Austin’s “Great Streets” Plan Will Endanger Citizens
COST Commentary:The report below ends with the following paragraph about a study in the mid-1930’s. This 2009 report verifies that today’s busy, two-way streets have the same accident-prone, dangerous characteristics as those in the 1930’s.
“Sidis (or Mulligan) was right. The failure to understand the value of one-way streets is leading to unnecessary human injuries, destruction of property, excessive fuel consumption, and wastage of space in American cities. If the present movement to eradicate one-way flow is not stopped, the price paid will be enormous. Rather than convert remaining one-way streets to two-way, it would be beneficial if more two-way streets, in suburbs and small towns as well as large cities, were made one-way, as is being advocated now in Los Angeles, New York, and elsewhere and as has been done in much of Europe.”
As Mr Cunneen, the author of the paper below, states: “Those who want to convert one-way streets to two-way streets ignore a lifetime of accident studies showing one-way streets to be much safer.”
Austin’s Comprehensive Plan, with its “Great Streets” program, has already resulted in conversion of downtown one-way streets to two-way streets and numerous additional conversions are planned for the near future. For the reasons stated below, COST recommends this ill-advised street conversion trend cease immediately to better protect our citizen’s safety and provide enhanced mobility with reduced pollution.
CONVERTING ONE-WAY STREETS TO TWO-WAY STREETS CREATES HIGHER ACCIDENT RATES
Michael J. Cunneen, April 2009
The Traffic Calming Movement’s Crusade Against One-Way Streets
One of the oddest movements making headway in North America over the past quarter-century has been one led by urban planners and neighborhood activists in many cities to eliminate one-way streets, converting them back to two-way flow. This movement began with those who had opposed the creation of one-way streets but now has spread to a new generation unacquainted with why one-way streets were created and what impact a reversion to two-way flow has.
Not knowing the impacts has not hindered advocates in propagating their ideas about why one-way streets are bad and should be eliminated or why they think two-way flow would be beneficial. Whole web sites have been dedicated to this issue, advocating the elimination of one-way streets, and local politicians and activists have championed this cause, causing many one-way streets to be eliminated and many more to be placed under study to be eliminated. Many books on urban planning, beginning with Jane Jacobs’ “The Death and Life of Great American Cities”, attack one-way streets as favoring traffic flow over neighborhood “livability”.
The advocates for two-way flow claim that one-way streets were only created to better move a higher volume of traffic and operate simply as urban roadways that deliver high volumes of traffic at high speeds through cities, dividing neighborhoods and intimidating pedestrians, and generally existing only to enhance an automobile-oriented culture. In contrast, they claim that two-way streets would be more “pedestrian-friendly” and safer as traffic operates at lower speeds on these while less two-way traffic can be carried. Therefore, they say that converting one-way streets back to two-way flow is a “traffic calming” measure, improving safety and promoting pedestrian and bicycle movement as opposed to auto travel. The “pedestrian-friendly” claim has generally been used the most, frequently coupled with other beliefs that a reversion to two-way flow would help promote or popularize a downtown area such conversion is planned for. Emphasized most of all is that reversion to two-way flow would slow down traffic, thereby enhancing safety and making things generally nicer.
A recent report by the Rand Corporation on transportation improvements for Los Angeles noted that “the primary motivation for one-way to two-way street conversion plans was to help … bike- and pedestrian-friendly … districts” and that “Two-way streets are generally considered to have lower vehicle speeds than one-way streets and are thus more accommodating to pedestrians and bikers” with “a higher-quality environment for pedestrians and cyclists”. They believe that two-way streets are “more accommodating to pedestrians and bikers” and yield “a higher-quality environment for pedestrians and cyclists” (see page 274, Rand Corporation, Moving Los Angeles: Short Term Policy Options for Improving Transportation, October 2008, MG-748-JAT/METRO/MCLA).
Advocates have been so successful that many cities have or have had programs just to convert one-way streets to two-way flow and publicly label this as a “traffic calming” or a “safety” measure, or both. Even in major cities where city transportation departments tend to favor one-way streets, such as New York City and Los Angeles, many community groups advocate a reversal of policy and actively prevent more streets being converted to one-way flow.
The Evidence from the Past on One-Way Streets
The main reason why the city departments of transportation in New York, Los Angeles, and elsewhere have favored one-way flow is the lessons they draw from city impact studies done mostly in the 1940’s and ‘50s to asses what happened when they first converted two-way streets to one-way flow. These studies generally found that under one-way flow, accident rates were considerably lowered, especially for pedestrian accidents, while traffic was able to flow with less delay and greater speed.
Almost universally these older studies found that one-way streets had 10-40% lower accident rates than when previously two-way. Most significantly, pedestrian accidents declined far more, by 30-60% (see pages A-126; A-162, National Highway Safety Needs Study, Appendix A, Research Triangle Institute, March 1976 (DOT-HS-5-01069); Pages 7-2 to 7-8, “One-Way Streets and Reversible Lanes”, Synthesis of Safety Research Related to Traffic Control and Roadway Elements, Volume I, Research Triangle Institute, March 1976 (FHWA-TS-82-232), December 1982; Page 28, Dr. Charles Zegeer, University of North Carolina, “Pedestrians and Traffic-Control Measures”, National Cooperative Highway Research Program, Synthesis of Practice, #139, November 1988; and Chapter 10, Peter A. Mayer, “One-Way Streets”, Traffic Control and Roadway Elements, Their Relationship to Highway Safety, Highway Users Federation for Safety and Mobility, 1971).
Typical of the positive safety experience achieved by converting to one-way streets was that of Portland, Oregon. The City of Portland converted most of its Downtown area to one-way on March 1, 1950. Their before-and-after data (1949 versus 1951) on the streets that were converted found that vehicular accidents decreased from 6,127 to 3,361 (-45.1%). Adjusting for the increase in volume, the vehicular accident rate per vehicle volume (the standard measure) actually decreased 58.1%. The number of pedestrian accidents on the downtown streets that were converted decreased from 237 to 126 (-46.8%). Adjusting for the increase in volume, the pedestrian accident rate per vehicle volume actually decreased 59.7% (see Fred Fowler, “One-Way Grid System for Portland, Oregon”, Traffic Engineering, April 1953). This vast increase in safety was achieved even though volumes increased from 12,734 to 16,708 vehicles (+31.2%) and average speeds increased from 7.9 mph to 14.2 mph (+79.7%). The conversion to one-way was also credited with aiding bus transit, reducing delays, and increasing access to the downtown area.
In 1959, the Oregon State Highway Department published a report which summarized the overall impact of converting two-way state highway sections to one-way couplets through town and city centers in twelve smaller Oregon cities. The weighted average traffic accident rate declined 24% while the weighted average pedestrian accident rate declined 38% (see Oregon State Highway Department, A Study of One-Way Routings on Urban Highways in Oregon, Technical Report #59-4, April 1959). This report remains as one of the most comprehensive scientific investigations of the safety impacts of one-way flow on record.
Impact studies done by New York City for 5th and Madison Avenues found that after being converted to one-way in1966 accident rates dropped by 38% overall with accident injuries declining by 28% while both traffic volume and speed increased. Similar studies in London, England found that conversion to one-way there resulted in accidents declining up to 40% while speeds increased (see page 808, Institute of Transportation Engineers, Transportation and Traffic Engineering Handbook, 2nd Edition, 1987. Studies for Hamilton, Ontario for 1956-1960 found that conversion to one-way flow there resulted in a 17% reduction in accidents (see Chapter 10, Peter A. Mayer, Chapter 10, “One-Way Streets”, Traffic Control and Roadway Elements, Their Relationship to Highway Safety, Highway Users Federation for Safety and Mobility, 1971 ). Similar results also were observed in small cities. A 1957 conversion to one-way in Modesto, California resulted in a 57% decrease in pedestrians injured and a 10% decrease in overall accidents even though average speed was doubled (see Douglas Carmody, “First Year Report on Modesto’s One Way Streets,” Street Engineering, December 1958)
The Evidence from Recent Studies on One-Way Streets
Few cities that have converted one-way streets to two-way will release accident impact data on this change. Typically, studies favoring two-way avoid any real before-and-after data on vehicle or pedestrian safety or avoid the safety issue altogether. Three cities that have produced before and after data on conversions to two-way flow are Denver, Colorado, Lubbock, Texas, and Cincinnati,Ohio. All three of these cities found that major increases in accident rates were the result of reverting to two-way traffic.
In 1986 Denver converted seven streets on three one-way couplets. They found that average intersection accident rates increased 37.6% while average mid-block accident rates increased 80.5%. The City report noted that accident rates were up on all three couplets “as is expected with two-way operation” (see Pages 15, 23, and 29, City of Denver, One-Way Street Monitoring Study, Phase 1 Conversion Report, January 1990). In spite of this the City of Denver rated the conversion as a “success”.
Lubbock, Texas in 1995 converted two downtown streets back to two-way. Overall accident rates increased there 41.6% (see City of Lubbock, Main and 10th Street Accident Analysis, Before/After Study, 1998). The before and after accident data for Lubbock have appeared in few places outside the City government. However, advocates for two-way conversion have long used the Lubbock experiment as proof of success, largely by ignoring this data and relying instead on an article published in the ITE magazine which claims the conversion produced no accident problem in Lubbock (with no supporting data).
The study done for the City of Cincinnati,Ohio is the latest and most comprehensive of these. This Cincinnati report is the most useful done recently for a city transportation department in that it monitored impacts on a major street both when converted from two-way to one-way in 1975 and also when the same street was converted back from one-way to two-way in 1999 (see Edwards and Kelcey Associates, Over-the-Rhine/Vine Street Circulation Study, February 2003).
While many in favor of reconverting one-way streets to two-way often claim that city studies are so old as to be not worthy of examination this study is both recent and based on a 1999 street conversion. Table 1 summarizes the before and after conditions found for the November 1999 conversion from one-way to two-way flow on Vine Street while Table 2 summarizes the before and after conditions found for the August 1975 conversion from two-way to one-way flow on Vine Street.
The Cincinnati report found that a 15% increase in daily traffic volumes occurring on Vine Street when converted from one-way to two-way. There was also a 31% decrease in average vehicular speed that occurred when the street was converted from one-way to two-way. This slowing down of speed was “expected”.
•Volume refers to total weekday traffic volumes counted on Vine Street between 12th Street and Findlay Street/McMicken Avenue for 1995 and 2002 (Table 1)
•Average speed is given in miles per hour. This refers to total time from one end of the street section to another, including time spent idling in 1995 and 2002(Table 7).
•Total accidents refers to the average annual number of accidents on Vine Street between 12th Street and Findlay/McMicken Streets in 1991-97 versus 2000 (Table 4).
•Pedestrian accidents are all those on same section of Vine Street (Table 4).
•Intersection accidents are all those at intersections in the same section of Vine Street (Table 4).
•Midblock accidents are all those in between intersections on same section of Vine Street (Table 4).
•Volume refers to total weekday traffic volumes counted on Vine Street between 12th Street and Findlay Street/McMicken Avenue for 1974 and 1976 (Table 1)
•Total Accidents refers to the average annual number of all accidents on Vine Street between 12th Street and Findlay/McMicken Streets for the 1972-74 average versus 1976 (Table 4).
•Pedestrian accidents are all those on same section of Vine Street (Table 4).
•Intersection accidents are all those at intersections in the same section of Vine Street (Table 4t.
•Midblock accidents are all those in between intersections on same section of Vine Street (Table 4).
The report notes that: “With only one travel lane, more congestion occurs and travel times are higher and speeds lower” (under two-way flow). Average speeds were, however, fairly low both before and after this conversion. The average speed when one-way was 18 miles per hour. Under two-way flow, this decreased to 12.4 miles per hour. The report further notes that with two-way flow ”congestion and delays were prevalent” along Vine Street and that “traffic moves less efficiently under two-way operation … with resultant congestion and delays” (page 59). The change from one-way to two-way flow more than doubled the time it took to drive down this 3,133-foot section of Vine Street, from two minutes to over four and a half minutes and interfered with local bus operations.
As the slower two-way street is “not user friendly” (page 59), another phenomenon is taking place: “motorists are driving around this area, probably avoiding the congestion along Vine Street” (page 58). This would mean some traffic is being exported to parallel streets as “motorists are using alternate routes” (page 58).
Converting this one-way street to two-way flow resulted in a massive increase in accidents with the overall traffic accident rate going up by 116%. In contrast, when the street had been two-way but then converted to one-way flow the accident rate had decreased nearly 40%.As the report notes:
“The total of all reported accidents and pedestrian related accidents had fewer incidents when Vine Street was one-way. The assumption that one-way streets provide safer traffic operations for both motorists and pedestrians is true for Vine Street …. Two-way traffic introduces multi-directional flow with more conflict points, turning movements, and resultant congestion, hence more exposure to potential accidents” (Pages 3, 59).
The report further notes:
“It is generally assumed that, all other things being equal, one-way traffic on a street will provide safer traffic operation than two-way traffic, both for motorists and pedestrians.” (Page 22) .
The safety benefits for pedestrians in this study, as found in several other studies, indicate that pedestrian safety in particular is enhanced by one-way flow. When the street was originally made one-way in 1975, the pedestrian accident rate declined by over 21%. In contrast, when it was changed in 1999 back to two-way, the pedestrian accident rate increased by 103%. Pedestrian accidents increased both at intersections and much more so at mid-block locations (Table 4, page 26) when the street reverted to two-way flow. The Business Courier of Cincinnati article on this study (“Study: Keep Vine Street 1-Way in OTR”, June 21, 1996) noted that “it was a pedestrian fatality in 1975 that led to making Vine one-way through Over-the-Rhine”. As the report notes (page 3) “there were no reported fatal pedestrian accidents” in the one-way period analyzed.
The study asked the local bus operator, Metro (Southwest Ohio Transit Authority) for an assessment of two-way operation on the six bus routes (with 243 weekday bus trips) that operate on Vine Street. It was not good: “Metro has had to lengthen their bus schedule times along Vine Street due to the increased congestion” (page 60). Metro’s letter on the change to two-way reports that “the changes to Vine Street have had a negative affect on Metro bus operations …. (with) more delays”. With only one lane in each direction “a left turn can block all northbound traffic”.
Recent Evidence from Downtown Albuquerque, New Mexico
Because of the widespread claims for one-way to two-way conversion being “pedestrian-friendly” and “bicycle-friendly” and appropriate for downtown areas, the author sought a major city downtown area that had been extensively converted from one-way to two-way street flow. The prime example was found in the downtown area of Albuquerque, New Mexico. There, city planners had implemented a host of pedestrian-oriented features and had, between 1999 and 2003, converted 62 blocks from one-way to two-way street flow on what had been four different one-way couplets. The four street couplets involved were Copper and Gold Avenues (converted in June and July of 1999), 2nd and 3rd Streets (converted in November of 2001), 5th and 6th Streets (converted in June of 2003), and Coal and Lead Avenues (converted in July of 2003). Signal devices showing a digital readout of the number of seconds left for pedestrians to cross the street and other pedestrian-oriented measures had also been implemented as part of this “pedestrianization” of downtown.
These special pedestrian measures, coupled with the great size of the area covered by this conversion and the availability of up to four years worth of before and after data per street made downtown Albuquerque the most comprehensive test of converting to two-way flow. The entire study was made by the author from NMDOT accident data and MRCOG traffic volume data and City of Albuquerque reports on the conversion.
This independent study found that conversion from one-way to two-way flow in this major downtown area had resulted in a 33.9% increase in the overall accident rate with the pedestrian accident rate going up by 134.9% (more than doubling) and the bicycle accident rate going up by 213.7% (more than tripling). Table 3 shows composite results for the downtown area. The reasons for these changes are discussed later in this report.
Prior to the conversion from one-way to two-way flow downtown, the City had converted a section of two avenues just outside the downtown area to two-way flow in June of 1996. These were Coal and Lead Avenues between 8th and 14th Streets. By applying the same data to this conversion the author was able to find that this had resulted in a similar 37.9% increase in overall accident rate with the pedestrian accident rate going up by 16.6% and the bicycle accident rate going up by 249.9%.
•The four street couplets involved were Copper and Gold Avenues (converted June and July 1999), 2nd and 3rd Streets (converted November 2001), 5th and 6th Streets (converted June 2003), and Coal and Lead Avenues (converted July 2003).
•Volume refers to total weekday traffic volumes counted from a sample of counts on all four street couplets involved, averaging four years before and four years after conversion.
•Total accidents refers to the number of reported traffic accidents four years before and four years after conversion from NMDOT data.
•Pedestrian accidents are the number of reported pedestrian accidents four years before and four years after conversion from NMDOT data.
•Bicycle accidents are the number of reported bicycle accidents four years before and four years after conversion from NMDOT data.
Misconceptions Regarding One-Way Street Conversions
General Safety: The author has yet to find any comprehensive before and after study on accident rates for any American city showing that accident rates declined after converting one-way flow to two-way. On the contrary, all data found showed the opposite to be the case. In every recent case found wherever one-way streets were converted to two-way flow, accident rates increased substantially. The City of Albuquerque data on this seems especially conclusive as it covers a large potion of a major downtown area with four years of data both before and after the directional conversion. The comparatively recent data from Albuquerque, Cincinnati, Denver, and Lubbock seems to confirm what the studies of the 1940’s and ‘50’s showed: one-way streets are considerably safer.
Speed and Safety: The author has yet to find any comprehensive before and after study on accident rates for any American city showing that accident rates declined after converting one-way flow to two-way. On the contrary, all data found showed the opposite to be the case. In every recent case found wherever one-way streets were converted to two-way flow, accident rates increased substantially. Speeds also were reduced. The City of Albuquerque data on this seems especially conclusive as it covers a large potion of a major downtown area with four years of data both before and after the directional conversion. The City of Cincinnati data shows conversion to two-way reduced speed by over 31% but also increased accidents by over 87% (with pedestrian accidents up by over 76%).
The “traffic calming” advocates generally stay far away from actual accident data, preferring to concentrate exclusively on the misleading issue of traffic speed. Nearly all their claims for safety are predicated on the mistaken belief that lower speeds must mean greater safety. The Cincinnati study in particular disproves this: going two-way did greatly slow down traffic but also increased the traffic accident rate. Some of the older studies from decades ago showed a similar pattern in reverse: going one-way did speed up traffic but also decreased the traffic accident rate. There is no correlation between speed and safety; as one-way streets are inherently simpler and involve far fewer turning movements, they tend to be safer regardless of speed. It should be noted that with roadways in general, the fastest class of roadways (freeways, expressways, motorways) has the lowest accident rate while the slowest roads (local streets) typically have the highest accident rates.
Why One-Way is Safer for Vehicles: There are several dynamics at work here. First, far fewer turns can be made at intersections on one-way streets so there are far fewer turning conflicts. (Many articles favoring conversion to two-way claim the opposite, confusing the turning dynamics of one-way with two-way and usually inserting the language from old reports favoring one-way flow into their arguments for two-way flow without realizing they do not apply.) Second, traffic moving all in the same direction either prevents or greatly reduces the likelihood of some types of vehicle-to-vehicle collisions. Third, one-way flow lends itself best to traffic signal coordination such that traffic can continue moving at the same speed yet meet one green signal after another by sticking to that speed; this consistency in flow enhances safety and allows greater attention to be focused by the driver on matters beyond his own vehicle. Fourth, left turns can be made without waiting so that vehicles waiting to make a left turn are not rear-ended or side-swiped as they are on two-way streets. Fifth, with the greater traffic signal coordination and lesser delay, traffic moves smoothly at fairly uniform speed, the speed governed by signals. This leads to traffic grouping into “platoons” with wide gaps left on the street between these platoons. These wide gaps make it easier and safer for side street traffic to either cross or turn onto the major one-way street. This impact was visible in the older studies in which accidents relating to side street traffic declined greatly
Among the “benefits of one-way streets” cited in the 2008 Rand study for Los Angeles was that they “allowing existing lanes to be widened …” Widening lanes is a well-proven safety benefit that lowers accident rates. Two FHWA studies with data from several states found that widening lanes from 10 to 12 feet on two-lane rural highways would reduce accidents by 10-23% (see Page 2, “Safety Effectiveness of Highway Design Features, Volume III, Cross
Sections”, November 1992 (FHWA-RD-91-046); and Table 7, “Prediction of the Expected Safety Performance of Rural Two-Lane Highways”, Midwest Research Institute (FHWA-RD-99-207), 1999). The same two studies showed that widening from 9-foot to 12-foot lanes produces even larger gains of 15-32%. The Rand study also notes that one-way streets are “safer to make left turns on”.
Why One-Way is Safer for Pedestrians and Bicyclists: With traffic grouping into “platoons” with wide gaps not only side street vehicular traffic benefits but anything seeking to cross the one-way street has an easier time. Hence, the wide gaps make it easier and safer for pedestrians and for bicyclists to cross the street. This impact was visible in the older studies and in the most recent ones; one-way helps pedestrian and bicycle movement to be safer to a far greater extent than it does vehicular movement. In fact, almost no other measure improves pedestrian safety as does one-way flow. Regarding pedestrians crossing one-way streets, one leading safety expert noted: ”Conversion from two-way to one-way street systems has consistently been found to reduce pedestrian accidents” (Dr. Charles Zegeer, University of North Carolina, “Engineering and Physical Measures to Improve Pedestrian Safety”, from 1988 WALK ALERT Program Guide, National Pedestrian Safety Program).
Two-way streets typically have twice the pedestrian accident rate of one-way streets so they are definitely not “pedestrian-friendly”, as is widely being claimed. The value of one-way streets for pedestrian safety is well appreciated in the pedestrian capital of North America. The New York City DOT continues to convert more two-way streets to one-way flow and publicly claims it as a pedestrian safety measure, a claim well substantiated by their before-and-after data going back for decades.
Another report done for the USDOT on safety contained this assessment of pedestrian safety and one-way streets:
“Perhaps the most effective urban counter-measure has been the one-way street … one-way streets not only increase the capacity and efficiency of busy roads but also greatly reduce vehicle-pedestrian conflicts. Jones, Repa, and Potgiesser (1974) indicated the following reductions in pedestrian accident totals as a result of conversion to one-way street systems: Sacramento, California 62%, Hollywood, Florida 51%, Raleigh, North Carolina 50%, Portland, Oregon 50%.” (see Page A-128, Research Triangle Institute, National Highway Safety Needs Study, Appendix A, 26U-1090-13 (DOT-HS-5-01069), Raleigh, NC March 1976).
Speed and Severity of Accidents: Some opponents of one-way flow are not impressed by the before and after accident data showing it to be safer because they believe that data does not tell the full story. They believe that with the greater speed under one-way flow the accidents that do happen must be more severe and result in more injury and damage.
There are three major problems with this theory. First, as usual, the opponents cannot point to any real data substantiating this theory. A final version of this report will deal with this more as the Albuquerque accident data is classified by severity of accident and other data exists detailing injury accidents before and after directional conversions.
Second, it is far better not to be involved in any accident whatsoever and the data shows this is what one-way flow achieves.
Third, the people who fear that speed is so linked to severity misunderstand what data there is on traffic speed in these studies. Nearly all these studies generally give results in terms of “average speed”. What that means is the average speed from one point to another, the “average” including time in which vehicles are idling at a stop and not moving. This is not the same as “moving speed”, the speed at which vehicles move when they are actually moving, with no idling time included. A typical study would show that under two-way flow, vehicles were delayed (not moving but stopping for red lights) for 100 seconds and had an average speed of 20 miles per hour. The same study would then go on to show that under one-way flow, vehicles were delayed (not moving but stopping for red lights) for only 40 seconds and had an average speed of 25 miles per hour. Sounds like the one-way vehicles are moving 5 miles per hour or 25% more faster, doesn’t it ? That is universally the way that two-way advocates take this information.
The trouble is that the one-way vehicles may actually be moving at pretty much the same “moving speed” as under two-way flow. The higher “average speed” is the result of them spending less time stopped before red lights. The speed when they are moving may be the same as before but the “average speed” (total time from one point to another, including time spent idling) is higher. The failure to understand the difference between “moving speed” (as in how fast it’s moving when it’s actually moving) and “average speed” (based on total point-to-point travel time) has led to misinterpretation of data and the misconception that one-way greatly increases speed. Examining the data from DOT speed studies actually shows that the real change in “moving speed” (eliminating delay time) is considerably less than the change registered under “average speed”. This data is usually ignored because it shows the speed differences to be much smaller than “average speed” differences. Also ignored is that speeds under one-way flow are closer to the posted speed.
The Quack “Public Health” Case Against One-Way: One tactic that traffic calming advocates have turned to is to use people with medical degrees to write articles claiming some “public health” benefit for measures they support. This is especially so when real accident data does not support their claims, as with one-way flow, and where people unfamiliar with traffic safety are prone to draw erroneous conclusions.
A few years ago an article appeared in the Journal of the Canadian Medical Association making such a case against one-way flow (see Wazana, Rynard, Raina, Krueger, Chambers, “Are Child Pedestrians at Increased Risk of Injury on One-Way as Compared to Two-Way Streets ?”, Journal of the Canadian Medical Association, May 2000). The authors claimed that they had found a higher pedestrian accident rate on one-way streets in Hamilton, Ontario. This article has been widely used to support the case against one-way. What is wrong with it is that the doctors who did this study were not using the normal accident rate per traffic volume as used in traffic engineering studies (though it has been misrepresented as such). Instead they were using the rate of pedestrian accidents per linear mile. They found many more pedestrian accidents per mile on one-way streets than on two-way streets. Of course they found this and would find the same in nearly all North American metropolitan areas. This is because one-way streets were put in downtown and other areas where there are very high pedestrian crossing volumes whereas the bulk of two-way streets are small, residential streets with negligible pedestrian crossing volumes. What the authors did not realize was that all they had discovered was that there were many more pedestrians crossing one-way streets not that they were less safe to cross. Had they bothered to count those crossings they might well have discovered that while 2.5 more pedestrians were injured crossing one-way streets, the number crossing may have been over 5.0 times that of two-way streets. The rate per volume of pedestrian crossings (odds of being hit) was likely about half that of two-way streets.
To apply the “logic” used in the JCMA article further, one would find that there are several hundred times as many pedestrian accidents per mile in Manhattan as there are in South Dakota. Therefore, South Dakota is fantastically safer for pedestrians than Manhattan and Manhattan should be entirely redesigned to look like South Dakota. This kind of illogical “incidence” cause-and-effect thinking, by the way, has become rife in traffic calming reports dealing not only with one-way but speed humps and other measures.
Why One-Way Does Not Lead to Longer Trips:Some people argue that the benefits of one-way flow are counter-balanced by forcing drivers to drive further and make longer trips as they cannot always go directly the way they wish on a one-way network. The Rand report makes the statement that “one-way operation will increase the required travel distance for many trips … leading to increased trip distances and … increased travel times”. (see page 278, Rand Corporation, Moving Los Angeles: Short Term Policy Options for Improving Transportation, October 2008, MG-748-JAT/METRO/MCLA).
This is speculation, not the presentation of scientific evidence. The typical urban arterial vehicular trip is 3-5 miles (maybe roughly 20,000 feet); the typical extra distance added by one-way systems is perhaps about 2 blocks (500 feet). This adds only 2-3% to the distance and this only for motorists with origins or destinations on the one-way segments, not for through trips. The far steadier speed profile, accompanied by fewer stops and less stop-and-go speed changes with one-way flow, would likely result in less delay, less overall travel time, less fuel consumption, and less pollution generated even with this slight addition in distance. With less delay the one-way trip time will be shorter than under two-way flow even if the physical distance is slightly longer.
Why One-Way is Better for the Environment: One-way operation permits much better traffic signal progression for smoother traffic flow. This results in traffic moving at regulated speeds with less stop-and-go driving. Less fuel is consumed and there is less air pollution. Another benefit is in conservation of space. Because one-way streets move more traffic per lane than two-way streets cities with one-way systems need to devote less space to roadways. Four lanes of a one-way couplet carry as much traffic as a seven-lane two-way street. The main reason for this is that special left-turn signal phases and lanes are not required. At intersections a one-way approach requires only one signal phase and no extra lanes.
The Transpo Group did a study for Bellingham WA, in which conditions were simulated by computer model for existing one-way versus change to two-way, quantified an enormous increase in air pollution and delay. Many similar area reports have been done showing the same thing. The higher level of idling and delays experienced under two-way flow leads to greater air pollution and fuel consumption. One-way leads to less pollution and less fuel wastage.
Why Traffic Calmers Don’t “Get It” About One-Way Streets: The “traffic calming” movement shows little knowledge regarding real traffic safety and typically ignores or denies actual accident data. Traffic calmers believe that whatever impedes automobile movement must be good and that reducing automobile speed is inherently good. They simply favor whatever hinders and slows vehicles and are oblivious to the impact on safety, including pedestrian and bicycle safety. Most studies they like only measure changes in speeds and neglect any accident analysis.
The author was told by one such advocate that accident data does not matter because “We ought to be concerned with the accidents that might happen in the future and not the ones that have happened”. This is a common view among traffic calmers. It is also an anti-scientific and anti-rational attitude: the only real data we can measure safety by is to be neglected whereas subjective impressions about theoretical accidents that don’t happen are given great weight. Traffic calmers need to think scientifically, stop being in denial, look at real data, realize their theories are wrong, and accept the proven fact that one-way streets represent a “win/win” situation, good for vehicles, good for pedestrians, good for bicyclists, and good for transit. The one-way street is, in fact, a rather good traffic calming device.
What Can Be Done to Promote One-Way Streets: The author will be transforming this short report into a longer, more comprehensive one, incorporating data from other studies and providing references to other studies on this subject. In final form, this can act as a resource for use in court cases, public hearings, other studies, and so forth to influence state and local government policy on this issue. Many cities and regions have laws or planning guidelines that preclude them from implementing something that would make streets less safe. The challenge is to show them, or show a court, that a conversion to two-way flow does make streets less safe and endangers the public.
The knowledge has been out there for a lifetime that one-way streets are safer, especially for pedestrians. Enough data on this had been gathered in the 1920’s and ‘30’s that in 1936, America’s “boy genius”, William James Sidis, wrote an entire book (under a pseudonym) about traffic safety, in which his top recommendation was to: and, Sidis (or Mulligan) was right. The failure to understand the value of one-way streets is leading to unnecessary human injuries, destruction of property, excessive fuel consumption, and wastage of space in American cities. If the present movement to eradicate one-way flow is not stopped, the price paid will be enormous. Rather than convert remaining one-way streets to two-way, it would be beneficial if more two-way streets, in suburbs and small towns as well as large cities, were made one-way, as is being advocated now in Los Angeles, New York, and elsewhere and as has been done in much of Europe.
“…. extend the use of one-way streets to cover all streets … to have safe and convenient conditions for pedestrians” as “ one-way streets help the pedestrian to an extraordinary extent” such that “The one-way operation of roads will insure a large measure of safety for pedestrians crossing at any point”.He further wrote:
“The advocacy of the universal use of one-way streets is the most fundamental suggestion embodied in this book … there does not appear to be any important reason why streets in cities should be operated upon the two-way principle”.
“The best solution would extend the use of one-way streets to cover all streets … from a safety standpoint then, this is the most logical reason for adoption of one-way method”.
“Safety considerations … Are wholly in favor of the one-way idea.
(Source: pages 100, 106, 134, 212, 251, and 256, Barry Mulligan, Collisions in Street and Highway Transportation, Dorrance & Co. Philadelphia, 1936.)
Michael Cunneen is a Senior Transportation Analyst, formerly working for the Port Authority of New York and New Jersey, with the Metropolitan Service District of Portland, Oregon and with Kittelson & Associates of Portland, a Transportation Engineering/Planning firm. Mr. Cunneen has studied, analyzed, evaluated and written extensively regarding traffaic impacts including street conversions from two-way to one-way and the reverse, alternative transit systems, safety impacts of speed humps and other devices, and the impact of light rail systems. He has a Masters of Science Degree in Tansportation Planning and Engineering from Polytechnic Institute of New York.
Sidis (or Mulligan) was right. The failure to understand the value of one-way streets is leading to unnecessary human injuries, destruction of property, excessive fuel consumption, and wastage of space in American cities. If the present movement to eradicate one-way flow is not stopped, the price paid will be enormous. Rather than convert remaining one-way streets to two-way, it would be beneficial if more two-way streets, in suburbs and small towns as well as large cities, were made one-way, as is being advocated now in Los Angeles, New York, and elsewhere and as has been done in much of Europe.