time--most would prefer the convenience of driving themself to/from work without having to worry about others.

What if we make 50% of the freeway HOV, as you suggest. I'll try to analyze an example with numbers... (Writing this in the overnight hours, hope it makes sense...)

Pretend we have an existing freeway with 1 HOV (2+) lane and 3 general purpose lanes in one direction. For the sake of argument, we'll assume we have a spot on the freeway where we can easily count the number of *people* moving along this freeway. In the existing condition, 10,000 people per hour travel along this stretch; 1000 of those carpool in pairs and the remaining 9000 are SOVs. Thus, we have 500 vehicles per hour in the HOV lane, and an average of 3000 vehicles per hour in each general purpose lane.

Now, in our effort to increase carpool awareness, one existing general purpose lane is converted to HOV--no other improvements to the transportation system are made at this time, so regional traffic patterns are unlikely to change dramatically enough to add new traffic to the route. A media campaign and regional transit agency incentive program manages to sway 30% of drivers that were SOVs to start carpooling in pairs. 30% of 9000 people is 2700. Adding in the previous carpoolers results in 3700 people carpooling, or a grand total of 1850 vehicles carpooling, averaging 925 vph per HOV lane. Meanwhile, the remaining 70% of the original 9000 SOVs are still in driving alone. This means that there are 6300 people driving alone, or 3150 vph per lane.

So in this example with constraints, we have the same amount of people traveling the freeway. The switching of a lane to HOV and 30% conversion of SOV drivers to carpools results in 150 more vehicles per hour using the general purpose lanes than there were before. This may not seem like much, but we're using small traffic volumes and, in my opinion, a very generous SOV-to-HOV driver conversion percentage. If the number of people using the freeway were higher (likely) and the conversion rate smaller (also likely), there would be much more strain on those general lanes.

[Riverside Frwy]

I think I see your point.(Had to read it a few times) But I ask, what happens when there is no room or money to add a new general lane, and the traffic volumes only continue to increase? Are we just doomed? Plus, I would rather have 50% of the freeway(The HOV lanes) flowing than have 100% in a jam. Personally, I don't care too much for general lanes. I think way too much leeway is given to the SOV. It seems like all steps must be taken to not threaten the precious SOV. I say let the general lanes sit in traffic. If they really want to get traffic flowing again, let them actually make an effort to Carpool. Personally I would have the busiest freeways 100% HOV during rush hours, and lets see how quick thousands of commuters find Carpool buddies, especially the 405.

However, I think this just shows the difference of 2 cultures. New York has had no problem setting up 2 lines of their Select Bus Service, each having a dedicated bus lane at the sacrifice of one general lane. Like that will ever happen in LA....

[agentsteel53]

if they were serious about encouraging carpool lanes, they would enforce two laws:

1) speed limit 120
2) minimum speed 95

you'd get people in pairs doing 115 in no time.

[roadfro]

Personally I would have the busiest freeways 100% HOV during rush hours, and lets see how quick thousands of commuters find Carpool buddies, especially the 405.

If that were to happen, I'm sure you'd find that some carpooling might happen... Also likely, cars would flock to any available alternate routes, and HOV violations would increase dramatically.

However, I think this just shows the difference of 2 cultures. New York has had no problem setting up 2 lines of their Select Bus Service, each having a dedicated bus lane at the sacrifice of one general lane. Like that will ever happen in LA....

Not just cultures, but effects of urban planning and suburban sprawl. New York generally has much greater densities, such that this kind of transit service and change in lane use is much more likely to be utilized effectively.

[NE2]

I-66 in Northern Virginia is HOV-only during rush hours. SOVs can park and take the Metro down the median.

[Brandon]

I-66 in Northern Virginia is HOV-only during rush hours. SOVs can park and take the Metro down the median.

That works for DC since DC is a one industry town, and most of that industry is clustered downtown.  It would fail miserably in Chicago since people start in different locations and go to workplaces almost anywhere in the city and suburbs.  To illustrate, outbound rush times are almost as high as inbound rush times in the morning, and they're darn near equal in the afternoon.  That is exactly what happens on I-55 between Bolingbrook and the Ryan.

[NE2]

In Chicago it would be more like making LSD HOV-only. Traffic not going downtown has alternate routes, and SOV traffic going downtown can park and take the L.

[vdeane]

If you get to the point where you can't easily add lanes, why not restrict growth?  If towns/cities simply said "no" to subdivision development, we wouldn't had sprawl problems.

I-66 in Northern Virginia is HOV-only during rush hours. SOVs can park and take the Metro down the median.

You can bet that if I-66 didn't end the moment it got into DC that wouldn't work.  It works because traffic on I-66 is going to/from downtown DC and areas the metro line serves and the restriction is only during rush hour.

[NE2]

Actually, via the SR 110 almost-freeway, I-66 could be used as part of a through route to the south.

[HighwayMaster]

Guess this is a reality now:

Hey, I said that over a month ago (albeit in the Road-Related Illustrations thread)!  

Oh. Didn't see that. on me.