Magnetic Anomaly - H-3

[Kaonohi]

Re: Magnetic Anomaly - H-3

After considerable digging around in my numerous drives I found some decent data and a fascinating link. The contractor for a lot of the tunnel electronics was Transdyn inc. to be found at (you guessed it!) at www.transdyn.com. From the home page go to Systems:Transportation systems. The buttons are near the top of the page.One is shown a list of projects including the trans-Koolau H3 tunnel.Take a look at where it says am/fm rebroadcast abilities. I still have to locate some archived data but I am pretty sure that is where I recall the slotted antenna stuff. Still diggin for more. Regards, Chris

WOW! Thanks, Chris. If we are to solve this mystery we need more folk like you.

K

[lensperson]

Re: Magnetic Anomaly - H-3

After considerable digging around in my numerous drives I found some decent data and a fascinating link. The contractor for a lot of the tunnel electronics was Transdyn inc. to be found at (you guessed it!) at www.transdyn.com. From the home page go to Systems:Transportation systems. The buttons are near the top of the page.One is shown a list of projects including the trans-Koolau H3 tunnel.Take a look at where it says am/fm rebroadcast abilities. I still have to locate some archived data but I am pretty sure that is where I recall the slotted antenna stuff. Still diggin for more. Regards, Chris

[GeckoGeek]

Re: Magnetic Anomaly - H-3

I'm surprised there is such a lack of interest in this at various levels of government and education.

1) It's not a problem
2) No one can figure out how to use the information in their favor. (perhaps by making it a problem they need funding to solve.)

[Kaonohi]

Re: Magnetic Anomaly - H-3

A recap of what we know for sure (by request):

The phenomenon is limited to an area above the H-3 roadbed. Outside the crashbarriers there is no effect. This eliminates microwave antennas or antenna radio waves. Whatever it is is an electromagnetic effect eminating from either the roadbed or within the barriers. Although the effect seems blocked by the Jersey Barriers (crash barriers), it easily penetrates the steel frames and bodies of motor vehicles.

It is intermittant (turns off and on with distance from the start point), and variable in intensity for some unknown reason.

It is limited to both Westbound and Eastbound lanes of H-3, but begins about an 8th mile outside the tunnels and continues for only a few miles. It is evident ONLY on the Halawa (leeward) side of the tunnels. The Haiku elevated roadway (where the steel grid has been removed from the highway after the closing of the Haiku OMEGA station antenna) loacks the magnetic properties of the Halawa side.

Lightning? Magnetic crane?

I'm surprised there is such a lack of interest in this at various levels of government and education.

K
The magnetic phenomenon has been noted on other elevated highways on O`ahu, to an undetermined degree.

Did I miss anything?

[lensperson]

Re: Magnetic Anomaly - H-3

Howdy. I am digging through my archives to find the supporting data re:antennas

[GeckoGeek]

Re: Magnetic Anomaly - H-3

Can the emissions effect magnetics?

A mechanical compass? No freaking way.

Yes, the emissions are electromagnetic, but they oscillate at a minimum of 540,000 cycles per second (if not 90 millions of times per second). There's just no way that something cycling that fast affect a mechanical compass. Each cycle is roughly even in it's north/south peak. I don't see how it could give a sustained constant/low frequency magnetic field needed to throw off a mechanical compass.

I think the best theory is that it's just the rebar somehow got magnetized. Perhaps they used a crane with a big electromagnet to move it around.

[Kaonohi]

Re: Magnetic Anomaly - H-3

It's not unusual for roadways to have induction loops to sense traffic. Most commonly used to trigger traffic lights, but also used to sense traffic flow. Given that H-3 has it's own traffic office, it wouldn't surprise me to know that the highway has such sensors - which also work on AC magnetic field. If they're just the right frequency, they could well confuse a flux gate compass.

According to Wikipedia, there are induction loops every 500 feet INSIDE the tunnel, to monitor traffic flow. I don't know why they would be on the road in both directions (East and West), but OUITSIDE the tunnel and only on the leeward side.

I like lenspersons idea of slotted 'leaky' coax cables for radio warnings, but can find no references to it online. And again, why only on the leeward side, and why both East and West?

[Kaonohi]

Re: Magnetic Anomaly - H-3

The antenna in the tunnel was coaxial cable that was slotted every so often to allow the broadcast to "leak out" of the antenna..The slotted aperture antenna structure is now in wide use.As far as anomalous magnetic readings go, they may well exist.

We pretty much have determined that the anomaly is in the roadbed, since when a compass was held out over the valley, it normalized.

This slotted coaxial cable theory makes a lot of sense, since the anomaly is intermittent. I'll have to see if I can determine any regularity in distance between 'pulses.' It will require slow driving and observers to watch the compass and determine distance by counting the Jersey Barriers (the odometer reading isn't fine enough).

I'd like to know where you got this information and how I can find out more. I'd be interested to know the following:
Is the cable embedded in the roadbed?
Can the emissions effect magnetics?

Another question is why is it only on the Pearl Harbor side, and not the Windward side? If the intent was to alert motorists of incidents or danger, both sides need it. And why both approaching and leaving the tunnel?

[buzz1941]

Re: Magnetic Anomaly - H-3

A UH geophysics prof postulated that the rebar used to construct that stretch of highway had been hit by lightning and magnetized.

[Vanguard]

Re: Magnetic Anomaly - H-3

Apparently, there are magnetic anomalies in Cappadocia Turkey that are attributed to volcanic activity. It's possible the causes here are similar. In this case they seem to be heavily localized in one area of the H-3, so I think any questions about this phenomena are best submitted to one well versed in geophysics.

[lensperson]

Re: Magnetic Anomaly - H-3

The antenna in the tunnel was coaxial cable that was slotted every so often to allow the broadcast to "leak out" of the antenna..The slotted aperture antenna structure is now in wide use.As far as anomalous magnetic readings go, they may well exist.

[Kaonohi]

Re: Magnetic Anomaly - H-3

It also occurred to me that the fans, lighting, etc., associated with the tunnels are likely attached to the roadbed, and likely on the leeward end.

This can explain the deflection, but not the variation.

[Kaonohi]

Re: Magnetic Anomaly - H-3

..and posted up a video. I wish I could find the link.

In fact, I thought it was Kaonohi who posted up the video. Kaonohi?

Hmmmm, I don't recall posting a video, just this thread. I've been through a couple computer crashes since then, and may have forgotten.


Oh, yeAH, just go back to post # 53 in this thread.

[lensperson]

Re: Magnetic Anomaly - H-3

The H-3 tunnel goes right through a mountain with large amounts of iron oxides (hence the red soil color) which may influence compass readings. GPS will certainly be hampered while operating in tunnels. The Hawaii road builders installed a radio transmitter in the H-3 tunnel to advise motorists of hazards.The transmitter used a form of phase modulation that the car radios of the time could hear.

[craigwatanabe]

Re: Magnetic Anomaly - H-3

I think somebody stole the grounding copper wire from the confunctionator again. Damned those copper thieves!