Traffic - Greater Greater Washington

Don't expect green lights all the time

Wed, 08 May 2013 10:56:00 EDT

You're driving along in downtown DC. You get a green light and start moving, but just as you get to the next corner the light turns red. It's frustrating! But it's no conspiracy. There could be reasons this happens, even besides trying to help pedestrians and cyclists.

Photo by apium on Flickr.

Adam Tuss's latest NBC TV news segment brings the shocking revelation that drivers don't like to stop at red lights, and that at least one person thinks it's another part of the war... I mean, the nonexistent general pattern of DC deliberately pursuing policies that make things worse for drivers.

Tuss read an email on the Tenleytown listserv, by semi-anonymous poster "Paul," alleging that DC deliberately times lights to slow down drivers. Tuss makes this the core of his story, with a response from DC transportation officials who say that this is not true, though actually, they'd really like to install a more modern signal system that makes it easier to time lights.

In the TV news tradition, Tuss also interviews a few "people on the street," and does make sure to talk to people with multiple points of view. One driver thinks DC can probably figure out a better system, though he doesn't say anything inflammatory. Another says it's important to design signals to accommodate pedestrians, adding, "cities are for people, not for cars."

At the end, Tuss and his crew take a drive on Wisconsin Avenue. We can see them leaving one intersection with a green light and getting to another one. He concludes, "Clearly, from the driver's standpoint, some signals were not timed properly."

Actually, no, and this is the most dangerous part of this report because it reinforces the notion that if you hit a red light, there is something wrong with the timing.

Quite simply, lights are not going to be green for everyone all the time. Wisconsin Avenue, for instance, is a 2-way street. Any timing that gives successive green lights to people driving one direction will mean more red lights the other way.

Parts of 16th Street do have "platooning," where lights turn green in succession. This also encourages people to drive the speed limit, since if they go faster, they'll just hit red lights each time. Some people surely think 16th's lights are terrible because they keep hitting red lights. Others, driving the opposite way, have a legitimate beef that they timing makes things worse for them.

Downtown, there are many main streets intersecting at various angles in close proximity. There's no way to time all of the streets for continuous greens in every direction. Should the timing encourage people to drive north on 16th or west on streets like R and U in the evening? Both have a lot of commuters traveling in conflicting directions.

One way to combat that particular problem is to close segments of streets to car traffic. When New York closed the diagonal Broadway around Times and Herald Squares, it found that traffic flowed better because the diagonal confounded signal timings on the avenues. DC could probably help everyone better traverse a place like Dupont Circle if it reduced the number of roads coming in, but that would surely spark even more "war on cars" claims even if it actually helps cars and the people inside as well as pedestrians, cyclists, and bus riders.

There are many other reasons traffic engineers might time lights in a way that appears wrong to a driver traveling a particular direction. Contributor and engineer Andrew Bossi offered many examples, such as:

Gap Provision: Providing breaks in traffic, such as to allow nearby uncontrolled interactions to operate adequately. Without these breaks, some uncontrolled intersections may never be able to clear out, subsequently requiring some treatments such as an additional traffic signal—which would only increase motorists' delays. Breaks in traffic improve net mobility for the greatest amount of road users.

Still, many signals in DC aren't timed with a lot of forethought. DC doesn't have a state-of-the-art system to control all of the lights centrally. Many individual decisions get made based on local neighborhood pressure, the District Department of Transportation (DDOT)'s James Cheeks has told me and others. That can have its pros and cons; sometimes neighbors know well where the trouble spots are, but it also makes the overall system haphazard.

Many signal timings could be better. If DDOT changes them, however, it won't necessarily ensure that Adam Tuss always gets a green. What helps move on group of drivers could slow down another group. Also, as people say in Tuss's story, drivers aren't the only people on the roads.

In some places, DC could time signals to help buses get past a trouble spot when they cross a busy road. That might mean drivers on that main road more often get a red, but if the bus caries 20 people and 5 drivers have to wait a little longer, it's a net gain. Pedestrians need time to cross, especially wide roads like Wisconsin in places with a lot of seniors like upper Northwest.

Any fixes to signals have to take everyone's needs into account. That'll surely make someone frustrated, creating good fodder for another Adam Tuss transportation story.

90 comments

And...

Tue, 07 May 2013 08:47:00 EDT

by Jereme Altendorf

If Congress allows online sales taxes, Mary Cheh and Jim Graham want to use the money to fight homelessness. (City Paper) ... Another congestion study ranks DC-area traffic at number 9. (DCist) ... Have you read Walkable City yet? (BeyondDC)

Comment

Rs say no to Outer Beltway

Tue, 30 Apr 2013 08:36:00 EDT

by Jereme Altendorf

6 Virginia Republican legislators came out against Governor McDonnell's plan to build the Outer Beltway in Virginia. They say it's too costly and will worsen traffic on I-66, which is the higher priority. (Examiner)

Comment

And...

Thu, 25 Apr 2013 08:37:00 EDT

by Steven Yates

What would DC look like if sea levels rose? (Post) ... Ever wonder how some of the area's more oddly named roads got their name? (WTOP) ... The good news about sequestration? It might be easing congestion. (Examiner) ... Trump's Old Post Office hotel gets initial approval. (Post) ... Stoddert auctions off a parking space. (Hyperlocal GP)

Comment

Online maps now send through travelers into DC

Wed, 24 Apr 2013 13:12:00 EDT

by David Alpert

The Southeast-Southwest Freeway and 14th Street bridge are very congested. They don't need cars carrying people who are just passing through the region. But now that DC has added new ramps to the 11th Street bridge, online maps tell drivers to do just that.

Driving directions from Google Maps.

If you're driving from Baltimore to Richmond and figure you'll just stay on I-95, you'd take the eastern side of the Beltway to the Woodrow Wilson Bridge, which recently got a massive expansion to handle more traffic. That used to be the route online maps would recommend as well.

But if you ask Google Maps or Bing Maps or another map site, it'll suggest taking the Baltimore-Washington Parkway to DC-295, then the 11th Street Bridge to the Southeast Freeway (now with the visitor-attracting I-695 label), then I-395 over the Potomac and down through Arlington.

Driving directions from Bing Maps.

This is probably not the best way. DC-295 is narrower than interstates. The freeways through DC and Arlington probably have more congestion than the Prince George's Beltway route. Try telling that to the map programs.

They think the Beltway route is 1-2 minutes longer, so they route travelers right through the core. Many people's GPSes are likely doing the same thing. This will make life worse for all other drivers who actually need to go to DC, even though those through drivers would only gain a minute or two even when there is no traffic.

The extra ramps certainly add options for residents and commuters, and will draw some traffic off some local roads, but an independent traffic analysis for the Capitol Hill Restoration Society predicted other roads will get worse thanks in large part to drawing traffic off the Wilson Bridge.

Effects of the 11th Street Bridge project based on the Smart Mobility analysis. Red segments get more congested, green segments less.

Yet DDOT never really engaged with CHRS's concerns or my warning about what it would do to casual travelers relying on technology.

Has traffic gotten worse or better on the freeway? If you drive (or walk or bike) there, what has your experience been?

67 comments

Transit relieves parallel traffic

Tue, 02 Apr 2013 08:41:00 EDT

by Jereme Altendorf

Transit does relieve congestion, but primarily on roads that parallel heavy transit corridors, a Berkeley researcher concluded by analyzing the 2003 Los Angeles transit strike. (Atlantic Cities)

Comment

Breakfast links: Get it moving

Mon, 01 Apr 2013 08:05:00 EDT

by Seymour Rhodes

Rendering by thisisbossi.

This article was posted as an April Fool's joke.

Purple Line gets first sponsor: Maryland has a transportation funding bill, but to help get the Purple Line moving, MDOT has signed a deal with Six Flags Corporation to sponsor the Purple Line. The new roller coaster design will include a loop-the-loop at Columbia Country Club and feature significantly higher speeds, reducing travel time.

New tax plan for Virginia: Governor Bob McDonnell proposes eliminating the state sales tax. He would make up the revenue by a 50% tax on hybrid or electric cars, organic produce, reusable grocery bags, and bicycle inner tube replacements. Observers now consider him a shoo-in for the 2016 GOP Presidential primary.

Congestion solved: The Texas Transportation Institute found that lost jobs from sequestration improved congestion. "Therefore, the logical policy for transportation must be further job loss," said Tim Lomax. Plus, Stockton, "foreclosure capital of the world," has the nation's lowest congestion, making it a clear model to emulate.

Where's the birth certificate?: Donald Trump is offering a reward for anyone who can prove DC Councilmember McDuffie isn't a "native Washingtonian." Stronghold resident McDuffie owns the house he was raised in and says he was born here, but no incontrovertible proof was immediately available after a 5-minute Google search.

Metro becoming more self-service: As part of its efforts to create a more "self-service" system in the Momentum plan, Metro will replaces all escalators with stairs and convert trains and buses to a Flintstone's-style power system.

Examiner will keep going: The Washington Examiner has reversed course and will continue its current publishing format. "Once we saw how upset our editorial style made David Alpert, we figured we were doing our job and had to continue," said editor Stefan Schmitt. The paper will, however, still fire Kytja Weir and Liz Essley, as both sometimes had positive things to say about transit.

Cheh apologizes: After weeks of speculation and inquiries from the local press, Mary Cheh relented and issued a letter of apology for her completely legal campaign fundraising activities. "DC residents have come to expect so much more of their elected officials," said DC voter Amy Zoneger.

28 comments

Traffic causes asthma

Tue, 26 Mar 2013 08:28:00 EDT

by Steven Yates

For the first time, scientists have found that traffic pollution causes asthma in children. Before, scientists knew pollution could trigger episodes in children who already had asthma, but weren't sure if it was a cause. (LA Times)

Comment

Traffic flows in waves (Feb 2, 2008)

And...

Tue, 26 Mar 2013 08:28:00 EDT

by Steven Yates

Some cool stuff people are doing with open data. (Atlantic Cities) ... As Arlington has grown enormously in 15 years, traffic hasn't gotten worse. (WAMU) ... The Washington housing market is not in another bubble. (Post)

Comment

Where the jams are

Tue, 19 Feb 2013 07:55:00 EDT

by Steven Yates

By using anonymous cell data and mapping, one study found that specific areas around Boston were causing massive traffic. The study used data that was easily available, and could be used in DC. (Ars Technica, Drake Perth)

Comment

Let's solve traffic jams by creating more! (Apr 5, 2004)
What information needs mapping in Washington? (Sep 11, 2012)

And...

Wed, 06 Feb 2013 08:48:00 EDT

by Steven Yates

More on what's wrong with the TTI ("DC's traffic is #1") report. (Streetsblog) ... Why do we care so much about authenticity? (Atlantic Cities) ... The Air Force wants to build subway tunnels to carry ballistic missiles, or maybe use trucks. (Daily Mail)

Comment

DC #1 at not being like Texas

Tue, 05 Feb 2013 08:40:00 EDT

by David Alpert

The Texas Transportation Institute released its annual rankings once again showing DC congestion worst in the nation. As usual, reporters blindly parrot it without examining the flaws in TTI's methods. (Post)

Comment

A lot rides on how USDOT defines "congestion" (Aug 16, 2012)
Congestion report pushes sprawl through flawed analysis (Jan 20, 2011)
"Best Cities" rankings push "picket fence" ideal (Jul 14, 2009)
DC's parks are 5th best in the nation, says "Park Score" (May 23, 2012)
WalkScore heat maps (Jun 13, 2008)

Short blocks cut small city traffic

Tue, 08 Jan 2013 08:38:00 EDT

by Thaddeus Bell

Small block size may reduce traffic more than mixed-use development in smaller cities. These smaller mixed-use areas are unlikely to be self-sufficient and so attract traffic from other areas. (Streetsblog)

Comment

Which came first, the city or the liberal? (Jul 4, 2005)
Development moratoriums make traffic headaches worse (Apr 19, 2012)
North Capitol: Competing visions for handling traffic (Dec 19, 2007)
Why are blocks that size? (Jun 2, 2010)
The only thing we have to fear is fear of traffic (Jan 13, 2010)

DDOT wants to build new South Capitol bridge; should it?

Wed, 02 Jan 2013 14:31:00 EDT

by David Alpert

DDOT needs to fix or replace the Frederick Douglass Bridge on South Capitol Street, and the Gray administration has started moving decisively forward with the project. We need some project in this area, but new renderings should raise questions about whether DDOT is building the right thing, or just continuing an existing old plan on autopilot.

The centerpiece of the project is a new bridge on South Capitol Street. The old bridge either needs replacing, or DC will have to keep shoring it up every few years. The proposed new bridge would be 1 lane wider than the existing bridge.

In addition, the plans call for moving the bridge slightly to the southwest and creating a large racetrack-shaped traffic oval on the ballpark side and a circle on the Poplar Point side. Near Anacostia Metro, where South Capitol/Suitland Parkway crosses 295, they also plan to redesign the interchange to be more compact than the cloverleaf it is today.

Is this a good idea?

These plans come from an Environmental Impact Statement that DDOT did in 2008. A lot has changed in 5 years, including evolution in our understanding of what kind of transportation network we want. It's easier for DDOT to simply take the existing plan and implement it, but that doesn't mean it's necessarily the right plan for 2013.

Certainly, something needs to be done with the bridge. DC can also do much more to better connect the east and west sides of the river. However, leaders need to ask some tough questions about whether this is the best way to do it, because a few parts of the plan raise red flags.

Are the circle and racetrack a good idea?

That racetrack has a lot of traffic lanes—5 in many places. DC's traffic circles aren't especially comfortable to walk or bike around. The EIS says the corners will have traffic signals, like Dupont or Logan Circles, so pedestrians will be able to cross at the crosswalks, but they will still have to cross multiple wide roads to traverse the area.

The same goes for the circle east of the river. The animation shows this as a 5-lane circle, which is far larger than DC's other circles. To cross into the center, you'd have to traverse 2 crosswalks. Do we get any of the benefits, or just the drawbacks, from a circle where each side is as wide as many major boulevards?

Plus, what will go in the middle? These are not going to become any kind of neighborhood public space. Is the circle really that much better than the existing approach ramps on the southeast end that it's worth a lot of money to demolish them and move the bridge?

What happened to the 295 interchange?

Fixing the interchange with 295 could create a more walkable place, but DDOT seems to have backed off the initial designs for an urban diamond and created something that's still more focused on moving cars quickly than walkability.

Top: Image from the 2008 EIS. Bottom: Image from the new video.

Sidewalks run along off-ramps and then cross at what engineers have presumably determined is the safest place, but if there's no intersection with a light, it's not really that safe. It's the same problem we have at the Pennsylvania Avenue cloverleaf with 295.

DDOT spokesman John Lisle promised to get back to me with more information about this interchange.

Can we really not fix the bridge?

At $660 million, this is a really expensive project. It's even more expensive if DDOT has to replace the swing span, which they're asking the Coast Guard and Navy to let them leave out of the new bridge. The whole project could top $900 million if you include other plans in the EIS to change the intersection of M and South Capitol Streets.

The Gray administration says it will be cheaper in the long run to replace the bridge as opposed to fixing it. The press release also says that if they keep the old bridge, trucks might have to divert off South Capitol because of safety concerns. That last part doesn't seem like a big deal, as we just built a new 11th Street highway bridge, but we certainly don't want bridges falling down.

DDOT says it would cost $120-150 million to fix the existing bridge. That kind of figure has some appeal to many in the Council who have to make tough budget choices among many projects.

Is this really better for people east of the river?

The DDOT press release quoted Mayor Gray as saying:

By better connecting both sides of the river, the new crossing will be the single largest physical embodiment of my "One City" governing philosophy of bringing the District together across geographic, income and ethnic boundaries. This graceful new bridge will be a welcoming gateway to the center of Washington, while also serving as an anchor for the revival of the Anacostia waterfront.

Speeding up traffic across the river could help some residents who drive that way in the short run, but may also ultimately attract drivers between Maryland and Virginia, or traversing the region longer distances, to use this as a cut-through, or encourage Prince George's County commuters to drive instead of parking and riding Metro. In poor neighborhoods already struggling with public health and cut off from the river by a large freeway, more through traffic could be just the environmental injustice they don't need.

It's important to ensure the South Capitol Street bridge is structurally sound. We also should improve connections across the river. But just because there's a 5-year-old plan doesn't mean we have a project worth spending hundreds of millions even beyond the cost of the bridge itself. DC leaders need to ask a lot more tough questions before rubber-stamping this plan.

57 comments

South Capitol: L'Enfant strikes back (Feb 17, 2008)
Build a circle at North Capitol and Irving (May 5, 2009)
11th Street bridges, part 1: The plan (Feb 9, 2009)
11th Street bridges design makes some improvements (May 29, 2009)
St. Elizabeths plan threatens South Capitol Trail (Jan 11, 2011)

Potomac study a foregone conclusion?

Mon, 26 Nov 2012 08:18:00 EDT

by David Alpert

VDOT is beginning a study on cross-Potomac traffic. Officials claim they have an open mind, but given their well-known bias toward highway lanes in all cases, will the study even seriously look at transit or inevitably push the Outer Beltway idea? (WAMU, DCist)

Comment

More people support transit than new or wider highways (Mar 6, 2012)
The zombie outer beltway returns (Aug 5, 2011)
Highway departments set on HOT lanes (May 8, 2009)
The Outer Beltway: The bad idea that won't go away (Dec 19, 2011)
WAMU missteps with one-sided Outer Beltway story (May 1, 2012)

A Mark of success

Fri, 19 Oct 2012 08:32:00 EDT

by Steven Yates

A year after Mark Center opened, traffic has not been that bad. More than half of workers opt to commute by means other than single-occupant car, thanks to a parking cap and many transit options. (Patch)

Comment

Car-centered traffic engineering ties Bethesda in knots

Wed, 03 Oct 2012 11:54:00 EDT

by Ben Ross

Construction-related street closings in downtown Bethesda have put pedestrians and cyclists at risk, while needlessly jamming up car traffic. The Montgomery County DOT, by treating a busy urban crossroads like a suburban highway, has made the streets less friendly to all.

Bethesda and Woodmont Avenues last Saturday. Photo by the author.

The intersection of Bethesda and Woodmont Avenues is the best-known place in downtown Bethesda. Located a few blocks from the Metro, it is surrounded by shops, offices, movie theaters and apartments. A complex mix of motorists, cyclists, and pedestrians traverse it every day.

Faced with the problem of managing traffic while a large mixed-use development goes up, the county took a standard traffic engineering approach. It treated the crossroads as an intersection consisting of 3 roads that carry cars and sought to eliminate "conflicts" by removing obstacles to automobile movement.

But Bethesda & Woodmont is also a major travel node for bicycles—vehicles too—which arrive on two other routes, the Capital Crescent and Georgetown Branch Trails. Suburban traffic engineering concepts, applied in this highly urban setting, have made a mess for pedestrians, cyclists, and motorists alike.

A 20-month road closure began 3 weeks ago. Woodmont Avenue, which crosses the construction site, had one block shut completely. On Bethesda Avenue, MCDOT removed turn lanes and eliminated a section of sidewalk. It moved back stop lines for the traffic light, sending bicycles exiting the Capital Crescent Trail directly into the intersection.

Aerial view of Bethesda and Woodmont Avenues before construction. Photo from Google Earth.

Problems quickly emerged. Because motorists can no longer use Woodmont Avenue to reach Bethesda Row from the south, Bethesda Avenue carries more traffic than before. Traffic on that newly narrowed road regularly backs up.

Closing a section of Woodmont shut down an important pedestrian corridor, which connects a densely populated apartment district with downtown Bethesda and the Metro station. Pedestrians now detour through a drive-through bank.

In addition, Bethesda Avenue has foot traffic of its own. A 190-unit apartment building (where I live), stores, and restaurants adjacent to the closed sidewalk generate significant pedestrian activity. Yet the traffic plan did not replace the crosswalk lost to construction. Pedestrians now dodge cars as they cross the street.

One cause of these difficulties is that the county did not retime traffic lights. A longer green light could move through traffic faster on Bethesda Ave. But with this fix alone, turning cars would still back up at crosswalks. And faster-moving traffic would endanger pedestrians crossing Bethesda Avenue and bicyclists leaving the trails.

The traffic engineers, focused as usual on cars, made another, more fundamental mistake. They ignored the movement of bicycles between the trail and the roadways. The great majority of weekday cyclists go from the trail into the traffic lanes. The new traffic pattern endangers these cyclists with a signal that sends them into moving auto traffic.

On-street cyclists moving to and from bike trail during morning rush hour. Photo by the author.

Also, the construction traffic pattern continues the county's ongoing disregard for the safety and convenience of pedestrians. There may not be room for a temporary walkway next to the construction, but a crosswalk could have been marked where the sidewalk ends on Bethesda Avenue. Instead, the county erected a "Sidewalk Closed" sign a block away, needlessly driving away walk-in customers that the street's businesses depend on.

This construction project cries out for innovative traffic management. A two-phase traffic signal could fix many of the problems pedestrians and cyclists face during the construction. One phase would be green for all pedestrian crossings and for bicycles entering from the trails, making the intersection much safer and more convenient.

The other phase would be a flashing yellow that allows cars to move slowly through the intersection in all directions. The significant reduction of traffic on Woodmont Avenue since the closure of the block south of the intersection could make this feasible. Pedestrians and cyclists would be much better off, and auto traffic would back up less.

That might or might not be the best solution. What is certain is the need for more multimodal thinking. In this sort of urban setting, traditional traffic engineering fails pedestrians and cyclists, and hurts motorists too.

30 comments

Arlington County installs new bike signal on Custis Trail (May 21, 2011)
On-street Crescent Trail may be better for bikes and peds (Nov 17, 2011)
Wall in White Flint endangers pedestrians (Aug 18, 2010)
Gaithersburg police target people in the way of cars (Oct 4, 2010)
Short-sighted bus stop placement puts pedestrians at risk (Feb 29, 2012)

And...

Wed, 03 Oct 2012 08:28:00 EDT

by Thaddeus Bell

Bike sales in Italy surpassed car sales for the first time since 1945. (Telegraph, charlie) ... The Dupont Metro station's south entrance reopens this month. (Post) ... Temporarily closing LA's Route 405 didn't bring much congestion. (Streetsblog) ... Tricycle-based food trucks will serve ice cream sandwiches. (City Paper)

Comment

Metro improves bike parking at NoMa station (May 3, 2012)
Ask GGW: Why is Farragut Crossing longer on weekends? (Nov 16, 2011)
Bike news (Jul 3, 2009)
Montgomery Council boosts Purple Line, Bethesda entrance (Mar 14, 2012)
Arlington plans to increase capacity at Rosslyn Metro (Sep 24, 2010)

New York streets get more dangerous

Tue, 02 Oct 2012 08:16:00 EDT

by Thaddeus Bell

New York City experienced a rise in traffic fatalities over the past year, after years where new traffic policies were accompanied by falling traffic deaths. (NYT)

Comment

Traffic fatalities at historic low, but there's more to the story (Sep 14, 2010)
Term limits are a dangerous policy (Apr 6, 2011)
Quantitatively compare New York neighborhoods (Apr 12, 2010)
Weekend video: Complete streets mean more than bike lanes (May 14, 2011)
Map shows the consequences of our automobile addiction (Nov 23, 2011)

A lot rides on how USDOT defines "congestion"

Thu, 16 Aug 2012 10:37:00 EDT

by Tanya Snyder

Congress has done its job, such as it is, and passed a transportation bill. Now it's handed off the policymaking to USDOT, which must issue a raft of rules, definitions, and guidance to accompany the new law, known as MAP-21. According to sources with intimate knowledge of this process, much depends on how DOT decides to measure congestion.

Photo by Joe Shlabotnik on Flickr.

New performance measures for the Congestion Mitigation and Air Quality Improvement program (CMAQ)—and quite possibly for the entire national highway system (depending how they define "roadway performance")—require a working definition of congestion.

If the agency follows the prevailing orthodoxy, states could be rewarded for wasteful highway spending. If it adopts better measurements, smarter investments and less wasteful spending will follow.

The CMAQ measures will also require a definition of "cost-effectiveness," a related but somewhat separate can of worms.

Graphic from CEOs for Cities.

The above graphic shows the wrong way to measure travel performance. The "Travel Time Index" awards a better score to Charlotte than Chicago, even though commutes in Chicago are shorter, because drivers in Charlotte spend a higher percentage of their time in free-flowing traffic.

USDOT should include distance driven in any measure of congestion

Performance measures in the MAP-21 law have been criticized for being toothless, since many of them don't have consequences attached. However, there is still the possibility that state performance rankings could be made public. And a spotlight on state failures could be an effective way to encourage good decisions.

Streetsblog asked Joe Cortright for his advice to DOT officials struggling to define congestion. Cortright is an economist and senior policy advisor for CEOs for Cities. In 2010, the organization commissioned him to write Driven Apart, a critique of prevailing methods of measuring congestion. His words of wisdom for USDOT: "Don't make the mistake the Texas Transportation Institute makes."

TTI's Urban Mobility Report, released every year, invariably gives top honors to places that have overbuilt road capacity. The institute measures congestion only by looking at the degree to which traffic slows down people's commutes. The problem with that, Cortright says, is that "you end up rewarding places that encourage people to drive longer and longer distances, and then you look at those long distances that they're traveling, and say because they're moving at a relatively higher speed much of the time that they're driving, that the system is somehow performing better."

Over the past few years, USDOT has been very deliberately working hand-in-glove with HUD and the EPA to treat transportation and land use as one cohesive system. It only makes sense that the agency use the same ethic in measuring roadway performance and congestion. By doing so, DOT would have to acknowledge that a long commute along miles and miles of free-flowing highways is no bargain compared to a short commute in dense traffic, not to mention an even shorter commute on transit.

Clark Williams-Derry, research director for the sustainability-focused Sightline Institute, suggests that congestion may simply be the wrong thing to measure. "Focusing on congestion is like, in a basketball game, focusing only on the number of assists you get," Williams-Derry said. "It's an interesting fact, but it doesn't tell you the final score."

But people treat this one piece of the picture as if it's "the whole story," he says. Why not measure how long it takes to get from place to place? Or how much it costs? After all, a major argument against congestion—and the reason that congestion reduction is elevated to a national priority—is that time spent stuck in traffic is lost productivity, which adds up at a national level. But the TTI method actually masks how projects affect total travel time, and wouldn't help measure productivity gains or losses.

The upshot is that following the same methods as TTI's Urban Mobility Report to set performance goals under MAP-21 would be a huge mistake. "It would focus resources on projects that are sprawl-oriented, that encourage decentralized development," Cortright said. "You can raise your performance on that measure most by having people drive more, as long as they're driving faster."

Cortright recommends that DOT put more emphasis on vehicle miles traveled than travel speed, and notes that this is especially important when it comes to measuring the cost-effectiveness of projects that are supposed to mitigate congestion and improve air quality. That's another tricky definition DOT is going to have to figure out.

It's not cost-effective for USDOT to encourage projects that induce driving

When DOT decides how to judge the cost-effectiveness of a CMAQ project, they can either focus on the CM (Congestion Mitigation) or the AQ (Air Quality), but those aren't the same thing. "It's unambiguous that if people drive fewer miles there's going to be less pollution," Cortright said. "A lot of the quote-unquote 'congestion reduction' projects essentially encourage more VMT."

Widening roads induces more people to drive, which makes it a poor method to address congestion. Image from Todd Litman at the Victoria Transport Policy Institute.

"There's this pervasive mythology that our pollution problems are chiefly caused by people having to idle in traffic," he continued. "There's no evidence for that, and the evidence there is suggests that if you reduce congestion, people actually drive further, and that more than offsets the benefits of less idling."

In addition, Williams-Derry pointed out that not all congestion is stop-and-go traffic. Congestion that consists merely of slower but smoothly flowing traffic actually improves air quality, since cars work more efficiently at slower speeds. That's what makes CMAQ a tricky program to judge, since its two goals are sometimes at odds with each other.

If DOT is going to measure cost-effectiveness, Cortright and William-Derry say, it needs to think like a business. Starbucks would never build a second caf� next door so that it could move the line faster at 9:00 a.m. and then have it sit empty the rest of the day. Building more roadway capacity to handle peak-of-the-peak traffic makes just as little sense.

Cost-effectiveness also can't be measured without examining what are known as "externalities"—the costs of driving that are passed on to the public. "The existing gasoline tax doesn't even cover the maintenance on the highway system that we have now," Cortright said. "It doesn't reflect the economic losses to crashes, it doesn't reflect the economic externalities associated with the environmental effects of burning all this gasoline and putting carbon in the atmosphere, and it doesn't reflect the foreign policy and military costs of being so dependent on foreign oil."

"If I were USDOT, I'd try to add in, in figuring cost-effectiveness, the cost of all those other subsidies to automobiles," he added.

There are still people inside and outside DOT—including some of the authors of MAP-21 inside the halls of Congress—for whom the only cost-effective transportation solution is to expand roads so cars can move faster. Not only would this do nothing to solve the problem of congestion, it would actually exacerbate the air pollution that the CMAQ program is designed to address.

By being thoughtful about how to define success in the CMAQ program specifically, and roadway performance generally, USDOT can have a tremendous and lasting impact on whether our transportation system is sustainable and sensible—or whether it drives us off a cliff.

4 comments

Traffic on and around WAMU (Nov 28, 2009)
Golden Gate congestion pricing out, performance parking in (Aug 20, 2008)
GAO: Trucking the least efficient mode of freight shipping (Mar 1, 2011)
Congestion pricing, pro and incoherent (Nov 22, 2005)
New Partners: Congestion pricing and transportation finance (Feb 8, 2008)

And...

Tue, 07 Aug 2012 08:24:00 EDT

by Thaddeus Bell

DC had a higher ratio of pedestrian deaths in traffic fatalities than most states. (WTOP)... In 19th century New Jersey some workers commuted on a bicycle railroad. (Atlantic Cities)... The Lincoln Reflecting Pool will open after two years of closure. (Post)

Comment

Accent lighting can transform the Mall (Oct 18, 2010)
Struck in DC this week: 5 pedestrians, 1 cyclist (Oct 3, 2010)
15th Street sidewalk closure endangers peds and cyclists (Sep 30, 2011)
Cannon almost stopped the Lincoln Memorial (Feb 4, 2008)
Map shows the consequences of our automobile addiction (Nov 23, 2011)

Portland broadens road metric

Wed, 01 Aug 2012 09:23:00 EDT

by Thaddeus Bell

Portland is planning to develop a new standard to measure multi-modal road performance. Current "level of service" standards only measure automobile traffic. (BikePortland)

Comment

Obama endorses transit and bike lanes (May 27, 2008)
Connectivity: a good way the stimulus can invest in roads (Jan 9, 2009)
Portland gets excited about transit with a Mobile Music Fest (Nov 1, 2011)
Amsterdam proves bikes and streetcars are allies (Nov 7, 2011)
MoCoCo agrees with Planning Board on Road Code (Oct 7, 2008)

Travel early, get paid?

Tue, 31 Jul 2012 08:21:00 EDT

by Thaddeus Bell

Stanford's campus has encouraged commuters to push their travel earlier to ease congestion. With a smartphone app and an RFID tag, participating drivers can receive money to travel at off-peak times. (Ars Technica, charlie)

Comment

15 cents a mile for no traffic? (May 19, 2009)
Field report: San Francisco congestion pricing workshop (Aug 5, 2008)
Congestion pricing, pro and incoherent (Nov 22, 2005)
Conservatives for congestion pricing (Feb 8, 2007)
MoCo planners considering congestion pricing (May 27, 2008)

And...

Sat, 28 Jul 2012 11:19:00 EDT

by Steven Yates

Rockville and Gathersburg have a border fight. (Examiner) ... More residential units are coming to the Riverfront. (Urban Turf) ... Traffic is best Friday mornings, worst Friday afternoons. (Patch) ... DC looks to sell the Lincoln Theatre. (City Paper)

Comment

Zoo tram an opportunity to not need parking (May 28, 2008)
Nationals Park falling behind in green standings (Nov 18, 2011)
That parking the Nats couldn't live without? Never mind. (Apr 22, 2008)
What's the longest street in DC with no traffic control? (May 18, 2011)
Throwing the baby out with the 400-foot buffer (Apr 7, 2008)

Instead of projecting traffic, reduce our dependence on it

Wed, 25 Jul 2012 10:29:00 EDT

by Charles Marohn

We spend billions every year in this country on our transportation network, large percentages of it based on traffic projections. This despite the fact that we have a long record of not being able to accurately project traffic. The answer isn't better projections but a better transportation system, one that is robust to modeling error.

Photo by Cameron Bevers.

My home town newspaper recently ran the standard repeat-what-the-engineer-says article on traffic projections. Essentially, the report indicated that we're going to be inundated with traffic.

As things continue to "full build out" (it was in quotes so I'm assuming it is an engineering term), traffic is going to increase by 75 percent, an astounding amount since most locals will attest we are already drowning in traffic (we're not, but most would attest that we are).

The recommendation for dealing with all this traffic seems sensible: make some prudent investments today to acquire more land for future road expansion and then, as they are built, oversize the roads to meet this future demand.

A lot of the rationale for these projections—as well as the public's acceptance of them—comes from the fact that growth has been robust. In fact, if you go back decades and look at the projections that were made for the present time, they are laughable in how dramatically they underestimated the amount of traffic. We projected out based on what our experience had taught us to anticipate, but we were wrong, and it cost the city a lot of money to retrofit all of the places that were inundated with cars.

This reality fits a national trend. My experience is backed up by studies demonstrating that, the higher the functional classification and the larger the traffic volumes, the greater the degree of underestimate. This correlates with work by Patron Saint of Strong Towns Thinking, Nassim Taleb, who has made the same observations of economic systems, governments, etc. (For one example, go to the 5:10 mark of this recent video.)

Amazingly, the fact the we have been so consistently wrong doesn't make us any less confident today, either in my hometown or nationwide. We've "enhanced" our models now and believe we have it figured out this time, revising the data upward to reflect what we have experienced in the "real" world. This is the essence of modeling, and what else could be more rational?

Or more foolish. In these models, we've taken something that is unpredictable—driver behavior—and treated it as if it were actuarial science, akin to estimating life expectancy or your odds of drawing a face card when the dealer is showing fifteen. The idea behind our hubris is that, while one driver may be unpredictable, the average driver will react in a predictable way and, thus, we can model based on a normal distribution. These models are failing to account for things like consumer preference, the ability to access financing, overall market growth, cost of construction materials, gas prices, government employment levels, and on and on and on�. We assume all drivers make predictible traffic decisions. They don't.

I'll take my hometown in Minnesota as an example. Our old traffic projection models assumed that cars multiply like people (I guess that's what's going on in all those two car garages), so we projected traffic based on historical growth rates the same way we projected population. Then what happened? I live in a resort/tourist area with cheap, abundant land and lots of natural resources, just the kind of place retirees and near-retirees wanted to move to starting in roughly 1990. Fuel that desire with a stock market bubble (I wrote a lot of permits for people who paid cash for their new lake home after selling stocks) and then with a cheap credit housing bubble, and—unexpectedly—we are inundated with traffic.

Today we already have Super Walmart, Super Target, Home Depot, Menards, Fleet Farm, Kohls, JC Penny's, Best Buy, CostCo (under construction) and a myriad of chain restaurants, gas stations and other highway parasites sucking off of the hundreds of millions we've invested in the adjacent STROAD (street/road hybrid). The baby booomers are stuck in their existing homes, which are now worth much less than they had hoped, while many are also stuck in their job as their retirement savings suffers much the same fate. The cheap shoreline is gone, sold off decades ago to people who are now reaching the age where maintaining a lake home may not be worth the effort. The cheap gas is gone too and it doesn't seem too likely that the state is going to throw hundreds of millions more into shortening travel times from the Twin Cities.

Has any of this new reality informed our projections? Of course not. Like a mad scientist adding random chemicals to a potion they just don't understand (and then testing it on unwilling human guinea pigs), we've tinkered with our models now, convinced ourselves that this time will be different. And you can bet that there is no way we'll be caught underestimating. We've "seen" what happens and so we've "fixed" that problem. The new answer is simple: estimate high (which is, in the perverse vernacular of the trade, called being "conservative" with the estimate).

We have a couple of discussions going on right now at the Strong Towns Network about traffic projections. One of my friends there sent me the following:

We're working on a traffic study for a small development. According to their comp plan (from 2007) we need to offer recommendations for a county road equivalent assuming 4 percent annual growth. We looked up the numbers and found that VMT has (of course) declined steadily in the area since 2003/4. Someone at our firm contacted the county about the growth rate (a 26 yr old traffic engineer by the way) and, from the message that was relayed back to me, we were instructed to just proceed with the Comp Plan's assumptions. Long story short, we're probably going to have to recommend a turning lane.

In another conversation, one of our members from California is knee deep in the debate over widening I-710 to 14 lanes. In a note to the spokesman for the Los Angeles County Metropolitan Transit Authority, he asked:

I know that the analysis of vehicle trips and container traffic for this project were done prior to the global financial system collapse in 2008, and so the idea of traffic volumes or container shipment volumes decreasing by 2035 were not considered.

However, when the Panama Canal is open, it looks like our region will be receiving less cargo simply because going through Panama is much cheaper than shipping to LA or Long Beach and moving via trucks, trains, etc.

Is anyone at Metro thinking about this project differently now? Shouldn't the "No Build" alternative for this project (and all the alternatives) be revised?

Here is the answer he received:

The Ports re-evaluated their growth projections after the recession and made adjustments. The revised projections show slower growth in Port activity in the next decade, but the 2035 total TEU estimate remains the same: 42.7 Million. In other words, the Ports anticipate to handle 42.7 Million TEUs by 2035, even if growth is slower in the next few years.

In other words, it might slow down for a while, but we're confident it will go back up ultimately because our projections say it will.

There is a certain contingent out there that is already pounding out their email to me demanding that, if I'm so smart, I provide a better way of estimating. There's the fatal flaw in our current system. I'm not so smart, but neither is anybody else. The big difference here is that I'm not pretending to be able to predict the future.

Inherent with the auto-centric pattern of development that defines the Suburban Experiment is the hierarchical road network. Like a river swelling during a steady rain, changes on the periphery have an enormous impact on the trunk components of the network, as do many other things that have nothing to do with driver behavior. The reason we put so much time and effort into projections that we know will be wrong—that we have no consistent history of getting right—is because the cost of being wrong is so great. When the projection is off by even 10 percent, the level of service on major roadways can plummet. Since nearly every trip is funnelled into this network, failure is catastrophic. This is an incredibly fragile approach.

We don't need better projections, we need a system that is robust to modeling error. We need a system of growth and development where we don't need to project correctly in order to succeed. We need a system where we build incrementally in a replicable and evolving pattern, one where each fractal evolves continually and naturally over time. We need a system where we're not required to place huge bets on the future, oversizing infrastructure in service of projections, but instead can invest in high return endeavors where the likelihood of success is great.

We need a strong towns approach which, if you stop and look, is a lot like the pre-automobile approach that served us well for thousands of years. I'm not saying we get rid of the automobile, but when we build our entire environment around its propagation, we are slave to our own hubris and lack of understanding.

Cross-posted at Strong Towns. Note: A brief link to the original article was included in Tuesday's links, butthis issue is worth a fuller discussion here on Greater Greater Washington.

48 comments

Why is the ICC so empty? How long will it stay that way? (Jan 3, 2012)
The only thing we have to fear is fear of traffic (Jan 13, 2010)
A conversation with a traffic engineer (Dec 9, 2010)
Loudoun blindly pushing massive, senseless road widenings (May 19, 2010)
Is the 1,000 space garage in Columbia Heights a good investment? (Feb 21, 2008)