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Many bus stops are just a pole with a plate or sign attached.
Frequently, they are so positioned that they cast a shadow when the sun is shining.
If a suitable pattern of lines were painted radially from the base of the pole, it would act as a sundial. Since the poles are quite tall, fairly accurate
time indication would be possible.
A reminder would be needed to apply an adjustment for Daylight saving time (where and when applicable).
In overcast conditions, or at night, bus passengers would be thrown back on their own resources as regards timekeeping.
Equation of time, at Wikipedia
http://en.wikipedia...ki/Equation_of_time
[Jim Bob of Merriam Park, Oct 08 2009]
[link]
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Ordinary, simple sundials aren't that accurate, either. They can be as much as 16 minutes off. To accurately tell time by the sun, you've got to take into account the "equation of time"; that is, you've got to add or subtract a correction factor that varies according to the time of the year. Accurate sundials are possible, but their markings are so complicated it would be a challenge for most people to learn how to read them. |
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However, I like the idea of large, public, accurate sundials. They could be great teaching tools, as well as works of art, appropriate for a plaza in front of a science museum or planetarium. You'd need a lecturer or tour guide to explain how to read them, and why a correction is necessary. I just don't think they are practical for so mundane a purpose as checking bus schedules. |
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Practical, you say? Why, no, probably not. [+] |
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And the shadow of the bus could point at 2 other buses on the floor that will be along very shortly. |
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[+] I'm normally opposed to transit services' advertising but this would be a good and inexpensive PR exercise. |
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Since the equation of time has a variation of as much as 30 minutes, and a simple sundial a *potential* accuracy as high as about a minute, merely painting the sundial's markings on the ground isn't an idea solution. |
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Instead, paint them onto a ring or a plate, which can be rotated around the bus stop pole. The equation of time could be encoded into markings indicating where the 12:00 marking should be moved to, for each date of the year. |
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You wouldn't need to explain why the adjustment is needed, you would simply paint next to the ring (or disk): "This sundial is accurate if and only if the 12:00 mark is pointing to today's date." |
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[Jim Bob...], in Invercargill, NZ, there is a large sculpture of an umbrella. I always wondered why it was on a funny angle, until a fellow amateur astronomer informed me that it was in fact a sundial. It's about 5m high. The correction factor graph is on a plaque at the base (being Invercargill, it needs correction of around 2.5 hours to give local time in the worst case). |
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wait wait, hold on, just set the bus schedule to the lines on the ground and then they are always right. Without the external reference the lines are 15min. apart and the bus comes every 15min. (or less frequently in the more remote locations, four times a day perhaps.) |
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You could use "e-paper" technology (embedded balls
with light and dark hemispheres) on the pavement
to dynamically correct the time and display buses. |
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The problem: shadows from nearby buildings (and bus
shelters) would offer shade for bus passengers but
would confound this system. |
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getting retentive about keeping a "clock based" rather than "interval based" schedule makes the sundial worthless. If it is to be effective it must use the sun at noon as the absolute reference all other times being relative to that time. At night you will need a astrolabe mounted at each stop, and a complete table of astronomical observations: |
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On August the third the North End {stop 13} B Route comes when Venus reaches an incline of 13*. Visible moon inclination 22*. |
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This is a gorgeous idea. Now bring back the real 8th of
7 you,...you,... vagabond tribe of aliens you... |
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"Set the bus schedule to the lines on the ground"? That would require a schedule that varies incrementally from day to day, rendering clocks and watches useless, unless you apply a correction factor to them. What would you do on cloudy days? Anyway, you want to know what time the bus comes before get to the bus stop. |
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"e-paper technology"? You're pulling my leg, right? If you're going to go high-tech you might as well dispense with the sundial and have a digital display: "Next bus arrives in 3 minutes"—which is already being done in some places, and I wish they'd do here. |
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// Most countries' bus services are little more than human cattle trucks. // |
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In Australia, certainly. And there's a reason .... you don't have to be Sherlock Holmes to deduce it. |
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Who cares whether it's accurate? As long as the buses
are usually not on time, people won't be able to tell
whether it's the sun dial or the bus. In fact, people
would probably always blame the bus.....
"well would you look at that, the bus is precisely 16
minutes early/late!" they would exclaim. |
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Well, how else does Australia convey its floating population of french backpackers ? |
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[Jim Bob of Merriam Park] However it wouldn't be as
as fun or surreal. |
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Maybe you should start a countervailing "Cheap Airline Scam" ? |
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// the British style of customer service.// |
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What is this "customer service" of which you speak ? Your words are strange to us .... |
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//RyanAir...British//
Grin. |
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/ They can be as much as 16 minutes off. To accurately tell time by the sun, you've got to take into account the "equation of time"; that is, you've got to add or subtract a correction factor that varies according to the time of the year. / |
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A solar powered adjustment could move the spike at the top of the bus stop pole to compensate for the variation. (The sun is half a degree wide so the will always be a bit of slack.) |
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Forgot to bun this one. Error corrected. |
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