Widening parts of I-270 and I-64 by reducing lane widths/St. Louis TIGER II

[agentsteel53]

Nope, the cross-section you describe for the main drag in Marfa is classic poor-boy. 

there was absolutely no indication that the slow lane was to be used intermittently by slow vehicles only.  I think I drove from one end of town to the other on the shoulder!

[J N Winkler]

Sorry--I read your description of US 90 through Marfa without cross-checking in StreetView and so failed to arrive at a correct understanding.  I think it is just an urban two-lane with a parking lane on each side.  Classic poor-boy cross-section is more like, e.g., Broadway Avenue between Wichita and Newton.

[agentsteel53]

without any instruction to the contrary, I would drive Broadway in the right lane the whole way.

the question all seems to depend on traffic counts.  All of these roads seem to be pretty underutilized - as opposed to, say, a road with four lanes, each filled to capacity.  here, these roads (both Marfa and Broadway Ave) could be restriped to two-lane tomorrow morning and meet traffic demand just as they do now.  A four-lane with much more traffic on it would not be served well with a restriping.

[J N Winkler]

here, these roads (both Marfa and Broadway Ave) could be restriped to two-lane tomorrow morning and meet traffic demand just as they do now.  A four-lane with much more traffic on it would not be served well with a restriping.

This is basically true, but the main burden of this thread is the merit of restriping for additional lanes versus spending much more money to build them properly (12' width with full shoulders).  From this standpoint, Broadway Avenue is relevant at a much earlier point in its history.  It carried the US 81 designation until the late 1960's/early 1970's when I-135 was finished between Wichita and Newton and US 81 was moved onto it.  In a newspaper article which appeared in the Wichita Eagle some years ago and dealt with the possibility that I-135 might need widening to six lanes between Wichita and Newton, a KDOT engineer remarked that this length of Broadway had been built during the 1930's as an early experiment with multilane construction (US 81 being then already too congested for just two lanes), and could fit entirely within the median of present I-135 (which would be true even with a 45' median, and I think I-135 was built with a 70' median).

[agentsteel53]

so at some point this alignment of US-81 must've been quite congested, with all four lanes in regular use?  in that case I'd argue it's a lot more dangerous than a typical rural two-lane road, which - while possibly equally congested - has only two lanes of potential traffic to intermingle in the crashy sense.

[J N Winkler]

Actually, no, at least not on a deaths-per-vehicle-kilometer basis.  You do get more cars that can be involved in crossover crashes, but that is more than offset by the reduction in crashes from badly judged overtakes, and the continuity in passing opportunity allows much higher traffic volumes.  Four-lane roads can post higher accident numbers (including absolute numbers of fatalities) but also handle proportionately higher VMT.  The hierarchy (least safe to most safe) is ordinary two-lane up to poor-boy four-lane up to full four-lane divided.

There is also a level-of-service consideration.  On divided highways, LOS can be estimated reasonably faithfully by VPH divided by lane count.  On two-lane highways this does not work very well because the key variable is the amount of time a car has to wait to pass a slower vehicle in front, which in turn is influenced by the geometry (availability of passing zones) as well as the traffic volumes.  Two-lane highways can fail at very low AADT (5,000 VPD has been cited as a criterion for widening to four lanes for mountain roads, for example).

[agentsteel53]

oh, you were thinking safer in terms of "scrape 'em off the road" fatalities, not just "you moron, can't you see where you're going?" fender benders, which I imagine occur in greater numbers on four-laners... at least if any of the four- or six-lane arterials in my neighborhood are any indication.

the question is, then: why is the poor-boy four-lane so rare?  I can totally see US-395 being upgraded to that between I-15 and CA-14.  No, instead, they put in extremely long no-passing sections, even when visibility is great.  I wonder when they'll install a Jersey barrier like they did on CA-37 to prevent passing.

the poor-boy would work well on 395 given that such a significant portion of traffic is underpowered RVs, which have a legal speed limit 10mph below those of cars (55 vs 65) and are struggling to meet even that.  Well, that is, if we could ever teach the bastards to drive in the right lane.  Sunday-driver RVs are notorious for not using turnouts, slow lanes, etc.

[3467]

I too wonder why the poor boys are so rare. There is one next to Interstate 57 along Illinois 50 which carries 8000 vpd ,apparently safely. That is more traffic than ANY of the downstate routes under study as very high grade 4 lane divideds with interchanges and very expensive structures.

[Sykotyk]

The one thing I notice when driving in Texas is I feel more comfortable on a two-lane with wide shoulders using the Texas courtesy of driving on the shoulder when being overtaken. Which, agentsteel, is the way. In all my time driving in Texas I've rarely come across someone in west Texas not get over to be passed (this is done at normal speed, no slowing down required). The only instances that I can recall are from non-Texas licensed vehicles. In fact, Oklahoma signs, regularly, near the borders that you can't drive on the shoulders simply because of this practice.

The poor-boy four-lane's problem is that generally the lanes are narrow with no room for error in the right lane. Also, a lot of the four-lanes appear to be made out of the shoulder of what was originally a two-laner. This gives the lane a persistent pull to the right (which is annoying for long stretches). Also, because the lane is clearly marked, if you do drive in the left, because of the mandatory space used for the right lane, the opposing traffic passes much closer.

In a two-laner, traffic will stay wide to the fog lines and clear with anywhere from 5-10 feet when the road is equipped with shoulders. At 70+ each direction, it makes sense to give plenty of room to eachother. The shoulder is used as a lane only when necessary. Thereby requiring the tighter driving, smaller space, angled surface, etc to only factor into your driving for all of a few seconds, instead of miles upon miles of driving.

US77 just north of north of Giddings, TX
http://maps.google.com/maps?q=san+antonio+tx&oe=utf-8&client=firefox-a&ie=UTF8&hq=&hnear=San+Antonio,+Bexar,+Texas&gl=us&ll=30.256798,-96.940364&spn=0.350526,0.837021&z=11&layer=c&cbll=30.256798,-96.940364&panoid=5V9CrJtMoKFRMHFWCRWkeg&cbp=12,346.56,,0,8.84

Is a prime example of the problems I mentioned with the poor-boy. Also, its traffic volume has never appeared to be heavy any time I've driven it. Yet, because of the creation of the outside lines, you're compelled to ride in your 'lane' rather than take advantage of the space available to you even when no one else is driving near you.

US79/190 near Hearne, TX
http://maps.google.com/maps?q=san+antonio+tx&oe=utf-8&client=firefox-a&ie=UTF8&hq=&hnear=San+Antonio,+Bexar,+Texas&gl=us&ll=30.795594,-96.706852&spn=0.174294,0.41851&z=12&layer=c&cbll=30.795594,-96.706852&panoid=DlbT7_WJqCz0Qc3UIotSlg&cbp=12,50.21,,0,13.2

Much wider lane (you can even notice in the pickup behind the Google car). When someone approaches you, you stay wide. When someone comes behind you, you ride the shoulder as best you can and let them pass, oncoming cars or not.

Sykotyk

[agentsteel53]

In all my time driving in Texas I've rarely come across someone in west Texas not get over to be passed (this is done at normal speed, no slowing down required).

in all my time driving in California, I can count on one Mordecai Brown handful the quantity of people who have pulled onto the shoulder to let me pass. 

like I said, here we subscribe to the "rolling roadblock" theory of vehicular operation.

Adding the other 49 states, it's still a pretty small number.

[Sykotyk]

Like I said, agentsteel, despite your banter to the contrary that the driving on the shoulder way of operating is a Texas custom that is widely followed. Some states may not give wide enough shoulders to do such a maneuver. I know I couldn't imagine doing that in Ohio or Pennsylvania. The 'rolling road block' is actually required to stop and let traffic pass, not drive the shoulder at 65 mph because a car wants to pass doing 70mph. That's the point I'm making.

As far as I've been aware, most states it is illegal to drive on the shoulder without proper signage indicating an exception (WA has this on mountains, as does Oregon on I-5 just north of California).

Sykotyk

[agentsteel53]

"required to stop and let traffic pass"

yes, I've seen the signs.  "If you have five cars behind you, use next turnout."  The probability of anyone ever doing that is inversely proportional to their speed.  Someone doing 60, you might have the offhand chance.  Someone doing 40?  Only if it's a professional driver.  An RV, good luck with that - they seem to offer a perverse sort of defiance.

[Sykotyk]

Exactly, but in Texas it is the standard that most adhere to and failing to do so is the extreme minority because the overtaken traffic doesn't ever slow down (therefore, no negative consequence to them).

In Washington, the shoulder-driving-lanes are so short, in order to let anyone by, you would have to slow down considerably.

[agentsteel53]

Exactly, but in Texas it is the standard that most adhere to and failing to do so is the extreme minority because the overtaken traffic doesn't ever slow down (therefore, no negative consequence to them).

In Washington, the shoulder-driving-lanes are so short, in order to let anyone by, you would have to slow down considerably.

well then Texas is a superior driving environment.

too bad there's nothing to see there.  TXDOT is Hell-bent on tearing apart any old infrastructure, leaving only Clearview behind.