Interstate traffic volumes, ca. 2011-2012

[froggie]

Posted this in another thread, but it's relevant here.  It's an update of a map I created a couple years ago.  This map shows average annual daily traffic (AADT) volumes on the Interstate system.  A spotcheck of the national database I got the data from shows that the AADT volumes are generally from the 2011/2012 timeframe.



Green shows light daily volumes of less than 8,000 AADT.  Several west-of-the-Mississippi segments, but it also includes I-75 in "Yooperland", part of the Southern Tier Expressway (I-86 NY), I-81 into Ontario, part of the Northway (I-87 north of Glens Falls), and Interstate segments in northern New England.

Meanwhile, red shows busy segments with daily volumes over 40,000 AADT.  Segments that stand out here (besides the obvious urban corridors) include I-35 from San Antonio to the 35E/35W split near DFW, I-81 from Wytheville to Harrisburg, and I-85 from Atlanta to Durham.

[noelbotevera]

I'm having a hard time thinking that I-5 in Northern California between Sacramento and Portland has red segments. The towns that have those segments aren't exactly large.

[Brian556]

Nice. Thanks for posting.

Out of the ones that I have driven, I-10 from I-49 to Baton Rouge stands out as the only one that is red, but only has two lanes in each direction. All the other red sections that I am familiar with correspond nicely with 3+ lane per direction sections.

[sdmichael]

I'm having a hard time thinking that I-5 in Northern California between Sacramento and Portland has red segments. The towns that have those segments aren't exactly large.

Redding and Red Bluff produce a fair amount of traffic by themselves and is the connection point for some major State highways. I can easily see it as red there.

[hobsini2]

I'm having a hard time thinking that I-5 in Northern California between Sacramento and Portland has red segments. The towns that have those segments aren't exactly large.

Redding and Red Bluff produce a fair amount of traffic by themselves and is the connection point for some major State highways. I can easily see it as red there.

As well as Medford, Salem and Eugene/Springfield.

[noelbotevera]

I'm having a hard time thinking that I-5 in Northern California between Sacramento and Portland has red segments. The towns that have those segments aren't exactly large.

Redding and Red Bluff produce a fair amount of traffic by themselves and is the connection point for some major State highways. I can easily see it as red there.

Ah. Makes sense. It's just that it seems a little bit too out of place for my tastes.

[jemacedo9]

Nice. Thanks for posting.

Out of the ones that I have driven, I-10 from I-49 to Baton Rouge stands out as the only one that is red, but only has two lanes in each direction. All the other red sections that I am familiar with correspond nicely with 3+ lane per direction sections.

That would be an interesting map to see...traffic volumes with # of lanes...though I don't know how you would do that easily.

[hotdogPi]

Nice. Thanks for posting.

Out of the ones that I have driven, I-10 from I-49 to Baton Rouge stands out as the only one that is red, but only has two lanes in each direction. All the other red sections that I am familiar with correspond nicely with 3+ lane per direction sections.

That would be an interesting map to see...traffic volumes with # of lanes...though I don't know how you would do that easily.

Color of the line and thickness of the line.

[froggie]

That would be an interesting map to see...traffic volumes with # of lanes...though I don't know how you would do that easily.

Volume per lane would be a more appropriate measure, and is already being conceptualized.

[kalvado]

That would be an interesting map to see...traffic volumes with # of lanes...though I don't know how you would do that easily.

Volume per lane would be a more appropriate measure, and is already being conceptualized.

Can be less than ideal metric as well - traffic distribution in time and type also play a role.
I can see relatively low absolute count, but highly concentrated commuter traffic requiring extra lanes, while more heavily traveled around the clock roads would stil do fine. Also both double tandems and cars count for single vehicle...
In particular, I am thinking about I-65 between Chicago and Indianapolis with lane literally fully occupied by trucks at 10 PM.

[cpzilliacus]

Also both double tandems and cars count for single vehicle...
In particular, I am thinking about I-65 between Chicago and Indianapolis with lane literally fully occupied by trucks at 10 PM.

I-81 across Virginia and Pennsylvania (with short sections in West Virginia and Maryland) fits that description.

[michravera]

I'm having a hard time thinking that I-5 in Northern California between Sacramento and Portland has red segments. The towns that have those segments aren't exactly large.

Redding and Red Bluff produce a fair amount of traffic by themselves and is the connection point for some major State highways. I can easily see it as red there.

Ah. Makes sense. It's just that it seems a little bit too out of place for my tastes.

Small towns in California are those with less than about a quarter million people! It is no trick at all to get 40K vehicles per day on the main freeway in a city with 150K people.

I wonder about how much traffic is diverted off of I-5 onto CASR-99 and whether the 2 combined might go over 40K per day all of the way up to Stockton (and therefor Woodland), maybe even all of the way up to Red Bluff.

[DTComposer]

I'm having a hard time thinking that I-5 in Northern California between Sacramento and Portland has red segments. The towns that have those segments aren't exactly large.

Redding and Red Bluff produce a fair amount of traffic by themselves and is the connection point for some major State highways. I can easily see it as red there.

Ah. Makes sense. It's just that it seems a little bit too out of place for my tastes.

Small towns in California are those with less than about a quarter million people! It is no trick at all to get 40K vehicles per day on the main freeway in a city with 150K people.

I wonder about how much traffic is diverted off of I-5 onto CASR-99 and whether the 2 combined might go over 40K per day all of the way up to Stockton (and therefor Woodland), maybe even all of the way up to Red Bluff.

According to Caltrans' data from 2014, all of I-5 between Wheeler Ridge and Stockton is already in the mid to high 30K range (in other words, very close to being red on the map); and CA-99 in that corridor well exceeds 40K for the entire stretch.

http://www.dot.ca.gov/trafficops/census/2014all/Route5-6.html

North of Sacramento it's a little lighter, but no lower than 25K all the way to Redding (where it's in the 40-60K range).

[CtrlAltDel]

This is a nice map. Thanks for the update. I've been flicking back and forth between the old one and the new one to see what's changed.

On an aesthetic level, though, yellow lines on a white background are hard for me to read.

[sparker]

Nice work, Adam!  The only thing I would have done a bit differently is to split the center (yellow) section into two, possibly diverging at 20K or 24K; this might make a statistical analysis of rural sections more precise.  Besides, you've got one primary color (blue) you haven't used -- would be appropriate for one of those divisions!  Otherwise, highly useful -- I'll be coming back to it for reference often!

[froggie]

Here's another map, using the same data as the first map and more accurately reflecting congested versus non-congested segments of highway.  This map shows average daily volumes per vehicle lane, using the vehicle lane data that was provided to FHWA by the respective state DOT's.



Green segments are generally LOS A/B, using default/generic roadway characteristic values.  Yellow segments are busier, generally LOS C/D, while red segments are generally LOS E/F.  These are considered general LOS values and should not be taken at face value due to the use of default roadway characteristics.  The national-level database I used does not have the level of detail needed for more detailed/correct LOS calculations.

The default roadway values I used for the calculations are as follows:

Lanes per direction: 3
Directional split: 65/35
K-Factor (peak hour volume): 10%
Percentage of trucks: 10%
Default speed: 65 MPH
Interchange spacing: 2+ miles
Lane width: 12ft
Lateral clearance: 6+ ft

As a general rule, a higher directional split, K-factor, and/or truck percentage will result in a higher vehicle density and possibly a worse LOS category.  A lower speed limit, shorter interchange spacing, and narrower lane width or lateral clearance will do the same.  The opposite of these would result in a lower vehicle density and better LOS.

[Rothman]

Although the map is nice to look at, to me there's at least something of a degree of "duh" in what the data shows:  Interstate Highways are more congested in urban areas.

To me, I-35 sticks out on the DFW-Austin-San Antonio route, simply because I think the perception is that there's more empty space between those cities than there really is.  To a lesser extent, I-4; people may think Tampa, Orlando, Daytona, but there's obviously a lot of sprawl along that corridor as well.