Comments on Widening I-66 is far from insignificant - Greater Greater Washington

Comment by Geof Gee

Thu, 02 Sep 2010 12:52:09 EDT

This is lame ... responding two years after the fact ... but I never noticed the reply. Since the traffic engineer was so forthcoming, I want to add this.

To clarify, one can certainly bootstrap some notion of a confidence interval of the simulation and its parameter estimate. Again, assuming that I understood the conversation, they are unable to produce notions of confidence that it contains the true value. So I think Chuck's point is my error in the use of "confidence interval" which typically refers to a parameter estimate assuming the model is truth.

Comment by Chuck Coleman

Tue, 28 Oct 2008 20:00:55 EDT

"Two, no notions of statistical confidence are possible with these simulations. In other words, if you ask, ;What is the probability -- with its 95% confidence interval -- that net travel times decrease?' the answer is that there is none and that the science has not progressed to that point." This is absolutely bizarre, not to mention false. By running a large number of simulations of a fixed model, the probability estimates and confidence intervals fall right out. The statement that travel times decreases has many interpretations. All that is necessary is to pick one definition and compute the number of simulation events in which travel time is lower than the baseline and divide by the total number of events for which travel time is computed. Voila! That is the estimated probability that travel time decreases. The centered (the usual one) 95% confidence interval of the travel time change is the 97-1/2th percentile travel time change less the 2-1/2th percentile travel time change. The only caveat is that these estimates are only as good as the model used. Strictly speaking, they are the estimates given the simulation model. If multiple models are used, multiple estimates can be produced contingent on those models. There are ways to combine those estimates, but, in the hands of these people, that would be fool's exercise. I don't know whether these people are fools or liars. Either scenario is terrifying.

Comment by xyzzx

Tue, 28 Oct 2008 17:03:10 EDT

David, I am somewhat confused by your repeated requests for specific examples. Is it possible that you don’t realize that your positions are based on doctrine and not facts? Can you not realize that for almost every project that you took a position on, your position was based on, at most, the literature provided by the developer or advocacy groups supporting the project. And sometimes less, just a short summary in the press or a blog. Perhaps you didn’t realize that some of the “research” that you quote again and again, such as the claim that if there are minimum parking requirements, residents who do not own cars would be subsidizing parking, is based on unsupported statements that simply have been repeated frequently, or unpublished, unavailable papers, where the advocate, rather than producing the study, simply repeats that he has the numbers to back it up. David, perhaps when you post a headline or a link to an advocacy piece and declare that a project is “smart growth” or promotes walkability, you do think that you have studied each of these issues. But, you seem to have time on your hands, and so I only ask that you think about this again, and look back through your archives, and determine whether you really studied the project carefully and really understand why some of these projects face opposition. You can probably count on one hand, maybe two, the projects where you really have looked carefully at the reasons given by opponents and fully understood the issues raised. Take a good look at the others, and you might find that the opponents, who are familiar with the project and the area in question, should not simply be brushed off as NIMBYs but actually understand things that you haven’t considered when you just apply your doctrine in a vacuum.

Comment by Geof Gee

Tue, 28 Oct 2008 13:09:43 EDT

I went to the meeting. I grew tired of the rants pretty quickly and starting conversations with the engineers and traffic operations people. Let me begin by writing that I am not inherantly against increasing auto capacity. Although I have leanings towards "smart growth" and environmentalism, I understand that effective transportation is important, people have different tastes that should be respected and that these concerns -- smart growth and the environment -- should be tempered by practical considerations such as cost, convenience, and so on. Judging from their descriptions it appears to me that Phase 2 -- the west-of-Lee Highway/I-66 project -- is somewhat different from the other two. So I think that it should be considered seperately. The other two phases can be described as an intermittent third lane connecting entrance and exit ramps. From what I gather, there is nothing preventing drivers from leaving the through lane to move up in the queue in the third/auxillary lane and re-entering the through lane later in the process. My understanding of queuing theory suggests that this type of interaction would increase travel times through the corridor as well as increase the variability of travel speeds. From a conversation with the traffic operations researcher at the meeting, the simulations still predict that the net effect of giving drivers for space for merging is still positive; i.e., the decrease in travel times from the longer entrance/exit ramp more than offsets the increased travel times from more merging. Assuming that I understood the entire conversation with the traffic operations gentleman, there are a few serious problems, IMO with the simulations. One, these models fail to consider a change in an accident rate due to the increased number of merges/aggressive driving. So if you believe that the number of accidents could increase due to the aforementioned behavior, then these simulated travel times are biased downwards. Moreover, a greater number of accidents increases the variance of travel times primarily by increasing its skewness. Consequently, even if the net average travel times decrease, it appears to me that a commuter is more likely to be screwed with a really long commute. Two, no notions of statistical confidence are possible with these simulations. In other words, if you ask, "What is the probability -- with its 95% confidence interval -- that net travel times decrease?" the answer is that there is none and that the science has not progressed to that point. Anyway, I am running out of time. Long story short, I think that calling the project -- at least for Phase 1 and 3 -- an "improvement" is an overstatement of simulation's veracity. Given the local opposition to the project and less expensive alternatives that are better understood -- this was the traffic operation guy's language -- it appears to me that the project is a bad bet and almost certainly not a huge improvement.

Comment by FourthandEye

Mon, 27 Oct 2008 17:39:53 EDT

@Froggie - I think commuters use Rt 50 more than Lee Hwy.

Comment by Froggie

Mon, 27 Oct 2008 17:28:25 EDT

Okay guys, I'll take your assessment of it, since I'm still new to the area and living in Alexandria instead of Arlington. But it strikes me as puzzling that I-66 is as congested as it is and that such traffic isn't spilling over to Lee Hwy, especially during rush hour when I-66 is HOV-2. Decided against going up to the public meeting (unless one of you convinces me otherwise in the next 15 minutes). Will E-mail my comments into VDOT instead.

Comment by FourthandEye

Mon, 27 Oct 2008 17:15:43 EDT

I will echo Joey's assessment of Lee Hwy traffic. Before moving to D.C. this spring I lived in Arlington for four years. It can occasionally be tough to turn left at a few spots like Kirkwood and Quincy. But overall I would not consider this a congested road even during rush hour. I will also echo that Lee Hwy often had the speed traps he speaks of.

Comment by Joey

Mon, 27 Oct 2008 16:57:37 EDT

@Froggie. Well, if Lee Highway traffic is really the concern, I think we could probably wait *another* 35 years from today to begin I-66 construction. I drive Lee Highway every morning (usually from Glebe to I-66 westbound near East Falls Church, but occasionally, for a meeting, toward the District from Glebe), and it's way overbuilt, except the one last eastbound section in Rosslyn that heads into Lynn Street (which is planned currently for a one-lane widening). The road is such a gem that there are frequently speed trap stings set up in peak periods, especially in the Old Dominion section and in the downhill section between Harrison Street and Washington Boulevard. The road is signed as 30-35 mph for most of its length in Arlington, but traffic frequently wants to move 40-45, because there's no congestion to speak of. This raises another point about I-66: it's almost purely for the benefits of everyone *except* those who live in Arlington. I almost never take it through the County, and there's almost never any traffic on the local arterials. People who complain about traffic in Arlington are almost universally going *through* it on I-66, I-395, or the GW Parkway (and, may I mention, not paying any type of property tax to offset the community costs of the widening). As a side note, Arlington's considered it already, and it's a long-term option, but I'd like to see Lee Highway marked for curb-lane parking in each direction, except during rush periods.

Comment by Froggie

Mon, 27 Oct 2008 16:14:14 EDT

A very good book, called Still Stuck in Traffic, by Anthony Downs. Recommended reading. David, amongst others, makes a point about "induced demand". Yes it does exist, but the level of such is highly debatable. That said, I know some jurisdictions already take "induced demand" into account when doing traffic forecasts for a road improvement project. Second thing to consider, at least when comparing freeways to nearby arterial roads, is that while freeway improvements do increase traffic along the freeway afterwards, they also will reduce traffic on nearby local roads...often for long periods of time. I know of one case in a major city where, after construction of the main freeway, it took about 35 years for traffic along the arterial to return to the level it was before the freeway was constructed. In this particular case, one has to look at this project not just from the standpoint of what will it do to traffic along I-66, but also what will it do to traffic on nearby streets (Lee Hwy in particular, but also Washington Blvd and others). Still debating about whether I'm attending the meeting tonight. It's about 3-4 hours that I could be using on projects around here (especially unpacking my apartment). Ironically, if I go, I'd be taking Metro instead of driving. Got about an hour before decision time.

Comment by David Alpert

Mon, 27 Oct 2008 08:13:04 EDT

xyzzx: If there are so many examples, why won't you give specific ones despite repeated requests by me to give some? I know it's easier just to assume that I must believe everything you hate and must not know what I'm talking about since I don't always agree with you, but continually throwing around completely unsubstantiated overgeneralizations does nothing to convince me that there could be any merit to your point of view. Why not try?

Comment by xyzzx

Mon, 27 Oct 2008 08:05:53 EDT

David, You might want to check your archives for the many corrections that have been posted clearly showing that you have supported projects or mocked opponents and mischaracterized their concerns—usually labeling them as NIMBYs-- without knowing some of the most basic relevant facts. You might also look back and review the many times when you gave an opinion of a controversial project based only on the developer’s literature or presentation and/or a short summary in the press, by an advocacy group or from the Office of Planning, and didn’t take the time to get information from the groups that opposed the project. Or if you got it, didn't read it except to look for a phrase to mock. And you have consistently made generalizations, wanting mixed use development nearly everywhere in DC, increasing density, removing parking requirements and removing height limitations. Again, since they are general policy recommendations, with your advocacy of applying this “new urbanism” model, you indiscriminately recommend replacing the walkable neighborhoods and walkable family-oriented neighborhoods that have grown organically over many years. Your recommendations are general, based on doctrine, and most without any research into the neighborhoods they affect, I won't provide specific points on that. But your archives are filled with examples of specific cases.

Comment by Douglas Willinger

Sun, 26 Oct 2008 16:08:09 EDT

"The simple fact is that decades of scientific evidence show us that when we add capacity to a freeway, new car trips actually use up that capacity within a few years, and therefore the freeway doesn't get less congested for existing riders." If this doctrine were true, why is I-87 in Westchester County N.Y. generally so un-congested? Why on the converse, is I-495 in Long Island N.Y. generally congested? Doctrine is a very poor substitute for considerations of variables as land use patterns, densities and numbers and placements of interchanges (plus alternatives).

Comment by David Alpert

Sun, 26 Oct 2008 08:35:01 EDT

xyzzx: Have you read my articles about the Hilton project? While I don't object to the overall amount of housing, I strongly criticized that project for its "urban renewal" type form, its "tower in the park" architecture and lack of engagement with the street. Can you please give an example of a project "destroying the fabric of our walkable neighborhoods" that I've supported without knowing the facts? Substantive disagreement on specific points is much better than vague, overgeneralized attacks. As for the freeway widening, please explain what there is to understand that I don't. I've read the plan. The simple fact is that decades of scientific evidence show us that when we add capacity to a freeway, new car trips actually use up that capacity within a few years, and therefore the freeway doesn't get less congested for existing riders. As a result, I don't believe that widening I-66 (whether you call it "adding auxiliary lanes" or what) will actually fix the problem people are reacting to of heavy traffic. It's very counterintuitive, which is one reason many well-meaning people and politicians continue to think more roads will solve our problems. However, it's not true.

Comment by xyzzx

Sat, 25 Oct 2008 21:23:39 EDT

David, It seems that life is so much simpler if everything is black or white. No need to actually understand the proposal or its impacts, just say that any such expenditure is “continuing the 50-plus-year bias” and your answer can always be the same. Look at any developer’s project and see that it adds density, and so, you don’t need to know anything about the project, what it replaces or how it would impact the urban fabric. This means that you invariably end up supporting something that is really urban renewal but calls itself “new urbanism” or “smart growth” and you don’t see a need to consider what you are changing, or any of the other normal, critical factors considered in evaluating a project. You can destroy the fabric of our wonderful, existing, walkable neighborhoods and replace our charming neighborhoods with high density mixed use developments, which are plastic facsimiles of real urban neighborhoods like the ones destroyed. The new development follows a template, which is just a suburban impression of what an urban environment should be. Unfortunately, evaluation of real issues requires that one consider the facts, and understand the relationship between all the essential factors, and good policy cannot be made by simply looking at whether something might involve a private vehicle (bad) or increase density in some neighborhood near some type of transportation (good). If you understood what Jane Jacobs wrote, you would realize how many of your recommendations would be exactly the type of urban renewal that she opposed.

Comment by Froggie

Sat, 25 Oct 2008 21:05:22 EDT

David: a balanced system doesn't ignore spot improvements to the highways where justified. And IMO, these spots are justified.

Comment by Douglas Willinger

Sat, 25 Oct 2008 12:36:23 EDT

We have completely ignored the grade separated highway network inside the Beltway from Maryland in the entire arc from the Potomac River to Route 50. If we had built the 1959 freeway network without WMATA and I was arguing for yet another freeway say through Rock Creek Park, David's view would be entirely correct. But that is not the context. Building a B&O North Central Freeway as a box tunnel with improved rr capacity IS necessary.

Comment by David Alpert

Sat, 25 Oct 2008 08:23:16 EDT

Answering Froggie's first question about my opposition: Either the "improvements" will make the road less congested, or it won't. If it doesn't, there's no point in spending the money to no effect. If it does, then it will induce demand by making driving on I-66 more appealing for more people. It doesn't matter what type of lane is being added. We should spend the money to improve non-auto alternatives. If we keep spending money to improve the driving commute instead, then we're continuing the 50-plus-year bias in our transportation policy that pushes driving and suburban sprawl over walkable urbanism and transit. And it'll induce more demand, worsening traffic in the long run. Call this a weave lane or a new lane or whatever you like: it's more highway construction that strengthens the economic incentives to drive and not ride transit.

Comment by Froggie

Sat, 25 Oct 2008 07:46:13 EDT

LOS is generally calculated in a 15-minute or one-hour block, not a full 24-hour-day block. So what might be happening (besides the pedestrians/buses) is that while less overall traffic may be using those streets, it's being concentrated more during the peak hours. As a side note, while that study cover Rosslyn, it doesn't cover I-66, nor the locations along 66 where VDOT is proposing these spot improvements.

Comment by Joey

Fri, 24 Oct 2008 23:59:51 EDT

http://www.arlingtonva.us/Departments/EnvironmentalServices/dot/images/page62240.pdf#page=2 It's part of the Rosslyn Multimodal Transportation Study that was released in March. It shows that almost every road into, out of, or through Rosslyn *decreased* in traffic counts from 2001 to 2006, except for the last stretch of Lee Highway near the Key Bridge. Interestingly, some of the LOSs have gotten worse (or far worse, in one or two cases). One interpretation for this is that far more pedestrians and buses are using the roadways and sidewalks, and that the additional congestion from them is reducing car throughput. With less space available to vehicles, perhaps fewer people are choosing to drive? Though this isn't the only possible explanation, it's a plausible case study on induced demand. I know, for one, that the light signal at westbound Lee Highway and N Lynn Street had an additional pedestrian-only leading phase added to it (previously it was a 2-phase light), stripping a bit of green time off of the other phases. Arlington did this because the pedestrian and bike traffic across the Key Bridge and using the Custis and Mount Vernon trails have skyrocketed in recent years.

Comment by Froggie

Fri, 24 Oct 2008 21:03:47 EDT

Go ahead...it's publicly available data anyway(http://www.virginiadot.org/info/ct-TrafficCounts.asp). I might get around to importing it into GIS and doing a map that way, but I've got several other projects going on and I'm feeling lazy...:o)

Comment by Michael P

Fri, 24 Oct 2008 20:58:36 EDT

Thanks, Froggie. Mind if I turn your data into a Google Map which illustrates the volumes as different line widths?

Comment by Froggie

Fri, 24 Oct 2008 20:19:30 EDT

This is mostly for Michael, and I haven't seen the specific report Joey referred to, but following is a quick-and-dirty table of annual traffic volumes on I-66 in Arlington I've put together from VDOT traffic volume publications: http://www.vahighways.com/i66traffic.htm From 2001 to 2007, most locations saw an overall decrease in traffic, but you're looking at overall differences from 1K-3K....not a whole lot in the grand scheme of things. And, curiously, volumes between the Toll Road and Washington St saw a net INCREASE through 2007. Although overall daily traffic volumes (as opposed to an hour-by-hour comparison) only paint a general picture of volume and congestion, these I-66 volumes point to noticeable congestion along much of the route, even with the recent volume reductions in some areas. Typically, a 4-lane freeway will get congestion once one-way volumes get to about 40K, and it'll be very congestion about about 50K.

Comment by Froggie

Fri, 24 Oct 2008 19:30:22 EDT

Joey: because overall traffic volume increases or decreases matter little. It's when during the day those traffic volumes occur. Meanwhile, partly in response to Michael and partly to David in the previous thread, I took a look at VDOT's material on this. All three spot improvements meet the classic definintion of an auxiliary lane: beginning the lane at the end of an on-ramp and continuing it to end at the next off-ramp. This is *NOT* a normal widening as some people have portrayed, because the lanes do not continue through the interchanges (that would be another case/story entirely if VDOT was proposing such). You will still have two through lanes, and only two through lanes, along the length of westbound 66 in question. What this WILL do (which is the whole reason behind auxiliary lanes to begin with) is smooth out the merges and diverges, which is more of a safety concern than a capacity concern. So I'm a little confused about David's opposition to it.

Comment by Michael P

Fri, 24 Oct 2008 19:22:00 EDT

Joey, link please or perhaps send the document to my email address? michael (at) infosnack (dot) org

Comment by Joey

Fri, 24 Oct 2008 16:47:06 EDT

Just read an Arlington County transportation report that showed a 1-3% DECREASE in I-66 traffic from 2001 to 2006 from Glebe to the Roosevelt Bridge. The decreases were broken down by section of I-66. Given such a decrease, how can we justify *widening*?

Comment by Jenny

Thu, 16 Oct 2008 09:35:53 EDT

Backup on 66 is not just a rush hour problem. I can see the road from my living room window. It's busy during morning and evening rush. Sometimes it's stop-and-go at 11PM on a Tuesday. It's regularly slow on Saturday mornings and Sunday afternoons. Two lanes simply are not sufficient for the amount of traffic that uses that road at all hours. Erin, regarding encouraging the use of public transportation, the problem is that many people don't start and end their trips along 66 - it's only part of the way. If the silver line ever gets built, there will certainly be a better option the Dulles corridor. But right now, bus options from WFC are limited and the fare is more expensive than the toll road. A longer commute at a higher cost is not a compelling argument to take public transportation.

Comment by Erin

Fri, 10 Oct 2008 15:19:53 EDT

Rather than widening I-66, we should figure out why so many drivers ignore other forms of transportation along that route. By the time east-bound drivers on I-66 reach Ballston, they have passed 4 (3 if they came from the beltway) metro stations with ample parking. Before the highway is widened, why not research why these drivers are bypassing these metro stations. By promoting other public transit options in the Falls Church to Rosslyn corridor (and possibly into Georgetown). Other transit options such as a street car could potentially reduce traffic on I-66 by turning the Orange line into a commuter rail line between Vienna and Rosslyn rather than a very busy subway. A commuter rail line may be more appealing to drivers from the exurbs.

Comment by Michael P

Mon, 06 Oct 2008 21:43:07 EDT

SG: I know I agree with the actual widening, but not the way they're doing it. Shouldn't try to sugarcoat it. David has already made it clear that he doesn't support widening. SWHere: I have received personal assurance from the engineer (Jeff Daily, PE) as well as verified on the website that the bike trail will not be cut off. The trail may be moved but VDOT will seek a FHWA waiver to narrow lanes and shoulders to make the trail fit. According to the project brochure, "The design of the spot improvements will preserve the Custis Trail and will not preclude future Metrorail or transit options." Joey: I ride the Orange Line and notice that there is a slowdown at the Fairfax Drive entrance ramp on most nights (I cross through there around 4:45pm). There is also a slowdown even during non-rush hour periods, such as Sundays, Saturdays, etc. I agree that the HOV restriction hours should be extended if the highway is congested after the current cutoff. NikolasM: There is no proposal in the works to widen the eastbound lanes as you suggest. Twice a week I drive home from Reston and end up in the jam getting on 66 from the Dulles Access Road. According to the project brochure: "Although the spot improvements will greatly improve traffic flow on I-66 westbound, and provide relief for people to enter and exit I-66 for some time, they are not the long-term answer to greatly improving mobility in the I-66 corridor. The Commonwealth Transportation Board has initiated the investigation of the long-term solution by funding a study of multi-modal alternatives such as express bus, high occupancy toll lanes, or modifications to HOV. Major improvements of I-66 such as a third Metro rail, Bus Rapid Transit, or widening to three lanes would require an environmental study under the National Environmental Policy Act and additional documentation under both Federal Highway Administration (FHWA) and Federal Transit Administration (FTA) regulations."

Comment by NikolasM

Mon, 06 Oct 2008 18:06:14 EDT

I support fully widening I-66 from the Dulles Access Road to Fairfax Dr in Ballston. Anything more would be a waste. Inbound from the Dulles Toll Road you have two lanes combining with two lanes (which just before went from 3 to 2) and merging that all together into two lanes by Lee Highway in Falls Church. It is a clusterf*** at rush hours and often crawls all the way to near Ballston, where quite a few exit. This can be fixed with 4 lanes to Lee Highway and three to Fairfax Dr and the two dedicated lanes into DC. Outbound the same problem occurs with Fairfax Dr/Ballston emptying into an already full 2 lanes with lots of slow merging that backs everything up. Fairfax Dr should enter onto I-66 westbound with its own lane, so from there three lanes out to the Lee highway and from there four lanes to the Dulles Toll road split. That would solve most if not all of I-66's issues inside of the Beltway. I also think nearly all of this can be accomplished within the current footprint of the highway. There would be a few short stretches that would not have any shoulders but for the most part they could be acommodated.

Comment by Joey

Mon, 06 Oct 2008 17:17:21 EDT

Can anyone speak to whether I-66 westbound is congested in the evening, between 4pm and 6pm? If the westbound periods of congestion are exclusively *outside* of this period, perhaps the hours of HOV restriction should be expanded instead. New reflective "7pm" or "8pm" signage stickers would involve a far smaller expenditure than 3-4 miles of asphault. On the other hand, if the westbound congestion is from 4pm-6pm, perhaps I-66 could revert to HOV-3, as it was previously. (For historical reference, it was once HOV-4.)

Comment by SWHere

Mon, 06 Oct 2008 16:58:12 EDT

Can someone who attends the meeting report back on the impact on the bike trail? I'll be out of town for this one...

Comment by SG

Mon, 06 Oct 2008 16:44:34 EDT

It's about time they widened that stretch of highway. I know that this site is opposed to any highways, and I agree to an extent. But I-66 is an absolute disaster, and let's face it, it is a major road that is necessary for movement within the DC area. It is already HOV within the beltway, which automatically makes it better than any other highway. I think the spot improvement is both necessary and desirable.