Ask me about being a Traffic Engineer!

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Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Excellent thread. I just spent two years working as a transportation planner, though I'm probably going to move toward land use planning once I'm done with my master's degree. I'm still a bit of a roadgeek at heart, but I don't think I'd want to make a career out of traffic engineering. Having to do anything with the Green Book bores me to tears. I'd rather draw lines on maps and let other people work out the details. Still, Synchro is a lot of fun to play with.

Anyway, for an actual question: what do you think of the proposed MUTCD updates?

# ¿ Aug 3, 2009 15:03

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# ¿ Apr 29, 2024 16:10

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

MUTCD

It seems to me that the increased visibility requirements would be fine if it were implemented with a long enough time frame that substandard signs get replaced as their service life is over. Down here in Florida, most signs already meet the higher visibility standards (take a guess as to why), but having driven a lot in other states recently, I can see the problem.

I like the new diagrammatic guide signs. The existing lane diagrams can be pretty confusing at 70mph if you're in an unfamiliar urban area.

What do you think of Clearview?

# ¿ Aug 3, 2009 18:17

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

smackfu posted:

"RIGHT TURN ON RED MUST YIELD TO U-TURN". What does that even mean? Would anyone understand that while driving?

If someone on the cross street is making a u-turn, anyone turning right on red would have to yield to them.

That's an odd one, given that they're trying to reduce the amount of text on signs. I can't imagine it'd be used anywhere other than intersections with a history of right-turning vehicles running into people making u-turns. Why not just prohibit u-turns instead?

# ¿ Aug 3, 2009 21:50

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Socket Ryanist posted:

Because people making U-turns have the right of way (as they have a green light, and not a red one). The sign is just informative.

Sometimes people need to make u-turns! (roads with medians and they need to enter a driveway on the opposite side).

I meant that only in specific cases of intersections where there is a history of RTOR vs u-turn crashes, where they'd likely be placing these signs. Prohibiting RTOR or u-turns would probably be more effective in solving a safety issue than putting up a sign with a lot of text on it reminding people of something they should already know. Of course, it'd be dependent on how removing RTOR would affect the operation of the intersection, too.

# ¿ Aug 4, 2009 02:32

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

We use far side only in CT whenever possible. Signal heads should be between 40 and 120 feet in front of the stop bar (150 in a pinch), and it's hard to get that kind of spacing on near-side spans. Of course, we have a lot of plows, so it's generally obvious where the stop bars are. Just for you, though, here's a rarity: a partial stop bar.

The story here is that when the DOT put in a driveway, it's left turn in only, so there's no reason for through traffic opposite the driveway to stop at all. They didn't bother to put up signal heads for the through movement, or a stop bar, instead just using a pole-mounted head in the median for the left turn.

Well, remember what I said about designing for the stupidest drivers? Those 1 in 5000 idiots (I like to pretend they're all out-of-staters) saw the left turn red light and thought, "Oh poo poo, better stop!" They'd screech to a halt in the middle of 50 mph traffic. Yeah... the DOT had to drop 10 grand just to put up a signal that stays green all the time. I can proudly say, only in Connecticut do we have drivers so stupid that you have to tell them to go constantly or they'll just stop.

Why didn't they just use single-head green up arrows? They use those here at Florida T intersections (I wonder why they got that name), and it's even less ambiguous than a regular signal that's green all the time because you'll know it'll never change. Are three-head signals cheaper?

# ¿ Aug 5, 2009 19:01

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

A month ago, when we had the tornado in Wethersfield and really nasty hail, I was driving past at the right time to see it lose power and it went into flashing yellow. May as well just have it turn off, there's no need to slow down. To answer your question, though, there are a few reasons.

1) If you look at that MUTCD page I posted earlier, there's no support for single face signals.
2) I don't know if we'd be able to get them any more cheaply than the standard kind.
3) We'd have to do all the calculations over again for the mast arm, which costs more than "just do what we always do."
4) Just in case we ever DO need to stop traffic there, say for an emergency evacuation, the capability exists.
5) Target value is much higher for 3 faces than one.

Thanks. Yet another lesson here: Just because it's being done on state highways doesn't necessarily mean it's in the MUTCD.

You should do a post on signal warrants once you're done with interchanges.

# ¿ Aug 6, 2009 13:33

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Vanagoon posted:

So they made you put in a signal so the mayor could get to Hooters that much faster? We can't be delaying the mayor in such an important endeavour. Mayor's got to get some titties in his face and it needs to be that way now!

No seriously, I love your graphics.

I saw this as a policy map being drawn on a Hooters napkin, which makes it that much funnier.

Great explanation of signal warrants. I had no idea those graphs weren't based on seconds of delay or anything actually engineering-related, but it makes sense.

# ¿ Oct 28, 2009 19:36

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Three-Phase posted:

Cichlidae,

At your job, have you ever shouted "YOU CAN'T CUT BACK ON FUNDING! YOU WILL REGRET THIS!" to anyone?

I had this on the wall of my cubicle when I was working for a transportation engineering consulting firm and no one got it.

# ¿ Nov 10, 2009 03:04

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

Which firm, if you don't mind my asking? I spend about half my day reviewing consultant designs.

Nobody you've ever heard of. Local firm, Florida-only.

# ¿ Nov 10, 2009 03:10

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

IOwnCalculus posted:

It's not just a stands for thing, scroll around - 2M, 2L, 2B, 2S...apparently since they're all somehow connected to I70 I guess they all have to be numbered on that system? No idea.

Just from eyeballing it, it seems like that whole loop is somewhere within mile marker 2 for I-35, I-70, and I-670, so they just started at 2A on the northwest corner and kept going clockwise around the loop. That's got to be a confusing mess, but I'm not sure there's any better way to do it.

# ¿ Dec 23, 2009 05:43

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

patricius posted:

Just out of curiosity, where can you find an interstate with a traffic signal on it? (Or a drawbridge for that matter?) I've never seen one, but I haven't exactly done a lot of driving, either. I thought that the lack of signals and at-grade crossings was the one thing you could count on any interstate highway to have as a defining characteristic, even if it wasn't up to standards in other ways.

I-70 in Breezewood, PA, is the most notable one. It splits off from the Pennsylvania Turnpike and follows a stretch of surface US 30 for a short distance.

http://en.wikipedia.org/wiki/List_of_gaps_in_Interstate_Highways#At-grade_intersections_and_traffic_lights

# ¿ Jan 12, 2010 01:24

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Vanan posted:

I live right next to this in NJ and it's a right pain in the rear end to use. However where I used to live in Kansas had about 7 or 8 roundabouts and they can be quite good. The real problem is drivers who don't expect them and do crazy things in them. Unfortunately the state I did my driver's test in never covers roundabouts and I suspect many other US states don't either.

God, I hate the Somerville Circle. I've only driven through it a few times, but each one was a frustrating experience.

There's also this fun one on the border of Washington, DC, and Silver Spring, Maryland. I almost ran a red light because I wasn't expecting that signal in the middle of the roundabout.

# ¿ Feb 14, 2010 22:43

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

Granted, it's a change for the better overall, but it's going to be intensely complicated and expensive. A quick back-of-the-napkin estimate put it at around $100 million to change our exit numbers, and that's not including lawsuits from all the businesses that we'll piss off.

Do you know how much it cost other states to do this? I remember Florida switching over all the interstates to mile-based exits starting in 2000 or so, and California's been adding exit numbers to a few thousand miles of freeways. It took Florida 3-4 years to get everything done, so the cost would be spread out somewhat, but that's still a pretty huge expense.

# ¿ Mar 2, 2010 21:04

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Choadmaster posted:

Rather, we have these tiny little while thingies which, if you notice them at all, give you the miles to whatever major city they've decided should be the next origin point.

(Hey look, we're 3.50 miles from Santa Barbara!)

These actually go from south/west to north/east but reset at county lines, and the letters tell you what county you're in. Also, they're known as postmiles, as opposed to mileposts/mile markers.

http://en.wikipedia.org/wiki/California_postmile

# ¿ Apr 8, 2010 18:36

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

The city I live in has decided to paint stop bars in front of pedestrian crossings with "Yield to Pedestrians" signs, both midblock crossings that used to have yield triangles and at unsignalized intersections with heavy pedestrian crossing but no stop control in that direction. I just noticed them driving around an area I was familiar with last night and thought I'd accidentally run a recently added stop sign because of them.

Am I missing something in the new MUTCD? Section 3B.16 seems pretty clear that you're not supposed to do that.

MUTCD posted:

Except as provided in Section 8B.28, stop lines shall not be used at locations where drivers are required to yield in compliance with a YIELD (R1-2) sign or a Yield Here To Pedestrians (R1-5 or R1-5a) sign or at locations on uncontrolled approaches where drivers are required by State law to yield to pedestrians.

It's possible they put up "Stop Here for Pedestrians" signs instead now. I'll have to go look again.

# ¿ Jun 14, 2011 15:33

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

Yes, that is absolutely not in compliance. The stop bar needs to go along with a stop sign. The stop bars really should be behind the crosswalks as well; putting them in front could lead to pedestrians getting run over from crossing between stopped cars.

Sorry, I meant "behind". The stop bars are before the crosswalk, but it's pretty obvious they were painted over yield triangles in both cases. It's great because there's another intersection where a T intersection was converted to a three-way stop, but they didn't bother to paint new stop bars on what used to be a free-flowing movement.

# ¿ Jun 14, 2011 17:43

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

It looks like a median island intended for traffic calming.

# ¿ Jul 29, 2011 00:15

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

https://www.youtube.com/watch?v=ZcPby71TNC0

This is the kind of signage that should be used in any congested area with a construction-related 2 to 1 lane reduction. I remember seeing this on I-694 near St. Paul last summer and it seemed to work really well.

Unfortunately, Minnesota is one of the few places in the country where people would actually do what the signs told them to instead of just being dicks like normal.

# ¿ Aug 14, 2011 19:49

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Millstone posted:

Sequential numbering had to be one of the poorest decisions in highway planning.

Leave them (and the non-MUTCD guide signs) on the New Jersey Turnpike, get rid of them everywhere else. It seems like pretty much everywhere outside of the Northeast and New England has already.

# ¿ Aug 19, 2011 01:54

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Millstone posted:

It really becomes a pain in the rear end if you do it on a long Interstate, or 400-series highway here, where population buildup is likely and additional interchanges will have to be added, thus loving everything else up.

We had to do a mass-renumbering of all exits in the metric changeover in 1977.

The whole area around Disney World was a mess for this before Florida renumbered the exits in 2001-2002. So many A/B/C/D/E exits in a 15 mile stretch between what used to be exits 24 through 27. Now it's a lot less confusing.

# ¿ Aug 19, 2011 04:55

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

I think that would only make sense if we posted everything in kilometers. As much as I'd like to see full metrication, I'd rather have exit numbers line up with existing posted distances if we're not going to get that.

# ¿ Aug 20, 2011 17:39

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

At least in Florida, roads like that tend to get four-foot paved shoulders added during resurfacing projects, but it looks like there's not even right-of-way for that with the utility poles and vegetation.

# ¿ Aug 21, 2011 01:36

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

I propose this as the theme song for this thread:
https://www.youtube.com/watch?v=tCfDLmcJc-g

In the time this thread has been around, I started and finished an urban planning master's degree and am still trying to get back into transportation planning with no luck finding a job so far. Be that as it may, here's to one of the best threads on SA and another two years of traffic engineering questions and complaining about bad highway design.

# ¿ Nov 18, 2011 23:29

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

I don't think this is MUTCD-compliant signage for an onramp:
http://g.co/maps/v2ujd

(There's a yield sign in the right place further back.)

The South Street left exit/entrance is one of the nastiest on the generally nasty Schuylkill Expressway in Philadelphia, also lovingly known as the "Surekill Distressway". If it were on the right, there would be even worse weaves from the University Ave/Grays Ferry exit to the south and the Walnut Street onramp to the north. There's no fixing it short of completely rebuilding the entire road, which will most likely never happen.

# ¿ Nov 20, 2011 00:50

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

Hahaha, that's ghetto as gently caress! Not even a spray-painted stop bar. There's no way that they actually expect people to see that.

Given the amount of absurd locations I've seen graffiti on in Philly, it probably wasn't officially done. As for *why* someone would put that there, who knows? That ramp would be even more suicidal if it was actually stop-controlled. Street View looks like it's from before the South Street Bridge replacement, so I doubt it's still around. I'm usually too busy trying not to get creamed by oncoming traffic when I'm driving through there to look.

# ¿ Nov 20, 2011 17:35

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Wolfy posted:

What?

A boulevard with service roads combined with a badly-made sign, maybe? It's hard to tell from the angle.

# ¿ Nov 22, 2011 22:00

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Tots posted:

I'm road tripping right now and am coming up on a 2 to 1 lane merge due to.constriction. Driver just said that traffic will move faster if two lanes are utilized until the merge point. I say the sooner everyone merges the faster the traffic will move. Who's right?

The driver is right. Zipper merging is more efficient. If there's no congestion, it doesn't matter. However, if everyone is merging before the merge point and there is congestion, then you run into the problem of wasted space on one lane, people running up to the merge point and then getting stuck or trying to edge into the lineup, and a greater difference in speeds between the two lanes.

# ¿ Dec 27, 2011 16:42

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Oh, this looks like fun. I might as well try to use that E.I. after my name that I usually ignore. It's been a few years since I've attempted to do any real traffic engineering, and even then it was just signal timings.

No guarantees I'll come up with anything reasonable, especially since I've never been to Connecticut and thus have never seen these roads outside of this thread.

# ¿ Jan 4, 2012 23:43

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Volmarias posted:

"Project cancelled due to lack of funds"

Do I win?

From last page, no less...

Grand Fromage posted:

# ¿ Jan 5, 2012 01:17

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

First questions:

Assuming existing conditions with design volumes, how well are the intersections at Airport Road/Brainard Road and Brainard Road/Murphy Road/those offramps operating? Would there be any queueing issues, especially with the offramps?

How much of the approach to the bridge over the river on CT 15/US 5 is fair game for reconfiguration?

# ¿ Jan 5, 2012 04:29

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

They've got some trouble currently, mostly because of how many driveways are in the area. You'd do best to avoid the heavily built-up airport area and tee the ramps directly into Airport Road, or the little branch down by the wastewater treatment plant.

The bridge itself has wide left shoulders and can fit a fourth lane in each direction. Don't touch the main span, but anything over land is flexible.

Sounds good. Thanks. I've got an idea bouncing around in my head (along with a really crude sketch) that I'm going to try to refine tomorrow. It may or may not involve a SPUI. I think it'll work, but I need to figure out how to deal with some weaving issues.

One more thing: How important are the two currently missing movements (I-91 SB to CT 15/US 5 NB and CT 15/US 5 SB to I-91 NB)? It seems like anyone wanting to do that would just use I-84 anyway.

edit: I remember when I used to get paid to think about this kind of stuff :smith:

Dominus Vobiscum fucked around with this message at 05:22 on Jan 5, 2012

# ¿ Jan 5, 2012 05:19

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Okay, here goes nothing. Sorry for the ugly sketch. All I've got is the GIMP. I could make this a lot less ugly if I still had access to AutoCAD or Illustrator.

Disclaimer: As I said before, I've never been to Hartford and am basing all of this on no more knowledge of local conditions than what Cichlidae gave us.

I modeled it after the I-65/38th Street interchanges in Indianapolis, using I-91 as a through route and CT 15/US 5 as somewhat of a collector/distributor system. Major features:

I-91 has 4 thru lanes in each direction.
CT 15/US 5 should have 3 thru lanes in each direction.
All ramps should have two lanes, except for the black ones to the south, which would be one lane each.
The existing ramps directly connecting to Brainard Road would be completely eliminated.
The big flyover for I-91 NB to CT 15/US 5 SB is optional. It's a fairly minor movement and traffic could be directed onto Brainard Road to use the Airport Road interchange.
Airport Road could either have a standard diamond or a big SPUI. For a SPUI, I think you'd need the freeways on overpasses with the interchange underneath.

What I don't like:

A bit of a nasty weave for traffic coming from Airport Road headed to I-91 SB. This could be eliminated by shifting those ramps in between I-91 and CT 15/US 5, making a left exit/entrance for CT 15/US 5 and providing direct access from I-91 SB.
I'm not sure about some of the merge lengths and whether or not you could reasonably fit 14 through lanes and a bunch of ramps within the existing ROW between the two railroad tracks. The interchange takes up approximately the same length as the I-65/38th Street section, so I think it could work.
I haven't given any thought to cost, MOT, intersection operational capacities, etc. This would take a fair amount of reconfiguring of the bridge approach.

And in the time I wrote this post Koesj posted something that looks a lot nicer and would probably operate better.

# ¿ Jan 5, 2012 17:34

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Koesj posted:

The niceness is mostly Illustrator which also messes up any nice lane-count depiction btw. I was dabbling with a C/D lane setup too until I got frustrated with merge lengths and came up with at least a decent solution for the south/north direction. It's always important to reuse as many bridges as possible to cut costs so that was a given.

On- and offramps don't really need 2 lanes with the given amounts of traffic though while the mainline freeway will probably eat up a lot of space.

e: Now this would be cheap.

I was thinking about costs and bridge reuse last night, but then I felt like being less realistic and decided to get a little more creative.

The Airport Road offramps could probably be knocked down to one lane. I think the on/offramps on either end of the C/D setup would warrant two, though.

# ¿ Jan 5, 2012 18:30

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

This interchange is very streamlined and rather close to what I ended up designing, though there is one pretty major issue: Route 15 southbound would need to carry 8214 cars, necessitating 5 lanes. Northbound would need four. That would compound those weaving issues you mentioned.

When I show you my first draft in a bit, you'll see a lot of similarities.

That's what I get for doing ballpark math in my head instead of putting it all in a spreadsheet like real traffic engineers do. Nice to know I came up with something reasonable, at least.

# ¿ Jan 5, 2012 23:22

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

I've seen shopping centers with green stop signs, painted wood. As a matter of course (and when it's safe to do so), I drive right through substandard stop signs. I don't want to risk being rear-ended over someone's beautification project.

One of the things I like about the 2009 MUTCD is that FHWA put in new language making it applicable to private roads, however much that will actually get enforced.

# ¿ Jan 7, 2012 00:08

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

grover posted:

What's with the blue car driving sideways?

The Fast and the Furious: Hartford Drift

# ¿ Jan 13, 2012 16:32

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Cichlidae posted:

Naw, it's nothing bad Just establishing cred at the office. Construction and Project Concepts Unit really want me to transfer over to them. Honestly, PCU would be like a dream job, and I'd really like to shoot for that. It's exactly the stuff we talk about most in this thread: working on a bunch of alternative designs for large-scale stuff, no details.

This is why I got into transportation planning (which is even more conceptual than this) rather than sticking with civil engineering. Drawing lines on maps is fun; designing curbs and gutters isn't.

# ¿ Jan 16, 2012 03:55

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Volmarias posted:

Somerville Circle

Jesus Christ, I hate the Somerville Circle. 206 is a good cutoff from the Philly area to upstate New York, rather than the added tolls and mileage from staying on the turnpikes, but the downside is you have to drive through that mess. I've only been through it a few times, but every time I've been going south, it's been a memorably confusing and harrowing experience.

# ¿ Jan 20, 2012 20:19

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

Looks like the ship was in the wrong channel. Someone screwed up pretty badly.

# ¿ Jan 31, 2012 05:42

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# ¿ Apr 29, 2024 16:10

Dominus Vobiscum: Sep 2, 2004; Our motives are multiple, our desires complex.; Fallen Rib

BrooklynBruiser posted:

Since you called the 2nd ave. subway "idiocy," I'm guessing you've never ridden the 4/5/6? The Lexington Ave. line is so incredibly overcrowded, I can't wait for the Second Ave. line.

I've always been amazed at how the Lexington Avenue line alone carries more riders per day than the entire rail transit system in any other city in the US.

# ¿ Mar 25, 2012 19:40

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