Did your state's early interstate system evolve intelligently?

[NE2]

I think it's now a full freeway past Atwater; just recently some at-grades between Livingston and Atwater disappeared. I'm talking about the at-grades between Merced and Chowchilla.

[TheStranger]

as far as I know, there are no unmodified references to US-99 left in California.  There is one sign in Seattle (also very well known) and a 99W in Oregon that is less well-known but does indeed date to the 60s. 

There's also that sign goof near Fresno's airport with the US 99 shield...

And we had the one from 2008-2009 on the WX (Capital City) Freeway that I was able to get a pic of before it was corrected.

[Quillz]

I like Hawaii's idea of numbering their interstates in the order they were built, not their direction.

[Rick Powell]

Illinois statred the Expressways and Tollways before the Interstates and then pushed and pushed for more milage and later came out with a post interstate plan(which has been discussed a lot under Midwest). The only interstate not completed was the Crosstown Expressway and it was not on the original plan.
There was a 78,000 mile Interstate plan and Illinois built all of those. It is still buildling a lot of the others supplementals as 4 lane divideds or Tollways. Lets say they have lost their old ambition

LOTS of help from Cook County and the IL State Toll Highway Authority to build the radial I-routes into and around Chicago in the early days.  The definitive web site for their history is www.cookexpressways.com.

Downstate, the interstates were completed in fairly logical order, with I-55 being the last "legacy" interstate, replacing a serviceable 4-lane expressway in US 66.  With the Supplemental Freeway routes, I-39 and I-72 came out OK.  US 51 south of Bloomington has turned into an endless mess of stoplights and reduced speed zones; some old timers at IDOT District 5 regretted what they allowed to happen around Clinton and in Forsyth.

[oscar]

I like Hawaii's idea of numbering their interstates in the order they were built, not their direction.

Coincidence.  The numbering was set long before anybody realized that H-3 would be much more controversial, and take much longer to build, than H-2.  Also, while part of H-1 was open (as a non-Interstate freeway) even before Hawaii became a state, the rest of it wasn't completed until after H-2 was completed.

[vdeane]

I-H201 ruins the whole thing too; if it was build order, one of them would need to be renumbered I-H4!.

[flowmotion]

19th's lack of synchronization probably relates to the city's desire to keep speeds low there.  For comparison, Great Highway on the oceanfront just a mile or two away has a perfect synchronization scheme to go 37 MPH without stopping!

Yep, I'm pretty sure they de-synchronized the lights along 19th about 10 years ago. I know they did so along Oak/Fell, where they used be perfectly synchronized for 43MPH (!) all the way from GG Park to the freeway ramps. (Now they are a more appropriate ~25MPH with several mandatory reds.)

[agentsteel53]

Yep, I'm pretty sure they de-synchronized the lights along 19th about 10 years ago. I know they did so along Oak/Fell, where they used be perfectly synchronized for 43MPH (!) all the way from GG Park to the freeway ramps. (Now they are a more appropriate ~25MPH with several mandatory reds.)

I can understand 43mph being a bit on the fast side, but why bring it all the way down to 25 and put in mandatory reds?  How does that help traffic flow at all??

[1995hoo]

I-H201 ruins the whole thing too; if it was build order, one of them would need to be renumbered I-H4!.

Although if you read the zero as though it were the letter "O," the name sounds very appropriate for a highway located on an island in the middle of the ocean (think back to high school science classes).

[oscar]

I-H201 ruins the whole thing too; if it was build order, one of them would need to be renumbered I-H4!.

H-201 should've been numbered H-4 in the first place, but that would've thrown off the completion order either way, since it was completed seven years before H-3.

"Build order" is kind of ambiguous, anyway -- do you count when it started, or when it finished?  And when is "started"?  Especially for H-201, which alone among Hawaii's Interstates is basically an upgrade of a road that existed before the automotive era.

[Duke87]

Connecticut never planned interstates. They planned freeways and some of them ended up with interstate designations.

As for intelligent evolution, well... the planning was sound, but local opposition has interfered with plans actually coming to fruition. We have a lot of unbuilt or unfinished freeways.

[myosh_tino]

I can understand 43mph being a bit on the fast side, but why bring it all the way down to 25 and put in mandatory reds?  How does that help traffic flow at all??

I think the lights are synced for 25 MPH not for traffic flow but for pedestrian safety.  Over the past couple of years, there's been an alarming increase in pedestrian fatalities on 19th Ave.

[agentsteel53]

I think the lights are synced for 25 MPH not for traffic flow but for pedestrian safety.  Over the past couple of years, there's been an alarming increase in pedestrian fatalities on 19th Ave.

sure, but what's the advantage of the mandatory reds?

[berberry]

...what's the advantage of the mandatory reds?

That's a damn good question, but it might take an engineer or a physicist to explain it.  I've heard it discussed by people who know a lot more about this sort of thing than I do, and although I certainly can't answer your question, I can tell you that it has something to do with fluid dynamics. 

The rules of fluid dynamics apply to traffic flow in ways that totally surprised me.  For another example I can't make sense of unless I'm actively listening to a dumbed-down explanation:  when mntc projects require a freeway to temporarily reduce the number of forward lanes - let's say from two to one - there's always that idiot approaching it during heavy traffic in the lane that's about to end, who at the very last moment manages to shove his or her way into the remaining thru lane, while everyone else patiently waits their turn.  Well, somehow you can use fluid dynamics to explain how that idiot is doing everybody a favor by making traffic flow more smoothly.  Really.

[agentsteel53]

that, despite not being intuitive, makes sense because I had studied that kind of thing before  

basically, I think the red lights will break up standing waves where traffic slows down pathologically at a given point - better to slow everyone down from 25 to 0 for one minute at various spots, than from 25 to 5 for three minutes at the same spot.  

but that only works if timed correctly. somehow, I cannot imagine 19th street is timed correctly.  or, maybe everyone in San Francisco is "that idiot" driver* and this really is the best we can do.

*practical experience suggests this to, indeed, be the case

[flowmotion]

The rules of fluid dynamics apply to traffic flow in ways that totally surprised me.  For another example I can't make sense of unless I'm actively listening to a dumbed-down explanation:  when mntc projects require a freeway to temporarily reduce the number of forward lanes - let's say from two to one - there's always that idiot approaching it during heavy traffic in the lane that's about to end, who at the very last moment manages to shove his or her way into the remaining thru lane, while everyone else patiently waits their turn.  Well, somehow you can use fluid dynamics to explain how that idiot is doing everybody a favor by making traffic flow more smoothly.  Really.

Based on experience, that's true. At various times I've reverse commuted over the Golden Gate Bridge and through the Caldecott Tunnel (CA24), both roads narrowing from 4 lanes to 2 through the bottleneck. The 'correct way' was to stay left as long as possible and then take turns merging where the lane disappeared. People who merged over early would cause the lane behind them to hit their brakes and stop the flow.

However, I'm guessing the 19th Ave logic is that they don't want people accelerating over several blocks, only to slam on their brakes or attempt to run the reds. So they stop people every few blocks to keep speeds down.

[TheStranger]

However, I'm guessing the 19th Ave logic is that they don't want people accelerating over several blocks, only to slam on their brakes or attempt to run the reds. So they stop people every few blocks to keep speeds down.

I recall that the state of California actually had a big debate with SF over this (as SF clearly wanted to lower the limit on 19th, while Caltrans did not).  What doesn't help is that beyond Sloat Boulevard, alternates to 19th are hard to come by:

- Great Highway only really works if you're coming in from the coastal cities of San Mateo County (i.e. Pacific, western Daly City and San Bruno) as coming in from 280 requires cutting over on surface streets with plenty of lights (John Daly Boulevard, Lake Merced Boulevard, Brotherhood Way)
- Sunset Boulevard, while less busy than the 19th, stops at Lincoln Way at the south edge of Golden Gate Park.  I recently used it to avoid 19th after heading southbound on the short Park Presidio Boulevard segment of Route 1. 
- Junipero Serra Boulevard ends at Sloat Boulevard, so north of there requires the narrower 7th Avenue to get past Golden Gate Park, not particularly designed for through traffic at all.  (IIRC, Serra and 7th was the planned corridor for the pre-1968 I-280/Junipero Serra Freeway extension north of its final terminus at Brotherhood Way)
- If one wanted to try skipping the Sunset altogether, they could use 280 north to San Jose Avenue (the corridor for the unbuilt Mission Freeway, which is expressway standard to 30th Street) to Dolores Street to Market to Franklin up to Lombard/101, but plenty of lights on Lombard, and stop signs on Dolores stymie flow.

[ShawnP]

Being new to Indiana. I have wondered why I-64 went further south instead of following US-150 most of the way. Ok Evansville might have had a bit of pull.

[RoadWarrior56]

Shawn P - There are other postings on this site that go into detail on the location of I-64.  Being from Evansville, I have always had an interest in that subject.  There is a written history on the Interstate System in Indiana that provides a definitive history on the location of I-64.  I don't remember what topic it is located in, but you will find it in the forum in one of the regional pages (Ohio Valley, I think).  It will answer all of your questions and more.

[RoadWarrior56]

Here's one of the links below.

http://docs.lib.purdue.edu/jtrp/1415/

[Brandon]

Illinois statred the Expressways and Tollways before the Interstates and then pushed and pushed for more milage and later came out with a post interstate plan(which has been discussed a lot under Midwest). The only interstate not completed was the Crosstown Expressway and it was not on the original plan.
There was a 78,000 mile Interstate plan and Illinois built all of those. It is still buildling a lot of the others supplementals as 4 lane divideds or Tollways. Lets say they have lost their old ambition

LOTS of help from Cook County and the IL State Toll Highway Authority to build the radial I-routes into and around Chicago in the early days.  The definitive web site for their history is www.cookexpressways.com.

Downstate, the interstates were completed in fairly logical order, with I-55 being the last "legacy" interstate, replacing a serviceable 4-lane expressway in US 66.  With the Supplemental Freeway routes, I-39 and I-72 came out OK.  US 51 south of Bloomington has turned into an endless mess of stoplights and reduced speed zones; some old timers at IDOT District 5 regretted what they allowed to happen around Clinton and in Forsyth.

Cook County effectively built the expressway system, but IDOT's predecessor did do a bit here as well.  I-55 from Gardner to Indian Head Park (Exit 227 to Exit 276C) was built by the state as a replacement for US-66 and US-66A in the area by 1956.

[flowmotion]

- If one wanted to try skipping the Sunset altogether, they could use 280 north to San Jose Avenue (the corridor for the unbuilt Mission Freeway, which is expressway standard to 30th Street) to Dolores Street to Market to Franklin up to Lombard/101, but plenty of lights on Lombard, and stop signs on Dolores stymie flow.

Actually the through street is Guerrero, one block over from Dolores Pkwy. (Only reason I menton is because Guerrero is yet another street which used have lights timed for traffic and now likes to stop you every few blocks.)

There are various other ways of getting to the S/W portions of the city. But in the end, if your destination is the GG Bridge, you don't have much choice other than 19th Ave.

[roadfro]

...what's the advantage of the mandatory reds?

That's a damn good question, but it might take an engineer or a physicist to explain it.  I've heard it discussed by people who know a lot more about this sort of thing than I do, and although I certainly can't answer your question, I can tell you that it has something to do with fluid dynamics.

basically, I think the red lights will break up standing waves where traffic slows down pathologically at a given point - better to slow everyone down from 25 to 0 for one minute at various spots, than from 25 to 5 for three minutes at the same spot. 

I've taken courses in traffic engineering that have dealt with signal timing and progression. The concept of "mandatory red" was never discussed. The whole objective of signal coordination is to keep traffic moving, so purposefully stopping platoons of traffic multiple times doesn't really make sense with that goal.

I recall a conversation with a signal engineer a few years ago who was talking about some coordinated signal timing of an arterial in the Las Vegas area. He described a point along the coordinated arterial as a "bump", which basically menat that the traffic was likely to get a red at that point. From what he was saying though, it sounded more like the crossing arterial was a higher priority in coordination as opposed to a conscious decision to halt the traffic flow.

One thing that does make some sense though is to use the 'mandatory red' concept in order to 'regroup' the platoon. On a higher-speed arterial, the variations in speeds will eventually lead to the platoon getting more and more spread out. Inserting a red would get the spread out vehicles more closely together. Perhaps the practical application of this is in coordinating cross streets, where you might need platoons to keep grouped in order to move traffic on side streets.

The rules of fluid dynamics apply to traffic flow in ways that totally surprised me.  For another example I can't make sense of unless I'm actively listening to a dumbed-down explanation:  when mntc projects require a freeway to temporarily reduce the number of forward lanes - let's say from two to one - there's always that idiot approaching it during heavy traffic in the lane that's about to end, who at the very last moment manages to shove his or her way into the remaining thru lane, while everyone else patiently waits their turn.  Well, somehow you can use fluid dynamics to explain how that idiot is doing everybody a favor by making traffic flow more smoothly.  Really.

The application of fluid dynamics to traffic crosses over a lot more than most people realize. Flow is primarily a fluid dynamic concept, so analysing "traffic flow" is an obvious connection--in the traffic engineering textbook I've used in grad school, many of the variables used to describe flow, capacity, etc. were the same as those used in my undergrad fluid dynamics class. I wish I had made the connection between the two topics much earlier...I probably would've done better in fluids class.

The merging example is another correct application of fluid dynamics and flow rate, except you need a lot more idiots. I believe it has to do with turbulence in the flow. If you have people merging over at random locations, it interrupts the steady flow at multiple points, causing the slowdown to propigate back upstream. However, if both lanes wait to merge at a single point (i.e. "zipper" merging), the upstream vehicles remain at constant speed and everything flows more smoothly. I believe this was actually studied a few years ago by a state DOT somewhere back east, that found when instructing drivers to merge at a specific point the delay was reduced by a significant amount.

[pianocello]

The merging example is another correct application of fluid dynamics and flow rate, except you need a lot more idiots. I believe it has to do with turbulence in the flow. If you have people merging over at random locations, it interrupts the steady flow at multiple points, causing the slowdown to propigate back upstream. However, if both lanes wait to merge at a single point (i.e. "zipper" merging), the upstream vehicles remain at constant speed and everything flows more smoothly. I believe this was actually studied a few years ago by a state DOT somewhere back east, that found when instructing drivers to merge at a specific point the delay was reduced by a significant amount.

Unfortunately, the people still slow down as they hit the construction and merging 2 lanes to 1 takes time. Throw in a few idiot drivers who don't know what they're doing and you get very long backups.

I read an article about "zipper" merging in the Quad City Times, and I wish I could find it online. Basically, it was a letter to the editor or something asking what the benefits of using the "zipper" at I-74 going into Iowa were. The author of the article said that it wasn't to save time, because it obviously hadn't, but to save distance by theoretically making the backup half as long, preventing backups in other ramps.

[berberry]

The rules of fluid dynamics apply to traffic flow in ways that totally surprised me.  For another example I can't make sense of unless I'm actively listening to a dumbed-down explanation:  when mntc projects require a freeway to temporarily reduce the number of forward lanes - let's say from two to one - there's always that idiot approaching it during heavy traffic in the lane that's about to end, who at the very last moment manages to shove his or her way into the remaining thru lane, while everyone else patiently waits their turn.  Well, somehow you can use fluid dynamics to explain how that idiot is doing everybody a favor by making traffic flow more smoothly.  Really.

The application of fluid dynamics to traffic crosses over a lot more than most people realize. Flow is primarily a fluid dynamic concept, so analysing "traffic flow" is an obvious connection--in the traffic engineering textbook I've used in grad school, many of the variables used to describe flow, capacity, etc. were the same as those used in my undergrad fluid dynamics class. I wish I had made the connection between the two topics much earlier...I probably would've done better in fluids class.

The merging example is another correct application of fluid dynamics and flow rate, except you need a lot more idiots. I believe it has to do with turbulence in the flow. If you have people merging over at random locations, it interrupts the steady flow at multiple points, causing the slowdown to propigate back upstream. However, if both lanes wait to merge at a single point (i.e. "zipper" merging), the upstream vehicles remain at constant speed and everything flows more smoothly. I believe this was actually studied a few years ago by a state DOT somewhere back east, that found when instructing drivers to merge at a specific point the delay was reduced by a significant amount.

You and flowmotion have given good, concise explanations for the phenomenon.  You've made it easier to understand than anyone else ever did, at least for me.

The question then is why DOTs don't use more of their media budgets to explain it to the public?  More cooperation between informed commuters might help to make construction zones safer for the workers, to say nothing of any improvement to commute x.

AbE:  Sorry, I've been using 'x' as shorthand for both 'by' and 'times' for decades, long before the internet.  I had a history teacher in high school who used it that way all the time on the chalkboard, and I picked up the habit.  I do it without thinking.  So in this case I was saying "commute times".