100 busiest roads in California

[Chris]

Using the most recent stats from Caltrans (2007)

[Voyager]

The Bay Area only makes it to 62? I thought the Bayshore Freeway had much more than that.

[mightyace]

The Bay Area only makes it to 62? I thought the Bayshore Freeway had much more than that.

Maybe it does.

Lies, damn lies, and statistics.

[mapman]

Actually, it's a good thing that the Bay Area's that far down -- that means we can actually get to where we want to go!   

[Voyager]

Doesn't seem like it.

[Chris]

Actually, it's a good thing that the Bay Area's that far down -- that means we can actually get to where we want to go!   

That depends on the amount of capacity available. the San Francisco Bay Area and Los Angeles have an equally undercapacity freeway system actually, although LA is a bit worse.

[mapman]

Yah, I know.  My comment was half-satirical (hence the  ).

However, the Bay Area is widening many of its congestion points (although slowly).  HOV lanes recently opened on US 101 in Marin County, I-880 was widened north of US 101 to 6 lanes (and there are plans for another 2 lanes), CA 87 gained HOV lanes, I-580 will be getting HOV lanes soon, etc.  LA and OC are now too built out to add substantive capacity to their freeway network without doing more out-of-the-box things, like the overhead HOV lanes on I-110 approaching downtown LA, or the toll lanes on CA 91 or I-15.  (I know, they recently built CA 210, but that's probably the last new freeway in the LA area.)

[rebel049]

Actually, since row 1 is the header that is only the 99 busiest roads in California.

[Truvelo]

Actually, since row 1 is the header that is only the 99 busiest roads in California.

There's always one isn't there

[J N Winkler]

Where there's one, there's another.

I would note that the list above isn't actually the 100 (or even the 99) busiest roads in California--instead, it is the 100 busiest traffic counter locations, and something like one-third of them are in District 7.  Do we have any reason to think that traffic counters are evenly distributed across California, or even among the metropolitan districts (3, 4, 7, 8, 11, and 12)?

[Chris]

The list show road sections, all freeways have a certain AADT between two exits, and that's what listed above.

[J N Winkler]

That is not quite the case.  The list shows AADTs at the postmiles where traffic counters are located.  There are a few runs of consecutive listings for the same freeway where a given level of high traffic volume on that freeway straddles several counter locations, but these are not listed in postmile order since the sort is by highest traffic volume.  As an example, a length of I-110 (Harbor Freeway) has AADTs ranging from 332,000 to 335,000, but the exits are listed as Gage-Florence-Manchester-Slauson when on the ground they are Manchester-Florence-Gage-Slauson (going northbound).

The listing is highly susceptible to counter density.  For instance, a lot of counters in locations which have high traffic volume (which you could expect to be the case since counter data is needed for active traffic management and for assessing the success or otherwise of minor capacity improvements, which are pretty much all that can be done in very busy corridors) will squeeze out busy locations further down the list.

One way to remove counter location and density as protential confounders would be to compile a list of the 100 busiest corridors in California.  For purposes of such a list, a corridor of high traffic volume would have to be centered on the location of peak counter AADT and extend to the points (on either side of the peak) where the AADT drops by a set percentage (perhaps 10% or 20%).

[Chris]

I don't think the Caltrans list has ATR locations only, but for all road segments (as in: between two exits). Counters are usually not installed between every exit, but between a couple of exits, and they estimate the other locations, at least that's how it's done in Europe.

This list I got from Caltrans has every road segment between two exits.

[mapman]

Chris is correct -- Caltrans doesn't count every location, and does estimate both total volume and truck volumes between count locations.

For freeways, Caltrans reports volumes between all interchanges.  For non-freeways, it reports volumes more sporadically.

[Chris]

For non-freeways, it reports volumes more sporadically.

I think between major intersections, not between every country road that leads to nowhere.

[J N Winkler]

This may be true, but the fact remains that busy lengths of road with multiple exits have multiple listings, which leads to a truncation problem.  This is evident in the AADT range spanned by this list--the top has 397,000 AADT while the bottom has 282,000 AADT.

The treatment of roads without full control of access is academic in this case, since the roads listed are all freeways.

[Chris]

You can download the reports here on the Caltrans website.

[Voyager]

How wide is 405 through the Seal Beach area?

[Chris]

14 lanes... Which still makes it overcrowded.

[Voyager]

Are they planning on expanding it?

[Chris]

There are already 7 lanes each way, so I don't think adding more would work, they will become hard to navigate, if not already. I would like to see 20 lanes there, divided over 4 carriageways, a local-express setup if you will. 5+5+5+5 lanes. That way you have enough capacity to handle this kind of traffic volumes.

[J N Winkler]

Yes.  OCTA is administering the I-405/I-605/Calif. 22 expansion project.  PBS&J is handling design.

[Chris]

What are the exact plans, J(onathan?)

[J N Winkler]

I had a quick look and it seems I was wrong:  OCTA isn't doing all of the work at I-405/I-605/Calif. 22, although it administered a related project to widen Calif. 22 east of the interchange (known as the Garden Grove Freeway).

OCTA does plan to widen I-405 south of the interchange by adding two lanes in each direction, substantially within the existing right of way, but it seems this project is still gathering environmental approvals.  It is therefore too early to be talking about an adopted alternative, but a "funding constrained" option with general-purpose lanes and express HOT lanes is under consideration.

http://www.octa.net/405improvement.aspx

According to this list, Caltrans has two projects at the 405/605/22 interchange, with an aggregate value of about $290 million.  This is Caltrans District 12's projected letting list for 2009, which implies that the contracts will be let and administered by Caltrans.

http://www.dot.ca.gov/dist12/projects/8x11ConstProjAdvetiseTable121608.pdf

12-071634--HOV connectors ($177 million)

12-071624--Widen interchange roadways ($114 million)

They are due for advertising this coming October and are the projects PBS&J has been working on.  I was shown the 30% complete plans for 12-071634 a while ago and the typical sections show widening of two lanes in each direction on I-405, one lane in each direction on I-605, and no in-contract work on SR 22.  In the case of both I-405 and I-605, the widening is on the outside.  The flyover HOV connector being built as part of this contract is bidirectional, between I-405 and I-605, and is designed to allow SB I-605 HOV traffic to continue in the HOV lanes on I-405 southbound and nortbound I-405 HOV traffic to continue in the northbound I-605 HOV lanes.

My recollection is that OCTA has been doing two contracts on SR 22, both as design-build jobs.  The first was a straightforward widening of SR 22, while the second consisted of upgrades at the 405/605/22 interchanges.  I am unsure of the scope of work in the latter contract, which has been an embarrassment for OCTA--it has had cost overruns into the many millions of dollars due to poor geotechnical information.  I believe, however, that it is designed to improve connectivity between 405/605 and the widened 22, possibly by building or widening HOV direct connectors.

[Chris]

So the I-405 will get 9 lanes in each direction? Wow.