Columnist solves traffic
As anyone who lives in Houston knows, Interstate
10 is home to some of the world's most horrendous traffic. Road rage on
I-10 is like snow in
Antarctica: There is no escape.
There is, however, hope. The answer to
traffic problems in Houston is surprisingly simple and cheap. An examination
of the causes behind this traffic
yields the solution. Several factors add
up to produce the nerve-wracking experience that is Houston traffic, and
they can all be explained both
mathematically and through common sense.
First, traffic occurs when the amount of
cars on the road inhibits the flow of travel, resulting in slow-moving
vehicles and frequent stops. When this
phenomenon occurs, most motorists find
themselves frustrated, asking questions like, "Why, when everyone is going
the same direction and the
speed limit is 70 miles per hour, is the
average speed in heavy traffic a breakneck 3 m.p.h.? What is wrong with
all these people?"
Think about it logically. A car is traveling
behind another car, and suddenly the driver in front puts on the brakes
(perhaps because someone entered
the interstate in front of that car).
To avoid collision, the driver of the rear vehicle also applies the brakes.
Then, because that car slows down, the car
behind it must do so to avoid collision
as well, and so on.
Three hours later, because there has been
no break in the stream of cars, every vehicle must still put on its brakes
when reaching that spot. Until there
is enough space between cars traveling
through that area to eliminate the necessity for the car in front to brake,
that cycle will continue. In physics, this
phenomenon is called density waves.
One might think the solution, then, is
to make sure all motorists travel with enough space between them and the
car in front that braking is not
necessary. Unfortunately, that only causes
Say that there are 30 cars in one lane,
with each car measuring 10 feet long and only 10 feet between each car.
These 30 cars, then, take up
approximately 600 feet of space. Rush
hour hits, and instead of 30 cars in one lane, there are 300 cars in each
lane with the same dimensions and
space between. Instead of 600 feet, each
lane now takes up about 6,000 feet.
Once this math is applied in the real world,
it paints an ugly picture. Take the span of road between Katy and downtown
Houston. Loads and loads of
people get onto the freeway, and each
car that gets on takes up 20 feet of space. The 15 cars that got on the
freeway at Chimney Rock Road now take
up 300 feet of space, and the cars that
were already on the freeway have to slow down to make room for them.
This results in motorists putting on their
brakes and slowing down all the way back to the exit before, where there
are 15 more cars merging onto the
interstate and, because the cars ahead
have their brakes on, those cars must enter more slowly.
This creates a snowball effect for each
successive entrance and exit, and it's why anyone who is driving from Katy
can't go more than five feet forward
at a time. All the people in front of
those poor souls have to slow their cars down to make room for the 15 people
who get on the freeway at every
entrance between Fry Road and downtown.
The situation is further compounded by
the fact that a few minutes later, there will be 15 more people merging
at every on ramp.
The mathematical formula for this is very
similar to compound interest and works on the same basic concept. Simply
put, the farther from downtown,
the slower and more congested the freeways
Now, consider the high occupancy vehicle
lane. At any given point during rush hour, the amount of cars traveling
in the HOV lane is roughly equal to
the amount of cars in stalled traffic.
The difference is that the HOV lane is going much faster. In fact, no matter
how many cars are in the HOV lane,
they always seem to be going at least
the speed limit, even though there is only one lane. Why is that?
The answer is that because there are so
few places to get on and get off, the number of vehicles exiting the HOV
lane is almost always equal to the
amount entering. No motorist in the HOV
lane has to brake to make room for new cars, since there is no real increase
in cars in the HOV lane (and
more importantly, because no cars can
enter in front of those already traveling on it).
The solution to Houston's traffic problem
is simple. The city of Houston should make one lane of I-10 (and all other
traffic-ridden roads that run from
downtown to the outskirts, such as downtown
to Katy) that has only one or two entrances and exits called the "Downtown
This lane would only be accessible at certain
points and would operate precisely like the HOV lane, but without the passenger
limit. Its limited
entrances would eliminate the effects
of any influx in the amount of motor vehicles while the lane itself will
alleviate the congestion on the other lanes.