Friday, September 27, 2013


"Roundabout" often gets a bad rap around the Burlington, VT area as it is equated with the failed traffic circle design in nearby downtown Winooski--a traffic circle which roundabouts cure.  Here is the example of a roundabout curing a traffic circle--New York's first roundabout built in 2000 in Kingston.  You could fit two of them inside the Winooski circle,or three of Vermont's two-laner in Brattleboro.  

Check out this Alaska DOT website showing before and after of the Kingston roundie, plus a simple directory covering how the roundabout safely handles walkers and bicyclists approaching from cycle track/bike lanes. roundabout history, U.S. examples 

The Kingston 660 foot (more than two football fields) diameter circle is now
a 220 foot diameter roundabout.  The Winooski circle--really an oval--is about 500 feet by 200 feet.   

(Note Montpelier's first roundabout (1995) is pictured in the section "Roundabout Links" subsection "Roundabouts around the world" as it is the first north of Maryland and east of Las Vegas, the 19th in the U.S).

Still noteworthy, there has yet to be a single walker fatality at the 3,000 or so U.S. roundabouts.

Thursday, September 26, 2013


The Burlington Free Press today bottom page 1 headline said a woman was shot and killed in St. Albans.  The story inside told of an incident at busy signalized intersection at Lower Newton Road and Main Street where the victim turning north on Main Street was almost hit by a car driving north on Main Street reported as running a red light.  The woman then followed the offender about four hundred yards, apparently accosted the driver, they both got out of the car and after some words he shot her several times and she died at the local hospital.

This was not midnight incident--it happened in daylight during the afternoon drive time, about 5:30 p.m.  The weather was fair and sunny, a beautiful early fall afternoon.

The newspaper report termed it a "road rage" incident, but the truth is a roundabout at the intersection would have avoided this fatality--it was clearly a case of a "signal rage" killing. The fatality will never show up on the highway fatality list--as did the death of a young father crossing on a crosswalk some years before and being hit and killed while with his young son.  Both the victim and the alleged shooter yesterday were relatively young adults.  A highway fatality is rated by the Federal Highway Administration as a $6.1 million in total social costs (1999 dollars).  

Roundabouts are a traffic calming treatment, but as a slow speed intersection it creates a social interaction between users--the positive kind of social interactions not the rage and killing kind.

So when the question of whether to roundabout or not to roundabout, keep in mind the kind of killing that takes place at signals, the kind that never gets reported in the road fatality reports.

Wednesday, September 25, 2013


The following is part of a monograph completed earlier this month.  It attempts to explain based on two key research studies of "before and after" injury rates at intersections converted to single lane roundabouts the sharp reduction in injury rates the single lane roundabout--the predominant type--accomplish. 

The basic safety by the numbers for roundabouts—car occupants,
walkers and bicyclists

First and foremost one must consider the incontrovertible evidence that roundabouts substantially reduce injury rates for the principle modes: walking, bicycling and car travel. For overall safety, the authoritative U.S. study by the Insurance Institute of Highway Safety (2000) found anything but a roundabout generated serious and fatal injuries at a rate about 800 percent higher than the average of signals and stop control level.  (The study language that roundabouts reduce serious and fatal injuries about 90% translates—using arithmetic—one roundabout [injury] to [ten] non-roundabout injuries, so one calculates non-roundabout injuries occur at an 900% greater rate.) The roundabouts surveyed in the before and after analysis were both single and multi-lane—and the statistical measures compared the “after” performance against typical intersections thereby avoiding the “reduction to the mean” issue.   Results did to a great extent reflect car travel as the U.S. walking mode share still remains below those of many developed nations, and very far below the bicycle mode share—with American bicyclists primarily younger adult males.

But two studies—one Dutch and the other Swedish—examining single lane
roundabouts clearly show the safety benefits to those who walk and bike reach near the same levels of safety gain as the overall numbers in the U.S. study. And secondary findings of both those studies point to a major breakthrough for bicycle facility design and the pivotal role roundabouts play in that breakthrough…[provision of separate .]paths for both bicyclists and walkers]…

In the U.S. any discussion of the walking and bicycling mode takes place during a time when car occupant fatalities in recent years have decreased, walking fatalities increased, and while bicycle fatalities have decreased the decrease is slower so that overall bicycle fatality numbers represent a slow increase in the overall percentage of U.S. highway fatalities.

Single lane roundabouts will be evaluated—they are roughly about 75% of all
roundabouts built. In Vermont to date 10 of 11 roundabouts are single lane. While studies of two lane roundabout have been produced, recent design practice involvesminimizing roundabout sizes when serving walkers and bicyclists since their safety depends in great part from lower speeds—and smaller roundabouts constrain speeds to a lower level than do larger roundabouts. For example, the Swedish study cited here two-lane data found roughly no change in bicyclist crash rates and possibly a slight increase. However that study reported in 2001 involved roundabouts with about
a 200 foot diameter typically versus the current practice of 150 to 180 foot diameter two-lane roundabouts where serving bicyclists and walkers.
Still, with the knowledge of the sizes of the study roundabouts, it can be concluded that there is a small increment of bicyclist safety at two-lane roundabouts in view of current designs which are smaller and employ on/off ramping or pathing so bicyclists do not have [to] “take the lane”…

Walker and bicyclist safety at one lane roundabouts—anything but a
Roundabout on average generates injuries at rate 200% greater for
bicyclists and 500% greater for walkers

The two best studies to date determining a safety gain for walkers and bicyclists at one lane roundabouts are: (1) “What roundabout design provides the highest level of safety?”, The Swedish National Road and Transport Research Institute (VTI) (2000) and (2) “The safety of roundabouts in the Netherlands” by Chris Schoon and Jaap van Minnen, Traffic
Engineering and Control, March 1994.
The VTI study of 58 conversions of intersections to single lane roundabouts predicted “after” injuries and fatalities based on standard Swedish formulas, formulas applicable to either signals or sign control as Swedish research determined crash experience for both signals and signs were the same. The Dutch study produced before and after
crash data on the conversion of 181 intersections to roundabouts. Most conversions were from sign control though a small number were signal to roundabout conversions.  No such similar studies are possible in the U.S.—even today—for a key reason: Western European nations modal shares of those who walk and bike in urban areas average upwards of third of all trips compared less than a tenth of U.S. urban trips on foot and bicycle. A cross section of Western European walkers and bicyclists represent a cross section of population by age and skills. In the U.S. small proportion of the populace who bicycle tend to be young adults and male. One needs to keep in mind when the Dutch and Swedish study reveal high reductions in either bicycle or walker injuries following converting intersections to roundabouts, those benefitting from the injury reductions are all ages for those who walk, and for bicyclists a cross section of all ages and skills. From another standpoint, the two studies reflect what the United States and other nations with low walking and bicycling levels can expect in terms of safety as walking and bicycling modal shares rise along with the addition of “non-traditional” populations of riders and walkers. The reduction of walker injuries were: (1) Swedish study 78% and (2) Dutch study 89%--an average of 84% reduced incidence of walker injuries, or any intersection other than a single lane roundabout generates, on average, a 740% greater rate of walker injuries. For bicyclists the reductions: (1) Swedish study 75% and (2) Dutch study 30%--an average of 52% reduction, or any intersection other than a single laner roundabout generates, on average, a 108% greater rate of bicyclist injuries.

Because the Dutch study revealed use of a bike lane within the roundabout generated a low percentage improvement in bicyclist safety (about a third of the conversions) that design subsequently was dropped, and other results of that Dutch study indicate that excluding laned roundabouts resulted in a bicyclist injury reduction in line with the Swedish study findings. In turn, the Swedish study—and likewise the Dutch study--found “take the lane” bicycle injuries at roughly 2.5 times the rate of roundabouts with paths which give the bicyclist the choice of taking a path through separate or shared crossings.

So, the Swedish and Dutch studies indicate the true bicyclist injury reduction may reach far closer to the 90%reduction for walkers.  One can expect further studies in this regard in the near future.  In sum, both the Swedish and Dutch studies clearly show a far higher level of safety single lane roundabout versus an alternative—an average reduction of 84% for walkers and at a minimum and likely higher than the 52% reported for bicyclists with users of all ages and skills. The quick adoption of the roundabout by some states and Canadian provinces as the standard intersection rests perhaps as much on the safety performance for walkers and bicyclists compared to signaled and signed approaches of the past as it does for the unquestioned benefits to car occupants.

Monday, September 16, 2013


Note this is an excerpt from a longer monograph written earlier this month.

Major Intersections along high-speed roadways (40 mph and above)--Roundabouts Only

The...Keene [NH] roundabout now going forward by the NHDOT [New Hampshire Department of Transportation] brings out the key reason why—and real world example--roundabouts are the only choice for intersections along high speed roads (40 mph and above)--something, as you know, comes from among others the counsel of Barry Crown, perhaps the most experienced roundabout designer and software author on the planet.  He deserves major credit (though with a lot of help and years of volunteer efforts as you well know) for the $60 million Keene Bypass project being stopped and converted to four roundabouts---one already built handling 60,000 average daily traffic.  The other Keene roundabouts are: (1) the first, a single laner in front of the Monadnock Region Medical Center and (2) a $4 million all-city-financed two laner at Marlboro/Main/Winchester Streets which forms a gateway to Keene State College and along with Central Square defines the downtown core.  

                  High speed intersections and the roundabout

That fifth Keene roundabout on a 55 mph speed zone will be between the Keene Bypass Roundabout and the Keene Turn Roundabout 15 miles distant in Brattleboro, about three miles from downtown Keene at NH 9/Base Hill Road cross intersection.  That intersection along a straight section of NH 9 at the bottom of a long ascending grade to the west has long been a high accident section.  After the latest NHDOT 2010 effort involving a median treatment on NH 9 outward from the intersection and further tweaking of the signals still led to another fatal crash within two years.  The NHDOT in fact truly wants to address the safety there and now--finally it must be said—decided to employ the only known treatment for high speed cross intersections providing a modicum of safety: the roundabout. To deal with the high speed approach NHDOT also intends to utilize a curving of the eastbound approach roadway (the downgrade), a recognized treatment, to constrain approach speeds from the west leg.  While the roundabout does not promise to be a cure all for crashes at high-speed intersections, it surely will reduce the numbers of crashes, the severity of any resulting injuries and avoidance of the T-bone crash.  And at high-speed intersections benefit cost for car travel is highest.  As you know, the Maryland State Highway Administration (MSHA) pioneered along with Florida and Vermont the beginnings of roundabout development in the eastern United States.  And MSHA used roundabout technology to respond to mostly rural high-speed (40-50 mph on one or more approaches) intersections where no solutions had been found to crashes with serious and fatal injuries—roundabouts slashed injury crashes by 88% (see FHWA website:  ).

The Base Hill Road/NH 9 project for the NHDOT does stand above in priority in comparison to other choices, such as the three intersections (perhaps four when you consider the nearby entrance to the new NH 9 to a major shopping complex) along the Keene Bypass--all those intersections except Main Street involve no bicycles or walkers.  As you know a fatality for benefit cost analysis is valued at a  $6.1 million cost and an injury $126,000  (FHWA, 1999 dollars).  (Note the excellent Cambridge Systematics paper prepared showing metro fatalities and injuries more than twice the cost of congestion--the study sponsor, AAA supports a “zero fatality rate” policy, one it calls for declaration through a White House safety conference.)

The foregoing, as did my original message, places the high-speed intersections first and foremost the standard treatment for high speed intersections.  Of course, this entire discussion does apply at all across the lake in New York State (or Florida, Virginia and two Canadian provinces, Alberta and British Columbia) where the roundabouts unless unfeasible remain by policy the preferred treatment.  The New York State Department of Transportation (NYSDOT) backs up their “roundabouts only” policy with a central office roundabout design unit responsible for review of any NYSDOT investment in intersections where something other than a roundabout is proposed.  The fatalities along the US 7 corridor in Addison and Chittenden County alone--even in the absence of bicycle and walker usage--suggest the roundabout treatment even with acquisition of right of way when needed.  Note the Brattleboro Keene Turn Roundabout at $4 million arguably has already paid for itself in reduced injuries per year since 1999 when it was built--about 120 injuries based on the previous five-year rate and not including the one fatality in the last five years of the signal configuration.  And, as you know, tens of thousands of gallons of gasoline are saved each year at this intersection through conversion to a roundabout (note the VAOT study of delay). 

So, what continues today along US 7 major high speed intersections with sigs or signals amounts to a form of "Russian highway roulette" whether at Ferry Road in Charlotte, Ferrisbugh State Highway, VT 103 in Clarendon and the intersections north of that point to U.S. 4 in Rutland (all fatality crash sites), and yes, Little Chicago Road in Ferrisburgh.  Unfortunately conscious decisions to build higher injury rate signals rather than roundabouts at US 7/VT 103, Taft Corners and US 2/Industrial Drive in Williston (now nearing construction and speed limits along those roadway approaches are 30-35 mph) provide us with a test of safety performance of intersections where roundabouts were predicted to perform at a higher level but were rejected for traffic signals.  Over the next few years the wisdom of those choices can be easily observed.  Is it not fair today to conclude what will happen because of the rejection of the roundabout choice will not be pretty?   Finally, the discussion to this point addresses primarily the car mode only, not walking and bicycling aspect  (although a bicyclist fatality did take place at the US 7/Ferry Road intersection).

Wednesday, September 4, 2013



Burlington, VT and other U.S. cities qualify through sincere and good works designations as “bicycle friendly” and “walk friendly” communities.  Yet Burlington like practically Vermont communities and others in North America rarely feature  a single both walkable and bikable busy street for all regardless of all age and skill.

True, Burlington does rightfully boast of its three-decade old Church Street Marketplace, a totally walkable four-block long plaza with three substantial cross street intersections where safe “shared space” takes place with all vehicles yielding to plaza walkers.  Actually, for about two early morning hours when coffee and breakfast eateries operate, an informal bicycle and walker use occurs, a brief period each day when the Marketplace truly achieves a completely walkable and bikable status.

       What qualifies as “bikable or walkable”?

A reasonable definition of a walkable and bikable busy street requires a context where those who walk and bike—regardless of age and skill—can move comfortably with a minimum of delay and with a high level of safety.  Until the advent of the modern roundabout in 1956—particularly single lane roundabout designs which now almost erase delay for all users and for walkers reduce injury rates by 90%--walkability could only occur through plazas and undergrounds other designs which ban cars.  Now corridors, nodes and areas involving busy streets can attain a walkable status using roundabouts, sometimes supplemented by other traffic calming devices.  Of course street segments throughout this discussion presumably include sidewalks.  Walker safety depends first and foremost on restraining vehicle speeds, something roundabouts uniquely do by design besides featuring median treatments as part of crossings so the walker deals when crossing with traffic operating in only one direction at a time. 

Vermont boasts downtown roundabouts in Montpelier and Middlebury with walkability nodes extending a block or so outwards, modest but still important contributions to qualified walkable streets.   Manchester Center joined the Church Street Marketplace as the second walkable corridor in Vermont last November with the completion of the second and third roundabouts along busy Main Street including one roundabout turning “malfunction junction” as it was called in the past for traffic jams during busy times in the upscale retail area to the “function junction” with the new roundabout. 

A bikable busy street remained elusive until the introduction a few years ago in North America of a second European innovation “cycle track”, a bike lane separated from vehicle travelways by curbing, planters, bollards or other barrier types.  The two-mile east-west Montreal DeMaisonneuve cycle track completed in 2007 highlights a major effort in bicycle network investments.  This City project and other bikeway installations extending several miles through the center of Montreal may well have inspired the “bixi” bike, a shared bike system invented and first installed in that City in 2008 and since exported with equivalent rousing success to cities like Melbourne, New York City, London Washington, DC, Boston and Minneapolis.   

While cycle track along with grade separated bikepaths or shared paths can place a street near a “bikable” status, busy intersections, mostly signalized, remain both a delay and safety risk, curtailing bike use by the less skilled, old and young.  In Burlington, the shared path along Riverside Avenue from the Community Health Center to the Winooski Bridge represents a similar case in point—walkable and bikable except for the complex signalized intersections at the Health Center, a second intersection about mid-way to the Winooski Bridge and the final intersection at Colchester Avenue/Riverside Avenue/Barrett, site of a walker fatality in 2012. 

Walkable and bikable now doable—cycle track along street sections and roundabouts at key intersections

But a bikable corridor can be fashioned with cycle track and a “pathed” roundabout at key intersections.  This reaches a bikable and walkable level. A roundabout at key intersections with pathing designed to handle both walkers and bicyclists—separately or in a shared format.  An alternate design—a shared or separate bike and walkway also rates as both walkable and bikable.  A perfect example of a pathed roundabout can be found just south of the City of Plattsburg on NY 9 where a sidepath composed of a two-way bicycle path and a separately marked walkway on the east side of the highway then crosses a roundabout on the east leg—an example of a short walkable and bikable corridor because of the distance between major intersections.

This emergence of a new paradigm of walkability and bikability owes a great deal to the Chicago Mayor Rahm Emmanuel who gave a major boost for cycle track since 2010 with his commitment to build 100 mile of cycle track in his first term, and the initial pages of a new book this year extolling the Mayor’s commitment.  That book, “Reconsidering the Bicycle”, by University of Vermont Professor Luis Vivanco, touted as the first anthropological study of the bicycle, builds on Professor Vivanco’s work as a Burlington bicycle advocate and historian.  Perhaps more important in the roundabout-path connection comes in two secondary research findings in a 1994 Dutch study authored by Chris Schoon and Jaap van Minnen and another study from the Swedish transportation research agency in 2000 (VTI).  In the two nations where a cross section of the population bikes and walks, each study identified the high level of safety gain at intersections converted to single lane roundabouts for bicyclists as for walkers (as compared to signed and traffic signal intersections) when roundabouts are combined with paths so that bicycles avoid having to “take the lane” to travel through the roundabout and instead use the separate or shared use crosswalks.   

In sum, the formula for converting existing streets and building new streets to attain walkability and bikability remains straight forward—cycle track/separate bike or shared paths for bicyclists, shared paths or sidewalks for walkers, and pathed roundabouts at key intersections.  Plans already exist plans in Vermont and elsewhere either ready to go or easily revamped to carry out the new walkable-bikable design formulas.  Case in point, again, Manchester Center where its 1995 called for a pedestrian circulation plan of all roundabouts on its T shaped street grid of Main Street and Depot Street.  The Main Street corridor of roundabouts completes the Main Street part of the plan and a revision of the Depot Street plan to include cycle track appears feasible and the completion of Depot Street includes about three roundabouts, including converting two traffic signals.  The entire shopping mecca becomes a walkable area and its east west spine—walkable and bikable.  And not a single traffic light in sight!   Putney Road in Brattleboro awaits construction funding for converting the three traffic signals south of the Keene Turn Roundabout to roundabouts and installing full walking and bicycling on each side of the roadway—thereby reaching full walkable and bikable status.  Now all that remains is for Vermont transportation planners and policy makers at all levels to use the walkable and bikable formula to remake our urban areas and town centers into truly havens for walking and bicycling.