More on Walkableness on Busy Streets--Roundabouts/Traffic Calming vs Signs/Signals

Walkableness on Busy Streets Defined by Slowing Vehicle Speeds Along Streets and Intersections Through Traffic Calming and Roundabouts, the Way to Substantially Attain Walk Mode Safety at Busy Street Crossings

Residents and policy makers increasingly search for proper treatments on busy downtown and village center streets and intersections to in order to reach walkable status.  Generally streets of concern are designed for or feature 25 mph speed limits.

However you approach it, minimizing serious injuries and fatalities on busy streets for those on foot requires, first, reducing vehicle speeds at crossings and, second, cutting the spread between high and low speeds along streets overall.  This appears to apply to both intersections and mid-block situations.  Mid-block crossings are of particular concern becaust about a fifth of all walker deaths occur at mid-block. 

Traffic signals and stop signs may bring vehicles to a stop, but they also foster high speeds between intersections and crossings as well as high speeds at mid-block.  And in the case of vehicles at signals, racing the stale green or amber behaviors are routine occurrences.  Traffic signals and sign controlled intersections experience about the same level of pedestrian injury rates. 

Crossing treatments involving signs or signals in the absence of traffic calming treatment very likely retain unacceptably high rates of injuries.  The one treatment which drops serious injuries at an intersection up to 90% while also reducing cruising speeds up to two blocks distant is the roundabout.  The roundabout functions as an injury reducer at the intersection itself and traffic calms speeds few hundred feet in each direction.  It is the one treatment experience reveals where the more roundabouts installed the better the injury rates of all existing roundabouts.  And as a U.S. study of over 50 roundabout corridors through vehicle travel times vary little at roundabouts versus signs and signals mostly because lower between intersection travel speeds are balanced by reduced vehicle delay at the roundabout intersections.

A variety of pedestrian signals are being introduced in urban areas as mid-block treatment without any traffic calming at all, that is, without installing roundabouts nearby and no traffic calming (vehicle speed reduction) at the mid-block crossing location itself.  Traffic calming at the mid-block crossing can take the form of vertical calming like a raised crossing, or a horizontal treatment like a median diverter which forces a vehicle slightly off a straight path thereby lowering vehicle speeds at the crossing. 

As Mark T Johnson emphasized in a roundabout workshop in Burlington, VT in March 2015, the roundabout reduces the range of speeds—low and high—along a corridor.   At an intersection, the roundabout uniquely allows the average vehicle to move through the roundabout at 5-15 miles an hour versus a stop sign or stoplight constraining all or a sizeable portion of the traffic flow to essentially 0 mph.  Between intersections the roundabout also reduces speeds, traffic calms, so the difference between the lower “cruising speed” created by the roundabout outward a block or two and within roundabout speed is further reduced.  The difference between a stop sign speed, 0 mph, and cruising speed along at 25 mph street may easily be 25, that is 25 mph-0 mph.  A roundabout by contrast with basic vehicle speed at the roundabout of 8 mph may also reduce the cruising speed by 5 mph to 20 mph, so the speed differential drops to 12, about one half the speed differential found at signals or sign controlled intersections.  The reduced difference between high and low speeds on roadways does provide another measure determined empirically of how roundabouts cut serious injuries by about 90%.

In conclusion, it is fair to question the installation of traffic signals of any type without traffic calming of some kind if a basic purpose is to increase walk mode service and safety.  At mid-block crossings installing walk signals in the absence of traffic calming also leaves walk mode crash rates unacceptably high.  Ideally, mid-block crossings with the best walk mode safety involve both traffic calming elements at the crossing and roundabouts at adjacent intersections. 

END URBAN AMERICA "UN-TRANSPORTATION" NOW!

AMERICAN UN-TRANSPORTATION OF CARS-ONLY MUST CHANGE TO INCLUDE WALKING, BICYCLING AND PUBLIC TRANSIT

Americans know first hand cars still dominate urban transportation—and anyone who travels to other advanced nations, particularly Western Europe, experiences what our transportation system could offer—sensible and safe walking, bicycling and public transportation along with supporting infrastructure for each mode.  

While ten percent of urban trips here are walking (nine percent) and bicycling (one percent), European urban trip shares typically amount to double digits for each non-car mode.  Public transit share of urban trips here?  Just three percent.  Even Canada with similar walking and bicycling shares reaches 13 percent public transit share and almost double the U.S. total of walking, bicycling and public transit share of urban trips of 13 percent.  America today truly presents a picture of un-transportation.

The solution to the urban U.S. un-transportation can, thankfully, follow the discoveries and applications of treatments now decades old in Europe.  Europe always did have an excellent rail passenger train network now featuring a new plateau of service provided by high speed rail lines which criss-cross the continent and extend to the British Isles through the Chunnel.  (The Europeans actually copied the first major high speed rail line, built in Japan, which has yet to experience a single fatality in more than a half century of operation.) 

There exist three major walking and bicycling innovations in Europe which provide both mobility and safety even on busy streets and thoroughfares.  For street sections sidewalks remain the key to the walking mode.  But for bicycles the invention of the cycle track—bicycle lanes protected from parked vehicles and travel lanes by curbs, cones or planters—provide an equality of the bicycle enjoyed by only cars and walkers in the past.   Cycle tracks emerged towards the end of the last century as a solution to the growth of car travel in Europe which caused ever increasing fatalities to bicyclists and in many cases crowding the bicycle off busy streets altogether.  (The story of cycle track in the Netherlands at UTube  http://www.youtube.com/watch?v=XuBdf9jYj7o  provides an excellent history of cycle track emergence and applications.)

The second innovation dates from 1966 in the U.K.—the modern roundabout.   With over 3,000 roundabouts in the U.S. and Canada now this intersection device performs magic—it cuts serious injuries and fatalities upwards of 90 percent, reduces delay for all users and cuts both gasoline consumption and pollutants by sizeable amounts.  While walkers and car occupant injury studies found indisputable benefits for both, bicyclist safety impacts were mixed.  For bicyclists smaller roundabouts do provide a modest safety gain—and now on/off ramps are being introduced, a treatment aimed at less expert bicyclists.  Further, the provision of a separate bicycle path or multi-use path at intersections assures a definite increment of safety for bicyclists at single lane roundabouts and likely one at multi-lane roundabouts.  A pathway for bicyclists at roundabouts needs to become standard practice.  For bicyclists, cycle track along street segments combined with roundabouts with a separated pathway present an infrastructure improvement unlocking the bicycling mode in urban America.

The overall category “traffic calming” represents the third innovation in bicycling and walking infrastructure, again a set of evolving treatments first developed in Europe and quickly adopted in the United States starting in the 1990s with the first emphasis  here their use on local streets.   Speed humps/tables/bumps, bulb-outs, median diverters, and also roundabouts are just examples of literally dozens of traffic calming designs.  Speed constraints on traffic provide a safer and more comfortable environment for walking and bicycling.   Traffic calming provides that environment.   For example, vehicle yielding to walkers reaches 100% when speeds at intersections are in the range of 0-10 mph.  The safest environment for walking and bicycling—again, a European innovation—is “shared space” where a number of traffic calming treatments are applied in a defined area where walkers and bicyclists retain the right of way over vehicles.

The three innovations—cycle track, roundabouts and traffic calming—apply to the walking and bicycling modes.  But efficient and effective public transit depends on a walkable, bikable community.  U.S. urban designer Peter Calthorpe emphasizes a walkable community must be in place for successful public transportation services.

Making a transportation system in the United States means investing heavily for the first time in the infrastructure for walking and bicycling at a rate of tens of billions of dollars yearly for a decade or so—that is just the federal level of funding required.  That level of funding leads to lower support costs for existing public transportation but also a much greater demand for new public transportation routes and services, particularly commuter rail and light rail. 

The payoff for these investments is clear.  First these investments promise reduced injury and fatality rates for all modes.   Car dependency declines along with associated urban congestion, improved air quality, and reduced energy consumption.  Health benefits from more walking and bicycling occur.  And perhaps most important, higher levels of urban density arise which in turn reduces car travel and fosters greater use of public transportation and the “active modes” of walking and bicycling.  The American economy benefits from the presence of an efficient transportation system and the disappearance of our current urban carcentric “un-transportation.”

CITY REDUCES ALL SPEED LIMITS TO 25 MPH, 20 MPH IN BUSINESS DISTRICT

A few years ago any suggestion of enabling towns to set speed limits under 25 mph quickly found the legislative waste basket--today the City of Burlington, VT starts the process of setting the maximum speed on all streets of 25 mph and the business district 20 mph (two streets excepted with a 30 mph limit).

The reason for lowering urban speed limits comes from the desire to improve walker safety--30 mph is the speed where the chance of surviving is a 50-50 proposition and at 20 mph walkers survive over 90% of the time.  All the traffic calming imported from Europe over the last two decades apparently brought a public opinion shift to the belief that speeds can be reduced in a way that does not cause much discomfort or hassle for drivers while bringing lots of comfort and ease of moving through busy intersections to those on foot.

Still, North American walker injury rates per mile of travel remain several times higher than those in urban Netherlands and Germany in a study by John Pucher of Rutgers University.  A key treatment, the emerging modern roundabout, reduces injuries by up to 90% while reducing delay for all users--another key encouraging citizens and public works folks that yes, you can improve walking and car traffic at the same time.  (The roundabout also cuts serious injuries for car occupants by 90%.)  The critical feature of the roundabout comes from its design which forces vehicles to slow speeds.  

 Still there exists another plateau for speed management which can be applied to lower volume streets including most residential areas and town and city centers, a speed limit of 0-10 mph.  This type of speed context already exists at the three cross streets at Burlington's Church Street Marketplace, including Cherry Street where upwards of 100 buses cross from the transit terminal just west of the Marketplace.   Europe already features this next plateau, termed "shared space" and in the U.K. "naked streets" where the low 0-10 mph speeds allow mixing of all modes with the safest movement for all users.  The "shared space" style design further features a total absence of signs and traffic signals. 

So, the new walking renaissance can now begin and Burlington soon be joined by hundreds of urban areas can move to impose the much slower vehicle speeds needed for the safety and comfort of those who walk the streets.