Pedestrian safety around light rail a balance: transport experts | Canberra Times

Finbar O’Mallon writes for the Canberra Times “Pedestrian safety around light rail a balance: transport experts“. I get quoted …

A pedestrian was struck by a light rail vehicle at the intersection of Northbourne Avenue and Barry Drive on Saturday morning.

University of Sydney transport expert David Levinson said in European cities trams shared the streets with pedestrians.

“It’s not a problem. Part of it’s the speed and the expectation,” Professor Levinson said.

But Professor Levinson said at Northbourne Avenue, pedestrians were crossing six lanes of traffic and now two tracks.

“That’s eight different points where someone can come in and hit you and you’re trying to make the decision before that happens,” he said.

“That’s a complicated thing for a human to do.”

He also suggested having one consistent green light for pedestrians when crossing Northbourne so they could travel across the entire avenue instead of having to stop midway.

“Cars don’t have to stop halfway through the intersection, why would pedestrians need to?” Professor Levinson said.

Professor Levinson also warned against overloading the network with safety warnings.

“You put a sign everywhere, no sign means anything. You put a sign nowhere and no one has any information,” Professor Levinson said.

Professor Levinson said getting it right was a balance.

Putting up fences risked making it too restrictive for pedestrians, having safety supervisors at major intersections would be too expensive in the long term and loud warning horns would disturb people living in or using the area, he said.

“You want this to be a self explaining experience for the pedestrian.”

Obviously the local engineers on the project, in consultation with the community, will have to consider the alternatives and site in-depth, and test various strategies. This is an issue many LRT systems face, including those in Minneapolis and St. Paul, and I expect the City and Southeast Light Rail in Sydney.

Eleven Sydney council areas where pedestrians die more than motorists

Nigel Gladstone in the Sydney Morning Herald wrote “Eleven Sydney council areas where pedestrians die more than motorists“. I got some choice quotes:

Professor of transport at the University of Sydney David Levinson said changing the way Sydney’s traffic signals give priority to cars over pedestrians in busy areas was one way to stem the flow of injuries.

“This inequality [in traffic light phasing] undermines many of the stated goals of transport, health and environment policy,” Professor Levinson said. “Creating an environment that is better for pedestrians with separated footpaths, easy and frequent safe road crossings, generally slower cars and trucks, better trained and more law-abiding drivers (via police enforcement) will reduce the likelihood of fatalities.”

Road deaths have been increasing in both NSW and the US recently, while most other OECD nations are reporting fewer fatalities.

One theory [Referring to: Chi, Guangqing, Jeremy Porter, Arthur Cosby and David Levinson (2013) The Impact of Gasoline Price Changes on Traffic Safety: a Time Geography ExplanationJournal of Transport Geography 28 1-11. [doi] ] is that as more people can afford to be on the road, drivers with less experience, who tend to be younger, and therefore more dangerous, are added to the mix of motorists.

“When there’s economic expansion, people are working more hours and they probably get a bit more aggressive,” Professor Levinson said.

Research [by Wes Marshall] comparing Australian and American drivers found the rate of fatalities was more than twice as high in the US, where more than half of drivers do not stop or yield to pedestrians at crossings.

In Hawaii’s capital Honolulu, fines for pedestrians who text while crossing the road at traffic lights began this year.

In the City of Sydney, one in three people crossing the road is using a mobile phone and it’s time pedestrians “start owning this problem as well”, Pedestrian Council chief executive Harold Scruby said.

“Pedestrian deaths and serious injuries are going through the roof,” Mr Scruby said. “There is nothing that we’re seeing that the government is doing to help pedestrians.”

Hitting pedestrians with a $200 fine for using a mobile phone while crossing the road, even on the green man phase, is on Mr Scruby’s agenda.

“There’s no barrier there just because the light’s green. Half of the drivers coming towards you are on the phone too,” Mr Scruby said. “If you’re hit as a pedestrian, the driver will be automatically drug and breath tested but that’s a box they [police] have to tick, no one then goes looking for the mobile phone, there’s no box to tick.”

Professor Levinson said fining pedestrians was “basically a form of victim blaming”.

“Distracted pedestrians don’t kill drivers or passengers. Distracted drivers kill pedestrians,” he said. “Deaths are due to high speed and high mass, and drivers of two-tonne machines have an obligation to be more alert.”

In the three years to 2017, one pedestrian was killed and 25 were seriously injured while distracted by a mobile phone. But this is likely to be an under-reported issue, as it relies on witnesses telling police and other forms of evidence.

There are no plans to introduce penalties for people using mobile phones while crossing roads in NSW, a Transport for NSW spokesman said.

 

I also got to be ABC Radio Illawarra Friday Morning (talking about traffic safety), and ABC Radio Adelaide Friday Afternoon (talking about Beg Buttons) (first few minutes of this).

Are Australian Vehicles Getting Bigger?

ABC Radio Sydney called me and asked essentially:

`Are Australian Cars Getting Bigger?’

The short answer is ‘No.’

AustralianNewCarMarket.003

Using data from the Federal Chamber of Automotive Industries that was once freely available online, and is now behind a paywall, I have produced graphs illustrating the Australian vehicle market.  The data show among the passenger cars: medium, small, light, and micro are all gaining in proportion of passenger cars, rising from half the passenger car market to 83% since 2000.

But

`Are Australian Vehicles Getting Bigger?’

The answer here is ‘Yes.’

As will be no surprise to Australians, or North Americans (See Canada data), the share of Sports Utility Vehicles has exploded since the beginning of the Millennium from about 13% to 39%, and now more SUVs are sold each year than passenger cars.

AustralianNewCarMarket.001

AustralianNewCarMarket.002

This trend, which mirrors that in the US, helps explain Ford’s recent decision to exit most of the passenger car business in the US.

Now 50%  of 70% is 35% (small cars share of all vehicles in 2000) while 80% of 38% is 30% (small cars share of all vehicles in 2017), so the share of small and medium cars of all vehicles is falling. But the total market of vehicles sold in Australia is still increasing from 787,000 in 2000 to 1,189,116 in 2017, and 30% of cars sold in 2017 is more than 35% of cars sold in 2000, so there are still more in terms of total number of small and medium cars sold in 2017 in total than 2000, even if it is a declining share of the market.

The Australian government also conducts a Motor Vehicle Census and just as the number of new cars sold each year rises with population growth, the total number of vehicles is also rising. This differs from the US, which has more or less peaked in cars per capita, and perhaps cars. I graphed this data for NSW for selected years (this data, is also, inconveniently, not in one place)

AustralianNewCarMarket.005

The reason for more SUVs vs. large cars are speculative. That is, why do people now prefer SUVs and not station wagons or big cars? It’s not as if people actually do a lot of off-road driving.

One is the idea of the extreme trip. Sometimes (say once a year or even once a month) a very large car would be useful. So instead of renting the specific vehicle when they want it, SUV-owners buy the vehicle they would use 1% of the their trips (or 0.05% of their time – since cars are only used 5% of the day anyway, and at rest the remainder, sleeping more than even cats), but which is too large 99.95% of the time.

One answer is the car Arms Race. In a taller car, the driver can see farther ahead (drivers are less likely to have their view obscured), which lets tall vehicle drivers anticipate better. It makes drivers feel safer, which they are for themselves, even when they are not for others.

More people are killed because of SUVs and light trucks, in the US, Michelle White estimated in 2004 “For each 1 million light trucks that replace cars, between 34 and 93 additional car occupants, pedestrians, bicyclists, or motorcyclists are killed per year, and the value of the lives lost is between $242 and $652 million per year.” Presumably the same logic holds in Australia.

Increasing the mass of vehicles on the road doesn’t do society any favours from an energy consumption, or air pollution perspective either. And of course, larger vehicles use more space, consuming more land in parking lots (which are now often restriped to accommodate more massive vehicles) and roads, where the width of lane consumed by larger cars rises, providing less manoeuvrability for other cars.

With the rise of autonomous vehicles, and especially vehicle sharing, the right sized vehicle will be summonable by app, so when travelers need the specific type of car for a large trip with many people, they can get it. The rest of the time, drivers will be able to use a car fit for purpose, one that holds one person for a one-person trip, and two people for two-person trips, and so on. This opens up the potential for skinny cars, enclosed electric cycles, and many other appropriate vehicles, which take up less road space, making it even easier to improve the environment for other road users, including walkers and bicyclists.

Toyota iRoad one-passenger concept cars, image courtesy Toyota.
Toyota iRoad one-passenger concept cars, image courtesy Toyota.

DEFINITIONS:

Passenger Motor Vehicles Passenger vehicles are classified dependent on size, specification and average retail pricing. Selected vehicle types will be assessed on footprint defined as length (mm) x width (mm), rounded, as follows:
Sports Utility Vehicles Vehicles classified as Sport Utility Vehicles (SUV) meet the FCAI criteria for classifying SUV vehicles based on a 2/4 door wagon body style and elevated ride height. Vehicles typically will feature some form of 4WD or AWD, however, where a 2WD variant of a model is available it will be included in the appropriate segment to that model.
Light Trucks Vehicles designed principally for commercial but may include designs intended for non-commercial applications.
Heavy Trucks Vehicles designed for exclusive heavy commercial application.

Car sizes:

Micro Hatch, sedan or wagon with a footprint < 6,300
Light Hatch, sedan or wagon with a footprint range 6,301 – 7,500
Small Hatch, sedan or wagon with a footprint range 7,501 – 8,300
Medium Hatch, sedan or wagon with a footprint range 8,301 – 9,000
Large Hatch, sedan or wagon with a footprint range 9,001 – 9,500
Upper Large Hatch, sedan or wagon with a footprint range 9,501 >
People Movers Wagon for passenger usage, seating capacity > 5 people
Sports Car, coupe, convertible or roadster

SUV Sizes:

Light Duty 3,501 – 8,000kg GVM
Medium Duty => 8,001kg GVM & GCM < 39,001
Heavy Duty 8,001kg GVM & GCM > 39,000

Light Truck Sizes:

Light bus < 20 Seats 8+ seats, but less than 20 seats
Light Bus > 20 Seats 20+ seats
Vans/CC <= 2.5t Blind/Window vans and Cab Chassis <= 2.5t GVM
Vans/CC > 2.5–3.5t Blind/Window vans and Cab Chassis between 205 and 3.5 tonnes GVM
Pick-up / Chassis 4×2 Two driven wheels, normal control (bonnet), utility, cab chassis, one and a half cab and crew cab
Pick-up / Chassis 4×4  Four driven wheels, normal control (bonnet), utility, cab chassis, one and a half cab and crew cab

Heavy Truck Sizes:

Light Duty 3,501 – 8,000kg GVM
Medium Duty => 8,001kg GVM & GCM < 39,001
Heavy Duty 8,001kg GVM & GCM > 39,000

Cage the Automobile

Is the purpose of bollards to keep people in or keep cars out? A reader writes:

 

Bollards done wrong, Egypt.
Bollards done wrong. It’s a long pedestrian street, would you bollard the entire street,  because they are proposing low risers. You will end caging the people like in Egypt.

After the attack in Toronto last week with a guy driving a van and killing 10 people and injuring 15, Montreal announced a new plan for Saint Catherine street making it pedestrian friendly, with a nice wide sidewalk showing young people walking, yet  when the mayor was asked if they planned for pedestrian safety from such attack she said ‘no, we did not.’

So the moral question: should we change our planning for pedestrians to ensure safety from a crazy person in a van, terrorists, drunk drivers,  just incapacitated drivers. This is not the first, and will not be the last, time a driver plows down pedestrians. By doing so we show weakness to terrorists? Are we converting the outdoors to a Zoo placing pedestrians in cages. Should the woonerf, for example, be like an open zoo.

It’s a moral and ethical question how much separation should we have in an era when crazy people uses cars as weapons to kill random humans. How many incidents and deaths will it take to change the approach for pedestrian environments to make it as safe as air travel.  If we  add more small obstacles, how much will they spoil the pedestrian environment and sense of freedom.

 

The crazy person in a van problem is only going to get worse with automation and especially connectivity, a remote control car bomb is even easier than a suicide.

This Delft Bollard is a casualty of the Car Wars.

In my view, cars should be in the cages, the people should be free. And then the cages need to be made smaller and smaller.

All urban streets in heavily pedestrian trafficked areas should have bollards or equivalent to keep the cars away from the people. Woonerfs are fine for residential streets, and if people want to encroach on shared space that is also fine, but cars should not encroach on people space. Just as we don’t let cars in most buildings, there should be outdoor public spaces where they are also prohibited.

We don’t need fences or chains like in the photo of Egypt, just lots of posts (trees, bike racks, benches, bus stops, street furniture, planters etc.) that make it impossible for a car to run down the sidewalk or into buildings. This furniture of course should not interfere with the free flowing movement of people, and might require taking lanes from the storage, or even movement, of cars. As with all good urban design, examples of this are in Delft, with some lowerable Bollards to allow service, emergency, and freight vehicles in when needed.

 

Delft defining Pedestrian domain.
Delft, lowerable Bollards on a bridge

 

 

 

 

 

Safety in Numbers: Pedestrian and Bicyclist Activity and Safety in Minneapolis

Recent Report:
AbstractThumbnail
This investigation aims to evaluate whether the Safety in Numbers phenomenon is observable in the midwestern U.S. city of Minneapolis, Minnesota. Safety in Numbers (SIN) refers to the phenomenon that pedestrian safety is positively correlated with increased pedestrian traffic in a given area. Walking and bicycling are increasingly becoming important transportation modes in modern cities. Proper placement of non-motorized facilities and improvements has implications for safety, accessibility, and mode choice, but proper information regarding estimated non-motorized traffic levels is needed to locate areas where investments can have the greatest impact. Assessment of collision risk between automobiles and non-motorized travelers offers a tool that can help inform investments to improve non-motorized traveler safety. Models of non-motorized crash risk typically require detailed historical multimodal crash and traffic volume data, but many cities do not have dense datasets of non-motorized transport flow levels. Methods of estimating pedestrian and bicycle behavior that do not rely heavily on high-resolution count data are applied in this study. Pedestrian and cyclist traffic counts, average automobile traffic, and crash data from the city of Minneapolis are used to build models of crash frequencies at the intersection level as a function of modal traffic inputs. These models determine whether the SIN effect is observable within the available datasets for pedestrians, cyclists, and cars, as well as determine specific locations within Minneapolis where non-motorized travelers experience elevated levels of risk of crashes with automobiles.
Recent publications from this report include:

Speed vs. Safety

March 21 [Updated with more accurate estimate/figure after fixing an excel bug] How fast should we drive? From a social cost perspective, faster speeds save time, which has a value, but faster speeds cost lives, which also have a value. To illustrate the trade-off I did some back of the envelope calculations, imagining, like a macro-economist, a single road represents the whole t

Speed vs. Safety (updated)
Speed vs. Safety (updated)

ransport system. Annually there are about 30-40,000 people killed in the US, there are an annual Vehicle Miles Traveled of 3,208,517,000,000. The average speed of travel isn’t known directly, but if we assume the average person travels in a car 60 minutes per day (the 1 hour travel time budget) this implies, at approximately 30 miles of travel per day per traveler, about 30 MPH, which seems about right (including 1/4 of travel on freeways at higher speeds and 3/4 on surface streets and roads at lower speeds, and including traffic signals). As the saying goes, Your Mileage May Vary, and this is intended to be indicative — not a universal answer. Some additional assumptions:

  • We take the Value of Life to be $10,000,000, and assume fatalities are the only cost associated with crashes (they are about 78 % of total crash costs according to our analyses, so we should inflate this number to get total crash costs) [US DOT says $9.6 M]
  • We take the Value of Time to be $15/hour [US DOT gives a lot of ranges, but this number is high for all surface travel excluding freight]
  • We assume the number of deaths drops linearly with speed, to zero at zero MPH. The improvement is likely non-linear, as reductions in speeds from high speeds are more valuable than from low speeds.
  • We assume the value of travel time savings is constant, independent of the amount of time saved.

To be clear, these are huge assumptions. Examining the figure we see the lines cross at about 75 MPH, which is the minimum total cost. So why don’t we set the speed limit to  75MPH? Note that:

A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
A Political Economy of Access: Infrastructure, Networks, Cities, and Institutions by David M. Levinson and David A. King
  • Travel time savings are, while still speculative in terms of their valuation, both private and real,
  • The statistical value of life is far more abstract. The value of my life to me is infinite. The value of your life to me is, sadly, not. Yet, I am willing to take risks that increase the probability of my dying in order to save time or earn more money. These are the kinds of factors that allow an estimate of value of a statistical life.
  • Death and crashes are probabilistic affairs, while the time lost is deterministic. People are gamblers.
  • There are some other benefits to faster travel not accounted for, such as more or longer trips (to better destinations, or the ability to get better real estate at the same price), which increase consumer surplus. The analysis here does not consider user response to lower speeds, which would be to travel less (or higher speeds and travel more).  There are also issues like travel time reliability.
  • Since 1988 The Statistical Value of Life has risen 6-fold in US DOT estimates, the value of time has little more than doubled. (If we cut the value of life to $3M, (effectively holding the tradeoff more similar to 1988 levels), the tradeoff is much higher .)
  • Speed limits reflect what travelers will travel at, not what we wish they would travel at.

If you dislike these number, you can roll your own analysis on individual roads. The difficulty is not measuring the speed of those roads, but measuring their safety. There is a Highway Safety Manual for such purposes, but crashes are highly random events.

UPDATE 2: Axel Waleczek made an interactive Tableau, so you can test your own scenarios.

Additional Readings

Uber’s self-driving car killed someone today

Uber’s self-driving car killed someone today. This is terrible tragedy, and in retrospect, it will probably be judged to have been preventible. Future versions of the software will better address the scenario that led to this crash. But mistakes are how people and systems learn, and someone was going to be the first. The victims are scarcely remembered.

A few key points.

  • The safety rate for Uber AVs collectively is now worse than that for human drivers (1.25 pedestrian deaths / 100MVMT) (MVMT = Million vehicle miles traveled) (Uber is at about 1 MVMT, Waymo at about 4MVMT). It will undoubtedly get better.
  • Don’t assume Uber AVs are the same as Waymo or others. Different software, vehicles, sensors, driving protocols, safety cultures. The stats for each will differ.
  • Also we need to see the full investigation (from NHTSA, NTSB).
    • How much victim blaming will there be?
    • Was it just sadly unavoidable?
    • Or was it preventable?
  • The opposition will use this to bang on against AVs while supporters will be quiet for a while.

Hopefully the developers learn something and this type of crash is rare. Other AV makers will take the scenario and run it through their own simulations and field tests.

Still the technology trajectory is strong, and even if the US slows down development, it’s a big world. China won’t slow down development.

How Railways Dealt With The First Notable Fatality:

The Liverpool and Manchester Railway killed former Leader of the House of Commons and cabinet member, William Huskisson during the opening day ceremonies. It was the UKs 2nd significant steam railway and the first that was opened with a big deal with   such publicity. We write in The Transportation Experience

On September 15, 1830, the opening ceremonies for the Liverpool & Manchester Railway were held. The Prime Minster (the Duke of Wellington), Cabinet members, Members of Parliament, and other assorted dignitaries were present. Among those were an MP from Liverpool, and a 60 year old former Leader of the House of Commons and cabinet member, William Huskisson. The dignitaries had been riding on a train pulled by one of Stephenson’s Rockets. Reports differ, but Lady Wilton, an observer on the same train wrote to Fanny Kimble:

The engine had stopped to take a supply of water, and several of the gentlemen in the directors’ carriage had jumped out to look about them. Lord Wilton, Count Bathany, Count Matuscenitz and Mr. Huskisson among the rest were standing talking in the middle of the road, when an engine on the other line, which was parading up and down merely to show its speed, was seen coming down upon them like lightening. The most active of those in peril sprang back into their seats; Lord Wilton saved his life only by rushing behind the Duke’s carriage, and Count Matuscenitz had but just leaped into it, with the engine all but touching his heels as he did so; while poor Mr. Huskisson, less active from the effects of age and ill-health, bewildered, too, by the frantic cries of `Stop the engine! Clear the track!’ that resounded on all sides, completely lost his head, looked helplessly to the right and left, and was instantaneously prostrated by the fatal machine, which dashed down like a thunderbolt upon him, and passed over his leg, smashing and mangling it in the most horrible way.

Stephenson personally helped Huskisson onto a locomotive and traversed 15 miles in 25 minutes (57.9 km/h) to receive medical attention in the nearby town of Eccles. But it was for nought. Huskisson amended his will and died within the hour. (Garfield)

This was not the first death by steam locomotive, it was at least the third, but it was still the most notable. Wikipedia notes

5 December 1821, when a carpenter, David Brook, was walking home from Leeds along the Middleton Railway in a blinding sleet storm. He failed to see or hear an approaching train … and was fatally injured.” — Richard Balkwill; John Marshall (1993). The Guinness Book of Railway Facts and Feats (6th ed.). Guinness. ISBN 0-85112-707-X.

According to parish council records, a woman in Eaglescliffe, Teesside, thought to be a blind beggar, was “killed by the steam machine on the railway” in 1827– “Corrections and clarifications.” The Guardian. 2008-06-21. Retrieved 2009-02-05.

Despite this inauspicious beginning, both passengers and freight services (the latter opened in 1831) were immediate successes.

Why Looking at Crash Stats Alone Doesn’t Tell the Whole Story About Pedestrian Safety | Streetsblog

Stephen Miller at Streetsblog writes Why Looking at Crash Stats Alone Doesn’t Tell the Whole Story About Pedestrian Safety: New research from Minneapolis shows that there is safety in numbers for pedestrians.

This map shows the number of crashes involving pedestrians in relation to the number of people who walk at a given location. Via Murphy, Levinson, and Owen

This map shows the number of crashes involving pedestrians in relation to the number of people who walk at a given location. Via Murphy, Levinson, and Owen

Some intersections are riskier to cross than others, but looking at the number of pedestrian injuries alone doesn’t tell the whole story. A new study from Minneapolis combines crash data with pedestrian counts to deliver a more nuanced picture of traffic dangers for people on foot. Among the findings: There’s safety in numbers for pedestrians.

Using data from the city government, University of Minnesota researcher Brendan Murphy and his co-authors looked at 448 intersections where both pedestrian counts and automobile counts were available, then cross-referenced that data with the city’s crash reports. They found a strong negative correlation between the number of pedestrians and the risk of being hit by a car.

While the study found people are less likely to be struck by a driver at locations where lots of people walk, it does not establish causation, Murphy says. “We don’t have good statistical evidence to show that if a place is safe, people will walk — or in the other direction, that if people are walking, they make the place safer,” he says. “I personally think it’s a bit of both.”

Per person, pedestrian-rich areas downtown and near the University of Minnesota pose a low risk for people walking, though they have a high absolute number of pedestrian crashes. Quieter intersections in more residential neighborhoods also pose a lower risk.

A few streets jump off the map as high-risk areas, like Lake Street, which runs east-west across South Minneapolis, and Penn Avenue in North Minneapolis. Both are used by a steady if not enormous number of pedestrians, but are meant first and foremost to move lots of cars. “We can ask, ‘How are those roads designed?’” Murphy says. “They are two lanes each way, no shoulder or bike lane.”

The study looked at all crashes involving pedestrians, not just injuries and fatalities, in order to include enough data points to reach reliable conclusions. It also looked at the stats from 2000 to 2013 in aggregate, rather than year-by-year, so it doesn’t take into account intersection redesigns or major changes like the opening of a light rail line. If there were enough data, Murphy says, “it would be really nice to do a year-by-year analysis.”

The study did not consider the relationship between pedestrian risk and income or race, but the authors say that needs attention. “Equity is a very big problem in terms of pedestrian safety and poor and minority people are getting killed by cars at much higher rates,” Murphy said.

The authors hope their research will lead to better measurements of pedestrian safety and methods to improve it. In 2016, the U.S. Department of Transportation’s four-year strategic plan set a goal of reducing fatalities for pedestrians and cyclists to 0.15 per 100 million vehicle miles traveled by 2016. But that’s the wrong way to look at the problem.

“If we frame pedestrian deaths in terms of VMT, we’re really framing it in terms of automobiles themselves and car traffic,” said Murphy. “We should be focused on reducing pedestrian deaths as a percentage of the pedestrian population.”

There’s also a need for better data collection. Cities and states regularly collect standardized data on car and truck traffic, but there’s no standard for non-motorized users. This data is often collected manually and its reliability varies from city to city. In Minneapolis, three counts throughout the day at each intersection were added together to create a six-hour total. Other cities have different methods.

“Ideally we would like to have our cities wired up and know how many pedestrians are crossing each intersection,” Murphy says. “We need to focus in on the pedestrian population and really ask ourselves, where are they really experiencing undue burdens of risk and what can we do about it?”

On Blood Alcohol Content

Candace Lightner, founder of Mothers Against Drunk Drivers recently published a counter-intuitive op-ed against lowering the blood alcohol content (BAC).

Hopefully everyone agrees that if there were fewer drunk drivers on the road, there would be fewer deaths from drunk driving. Hopefully everyone also agrees that BAC is correlated with impairment. The blood alcohol content limit, currently 0.08 in the US, is 0.05 in many other countries of the world. Should the US lower the BAC?1280px-Ljubljana_car_crash_2013

The argument against is that pulling over safe drivers (say in a police screenline, where all drivers on a road are pulled over and briefly tested) takes police resources that could be better spent pulling over observed dangerous drivers. Lightner writes: “Every dollar spent enforcing DUI laws against sober drivers is one not spent on getting the worst offenders off our roads.” Perhaps 2 drivers at 0.05 BAC are less dangerous than 1 driver at 0.10, so spend the time finding that driver.

But such police screenlines have the effect not just immediately about arresting people in violation of the law, and also as warning, reminder, and deterrent against future alcohol (and drug) impaired driving. To say the resources are a waste misses a major point.

International experience shows most other developed countries have significantly lower crash and fatality rates than the US, and they have 0.05 or lower BAC. Perhaps the US should just copy their traffic laws lock, stock, and barrel. Researchers have estimated ‘an additional 538 lives could be saved each year if the United States reduced the limit to 0.05,’ (Wagenaar et al. 2007)

Casual drinkers are a problem. Social drinking is a problem. I don’t care if you drink at home and don’t bother anyone (aside from the health insurance claims you impose on society from the damage you do to yourself), but when you drive a car, you endanger others. And because you are impaired, you don’t have the reasoning abilities to realise this.

The rules of the road should not only punish, but also provide a strong deterrent, which includes arrest and punishment even if you didn’t actually kill someone this time. Until robots fully rule the roads in 25 years, possibly another million Americans will be killed in car crashes. We can avoid tens of thousands of them with lower BAC limits.


The scientific evidence on this is fairly clear: Fell and Voas (2006) write:

Purpose

This scientific review provides a summary of the evidence regarding the benefits of reducing the illegal blood alcohol concentration (BAC) limit for driving and providing a case for enacting a .05 BAC limit.

Results

Fourteen independent studies in the United States indicate that lowering the illegal BAC limit from .10 to .08 has resulted in 5–16% reductions in alcohol-related crashes, fatalities, or injuries. However, the illegal limit is .05 BAC in numerous countries around the world. Several studies indicate that lowering the illegal per se limit from .08 to .05 BAC also reduces alcohol-related fatalities. Laboratory studies indicate that impairment in critical driving functions begins at low BACs and that most subjects are significantly impaired at .05 BAC. The relative risk of being involved in a fatal crash as a driver is 4 to 10 times greater for drivers with BACs between .05 and .07 compared to drivers with .00 BACs.

Summary

There is strong evidence in the literature that lowering the BAC limit from .10 to .08 is effective, that lowering the BAC limit from .08 to .05 is effective, and that lowering the BAC limit for youth to .02 or lower is effective. These law changes serve as a general deterrent to drinking and driving and ultimately save lives.