Should All Interstates be 6-laned?

[thisdj78]

I've spent a lot of time on the road the past 12 months, coast to coast. A thought that crossed my mind: Should all interstates be 6-lanes? I can't count how many times I've been stuck behind two semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas. Seems like an 3rd lane each way is needed...if anything for safety reasons. Apologies if this topic has been discussed before.

[ElishaGOtis]

Tunnels: hi

The mountain of money required to build new, or upgrade to, 6-lane tunnels is far greater than whatever barrier is being overcome, effectively halting any progress on the system.

HOWEVER, in less terrain-difficult areas, this may not be too far-fetched, but would still be highly expensive. Tolls or express lanes may be the only viable funding option in this case given the size of the overall system.

This standard could be beneficial in modernizing the system, streamlining capacity and safety, and even supporting National Defense (large military convoys wouldn't be as impeded by other traffic on 6-lane segments compared to 4-lane segments).

I love the concept, but I'm slightly concerned about implementation. Maybe it could be more beneficial if all NEW 2dis be 6 lanes?

Edited for clarity

[ilpt4u]

I've spent a lot of time on the road the past 12 months, coast to coast. A thought that crossed my mind: Should all interstates be 6-lanes? I can't count how many times I've been stuck behind two semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas. Seems like an 3rd lane each way is needed...if anything for safety reasons. Apologies if this topic has been discussed before.

Some interstates don't even deserve to be interstates (looking at you, I-180 of Illinois and of Wyoming), let alone 6 lanes of interstate

[oscar]

There are four-lane Interstates out west that were just two-lane freeways for a long time, and the traffic volumes barely qualify them for four lanes. For examples, I-70 in Utah between Salina and Green River (over 100 miles with no gas stations), and I-15 in northeastern Idaho/southwestern Montana.

I would prefer more six-lane rural Interstates if they were cost-justified, but some exceptions are needed, like the ones I mention above.

[gonealookin]

I'd say such a requirement would torpedo Interstate 11's chance of ever being extended north to Reno.

[Rick Powell]

Some interstates don't even deserve to be interstates (looking at you, I-180 of Illinois and of Wyoming), let alone 6 lanes of interstate

I-180 can't get no respect! Although agreed that neither route warrants an I-designation and the one in IL could function as a 2-lane.

In IL alone, I-72, I-57 south of the I-24 split, and most of I-74 are perfectly fine as 4 lanes. The tollway system has widened all of its needy routes to 6 lanes or better, including the recent Jane Addams I-90 to Rockford. I-80 from the Quad Cities to I-39 and rural I-55 (except for the Bloomington-Normal, Springfield and Metro St Louis areas) are OK as 4-lanes. I'd say the most deficient sections in IL for 6-lane conversion are I-80 from I-39 to the new construction near Joliet (which will soon be 6/8 lanes thru Joliet), I-57 from Kankakee to I-80, I-55 from IL 113 to south of I-80, and I-55 on the east side of Springfield. At some point, I-39 from Rochelle to Rockford will need it.

[SEWIGuy]

I've spent a lot of time on the road the past 12 months, coast to coast. A thought that crossed my mind: Should all interstates be 6-lanes? I can't count how many times I've been stuck behind two semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas. Seems like an 3rd lane each way is needed...if anything for safety reasons. Apologies if this topic has been discussed before.

No. It's an unrealistic expectation that travelling an interstate means you aren't inconvenienced by slow drivers. 

[michiganguy123]

No point in six laning any interstate when idiots turn it into a 4 lane highway by camping the middle lane or even worse, by camping the passing lane. The 3rd lane is just as much of a travel lane as the middle lane, move all the way to the right when done passing.

[epzik8]

Waste of money and resources IMO.

[jlam]

It would literally be impossible to upgrade I-70 through the Eisenhower tunnel and Glenwood Canyon to six lanes

[kphoger]

I've spent a lot of time on the road the past 12 months, coast to coast. A thought that crossed my mind: Should all interstates be 6-lanes? I can't count how many times I've been stuck behind two semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas.

On six-lane Interstates, I can't count how many times I've been stuck behind three semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas.  Therefore, all Interstates should be eight lanes.

[vdeane]

I've spent a lot of time on the road the past 12 months, coast to coast. A thought that crossed my mind: Should all interstates be 6-lanes? I can't count how many times I've been stuck behind two semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas.

On six-lane Interstates, I can't count how many times I've been stuck behind three semi-trucks or slow moving cars side by side, which can even cause traffic in the most remote areas.  Therefore, all Interstates should be eight lanes.

[insert New Urbanist "just one more lane" meme here]

[doorknob60]

I have sometimes felt this way in higher population areas of the country like CA, TX, and most of the east coast. Though there is still plenty of exceptions in those places too. But in my neck of the woods, hell no. Even the more moderately traffic areas of rural interstate here, like I-84 from Boise to Twin Falls, 4 lanes is totally fine. Sure, you occasionally get stuck behind a passing truck (usually here that means slowing down from 80 to 65 or 70 for like 30 seconds), but it's not really a problem.

My last drive from Boise to Ogden, UT, I probably lost a total of 2 minutes driving time due to "traffic", basically meaningless. Absolutely not worth investing serious money into (other than localized areas like Jerome to Twin Falls, or climbing lanes on hills). Head towards Oregon or Utah on I-84 and traffic levels drop even more, and then it's basically never a problem.

That's not even mentioning the less busy interstates around here like most of I-15 north of the I-84 split, I-86, Utah's I-70, etc.

If anything, sometimes 6 lane freeways seem to flow worse than 4 lanes when there's lighter traffic, because idiots think that gives them the green light to just camp in the middle lane even when they're not passing.

I'm curious what I'll feel about this after visiting some more "mid-density" areas on my road trip this summer, like Missouri and Minnesota.

[MikieTimT]

Only way it makes sense is to outlaw trucks (and enforce it) in the leftmost lane each direction.  Otherwise, there's still a likelihood that the rolling roadblocks go three wide.

[kphoger]

Do agencies really consider "sometimes people have to drop down to the speed limit" as a reason for widening a highway?

[thisdj78]

Do agencies really consider "sometimes people have to drop down to the speed limit" as a reason for widening a highway?

Of course not and I agree with the point you're making. But couldn't a similar question be asked for justification of  "limited access" highways in extreme remote rural areas?

I've driven on highways overseas in lightly populated areas that were 6-lanes,
so there had to be some justification for it beyond my personal example of being stuck behind slow vehicles.

[Rothman]

All Interstates should be one lane.

[kphoger]

I've driven on highways overseas in lightly populated areas that were 6-lanes,
so there had to be some justification for it beyond my personal example of being stuck behind slow vehicles.

1.  There may have been justification, but it may have been flimsy justification.  Depending on the country, things like 'appearing modern' might be justification.  This becomes easier to sell if there's heavy foreign investment in the project, such that the cost to country the highway is actually in is minimized.  I'm specifically thinking of some highway projects in Africa that have been financed and even built by Asian firms.

2.  Those highways may have been built when and where land was cheaper, materials were cheaper, labor was cheaper, legal and environmental hurdles were lower, the economy was stronger, etc, etc.

3.  What counts as justifiable may have changed between then and now, and may differ from there to here.

4.  I've driven on highways overseas in heavily populated areas that were 4-lanes, so there had to be some justification for their not having been widened.

[Revive 755]

I-80 from the Quad Cities to I-39 and rural I-55 (except for the Bloomington-Normal, Springfield and Metro St Louis areas) are OK as 4-lanes.

I-55 between IL 104 and IL 157 needs to go to at least six lanes, with auxiliary lanes in the Troy area.  It's very noticeable how much traffic flow improves or degrades at IL 104 where the existing six lane section ends.

[pderocco]

It might be easier to prohibit trucks occupying all lanes in a row unless they can pass and pull over in less than a minute. And if we ever get self-driving trucks, their own software could enforce that, even by causing the slow-poke to slow down a little more while being passed.

[Road Hog]

They don't all have to be 6-lane. Lots of 4-lane Autobahnen in Deutchland demand that LKW-Verkeher bleiben rechts. >

[kphoger]

It might be easier to prohibit trucks occupying all lanes in a row unless they can pass and pull over in less than a minute.

That's ridiculous.  Let's do some math.  Someone tell me if I'm doing my math wrong.

The FMCSA recommends that, for speeds over 40 mph, a driver leave 2 seconds of following distance per 10 feet of vehicle length.  For a 70-foot tractor-trailer combination, that comes to 14 seconds of safe following distance.

If we assume that the slow-moving vehicle is going 60 mph and the trucker is going 68 mph, then here are the distances each vehicle will have traveled within one minute:

slower vehicle @ 60 mph = 88 ft/sec → 5280 feet (1 mile)
passing truck @ 68 mph = 100 ft/sec → 6000 feet (1 mile + 720 feet)

At 68 mph, a 14-second following distance equals a 1400-foot following distance.  So, even though the trucker is going a whopping 8 mph faster than the other vehicle, if he keeps a safe following distance before moving out to pass, then he will only have made it halfway to the back end of that slower vehicle (720 out of 1400 feet) before one minute has elapsed.

And if we ever get self-driving trucks, their own software could enforce that, even by causing the slow-poke to slow down a little more while being passed.

If all 100% of vehicles on the road are self-driving, yes.  But...

1.  If fewer than 100% of vehicles on the road are self-driving, then that slower vehicle might not maintain a constant speed anyway, so the truck's software could be wrong.

2.  If 100% of vehicles on the road are self-driving, then who cares anymore about lane hogs?

[hotdogPi]

How are you supposed to leave 14 seconds if you often can't even see 1/4 mile ahead due to a curve?

[kphoger]

How are you supposed to leave 14 seconds if you often can't even see 1/4 mile ahead due to a curve?

I suspect that the FMCSA would suggest, if you cannot see far enough to leave the recommended safe following distance, that you slow down to the point that the recommended safe following distance is within your field of vision.

[CtrlAltDel]

The FMCSA recommends that, for speeds over 40 mph, a driver leave 2 seconds of following distance per 10 feet of vehicle length.  For a 70-foot tractor-trailer combination, that comes to 14 seconds of safe following distance.

I suppose this could be up to interpretation, but I don't think this is true, since that would mean that this is the safe following distance for a truck directly under at the bridge at 60 mph, which seems excessive.


If you're going by here, the statement is:

If you are driving below 40 mph, you should leave at least one second for every 10 feet of vehicle length. For a typical tractor-trailer, this results in 4 seconds between you and the leading vehicle. For speeds over 40 mph, you should leave one additional second

I don't think though that this is an additional second per 10 feet of vehicle length, but one additional second overall. So, that would mean, for a 70 foot vehicle, not 14 seconds but rather 8 seconds of following distance.