Tag Archives: bike box

Is the NACTO Guide a Design Manual?

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.

NACTO pages about two-stage turn box

NACTO pages about two-stage turn queuing box

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.

Specific comments

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 is so 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?

Had enough?

Right-turn lane as dual-destination lane?

I’ve had criticism from an unusual side about the video below. The complaint, from another cyclist, was essentially that I was not following the rules of the road, not operating as the driver of a vehicle, by riding straight through in a right-turn lane. Most criticism about my cycling, and my cycling advice, comes from people who would rather that cyclists not have to ride on roads at all!

Allston to Cambridge by Bicycle via River Street Bridge from John Allen on Vimeo.

To answer this criticism, let me first provide some background.

Anyone who uses the roads in the Boston area , whether as a cyclist, motorist or pedestrian, soon discovers that the street markings often contradict the requirements of normal traffic movement. Of course this is what knowledgeable cyclists complain about as it applies to bike lanes — emphatically so in the Boston urban core, where there is rarely room for bike lanes outside the door zone. Door-zone bike lanes have been installed anyway ever since the Cambridge bicycle coordinator introduced them in the mid-1990s. (Now she has moved on to X-merges, bicycle sidewalks, jughandle left turns and bowling-alley bus stops, and the City of Boston is working to play catch-up.)

We don’t only have bike lanes in the door zone here, we have bike lanes in the taillight zone — like this one on Massachusetts Avenue in Cambridge.

Bike lane in taillight zone, Cambridge, Massachusetts

Bike lane in taillight zone, Cambridge, Massachusetts

When I had the opportunity to ride in Albuquerque, New Mexico a couple of years ago, I had a real eye opener: I saw and rode on bike lanes which are mostly functional rather than dysfunctional. They are on streets without parking; motorists merge across them to turn right. I realized that bike lanes in the Boston area give others a bad name.

The Boston area has a terrible reputation for bad driving compared with other cities. In my opinion. strongly backed up by statistics, this reflects cultural differences rather than reality. There is somewhat of a chip-on-the-shoulder, butt-into-line attitude among many Boston drivers. It probably goes back as far as the Blueblood vs. Irish struggles for political power of a century and more ago. Some drivers feel a sense of entitlement and an emotional need for self-assertion. But the rudeness also at times reflects the practical need to get going. A Boston driver more often has blindly to inch out into the path of a vehicle which has the legal right of way, simply to get into the stream of traffic, than in most other American cities. A cyclist who doesn’t understand this will feel continually abused and endangered; a cyclist who understands the need to assert lane position and right of way finds Boston a very easy and safe place to ride. I describe how to be that cyclist, here.

There aren’t good statistics on bicycling, but Boston has the lowest rate of pedestrian fatalities of any of 52 major US cities. Boston drivers may be rude, but also they are clearly more attentive than elsewhere. They have to be. They know that they have to keep their eyes open, and that the street design and street markings have to be taken with a grain of salt.

The conflict between markings and traffic movements here in the Boston area didn’t begin with, and isn’t restricted to, bike lanes. It results in the first instance from an attempt to impose standard road markings and channelization on streets which are too narrow to accommodate them, or on multi-way intersections which are too complicated.

In order to accommodate parking, there are quite a few travel lanes too narrow even to fit a conventional dual-track motor vehicle. Here’s an example.

Narrow travel lane next to parking, Franklin Street, Framingham, Massachusetts.

Narrow travel lane next to parking, Franklin Street, Framingham, Massachusetts.

There are also multi-way signalized intersections where traffic engineers threw up their hands and let traffic enter from more than one leg at a time and merge inside the intersection.

And now, zeroing in on the topic of this post, there are numerous situations where an empty right-turn lane parallels a congested through lane, and neither lane is wide enough for side-by-side lane sharing. Often there is also a receiving lane or shoulder after the intersection — as in the example shown in the video.

I completely agree that it is foolish and hazardous for cyclists to ride near the right side of a right-turn lane when headed straight across the intersection. That is the “coffin corner” situation that we lament when it kills a naive cyclist. But, on the other hand, I consider treating an empty right turn lane with a receiving lane or shoulder after the intersection as a dual-destination lane, and riding in its center or toward its left side, only to be a variation on the decades-old advice to choose lane position according to the rules of motion, and ignore the bike-lane stripe. I’m not alone in this, not at all. Installations formalizing this treatment have been made in a number of places in the USA. It is accepted under the Manual on Uniform Traffic Control Devices if shared-lane markings are used, though state laws generally still do not allow it. It is still in the experimental phase if a through bike lane is to be installed inside a right turn lane. That is documented on this page on the FHWA site.

Most importantly though, treating a right-turn lane as a dual-destination lane when it is empty, or lightly-used, or carrying slow traffic while the through lane is blocked, and riding at its center or left side does not violate the rule of destination positioning and does not lead the cyclist into a conflict. I yield when entering the lane (if there is any vehicle to yield to) and I never place myself to the right of right-turning traffic. I have never gotten into a hazardous situation by doing this. I must anticipate that a driver waiting in line in the through lane to the left may decide instead to turn right and enter the right-turn lane late. This is the same concern as when overtaking any line of stopped traffic, and the countermeasure is the same; stay far enough away from the stopped traffic to be able to avoid a merging vehicle.

In my opinion, the assertion that a cyclist should never ride centered or left in a right-turn lane when preceding straight across an intersection is rigid, legalistic, and impractical. But on the other hand, it doesn’t make sense everywhere, either as an informal practice or a standard treatment. That is why, in my opinion, a standard is needed to establish where it may be formalized, and education is needed, as always, so cyclists will be able to judge when it is advisable or inadvisable.

Further information: I’ve had the same issue raised about my advice on riding the 9th Avenue sidepath in Manhattan, and you may read about it in the documents, photo captions and video linked under the 9th Avenue heading here.

Boston Globe: Reality Check Time

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.

Photo which appeared in the Boston Globe Metro section, June 9, 2012

Photo which appeared in the Boston Globe Metro section, June 9, 2012

(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.

A ride on Comm Ave., Boston, Massachusetts, USA

Comm Ave. Boston: Kenmore Square, Mass Ave. underpass from John Allen on Vimeo.

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 rearward view. We rode safely, and mostly by not using the special bicycle facilities.

Some highlights:

  • The block pavers, bricks and the granite curbstones used as borders for crosswalks made for a very bumpy ride across Kenmore Square and the next intersection.
  • The bike lane for the first block after Kenmore Square was unusable, due to double-parked vehicles. In the next block, it was unsafe, due to the risk of opening car doors and walkouts. One trucker was accomodating enough to park entirely outside the bike lane, inviting bicyclists to run the gauntlet between the truck and parked cars Gridlock Sam-style. We didn’t take the invitation.
  • As we waited for a traffic light, a cyclist raced past us on the right, entering the narrow channel between a row of stopped motor vehicles and one of parked cars. If anyone had walked out, or a car door had opened, the cyclist would likely have had too little time to react, and he would have had no escape route. At least he (and the pedestrian he could have struck) would have been fortunate in that one of the waiting vehicles was an ambulance.
  • There is a bike box along the route, and revealed an issue that I hadn’t noticed before. If the traffic light is red, you’re supposed to filter forward in the bike lane on the right, then swerve across two lanes of traffic to the middle of the 4-lane wide bike box, to be in line with the bike lane which is to the left of 2 lanes — see Google satellite view — note that this is an angle shot from the west. If the light is green, you could merge either before or after the intersection, but there is an advantage in merging before the intersection, as the counterexample of the video shows. You also don’t know when the light is going to change — so in either case, you make a widely divergent choice — merge left, or head for the bike lane at the right — based on insufficient information, and if the light is red, you also could be swerving abruptly across two lanes of traffic just as the light turns green.
  • The buffered bike lane in the underpass makes for an easier ride through the underpass, but where it connects to a narrow left-side bike lane outside the underpass, there is little clearance for motor traffic in the next lane, which is the faster of two travel lanes. There also is a risk of left-hook collisions. I used to ride in the right lane, claiming the lane, and that was simpler and less stressful.

More general comments:

  • The block pavers, bricks and curbstones buried in the street are not bicycle-specific, but certainly not bicycle-friendly. I predict that they will be paved over within a few years as they deteriorate.
  • The attempt to engineer a “bicycle friendly” or “low-stress” solution on busy, crowded Commonwealth Avenue is like ornamenting a pig with lipstick, costume jewelry and a party dress. The bicycle-specific measures, except the bike lane in the underpass, fly in the face of the way traffic works, and the way it uses this street. Experienced, competent cyclists like Gordon and me know how to avoid the hazards, but they worsen our experience anyway — it is in Kenmore Square (during another ride) that I first heard the call “get in the bike lane” in Boston. Less knowledgeable bicyclists garner a false sense of security, following the painted lines, and expose themselves unnecessarily to risk.
  • Meanwhile, other, better solutions beckon. I have long advocated that Boston designate and improve alternative routes on lightly-traveled streets for through bicycle travel. That would be especially easy in Back Bay, with its grid layout. My candidate for an alternative to Commonwealth Avenue would be Newbury Street, the next one to the south, a shopping street which could make a very nice bicycle boulevard, and which, with a little bridge across the Muddy River, would also connect under the Bowker Overpass into the Fenway area. A worse solution also has been proposed: the City is considering a so-called “cycle track” — a bikeway behind a row of parked cars — on the next Street after Newbury Street, Boylston Street. More about these topics later…

Bikes, Cars, Light Rail, E. Jefferson St., Phoenix, Arizona

Build it and they will…wait. Well, at least they’re supposed to wait.

If you click on the title in the image or caption, you can view this at a higher resolution.

Bikes, Cars, Light Rail, E. Jefferson St., Phoenix, Arizona from John Allen on Vimeo.

An intersection with light rail, motor vehicles and bike lanes requires bicyclists to cross from one side to the other of a multi-lane street, resulting in delays of 2 to 3 minutes. Alternative solutions are described.

The Six-Way in Rush Hour

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.

Scaling up and scaling down

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 Six-Way, Washington, DC, a Second Look

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:

  • The bike boxes are very small, also a problem with large numbers of bicyclists.
  • Motorist encroachment into the bike boxes is endemic.
  • Some motorists misunderstand the installation to the degree that they become angry at bicyclists who use it as intended. We were buzzed on one pass by someone driving a big black SUV.
  • Probably 90 percent of cyclists passing through this intersection on New Hampshire Avenue do not use the facility as intended. Rather, most use the crosswalks — commonly going around clockwise. With the option to go either clockwise or counterclockwise, bicyclists can start across on either pedestrian phase, rather than having to wait through as much as an entire signal cycle for the special bicycle phase.

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.

Manufacturing traffic jams on Grand Street, Manhattan

Someone has watched my video of Grand Street, in Manhattan, and commented:

John, I watched the Grand Street video (which was kind of fun) but I couldn’t help but notice you are passing a lot of cars, which makes your average speed seem reasonable for the environment.

That average speed, including waits for traffic lights, was 5.5 miles per hour, half my usual. Yes, I do wait for the lights, though many New York bicyclists aren’t so patient.

Please have a look at the video so you can evaluate the rest of this post. Note especially the bus stopped in the street near the start of the video, because that will play in my comments.

Why were my riding companion John Schubert and I passing a lot of cars — and not only parked cars? The others were stopped cars. Even at 5.5 mph, you can pass stopped cars.

Grand Street is one block north of a major arterial, Canal Street, and carries overflow traffic arriving from New Jersey via the Holland Tunnel. In case you want more detail, I’ve posted photo gallery with maps online. I thank John Ciccarelli, John Schubert and Steve Faust, my companions in exploring Grand Street, for the commentary and photos which they contributed.

Here’s one photo, as an example — and you may click on it to see it in the photo gallery. That’s Steve Faust, in the yellow parka.

Trucks blocking the Grand Street bikeway

Trucks blocking the Grand Street bikeway

Grand Street passes through Manhattan’s Chinatown — accounting for the street vendors standing and walking in the bikeway near the end of the video. Grand Street also is where the infamous Chinatown intercity buses pick up and discharge passengers, to avoid paying to use the Port Authority terminal uptown.

Grand Street now has only one travel lane. A second lane was removed to create the bikeway. Whenever a bus stops — or any other vehicle stops in the travel lane — all other traffic stops and waits behind it. Traffic backs up for several blocks.

The bus drivers park the buses diagonally to prevent motorists from sneaking past and colliding with bus passengers, though this does not prevent bicyclists from sneaking past and colliding with bus passengers. You can see one of the buses parked diagonally near the start of my video.

The traffic backups, then, illustrate the law of unintended consequences. The backups result from the redesign that created the bikeway. Possibly, the designers thought that they would calm traffic by reducing Grand Street from two travel lanes to one, in the hope that the traffic from New Jersey would go elsewhere. It didn’t work. To calm traffic, you have to reduce the actual traffic, rather than to try to cram the same traffic onto a street which can’t accommodate it. Instead of calming traffic, the designers created traffic jams, increasing fuel consumption and air pollution.

My observation about traffic flow before the redesign is confirmed by an early, prototypical pre-Streetfilms video. The video stars Mark Gorton, the money man behind Streetfilms, and shows conditions on Grand Street before the redesign. Motor traffic flowed smoothly. Gorton shows vehicles stopped to load and unload, but they don’t block the street, with a second lane available for overtaking.

Gorton’s main concern is with width of the sidewalks, a valid concern in my opinion, though the sidewalks are in fact only narrow in some blocks, and Gorton takes his advocacy to the opposite extreme. He shows a Photoshopped example of how we need to “return control of the street to the communities that live here and the people that live here” by converting part of the roadway into an open-air restaurant — placing restaurant patrons elbow-to-rear-view mirror with moving motor vehicles, where the diners can enjoy a fine mix of food aromas and exhaust stench. This treatment reflects the influence of the “shared space” designs of British architect Benjamin Hamilton-Baillie. These treatments turn the entire street into pedestrian space, and tame motorists, because they can now safely travel only at pedestrian speed without killing pedestrians.

Tellingly, Mr. Gorton never mentions bicycling. Evidently, he had not yet discovered it.

“Return to the people” is code language for “take away space from motorized uses.” That is, to take control away from people who use motor vehicles and give it to “the people,” who all agree perfectly with the point of view expressed in the video. If that sounds vaguely Leninist to you, well, yes, I think so too. Ah, New York, where a wealthy hedge fund manager sounds off with Leninist rhetoric!

Real-world, American-style political pressures came to bear, and we now see the outcome. It’s rather clear that the community, some community — some people — residents, or business people, probably both, and for better or worse — wanted parking for motor vehicles, because there’s still nearly as much as before. On the other hand, Grand Street now has restricted loading zones — and not enough to meet demand. The business community either didn’t understand what would happen, or had too little political clout to demand more space.

Part of the street’s width was, however, “returned to the people” as a bikeway which is, in reality, a sidewalk extension, an outcome so predictable that I would have to laugh if the street hadn’t become such a traffic tangle, and if I weren’t required by law to ride on that sidewalk extension.

Bicyclists didn’t come out very well in this political exercise, and neither did motorists. Pedestrians came out best. They got their wider sidewalk, even if it is supposed to be a bikeway.

OK, now I’ve complained, so it’s my duty to offer a positive alternative.

Are you expecting a screed now on the joys of bicycling in Manhattan traffic on streets without any special treatment for bicyclists? Sorry to disappoint you, I’m not going to claim that Grand Street was a great street to ride on before the bikeway was constructed.

In my opinion, the Grand Street design is not thoroughgoing enough — not radical enough in one sense and not conservative enough in another. To make the street safe and attractive to bicyclists, including younger and less skillful ones, it would be necessary to displace through motor traffic to another street, and to get bicyclists out of the pedestrian zone. A way to accomplish that would be to traffic-calm Grand Street (or maybe another nearby parallel street) using barriers and diverters, more or less like the ones in Berkeley, California — so the street carries only light, local traffic.

In other words, transform the street into a neighborhood street, whose main purpose is local transportation at neighborhood-friendly speeds, like the bicycle boulevards in Berkeley — not a segregated mess, and not a pedestrian playground like upper Broadway in Manhattan. Many crosstown streets in Manhattan look promising for the treatment I propose, and are quite easy to ride now, even without intentional traffic calming.

If the volume of motor traffic were much lower, we might also consider widening the sidewalks where needed.

You may notice my heresy, from the point of view of segregationist bicycling advocates: some motor traffic must remain, as on the Berkeley streets, so the entire street doesn’t become a shared-space ped zone where pedestrians walk with abandon, and bicyclists have to play dodg’em.

John Schubert and I shot another video on Grand Street the same day. At the end of the video, you may view how motorists harassed us on a section without the bikeway, but while on the part with the bikeway, we waited over a minute for a Chinatown bus to unload, had to ride very slowly at one point behind a man with a food vending cart, and had to ride in the travel lane for several blocks where the bikeway was obstructed.

You might also have a look at this video by a unicyclist. It’s a bit shaky, but he comes to the same conclusions I do.

Green Wave, Checkered Flag?

A green wave moves out, Manhattan, 1986.

I am writing this post in response to comments by Mighk Wilson and Khalil Spencer on another post on this blog. They discussed the difficulty of cycling in a city with synchronized traffic signals (a “green wave”) set to a higher speed than cyclists can manage, and the potential of a slower green wave to make a street more attractive for cycling. I’d like to take a more general  look at the green wave and how it affects traffic.

My understanding of the green wave is based mostly on experience. (And so, anyone who can provide more details based on theory, or can correct me, please do…)

In my high-school years, I lived and learned to drive in Baltimore, Maryland, USA, one of the first cities to implement traffic signal synchronization. I have also lived, driven and cycled in Manhattan, where most traffic lights are timed to create green waves.

A green wave can only work under a limited set of conditions. If these do not apply, then despite best efforts to time traffic lights for the smoothest possible traffic flow, a signal sequence can still appear random. Drivers have no clear strategy for avoiding red lights beyond speeding up when the next light is still green. On the other hand, when a green wave is working smoothly, drivers may feel as if a green-wave Tinkerbelle is darting along overhead and pointing her magic wand at every traffic light to turn it green.

Traffic engineers use clever math so a green wave, surprisingly, can be applied to streets heading in more than one direction the same time — though it words better if they are one-way. Heading north on Charles Street from church in downtown Baltimore, my family would get  green lights for block after block, except at the few two-way streets, where all bets were off. Then as we headed into the more random street pattern at the north end of the city, we just had to take each traffic light as it was. On the other hand, traffic lights were less frequent in this less densely built-up area.

My experience was similar in Manhattan. The green wave worked smoothly on one-way streets and avenues, but  when crossing two-way ones, and when driving on them, it didn’t. This obvious difference gives drivers a strong incentive to use one-way streets and avenues for through travel, where possible. Advocates of the sort who would view streets as a neighborhood resource often protest conversions of two-way streets to one-way, see for example this call to action. Traffic engineers who are concerned with the effect on congestion and crash rates have the opposite opinion — see, for example, this presentation. (I expect that the choice is not quite so stark as these two examples make it — as usual, such decisions must be made on a case-by-case basis.)

A green wave works smoothly only when there are no stop signs on a green wave street, though stop signs can be used on cross streets.  Double-parked vehicles, vehicles that have entered the street and are waiting for a light to change, vehicles — including bicycles — that can’t keep up with the pace set by the signals — anything that slows traffic down or reduces the number of lanes available increases the likelihood of not keeping up with the pase set by the lights.

A green wave often encourages travel faster than the pace set by the signals. That’s because there is an advantage in racing to the front of a platoon — where each signal has just changed to green — when preparing a turn — then after turning, racing to the end of the block so as to catch the end of the green there. A driver may speed through another few blocks to get to the front of the platoon before turning again. The advantage of this tactic is quickly obvious: After turning the corner at the head of a green wave onto another green wave street, a driver will be facing a signal at the next intersection which is about to turn yellow, then red.

The typical 30-mile per hour speed limit in grid cities like Manhattan often leads to motorists’ speeds considerably in excess of that limit, and to more unpleasant conditions for bicyclists.

On the other hand, synchronizing signals to a speed more comfortable for bicycling will discourage use of a street for through motor-vehicle travel, making it more attractive for bicycling. I have ridden on a street in Saint Petersburg, Florida, with the signals synchronized to 15 miles per hour, and it achieved that goal quite well. It would have worked better if it had been one-way — it ran up a moderate slope from the waterfront, and for most bicyclists, 15 miles per hour was hard to maintain. Downhill, on the other hand, the speed setting could have been 20 miles per hour without creating difficulties for bicyclists.

Bear in mind, though, that comfortable level-ground travel speeds for bicyclists cover a 3 to 1 range , from about 25 miles per hour down to 8 miles per hour — not nearly as uniform as for motorists, even considering the issues with motorists’ speed already mentioned. A predictable increase in the volume of electrically-assisted bicycles and motor scooters will complicate the issue of speed setting even further. The advantage of a slow green wave, given these issues, is not so much to allow bicyclists to travel farther before facing a red light as to discourage use of the street for through travel by motorists.