Traffic Signal Timing: Burnett at Rt 55 Clearance Interval

Back in the day, John Forester’s Effective Cycling defined how vehicular bicycling should be done; our now-fragile comb-bound 1980 Third Printing of the 1978 Third Edition still has a place of honor on our bookshelves. I recently discovered his analysis of how traffic signal timing should work online, which says I’ve drawn the wrong conclusions from my observations of the absurdly short green / yellow / red cycle on Burnett Blvd at Rt 55, just in front of NYS DOT’s Region 8 headquarters.

The phasing sequence that is required by current traffic law is as follows:

1. Green, which may be very short when only one vehicle is waiting

2. Yellow, of only sufficient duration to allow a stop from maximum legal speed before entering the intersection

3. Red (a 4-way red), for sufficient additional time for traffic to clear the intersection before the conflicting green appears.


With that in mind, here’s how his analysis stacks up against one of our recent trips through the intersection. The four-digit number in the picture titles gives the time in frames at 60 frame/sec.

We’re stopped one car length behind a long trailer of paving equipment sporting an Iowa license plate. The driver has stopped with the trailer straddling the lane divider line, so we cannot determine which way he will turn. Because we no longer trust turn signals, despite the trailer’s blinking left signal, we will not pull up beside it in the right lane.

Frame 0127, T = 0 s, Δt = 0 s: The signal has just turned green:

Burnett Opposing Green - AS30V - 2020-06-26 - 0127
Burnett Opposing Green – AS30V – 2020-06-26 – 0127

Frame 0264, T = 2.28 s, Δt = 2.28 s: The trailer has started moving and Mary is rolling behind it, with her foot just coming off the ground:

Burnett Opposing Green - AS30V - 2020-06-26 - 0264
Burnett Opposing Green – AS30V – 2020-06-26 – 0264

Frame 0721, T = 9.9 s, Δt = 7.6 s: The signal turns yellow, after DOT’s additional five seconds of green; previously, we had five seconds and would have been able to stop. We’re accelerating as hard as we can, but Mary has barely passed the stop line:

Burnett Opposing Green - AS30V - 2020-06-26 - 0721
Burnett Opposing Green – AS30V – 2020-06-26 – 0721

Of course, entering an intersection on a stale yellow is undoubtedly unwise. It is not so unwise for someone traveling fast, because that person may well clear the intersection before the conflicting traffic starts. It is much more unwise for someone traveling slowly, but it is done and it is lawful.

Forester, ibid.

We’ve traveled about three car lengths in the seven seconds since the trailer started moving. Our bikes will sometimes trigger the signal if we’ve stopped in exactly the right spot over the unmarked sensor loops, but we have never observed our bikes retriggering the signal to lengthen the green or yellow phases as we ride through the intersection.

NYS DOT apparently expects us to stop abruptly when the signal goes yellow, wherever we may be with respect to the stop line and regardless of how fast we may be moving. In fact, given what you’re about to see, we’re expected stop on green to ensure we can start from the stop line during the next green signal.

Frame 0983, T = 14.2 s, Δt = 4.4 s: The signal turns red. The trailer is visible on the left, beyond the median signage, but we haven’t reached the middle of the intersection. I’m lined up with the rightmost lane of westbound Rt 55 and Mary is about in the center lane. The white car on our right is stopped, the black car is slowing to a stop:

Burnett Opposing Green - AS30V - 2020-06-26 - 0983
Burnett Opposing Green – AS30V – 2020-06-26 – 0983

Frame 1101, T = 16.2 s, Δt = 2.0 s: The opposing signal goes green for Rt 55 traffic, while we’ve barely reached the middle of the intersection:

Burnett Opposing Green - AS30V - 2020-06-26 - 1101
Burnett Opposing Green – AS30V – 2020-06-26 – 1101

Frame 1205, T = 18.0 s, Δt = 1.8 s: I’m lined up with the median, Mary’s in the center lane of eastbound Rt 55, putting us squarely in front of drivers who may be unable to see us through the stopped cars. The drivers to our left are, fortunately, waiting, unlike a previous crossing:

Burnett Opposing Green - AS30V - 2020-06-26 - 1205
Burnett Opposing Green – AS30V – 2020-06-26 – 1205

Frame 1440, T = 21.9 s, Δt = 5.7 s: After 22 seconds, we’ve cleared the intersection and are proceeding eastbound on Rt 55:

Burnett Opposing Green - AS30V - 2020-06-26 - 1440
Burnett Opposing Green – AS30V – 2020-06-26 – 1440

Forester observes the all-red phase must be lengthened to allow cyclists to clear the intersection. Right now, two seconds isn’t enough. Ten seconds would suffice for a pair of reasonably fit, albeit aging, cyclists.

This system fails to provide the required safety in the case of bicycles for three opposite reasons.

1. Bicycles are small and are harder to see. In particular, the most visually impressive part of the bicycle and rider is low down where it is easily shielded from view by the hoods of motor vehicles. Sometimes the only part of the cyclist that can be seen by drivers waiting at the stop line with other vehicles on their left is the head of the cyclist.

2. The cyclist crossing a typical intersection is close to the fronts of the line of cars waiting at the stop line on the cyclist’s right. This is not good judgement on the part of the cyclist, but so much emphasis has been put on staying far right that this position is typical.

3. The cyclist who is traveling slowly, or, more importantly, is starting from a minimum-duration green, is barely into a wide intersection when the conflicting green appears.

The result is a car-bike collision as one of the vehicles in the lanes nearest the curb starts up, or speeds up, and hits the cyclist who suddenly appears in front of it.

Forester, ibid.

I’ve had a DOT engineer tell me, sneeringly, that they don’t design facilities for “professional cyclists”, which commuting to work evidently made me; he was not, however, a “professional driver” even though he used a car for a similar purpose. It’s obvious DOT doesn’t design facilities for “ordinary” cyclists, either, and the evidence suggests they don’t design facilities for cyclists, period, full stop.

I still want someone from NYS DOT to explain how this “makes our highway systems safe and functional for all users“, perhaps by bicycling with us through the intersection a few times, but I’ve never gotten a response, let alone an answer, to anything I’ve ever sent their way.

SJCAM M20 Action Camera: Stuck Battery

The SJCAM M20 action camera has been attached to the back of my Tour Easy for the last 16 months:

SJCAM M20 Mount - Tour Easy side view
SJCAM M20 Mount – Tour Easy side view

The Anker 13 A·h USB power pack on the rack provides juice for a week’s worth of rides, letting the M20’s internal battery keep its clock & settings alive between rides. I recently forgot to turn on the USB pack and discovered the camera shut down just after I cleared the end of the driveway.

As you should expect, the battery had swollen so much its pull tab … pulled off … when I tried to extract it:

SJCAM M20 - stuck battery
SJCAM M20 – stuck battery

So, we begin.

Pry off the trim ring around the lens by jamming a small screwdriver in any of the three slots:

SJCAM M20 - lens ring removed
SJCAM M20 – lens ring removed

Then pry off the entire front panel:

SJCAM M20 - camera front panel
SJCAM M20 – camera front panel

Thereby exposing the battery’s rectangular protrusion and three contacts next to the optical block:

SJCAM M20 - camera interior - battery terminals
SJCAM M20 – camera interior – battery terminals

Avoid shorting the brass terminals with, say, a small screwdriver, while shoving the battery out of the camera until you can grab it with your fingers and haul it out the rest of the way:

SJCAM M20 - swollen battery case - left
SJCAM M20 – swollen battery case – left

Yeah, that puppy looks all swoll up:

SJCAM M20 - swollen battery case - right
SJCAM M20 – swollen battery case – right

Remove the all-enclosing label to reveal the bag inside:

SJCAM M20 - swollen battery bag
SJCAM M20 – swollen battery bag

Pull the bag out to reveal the protection PCB:

SJCAM M20 - battery case interior
SJCAM M20 – battery case interior

Snip the wires and salvage the case against future need.

I bought the camera with three batteries, all three of which are now similarly swollen. I also got two official SJAM batteries with an official SJAM charger; both of those batteries seem to be in fine shape. I expect the codes on the five bags would reveal two different lots, but I’m not going to sacrifice a nominally good battery to find out.

All three swollen battery bags show the same BEP 782633PL lot code and 1704 date code. I bought everything in January 2018, so those batteries had been sitting on the shelf for the better part of a year. Maybe that’s why they offered a “deal” for two spare batteries along with the camera?

Installing one of the unswollen batteries, reconfiguring the camera’s settings & clock, and giving it a charge from the Anker USB pack put it back in operation.

Robin Nest: Fledging Day

The robin nestlings fledged fourteen days after we spotted the first eggshell on the driveway below the nest. The first one may have flown away the previous evening, leaving three increasingly restless siblings behind:

Robin Fledging Day - three nestlings
Robin Fledging Day – three nestlings

They’re recognizably robins now, covered in young-bird speckle camouflage.

Feeding continued apace:

Robin Fledging Day - feeding
Robin Fledging Day – feeding

After feeding, robin nestlings produce fecal sacs, which the parents either eat or carry away:

Robin Fledging Day - fecal sac
Robin Fledging Day – fecal sac

Robins aren’t big on facial expressions, but, speaking from personal experience, anything to do with diapers isn’t the high point of a parent’s day.

And then there were none:

Robin Fledging Day - empty nest with parasites
Robin Fledging Day – empty nest with parasites

The gazillion black dots on the soffit are pinpoint-sized insects / mites / ticks infesting the nest and, presumably, the birds. The earlier pictures don’t show them, so perhaps these missed the last bird off the nest and are now regretting their life choices.

Go, birds, … gone!

JPG Recovery From a Camera FAT Filesystem

You can do it by hand, as I used to, or use recoverjpeg:

dmesg | tail
cd /tmp
sudo dcfldd if=/dev/sde1 of=pix.bin bs=1M count=100
recoverjpeg pix.bin 
ristretto image00*

Nothing prizewinning, but better than no picture at all:

Garage Robin - recovered image
Garage Robin – recovered image

Note that you start by copying a reasonable chunk of the partition from the Memory Stick / (micro)SD Card first, to prevent a bad situation from getting worse.

Now I can remember the easy way the next time around this block …

Robin Nest: Nestlings!

All four nestlings emerged on schedule:

Garage Robin - four nestlings
Garage Robin – four nestlings

The oldest nestling was ready for feeding almost immediately, even with unopened eyes:

Garage Robin - Nestling begging
Garage Robin – Nestling begging

As any infant will tell you, holding your head up is hard work:

Garage Robin - Nestling dozing
Garage Robin – Nestling dozing

But doing only half the job won’t get you fed:

Garage Robin - Nestling recovering
Garage Robin – Nestling recovering

They’re just starting to make little chirps, so this isn’t nearly as raucous as you might think:

Garage Robin - Nestlings begging
Garage Robin – Nestlings begging

The adults seem to have no trouble bringing an endless stream of worms, insects, and unidentifiable organisms from the yard and garden.

Go, birds, go!

Robin Nest: Eggs!

After pausing to recover from construction, Ms Robin laid four eggs in four days:

  • Garage Robin Nest - first egg - 2020-05-28
  • Garage Robin Nest - 2 eggs - 2020-05-29
  • Garage Robin Nest - 3 eggs - 2020-05-30
  • Garage Robin Nest - 4 eggs - 2020-05-31

She’s surprisingly tolerant of our comings and goings, as well as garage door openings and closings:

Garage Robin Nest - robin brooding
Garage Robin Nest – robin brooding

We’re trying to stay out of her way as much as possible.

The gallery pix come from my phone, held against the soffit over the nest, and aimed entirely by feel, while standing on the Greater Ladder. If I had access to the top of the soffit, I’d drill a webcam hole, but …

Monthly Science: USB Current Testers vs. NP-BX1 Batteries

Having some interest in my Sony HDR-AS30 helmet camera’s NP-BX1 battery runtime, I’ve been measuring and plotting recharge versus runtime after each ride:

USB Testers - Charge vs Runtime
USB Testers – Charge vs Runtime

The vertical axis is the total charge in mA·h, the horizontal axis is the discharge time = recorded video duration. Because 1 A = 1 coulomb/s, 1 mA·h = 3.6 C.

The data points fall neatly on two lines corresponding to a pair of cheap USB testers:

USB Testers
USB Testers

When you have one tester, you know the USB current. When you have two testers, you’re … uncertain.

The upper tester is completely anonymous, helpfully displaying USB Tester while starting up. The lower one is labeled “Keweisi” to distinguish it from the myriad others on eBay with identical hardware; its display doesn’t provide any identifying information.

The back sides reveal the current sense resistors:

USB Testers - sense resistors
USB Testers – sense resistors

Even the 25 mΩ resistor drops enough voltage that the charger’s blue LED dims appreciably during each current pulse. The 50 mΩ resistor seems somewhat worse in that regard, but eyeballs are notoriously uncalibrated optical sensors.

The upper line (from the anonymous tester) has a slope of 11.8 mA·h/minute of discharge time, the lower (from the Keweisi tester) works out to 8.5 mA·h/minute. There’s no way to reconcile the difference, so at some point I should measure the actual current and compare it with their displays.

Earlier testing suggested the camera uses 2.2 W = 600 mA at 3.7 V. Each minute of runtime consumes 10 mA·h of charge:

10 mA·h = 600 mA × 60 s / (3600 s/hour)

Which is in pretty good agreement with neither of the testers, but at least it’s in the right ballpark. If you boldly average the two slopes, it’s dead on at 10.1 mA·h/min; numerology can produce any answer you need if you try hard enough.

Actually, I’d believe the anonymous meter’s results are closer to the truth, because recharging a lithium battery requires 10% to 20% more energy than the battery delivered to the device, so 11.8 mA·h/min sounds about right.

Memo to Self: Trust, but verify.