Metros along the coast

[James Attwell]

A random metro crosses a bridge along the southern KwaZulu-Natal coast.

[Stefan Andrzejewski]

I remember camping at Park Rhynie in 1981. The girls (adults) were playing and taking photos on the railway line. I took one look and could see the line was well used. I told them to get off. The pathway to the beach is on a curve on the line. The following week someone was killed walking over to the the beach. I wonder if that unguarded pedestrian crossing is still there. A Railway line is no play area.

[Steve Appleton]

Let me tell you about a Metro suddenly approaching at about 2 am across the Mtwalume River bridge whilst we had telescopes, each set up with at least one leg inside the track, strung out onto the southern embankment.

Many years ago (1979) before trains took over my life (I lie, I have always been interested in trains) I practised amateur astronomy (not astrology, which is totally unrelated and unscientific). For years the Durban ASSA centre had been trying to successfully observe a "grazing occultation" .This is when the dark edge of a partially lit moon - it must be less than half-moon - just passes (grazes) in front of a sufficiently bright star, apparently briefly extinguishing it [occluding it] before it pops out again. Unlike the old Johannesburg, Harare and Cape centres, this being Natal, the clouds always defeated them.

First a bit about the the event and from that you will know why we were there on the railway line in the first place.

Now the moon as we all know (or should know - a piece of useless information that might just save your life someday) is constantly and slowly moving against the stellar background. Each night at the same time you will see that the moon has shifted back against the stars relative to the previous night. One important charateristic of such an occultation observation is that it is possible to very accurately determine the moon's exact position in space by finding out exactly where the "graze line" line (running east-west) is located on the earth's surface. Even more fun, one can also generate a crude plot of the lunar mountains at the point where the graze occurs. Bear in mind that all those years ago, the moon's position in advance (ephemeris) was not as accurately known as it is today. Not knowing the moon's exact position meant that the graze line's latitude could only be calculated to an accuracy of several hundreds of meters and the event's predicted timing could be out by several seconds. So, to cover the bases, one needs to set up a number of observers, each armed with a telescope and very accurate timing clocks, at known measurable positions at intervals of about a hundred meters apart in a reasonably straight line running south to north so that the observers straddle the latitude of the predicted "graze line". All going well, those to the north of the graze line will see the star disappear completely for quite some time whilst those to the south of it will not see the star disappear at all. Hopefully, those roughly near the centre, at the point of the graze, will see the star very briefly disappear and reappear (perhaps even several times as the lunar mountains sweep by). This is the exact graze line that, together with the exact recorded timing, is used to set the moon's position accurately. The results are regarded very seriously and are sent to NASA which uses them to re-establish the moon's position and recalculate its ephemeris. Important for the space program - you don't want to send out an expensive lunar lander to have it miss the moon's surface by as little as 10 meters now, do you?

Well as the organiser, I had to decide where to put the observers and plot the locations in advance. The Natal south coast is not the easiest place to find a couple of kilometers for a clear reasonably straight line oriented north to south that is easily accessible and is mapped sufficently accurately to determine exactly where to locate each observation station. The main N2 road was one possibility, but the cars and their lights made that a poor choice. So, I settled on the railway. To get the end of the observation line far enough north, there was only one way: go out onto the embankment. To get far enough south was easy, the station area would do.

So, the small hours of the morning found a number of we keen amateur astronomers strung out along the railway line (with the local station master's permission) from south of the Mtwalume Station right up northwards ending just short of the bridge itself. Those on the embankment (including myself) had no option but to put at least one leg of the telescope tripod inside the track. Of course, the last thing we expected at that time of the morning was a train - especially not a Metro. You can imagine the consternation when, eyes glued to telescopes (not looking up the track), ears tuned to the clicking electronic clocks (not listening for trains) when indeed we suddenly heard a train coming. The northern approach curves had obscured it and its sounds and by this time the train was already on the northern section of the bridge. I shouted a warning, the driver hit the siren, and there was just enough time to remove telescopes and leap off the tracks before the train swept past us, driver wide-eyed in his cab! Getting those 'scopes off and getting clear without falling down the embankment in the darkness was quite some feat.

An even bigger feat was to to set the 'scopes back on the track, get them aligned, get the timers running and restart the recorders and a minute or two later, make the first successful grazing occultation observation done in Natal in literally dozens of attempts over several years! Observations over, there was no time to waste. We quickly packed the kit away, pulled out the picnic hampers, sat on the beach and watched the spectacle of a fabulous dawn and sunrise over the Indian Ocean.

Only now, after actively working on trains with FOTR and partaking in its commitment to safety, do I realise that it could all have turned out so differently.

[Adelbert Stigling]

Is there perhaps a narrowguage line in the foreground on the photo of the metrotrain crossing the bridge as it looks like narrow gauge trucks loaded with logs of timber passing in front?

[Steve Appleton]

I identify that the picture was taken from the south bank of the Umkomaas River just upstream from the combined road and rail bridge. The timber wagons in the foreground are on a cape-guage siding that runs from the station up along the south bank of the river to an exchange yard and ultimately into the Sappi Saiccor cellulose pulp plant just west of Umkomaas, also on the south bank of the river.

[Adelbert Stigling]

Thank you Steve