Fair Traffic Laws
SPEED LIMITS AND DRIVING
SAFETY
Are you among the vast majority of motorists who almost always drive faster than posted speed limits?
Have you ever paid a fine for exceeding a posted speed limit although you were driving safely when you received the citation?
These questions point to an unacceptable state of affairs that exists throughout the United States: Nearly all motorists drive safely while traveling faster than posted speed limits and most speeding tickets are issued to motorists who were driving safely when observed by the enforcement officer.
So, what’s going on? Either motorists are blatant lawbreakers flouting the law in their own selfish interest or government is at fault by posting speed limits that are too low.
We have a problem that
needs to be solved!
SAFEST DRIVING SPEED
Let’s first consider
the safest speed to drive in a stream of traffic as determined by scientific
studies.
Of course the safest
driving speed constantly changes as motorists proceed on their way. For
example, the safest driving speed is considerably faster in light traffic
moving at 75mph on open rural freeways than it is in congested 35mph urban
traffic.
It is also an
established scientific fact that vehicles moving more slowly or faster than the
average speed of traffic are at higher risk for crashing than those traveling near
the average speed—difference in speed is a far more important
safety factor than actual speed.
A study published in
1963 by David Solomon and later confirmed by others, identified the speed at
which the probability of a crash is smallest. The results of his study are
shown in the chart below.
Note that the minimum crash risk
occurs at a speed slightly faster than the average speed of traffic. In the
language of statistics, the minimum risk occurs at approximately the 85th
percentile of the traffic speed distribution.
This simply means that in order to
travel at the safest speed in a stream of traffic, drivers should drive faster
than 85 percent of the vehicles in the traffic stream. To find this “sweet
spot” drivers must pass eight or nine vehicles for every vehicle that passes
them—this is the working rule for choosing the safest speed.
Upon reflection, this makes perfect sense.
The 85th percentile is only a few mph faster than the average speed
and drivers at this speed can see virtually all problems that could affect them
because these problems are in the field of view ahead. Any problems that occur
behind them are of no concern because they are moving away from them.
It is not unusual that speed limits are
posted ten miles per hour lower than the 85th percentile speed. Motorists
who drive at such speed limits may be as far back in the traffic flow as the 10th
percentile or even lower, which places them at a far higher risk of a crash
that if they were at the 85th percentile.
In other words, in most situations
drivers must violate speed limits by a significant amount in order to drive at
the scientifically proven safest speed. This places motorists in an extremely
awkward position where they must choose between safety and obedience to the
speed limit.
Before we leave this point, let’s
address a question that may have occurred to the reader: If the fact that the 85th
percentile speed is the safest speed becomes generally known and everyone strives
to follow the “pass eight or nine vehicles for each one that passes me” rule,
wouldn’t the speed of traffic increase to dangerously high levels?
The answer to this question is no because
there is an upper comfortable and safe limit for each driver that they will not
exceed regardless of how fast others are driving.
However, with practice, motorists who
have customarily driven slower than the 85th percentile may find
that they are more comfortable and feel safer near the 85th percentile.
A this point, they may increase their normal driving speed.
As more drivers
learn to seek the 85th percentile speed, the difference in speed
between vehicles would decrease. This would remove some of the variation from
the speed distribution and traffic would flow more safely. It would also cause the
average speed of traffic to increase slightly but would not affect the speed of
the fastest drivers. Traffic flow would approach
the theoretically safest state where all vehicles would travel at the same speed.
RESPONSIBILITY OF THE
STATE
The State has a solemn
responsibility to create traffic regulations that define proper driving conduct
and allow for penalizing those who do not operate their
vehicles reasonably and prudently. After appropriate
traffic regulations are in place, the State must develop effective
enforcement and education programs.
The test for success of
these programs is whether or not they produce voluntary compliance from the
vast majority of motorists. If they do not, the State’s approach is flawed and ineffective—the
State may have imposed unreasonable regulations or its education and
enforcement programs may not be working.
Reasonable traffic laws must:
1. Reflect the
reasonable behavior of motorists.
2. Provide accurate
information so that drivers can make good decisions.
3. Be enforceable.
4. Foster voluntary
compliance by the majority of motorists.
Let’s see how speed
limits stack up to these requirements.
1. Do current speed limit laws reflect the
reasonable behavior of motorists?
No—Although the vast
majority of drivers choose to drive significantly faster than speed limits,
they are reasonable drivers as evidenced by extremely low fatality rates throughout the United States. Fatality rates continue to decline in the face of ever faster
speeds. From these facts it is clear that many of our present speed limits do
not reflect this reasonable behavior of motorists—they are too low.
The logical purpose for a speed limit is to
identify the maximum safe speed for a competent driver in a modern vehicle
under the best conditions. Speed limits set on this basis would identify truly
dangerous drivers and de-criminalize the reasonable behavior of the vast
majority of drivers.
2. Do current speed
limit laws provide accurate information?
No—Speed limit signs
cannot provide accurate information for all drivers at all times because they
are static devices that cannot control a dynamic process that is affected by so many
variables.
This inherent problem with speed limits
is compounded by the practice of posting speed limits that are lower than the
true reasonable maximum safe speed. Motorists cannot
rely on most speed limits to provide information useful in determining their
maximum safe speed.
3. Are current speed
limit laws enforceable?
Not Really—Speed
limits are enforceable only in the narrowest sense: They provide measurable
values that can be used as bases for citations.
Considering the fact that far fewer than 1%
of speed limit violators are cited and voluntary compliance is essentially
non-existent, it appears that, short of employing overwhelming force, enforcing present speed limits to the extent necessary to gain
voluntary compliance is not feasible.
4. Do current speed
limit laws foster voluntary compliance?
No—The vast majority
of motorists drive safely at speeds significantly faster than posted speed
limits—voluntary compliance is almost nonexistent.
Clearly, speed
limits, as presently applied, fail the reasonable law test.
Statutory speed
limits have not kept up with safe, normal highway speeds. Motorists
are safe when traveling our highways at speeds significantly faster than posted
speed limits and governmental agencies have
no moral right to collect fines for this reasonable behavior.
We need to correct this egregious injustice, which has persisted
for many years. If government will not take effective action on its own, a
grass-roots movement may be needed where the driving public recognizes the
extent of inequitable speeding citations and takes action to correct the
problem.
Data presented on
the following page show the magnitude of the gulf between statutory speed
limits and the present safe speed in the state of