Click on the photo for a larger view. Your comments are welcome.
The location as of September, 2016:
Click on the photo for a larger view. Your comments are welcome.
The location as of September, 2016:
Here’s a video of the intersection of Commonwealth Avenue and St. Mary Street, Boston, Massachusetts, USA, an example of the design expertise which earns Boston its place with the League of American Bicyclists as a Bicycle Friendly City.
The video is from 2013. As of 2016, one change has been made: the zigzag in the bike lane has been replaced by a diagonal transition.
The idea that cyclists should turn across in front of multiple lines of motor vehicles to change lane position is not unique to this location. Here’s another example, and it is by no means the only other one:
I have a blog post in connection with that video too.
In cities around the USA, politicians, under pressure from populist bicycling advocates, have pointed to the NACTO (National Association of City Transportation Officials) Urban Street Design Guide and directed their engineering staff to install treatments which it describes.
I’ll say right here that some of the treatments which the NACTO guide describes deserve attention and inclusion in national design standards — though their presentation in the NACTO Guide typically is flawed, inconsistent and incomplete. Why some deserving treatments are not included in the national design standards is a story for another time.
Other NACTO treatments are so troublesome that they are not widely applicable.
Engineers unfamiliar with bicycling issues may take NACTO designs at face value; other engineers may throw up their hands and comply, faced with the threat of losing their employment. Several engineers who have extensive background and expertise in design for bicycling have resigned, been fired or been demoted when they would not accept the NACTO designs.
What leads to these problems? To put it simply, the NACTO guide isn’t a design manual. It is a smorgasbord of design treatments formatted — right down to digitally-generated loose-leaf binder holes on what are, after all, Web pages — to look like a design manual to politicians and the general public. Bicycle manufacturers funded it to promote street designs which they expect will lead to greater bicycle sales. It lacks the vetting necessary for consistency and accuracy. Its purpose is to generate political pressure to apply the treatments it describes. It is weak on specifics: rife with errors, and with omissions even in describing the treatments it covers.
If I described all of my specific concerns with the NACTO Guide, I’d be writing a book, so for now let’s just look at a two-page spread of the NACTO Guide, the pages about two-stage turn queuing boxes (2STQBs, for short).
Maybe by now you are inclined to think of me as a naysayer, so, let me get down to some specifics to dispel that impression. I have had information about two-stage turn queuing boxes online for years, I think that they are a useful treatment, and I use two-stage turns: when I realize that I have reached the street where I need to turn left, but hadn’t merged to turn; when traffic is heavy and fast and I haven’t found an opportunity to merge; when ordinary left turns are prohibited. My favorite example is the left turn from Commonwealth Avenue onto the Boston University Bridge in Boston, Massachusetts, where a no-left-turn sign is posted: motorists have to go around a large loop.
Ok, now let’s consider the spread from the NACTO guide, below.
I have placed that spread online as a PDF file, zoomable to any size you might like. You may click on the link or the image above to get a larger view while reading this text. The PDF will open in a separate browser window or tab. I’ve also posted parts of the NACTO pages in connection with the text below.
Issues of organization and use of technical language
The NACTO treatment of the two-stage turn queuing box presents issues of organization and of use of technical language.
Problems start with the title of the section. A proper title is not “Design Guidance”, otherwise, every section would be named “Design Guidance”. A proper title is the name of the device, here “Two-Stage Turn Queuing Box”. [And not “Queue” but” Queuing.”]
In a proper design manual, the terms “shall”, “should”, “guidance” and “option” go from strong to weak. “Shall” is imperative: for example, a stop sign shall be octagonal. Should, guidance and option statements are increasingly weaker, leaving more room for engineering judgment.
The terms “Required Features” and “Recommended Features” correspond roughly to “shall and “should” but do not have the explicit, legally-defined meanings of “shall” and “should”.
None of the drawings on the two pages are dimensioned, and no dimensions are given in the text. That is to say, these are not engineering drawings, they are only conceptual drawings. How big are the turn boxes supposed to be? Who knows? The width of travel lanes differs from one drawing to the next, but no explanation is given for that. When politicians start beating on the door for NACTO treatments, standards-setting bodies and traffic engineers have to try to fill in the missing information. For specific projects, that task often is passed along to hired consultants who make their living by promoting and designing special bicycle facilities. Yes, there is a conflict of interest.
Now, either click on the image of each section of the page below to open it in a separate browser tab, or zoom the PDF to at least 50% size so you can read the text in connection with my specific comments .(You may open it now if you didn’t already.)
Comments on the left-hand page
The left-hand page includes text which may look like design specifications, and drawings which may look like design drawings — to a layperson.
Left half of left-hand page
Point 1: “An area shall be designated to hold queuing bicyclists and formalize two-stage turn maneuvers.” This is under the heading “Required Features.” A 2STQB is only one way to turn left among others, an option, subject to engineering judgment or specific design warrants. There is neither the room nor the need for a 2STQB at most intersections. Lacking here is any statement as to where a 2STQB is appropriate, but the “shall” statement here is inappropriate: appropriate shall statements would describe what features are required if a 2STQB is installed. As of May 2014, the 2STQB is still in experimental status with the Federal Highway Administration — as are all details of its design, and so no “shall” statement at all is appropriate.
A proper design manual would include guidance about speed and volume of traffic; the additional delay usually required for a two-stage turn; whether bicyclists might take an alternate route entirely; whether use of the box is mandatory, placing bicyclists who make other types of turns in violation of the law.
Point 4: “In cities that permit right turns on red, a no-turn-on-red sign shall be installed.”
According to the wording here, if the installation is not in a city, the sign is not required.
But also, the shall statement is overly broad, and incomplete. The sign is needed only if right-turning traffic would be in conflict with the bicyclists waiting in the 2STQB: unnecessary in the cross street if traffic turns right before reaching the box or cannot turn right, and unnecessary on the entry street if the cross street is one-way right-to-left. Does the sign belong on the entry street or the cross street, or both? That is not stated. Details, details…
Point 6: The comma makes nonsense of this sentence. Where is the box to be positioned?
The other, subsidiary “should” and “may” statements on this page also are contingent on official approval of the underlying design, and are lacking in detail.
Right half of left-hand page
Something really leaps out at me here: take a look and see whether it leaps out at you too.
OK, ready? Three of the six illustrations show a line of travel (in blue) for bicyclists straight across an intersection and then illegally and hazardously turning right, directly into the face of approaching traffic in a cross street.
In showing this bizarre routing, the NACTO Guide also fails to address issues with the actual route which bicyclists might take.
Five of the six illustrations show that bicyclists would somehow turn 180 degrees in place. That requires dismounting and is slow and awkward. How would a bicyclist turn when the traffic light is about to change? When other bicyclists are already in the box? What about tandems? Bicycles pulling trailers? Bicycles carrying heavy baggage?
The drawings show a subtly implied but selectively addressed-threat: lanes where motorists travel are shown in a threatening shade of pink — whoops: except in the cross street where bicyclists ride head-on at motorists.
Four of the six illustrations show motor vehicles in right-hook conflict with bicyclists headed for the queuing box. The motor vehicles are turning out of the threatening pink area into what is portrayed as the safe zone– the right-hook zone. In two of the pictures, vehicles have already impinged on the blue line which represents the path of bicyclists crossing the intersection. Green paint, which has become a catch-all warning of traffic conflicts in bicycle facilities, is shown in the queuing box, it is not shown in the conflict zone. (By way of comparison, Dutch practice in such conflict situations is that the motorist must always yield, and to use “shark teeth” markings to indicate a yield line.)
Two of the drawings show bike lanes in the door zone of parked cars.
The middle left illustration shows a receiving bike lane at the top, out of line with dashed markings in the intersection, so bicyclists bear right just before they cross a crosswalk, potentially colliding with pedestrians who would expect them to continue straight.
All of the illustrations show two-stage turns across two-lane one-way streets, though the two-stage turn queuing box is most useful where a conventional left turn is illegal, unusually difficult or hazardous — for example, when turning from a major, wide arterial street with heavy traffic, or one with trolley tracks in the median.
As already indicated, none of the drawings are dimensioned and no dimensions are given in the text.
Comments on the right-hand page
The right-hand page gives annotated pictures of conceptual installations, with angled views from overhead.
Left half of right-hand page
The street going from bottom to top in the picture is one-way, as can be inferred by the direction in which vehicles are traveling. That the cross street is two-way may be inferred from the locations of traffic signals and the existence of the queuing box. A real design manual would be explicit about how a treatment would apply, depending on the directions of traffic in the streets.
The end of the traffic island next to the queuing box protrudes so far and sharply as to make right turns awkward. No explanation or guidance is given on this issue.
Traffic signals are shown for motor traffic on both streets, but no traffic signal is shown facing the separate bikeway in the street!
Point 3: “Shall” — mandatory — wording differs from that in the same point as made on the opposite page. A real design manual would have a single, consistent statement.
“Queue box shall be placed in a protected area.” The queuing box shown here is not protected from right-turning traffic in the cross street. How would that right-turning traffic be managed, or is it permitted at all? Such issues are addressed in a real design manual.
Point 6: “Optional queue box location in line with cross traffic.” The preferred queuing box, then, is not in line with cross traffic. On getting a green light, bicyclists in the queuing box would have to merge left inside the intersection unless there is a receiving bike lane after the intersection, but none is shown. Merging inside an intersection results in hazardous conflicts and is generally illegal. What warrants the choice of one or the other option? It isn’t stated.
Point 8: The illustration shows motorists and a bicyclist inside the intersection, and so they must have a concurrent green light — or, they would if any signal were shown facing the bikeway. Markings guide bicyclists across the intersection, but also into the path of right-turning traffic. The bicyclist and the motorist in the right-hand lane at the bottom of the picture are on a collision course if the motorist turns right.
What is the meaning of the curved markings adjacent to the bicycle parking in the middle of the street? Does the lane with bicycle parking start as a lane with car parking, additionally hiding bicyclists from turning motorists? Or is this an additional lane for motor traffic, discontinued at the intersection, precisely where more lanes are needed to store waiting traffic? Not shown.
Right half of right-hand page
There is a right-hook threat at both bike lane entries to the intersection.
Bicyclists headed from bottom to top in the bike lane are riding in the door zone of parked cars, and closer to the cars after crossing the intersection.
Point 9: As in the left half of the page, placing the queuing box to the right of the travel lane when there is no receiving lane ahead assures that motorists will overtake bicyclists in the intersection and that bicyclists will have to wait for motor traffic to clear before they can proceed. Motorists waiting to turn right will be stuck behind the bicyclists. Placement out of line with motor traffic is described as the option here, rather than as the preferred treatment as on the left side of the page, and the problem is acknowledged in the caption to this drawing, though no explanation for the different choices is given.
Point 10: A jughandle may be useful if traffic is so heavy or fast that bicyclists have difficulty merging to the normal left-turn position near the center of the street, but then traffic is also so heavy and fast that a signal is usually necessary, not merely to be considered — unless there is already one upstream.
Point 11: Yes, signage may be used, but what signage? A real design manual would show the signs and where they are to be placed.
Point 12: A bicycle signal might be installed, but where? For the entry? For the exit? Its timing?
Point 13: Guide lines, pavement symbols and/or colored pavement. Which? Where? Why?
The caption with the picture below in the Starts and Stops column of the Metro section of the June 17, 2012 Boston Globe reads:
Cyclists stopped for a red light in the “bike box” on Commonwealth Avenue in the Back Bay. They provide the cyclist a safe space to wait ahead of cars at traffic signals.
(The Globe story may be behind a paywall, but you can probably access it through a public library’s Web site using your library card number.)
The smiling cyclists show that this is a posed photo; the photographer evidently only thought of the large puddle in the foreground as an artistic touch. How about the car encroaching into the bike box in the background?
Well, yes, OK, waiting in the bike box might be safe — drivers are unlikely to encroach on a cyclist who is already waiting in the bike box. The problem is with getting into the bike box. The Globe columnist, Eric Moskowitz, never considered that bicyclists approaching the bike box on a red light are encouraged to swerve sharply left across multiple lanes of motor vehicles, with no way to know when the light will turn green. A waiting motorist will not see the swerving cyclist if looking to the left for traffic at the wrong moment. A tall vehicle in one lane will conceal the cyclist from a driver waiting in the next lane.
Portland, Oregon has hosted a study of bike boxes, which found that this is actually a rare problem in Portland, because cyclists are smart enough not to swerve into the bike box. Instead, if the light is red, they wait at the right curb, blocking other cyclists behind them. I saw the same thing on Commonwealth Avenue. As I said before, the Globe photo is posed.
But on the green light, there’s another problem. Bike boxes and the bike lanes which lead to them invite cyclists to overtake waiting motor vehicles on the right, risking getting struck by a right-turning vehicle. A bicyclist was right-hooked and killed in Portland, Oregon, on May 16, 2012 but apparently that news didn’t reach the Globe’s columnist, or didn’t make an impression on him. Now a letter from the City of Portland is conceding that car-bike crashes have increased at some of the intersections where bike boxes were installed. So much for the Globe’s assertion of safety.
Conscientious bicycling advocates have been warning about the “right hook” problem for decades, based on the difficulty which motorists have in looking into their right rear blindspot, while also checking the intersection ahead.
Swerving across is illegal too: here’s the Massachusetts law, in Chapter 89, Section 4A. It applies to bicyclists, the same as other drivers. Every state has a similar law.
When any way has been divided into lanes, the driver of a vehicle shall so drive that the vehicle shall be entirely within a single lane, and he shall not move from the lane in which he is driving until he has first ascertained if such movement can be made with safety.
Bicycling advocates, planners and government officials who promote bike boxes have simply chosen to pretend that this traffic law doesn’t exist, or can be ignored. Same for the limits of human abilities.
Now, I wouldn’t be fair in making this criticism if I didn’t suggest alternatives.
The one I favor is for cyclists to merge before reaching the intersection. That can be facilitated by signal timing at the previous intersection to allow cyclists to merge across when motor traffic is stopped, and a clear lane into which to merge.
Other suggestions have been to prohibit right turns, or to install special signals to warn cyclists that the light is about to change. Denver’s retired bicycle coordinator, James Mackay, has described some of the measures used in European cities.
These measures will, however, result in more delay, for both cyclists and motorists.
It may be more practical just to designate another street as the one for through bicycle traffic, My favorite suggestion at this Back Bay location would be Newbury street, configured as a two-way bicycle boulevard with a bridge over the Muddy River to connect it with the Fenway area.
This is a 4-minute continuous video of a bicycle ride in Boston, eastbound on Commonwealth Avenue through Kenmore Square, to and through the underpass at Massachusetts Avenue. I recommend that you view it on Vimeo site, in full-screen high definition.
Gordon Renkes and I each had a camera, so you can see both a forward and a rearward view. We rode safely, and mostly by not using the special bicycle facilities.
More general comments:
Here’s another video showing conditions at the six-way intersection of 16th Street, U Street and New Hampshire Avenue NW in Washington, DC, where special bicycle facilities have been installed.
Also please see my earlier post about this intersection, with another embedded video.
New York bicycling advocate Steve Faust has stated that some ways of accommodating bicycling do not “scale up” — that is, they work with small numbers of cyclists, but less well with larger numbers.
His central complaint is that use of roadways with no special bicycle facilities, according to the conventional rules of the road, does not scale up well.
I might put that a bit differently. After all, more cyclists need more room. Mass rides such as New York’s own 5-Borough Tour avoid special bicycle facilities and occupy the entire width of Manhattan’s multi-lane avenues. Motor vehicles are excluded while these rides pass through. Interaction within the group of many thousands of cyclists is for the most part according to the conventional rules of the road, and falls short only in that many of the participants are inexperienced.
On roadways carrying both cyclists and motorists, cyclists inconvenience motorists when the motor traffic could go faster — that is, when there are many cyclists and few enough motorists that they could travel unimpeded, if not for the cyclists. Motorists inconvenience cyclists when motor traffic is congested, and stopped or traveling slower than cyclists might want to go. Level of service always declines as a road becomes more congested, and it declines faster when vehicles have differing speed capabilities.
On the other hand, there also are situations in which operation as intended does not scale down to smaller numbers.
Motorists are more likely, for example, to yield to a crowd of pedestrians than to a single pedestrian.
Another example is the leading pedestrian interval: the walk signal goes on a couple of seconds before motorists get the green light. The leading pedestrian interval is intended to get pedestrians moving out into the intersection before motor traffic can begin to turn across a crosswalk, encouraging motorists to yield to the pedestrians. The same approach is used sometimes on bicycle facilities, for example on the Boulevard de Maisonneuve bicycle sidepath in Montréal, Québec, Canada. But a leading interval only works if there is someone waiting to cross when the signal changes. With smaller numbers, so the first pedestrian or bicyclist reaches the crossing after the motorists get their green light, the leading interval’s only achievement is slightly to reduce the capacity of the intersection.
The same issue can occur with any “conflict zone” with poor visibility as users approach, including the “bike box” or bicycle waiting area ahead of the stop line for motorists at an intersection. Once one cyclist is in a “bike box”, a motorist is unlikely to move forward, because that would require running over the cyclist. Therefore, the bike box is then safe for the entry of other cyclists, at least into the same lane in which the first cyclist is waiting.
The”bike box” works as intended when there are large numbers of cyclists so the first one arrives well before the traffic signal turns green.
If there are few cyclists, so the first one is likely to arrive just as the traffic signal turns green, then there is the potential for a right-hook collision, or a motorist’s colliding with a cyclist swerving into the bike box.
Safety requires that there be enough cyclists that early-arriving ones block the way of motorists, or at least alert the motorists that others may arrive. This safety factor does not scale down to small numbers.
Research in Portland, Oregon shows that only 5% of bicyclists swerve into the bike box when they are first to arrive; about 35% if they arrive later. The reluctance of the first-arriving cyclist reflects risk avoidance to some extent, due to not knowing when the traffic signal will change, but also that the swerve lengthens the cyclist’s trip — none of the Portland bike boxes are designated for left turns. The later-arriving cyclists are to some degree protected by the arrival of the first one, but also they either have to wait behind or move over to the left of that cyclist, into the bike box.
“Safety in numbers” claims become rather interesting when such issues are considered.
The design challenge is to achieve efficiency and safety of all travelers, regardless of whether numbers are large or small.
The video embedded below documents a bicycle ride by the author and two companions in Washington, DC where special bicycle signals and road markings have been installed to establish continuity of New Hampshire Avenue at its intersection with U Street and 16th Street.
The video tells the story of an unusual pass through the intersection — the signal actuator somehow didn’t give us the green on the first go-round. It did on other passes.
Aside from that one quirk, the video shows the usual signal timing (though it might be different at another time of day). The most significant finding is the short time to get into the “bike box” which is located ahead of motorists’ advanced stop line. There wouldn’t be be enough time for any large number of bicyclists who had been waiting for the signal.
Several additional issues remain to be shown in other videos. Here is a preview of what they will show:
Before I actually rode through this installation, I thought that it was a particularly good one. I have a blog post expressing that opinion. That post also gives a detailed description of the installation and its history.
The installation doesn’t violate any principles of traffic theory. In particular, when used as intended, it doesn’t place bicyclists and motorists out of sight of each other and on a collision course. But as Yogi Berra, or maybe Albert Einstein, memorably said, “[I]n theory, theory and practice are the same. In practice, they are not.” This installation makes the intended movements unattractive due to the short timing and tight space. The installation also makes bicyclists wait much longer to take the intended routes than to take others — which don’t even necessarily require illegal movements. As such, this installation unfortunately is not, in my opinion, successful.
UPDATE: This post gives background information on the intersection. I have now ridden through it, and my opinion of it has changed. I have another post about it, and a video. Please check them out.
The image below shows a special installation of traffic signals and markings at the intersection of 16th street, U Street and New Hampshire Avenue NW in Washington, DC. To enlarge the image so you can read the text descriptions, click on it. You also may have a look at a Google map satellite view. Then please return to this page for my comments.
Pierre L’Enfant and Andrew Ellicott — and let’s also not forget African-American surveyor Benjamin Banneker — laid out Washington’s streets from scratch — in the pre-automotive 1790s. Washington’s diagonal avenues give it an openness and unique sense of place — but the resulting uneven-length blocks and multi-way intersections make for some serious headaches now. Some traffic movements are odd, traffic signals can not be synchronized efficiently…
Before the new installation, no signals in this intersection faced new Hampshire Avenue. Bicyclists would sometimes use New Hampshire Avenue for through travel, though its conflicting one-way segments made that illegal and there was no conflict-free crossing interval.
The illustration above is from a page posted by the government of the District of Columbia describing a new installation of contraflow bicycle lanes, bicycle waiting boxes and special traffic signals. At first glance, these may raise the hair on the back of the necks of people who are suspicious of special bicycle facilities treatments.
Look again. The bike boxes look odd only because they connect with diagonal New Hampshire Avenue. They are cross-street bike boxes — which bicyclists enter from the left. Bicyclists from New Hampshire Avenue enter on a separate signal phase from the motor traffic on 16th Street, rather than to creep up on the right side of motor vehicles, as with more-usual bike-box installations. Motorists do not have to crane their necks or stare into a right-side mirror looking for these bicyclists.
The cross-street bike boxes are even more conflict-free than usual. Because only bicycle traffic runs contraflow, bicyclists do not have to negotiate with any right-turning traffic when entering the intersection.
To summarize: this installation, importantly, does not violate the fundamental traffic-engineering principle of destination positioning at intersections, as so many special bicycle facilities installations do.
Or, looking at the same conclusion from a different point of view, the installation does not require or encourage bicyclists to do anything dangerous or stupid, and it offers reasonable travel efficiency considering the situation it addresses.
I am not going to say that this installation is perfect. I can see the following issues.
This installation is the subject of experimentation sanctioned by the U.S. Federal Highway Administration, with observation, data recording and analysis to see how it works in practice. The experimentation may turn up more issues, or reveal that some are of little importance.
Now, dear readers, you also may also have points to add to the discussion. Let the comments fly.
James Mackay is a practicing traffic engineer who participated in a summer 2009 scan tour of European bicycle facilities. He is a member of the National Committee on Uniform Traffic Control Devices Bicycle Technical Committee (NCUTCD BTC). His comments on European vs. US bike box implementations are published here with his permission:
Bicycle advance stop line implementations I saw in Europe amounted to a five-legged stool, with resultant stability and functionality.
I get very concerned with American implementations that amount to a two-legged stool.
Proposals I see over here lack the individual contribution and resultant system stability of the sum of following five factors which provides a functional system over there:
- Near-side-only signals, which greatly reduced motorist encroachment on bike boxes and pedestrian crosswalks;
- Traffic signals that provide an advance red/yellow phase indicating that a green indication is imminent;
- Trixi mirrors (convex, internally heated mirrors placed on the near side signal pole, directly beneath the motorist’s traffic signal);
- Right Turn on Red “RTOR” -or the UK equivalent of LTOR – does not exist in these countries (serving to preclude operational conflicts), and;
- Cell phones are not to be used while driving.
Overall the bike boxes were used in cultures with much higher numbers of bicyclists. A motorist in the countries we visited would be much more likely to see a bicyclist using a bike box. This would specifically include truck drivers.
I don’t recall seeing traffic enforcement in the scan tour countries. Seemingly, there was a much stronger social contract in effect. In particular, bicyclist compliance with signals and other traffic control devices was much higher than what we are used to seeing in the U.S.
James Mackay, P.E.
Secretary (Emeritus as of January, 2011), Bicycle Technical Committee, NCUTCD