Green Light Trigger HP
Traffic Signal Tripper
March 28,
2007
Dennis
DenHartog
If
you've ever come to a traffic signal in a left turn lane and had to sit
on your scooter through several light cycles before you decided to
either just run the light, or were fortunate enough to have a car or
truck come up behind you and trigger the signal, chances are good that
you encountered an inductive loop sensor system that is supposed to
trigger the left turn signal.
These
traffic signal sensors are like metal detectors buried in the
road surface. The "inductive loop" sensors can be easy to spot if
there are circular, square, or diamond-shaped saw cuts in the pavement
just before the intersection, however those that have been installed
for a number of years may have been paved over, so you can't tell how
large they are or exactly how they're positioned. There is a weak
radio frequency field across the coil, and a large mass of conductive
metal disturbs that field. The inductive loop detectors are meant to
pick up the presence of large metal objects, like cars and trucks
passing or sitting over the detector loop.
Most
modern bikes snd scooters don't have enough conductive material in
their frames to
trip the sensor, and what they have tends to be oriented vertically
above the loop (making it harder to sense) so we get stuck at the
lights. The
Green Light Trigger has a magnetic field that when
passed over a detector loop, disturbs the loop's RF field, creating a
signal. When the control computer sees that
signal, it knows someone's there, and the bike or scooter gets a green
light,
just like everyone else.
Scott
Kauffman is the inventor of the Green Light Trigger, which he claims
was
the first of the several such devices now on the market. After
searching for evidence of any commercial product
predating the Green Light Trigger, built for the
purpose of
tripping signal sensors, all the information I was able to find
supported his claim. I did find
earlier discussions over the possible use of magnets to trigger the
inductive loop sensors, but none commercially made for that purpose.
The
Green Light Trigger HP is much smaller than the Signal Sorcerer I
tested
a couple months ago. The  size of the magnet itself is 2" x 1" by 1/8"
thick, mounted on a plastic insulator, keeping it from direct contact
with the frame, and an adhesive with a peel off covering.
Although
physically smaller, the magnet was obviously more poweful than the
Signal Sorcerer magnet, and much more difficult to remove from a large
steel table. Installing it was easy. A little alcohol on a rag to
clean the lowest spot on the frame of the scooter where the Green Light
Trigger was to be mounted, pull the covering off the adhesive mount,
and put a zip tie around the frame member and magnet.
To
test how it worked, I rode around the same circuit as I did with the
Signal Sorcerer during low traffic time periods, a saturday morning and
a sunday afternoon. The first turn lanes I tried were a couple at
an intersection where a scooter without a magnet almost never (only
once in a year and a half) tripped the signal sensor. Worked like
a
charm! I had tried those same turn lanes(paved over with no
visible
cuts) with the Signal Sorcerer, and in one of them it always worked,
and in the other, it was hit or miss.
In those particular turn lanes,
the Green Light Trigger never failed to trip the sensors scoring 100%
in each one during all four out of four tries.
Next,
I tried three intersections with visible cuts in the pavement for the
inductive loops, following the same paths and stopping at the same
places relative to the loops where I stopped when testing the Signal
Sorcerer. Two of these had a series of smaller loops cut into the
pavement leading up to and just beyond the line that you're supposed to
stop behind, and one had a single large rectangular loop in the turn
lane just before the "stop" line, with it's longest dimension
paralleling the direction of travel. On all the loops with
visible
cuts in the pavement, by riding close to the lines that paralleled the
direction of travel, and stopping with the magnet inside the loop, but
near a corner, the signals never failed to trip, except for one time,
when I got there just too late. But that time the signal changed
for me on
the next light, even though no one had pulled up behind me, so it
actually worked that time too. The last turn lanes I tried were the two
that our
Ford Escort can seldom trip(apparently they made some small
adjustments to sensitivity since the Signal Sorcerer test). No luck there!
Summary of the Test Results:
Loops with cuts you can see, so you can ride near to the
sides of the
cuts, were triggered every time during my tests with the Green Light
Trigger, regardless of which loop pattern it was. During the
limited
number of times that I tested the Green Light Trigger at any given
intersection, sensors that were always tripped by the Signal Sorcerer
were always tripped by the Green light trigger, and those that were
sometimes tripped by the Signal Sorcerer, were also always tripped by
the Green Light Trigger. Those that our Escort trips fewer than
one out of
every 10 times, failed to respond to either the Green Light
Trigger or
the Signal Sorcerer. So if you want to know that you can trip
sensors identifiable by pavement cuts, get the Green Light
Trigger!
For the deeper ones that are paved over, it's still a crapshoot,
but there's a better chance with the Green Light Trigger HP than the
Signal Sorcerer G4.
Dennis
DenHartog
Signal Sorcerer Traffic Light Changer
Dennis DenHartog
How often have you ended up sitting on
your scooter in a left turn for several traffic light cycles waiting
for the light to change, or for a car or truck to pull up behind you
and trigger the traffic light sensor? If you're like me, at the
end of the second light cycle without a left turn arrow, you decide to
take the next safe opportunity on the green for the straight ahead lane
next to you and turn, regardless of the turn lane light. Or you
may leave the turn lane, going straight until you can pull a U-turn and
then turn right when you get back to the intersection. Other
people choose to go to the next right instead and go around the block,
going an extra distance and making a series of right hand turns for
what should have been a simple left hand turn.
The reason the turn signals aren't beeing triggered by your scooter is
that most of the traffic controlled left turn lights are activated by
magnetic induction loops in or under the pavement, and most scooters
and motorcycles just don't have a large enough mass of iron and steel
for the sensors to detect them. The Signal Sorcerer claims to be
the answer to that problem. It is a powerful magnet that gets
mounted on the lowest part of the scooter frame, which is supposed to
trigger the inductive loops that don't detect the comparitively small
amount of iron and steel in modern scooters. There are two
available Signal Sorcerer models offered, the SS-1, and the G42(G4).
The SS-1 is only recommended on their website for bicycles,
wheelchairs, and mobility scooters and has a weight of just a half
ounce. The G4 weighs over 4 ounces and is the
one recommended for everything else. Unfortunately you
really have to look their website over well to find out which is the
recommended unit for different uses.
 I got a G4 Signal Sorcerer
at Christmas time and recently installed it on my Strada RX150TE.
Installation is very simple. You look under your scooter for the
best mounting position, a low part of your frame closest to the
road. In my case that was still a little higher than some of the
plastic panels underneath the scooter, so I knew it should be safe from
hitting curbs or other things I ocassionally have to ride over.
Once you've decided where to mount it, clean that area with the
provided alcohol swabs, wait about 1 minute for the alcohol to dry, and
press firmly into place. The back side of the Signal Sorcerer is
flat, so if mounting on a round surface as I did, secure with twist
ties. Only one twist tie is supplied with the Signal Sorcerer,
and it was so stiff that it broke before it would bend around the unit
good enough to hold it securely in place. If you're a well
equipped scooterist, you probably have a supply of twist ties, so use a
couple large ties and cinch down tightly.
It's January with typical winter weather finally setting in, and I
finally got the chance to test the Signal Sorcerer G4. Traffic
was fairly heavy when we got some weather good enough to ride in(low 40s and 20mph winds), but I was able to do a preliminary
test in a couple of left turn lanes with magnetic loop activated sensors.
Both were at signals where the scooter always has failed to activate
the sensors. In fact only once in the past year and a half, since I've
been riding scooters again, have I had a left turn arrow triggered by
one of my scooters, and I was thoroughly amazed. I made sure to
pull up in both turn lanes right after cross traffic
began to go, so there would be ample time to trigger the sensors for
the
next light cycle. At the first light, the Signal Sensor equipped
scooter tripped the signal and the light changed right on schedule. At
the second intersection where I was the only vehicle in the turn lane,
the sensor didn't trip the signal, and I sat there, waiting for a car to
pull up for the next light cycle.... and one did, since it was
approaching evening rush
hour. The signal that the sensor failed to trip, was one that a
Ford Escort we own never trips either, so I have to wait for another
car
to pull up behind me, or just go when the way is clear.
I don't
expect miracles and didn't really expect the magnet to trip a signal
that a small car wouldn't trip. But I called and talked to the
local traffic engineering department, and they conceded that signals at
different intersections might have varying sensitivity levels.
They are sending someone out to test the sensitivity of that sensor and
adjust it if they deem it necessary.
According to the Signal Sorcerer website and included materials, the
inductive loops are often set into 'cuts' in the pavement and then
tarred over, so they are very close to the surface. In the area
where I live, they use inductive loop sensors to activate all the turn
arrows, but many of them have been paved over, which may account for
our Escort failing to trip close to 30% of the turn
lane sensors. Ran out of time, will do more testing on the next
decent day.
We had a 35 degree day again, with little wind and a few snow
flakes bolowing around. It looked like the best we're going to
get for awhile, so I decided to do more testing of the Signal
Sorcerer. I rode around fairly close to home, looking for turn
lanes where a car wouldn't pull up behind me and ruin the test. I
found several in places where the layout of the roads makes people
being in
the left turn lanes unlikely as there are obviously better routes to
almost anywhere than to turn where I found these. Just perfect
for signal
tripping in the turn lanes in the middle of the afternoon. A
couple of these had a series of smaller loops set into cuts in the
pavement, and one had a single large rectangular loop set into cuts in
the pavement. The last of the four turn lanes I tested in was a
paved
over loop, so I couldn't determine the size or shape of the
loop(s). Where there was a series of smaller loops in the
pavement, I could drive over them, and stop so the magnet was within
the last or next to the last loop, near a corner of the loop, and the
sensors would trigger the turn light on every light cycle, provided I
didn't get there just as the light was ready to change.... do
that and you're usually too late, no matter what you're
driving. On the large rectangular one, if I stopped inside
of a corner, with the magnet still just within the loop, it tripped the
turn signal three out of four times. The one under the pavement
was a crapshoot, and I managed to trip it only once out of three tries,
having no idea what shape of inductive loop system it is. The way
they place them in the turn lanes, if you ride as near the center of
the lane as you can without getting into the oil slick that's at most corners,
you're pretty sure to be riding through the inductive loops in the turn
lanes, but if that isn't enough and it takes stopping in the corner of
a loop to trip the sensor, it's a real hit or miss proposition when
they're under the pavement, since you can't see them. And the
fact that they're under maybe a couple inches of pavement can't help
things either. I wish I could say the Signal Sorcerer worked 100%
of the time, and I wish our Ford Escort would trip the sensors every
time too. I believe that it trips the left turn light sensors
about as well now as the Escort does, and that makes it worth the
$19.95 as far as I'm concerned.
Dennis
DenHartog
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