In a multi-lane hiway (e.g. three lanes in each direction) which lane
is the safest lane to travel in, statistically.  The right lane is
slower, but suffers from merge issues, the left lane is fastest, but
suffers from 'impatient driver' issues, etc.

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Request for Question Clarification by haversian-ga on 04 Nov 2002 16:57 PST

How are you defining safest?  I know that driving at the speed limit
(rather than with the flow of traffic) causes a tiny increase in the
liklihood of accidents, but the ones that occur (to you, at least, as
the slower driver) are much less deadly - would you call that safer
(fewer deaths) or more dangerous (more accidents)?

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Clarification of Question by rloura-ga on 05 Nov 2002 13:54 PST

Great comments, but these are all just assertions based on 'gut feel'
or some sort of rational argument.  I can (and have) made all of those
before.  What I'm looking for is actual statistical data that shows
safety data.

For instance, I can argue that the right lane is the least safe, as it
has merging, has more wear/tear, etc.  I can also argue that it is
safest because it tenfs to proceed more or less at the speed limit,
has less aggressive drivers, is more often traveled, thus has less oil
buildup in the tire lanes, etc.

What I want is data, not more supposition.

Hello,

After reading all of these comments, and making a cursory search on
the web, I decided to hit the library and see what actual research has
been done on this issue.  It turns out that the evidence supports NO
safety difference between lanes.

Now, that could mean that no one has looked at that particular
variable.  But, in fact, at least two of the following references did
look at lane as a safety factor.  Neither found it to be significant
(Abdel-Aty & Radwan,  2000;  Shankar & Mannering,  1998).

The variables that were found to be significant in car accidents were
traffic volume/density, number of traffic lane and speeding (Sawalha &
Sayed, 2001; Abdel-Aty & Radwan, 2000; Aljanahi, Rhodes, & Metcalfe,
1999; Shankar & Mannering, 1998; Johansson, 1996; FRIDSTROM, IFVER,
INGEBRIGTSEN, KULMALA, & THOMSEN, 1995 ).  One study suggested that
your speed in relation to the speed of the cars around you was also a
significant safety factor (Shankar & Mannering, 1998)

Each article defines ‘safety’ in its own way.  I did not make a search
to find the mean definition that they used, as that was not part of
the question.  I realize this may not be the answer that you wanted. 
But, the data suggests that where safety is concerned, there is in
fact, no difference between lanes.  But, since you wanted to know the
data on the issue, and not a gut reaction, I feel this is the actual
answer to your question.

Thank you
Pba


References:

Abdel-Aty MA, Radwan AE.  2000.  Modeling traffic accident occurrence
and involvement. ACCIDENT ANALYSIS AND PREVENTION: 32 (5): 633-642
SEP.

Aljanahi AAM, Rhodes AH, Metcalfe AV.  1999.  Speed, speed limits and
road traffic accidents under free flow conditions. ACCIDENT ANALYSIS
AND PREVENTION: 31 (1-2): 161-168 JAN-MAR.

FRIDSTROM L, IFVER J, INGEBRIGTSEN S, KULMALA R, THOMSEN LK.  1995. 
MEASURING THE CONTRIBUTION OF RANDOMNESS, EXPOSURE, WEATHER, AND
DAYLIGHT TO THE VARIATION IN ROAD ACCIDENT COUNTS. ACCIDENT ANALYSIS
AND PREVENTION: 27 (1): 1-20 FEB.

Johansson P.  1996.  Speed limitation and motorway casualties: A time
series count data regression approach: ACCIDENT ANALYSIS AND
PREVENTION: 28 (1): 73-87 JAN.

Sawalha Z, Sayed T.  2001.  Evaluating safety of urban arterial
roadways. JOURNAL OF TRANSPORTATION ENGINEERING-ASCE: 127 (2):
151-158. MAR-APR


Shankar V, Mannering F.  1998.  Modeling the endogeneity of lane-mean
speeds and lane-speed deviations: A structural equations approach.
TRANSPORTATION RESEARCH PART A-POLICY AND PRACTICE: 32 (5): 311-322
JUN.

It's no answer, but I can point you to this disucssion in
rec.autos.driving which had a similar debate:

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&frame=right&th=7f00c962a70cbfc8&seekm=a7edil%247ep%241%40news.duke.edu#link1

skermit-ga

If it's 3 lanes, the answer is the center lane.

If it's 2 lanes, the answer is the left lane.

Here's why:  in most US states, trucks (18-wheelers) are required to
travel in the right lane.  So if it's 3 lanes, the middle lane has
less merging than the right, and less passing than the left.  If it's
2 lanes, the left lane has passing, but far less merging and trucking,
which lead to blind spots and poor merging, the #1 cause for
non-alcohol related accidents on highways.

you can find more info at the National Highway Traffic Safety
Administration:
www.nhtsa.gov

and a good report at:
http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/Rpts/2002/Assess01.pdf

save your 10 bucks.

thanks for the cool question.
bax

Hmmm, Baxendale may or may not be correct in his analysis, but the
links provided, while containing much information regarding highway
deaths and injuries, do not address the issue the questioner specified
regarding the link between lane position and safety.
In addition, relating safety to merging, trucking and blind spots,
discounts the effect of alcohol which accounts for nearly 15,000 of
the almost 41,000 total deaths.
I haven't been able to find anything that specifically connects lane
position with fatality but would not consider this question answered
on the basis of this comment

I agree with bauxendale, however if too many people decide to be safer
by driving in the middle lanes, they will no longer be safest, so
don't expect the word to be widely published. Imprudedent lane
changers cause the most minor accidents, perhaps even the the most
major accidents. I suspect the slow = right lane is the least safe for
the average driver, but exceptions occur.  Neil

The reason that the left lane is statistically safer is because the
left lane has less traffic, being a passing lane. That probably
accounts for less wear on the left lane, meaning that water cannot
collect in tire indentations, causing loss of control in inclement
weather.

If you are interested in safety, avoid the left lane. If you drive
consistently in the left lane without the intention to pass anyone,
people will want to kill you. That's not safe. In some states, it'v
even illegal.

It may sound like a joke, but I'm not kidding. I've seen people cause
near accidents on the interstate trying to intimidate a car blocking
the left lane. Don't do it. It's not polite, and it's not safe.

alan_dershowitz says there is less traffic in the left lane.  That
isn't true here in Colorado.  Everyone moves into the left lane and
cruises.  They constantly use the technique you describe of sitting on
the bumper of the person in front in order to intimidate.  I don't
know about the rest of the drivers, but I am not happy with this
phenomenon.

All the statistics I found pointed to lane-changing as the greatest
cause of accidents on interstates.  If there is no dating on
differences between lanes, it may be because there is no safety
difference between lanes.

pba