High mount brake light flasher

[hks_kansei]

Frankly, one of the biggest reasons for people hitting the back of other cars is that they're following too close, not looking/concentrating, or both.

That, and the fact that a lot of people have trouble judging how hard a car is braking, especially in something like an MX5 where there tends to not be as much of a dramatic weight shift as say a van braking hard (you see the whole thing lurch forward and it's pretty obvious it's braking HARD)


For the ones not concentrating, a flashing light probably wont register in their mind any more or less than a regular lamp lighting and staying lit would.

For the ones following too close, it's not the light that's the problem, hell you could mount a stadium floodlight to the bootlid and it wouldnt make them able to stop any faster.



It would also add the problem of unfamiliarity to the mix, since most cars don't have flashing lamps (other than ones with electrical faults, or emergency vehicles)

You could argue that at night Blue light is more visible, and do a study showing that more people could see blue light and react faster to it at night.
But put it on a car in the real world, and most people will just think "what the hell does a blue light on the back of a car mean?" as they run into it.

[bruce]

More real world, it would be a Police car pulling you over for a flashing blue light (or for the red).

[LiteIsRite]

This topic has turned out to be a bit more controversial than I was expecting.

In taking everyone's comments on board, where the consensus seems to be that this mod creates more problems than it solves, I decided to do a bit more research. I finally came across a document produced by the National Highway Traffic Safety Administration (NHTSA) in the USA in 1996, where they investigated various ideas to make centre high mounted stop lamps (CHMSLs) more effective. One of these ideas was 'Flashing CHMSLs To Warn of Hard Braking'.

The following quotes are from that document, and I've done my best to keep them in context. Note I haven't just included a link to this document because it's actually part of a larger (490 page) 'Federal Register' of legal notices to the US public. That Federal Register is available at https://www.gpo.gov/fdsys/pkg/FR-1996-12-13/pdf/FR-1996-12-13.pdf

Long story short, it seems conclusive to me. I'll be removing the flasher module and just stick with the LED lamp which, at least, does light up fractionally faster than the incandescent bulb previously in use. I may replace the outboard bulbs with LEDs as well.

"The agency, has in fact, studied the possibility of flashing CHMSLs, as was reported in the report Field Test Evaluation of Rear Lighting Deceleration Signals, DOT HS–806–125 October 1981. Each of 600 taxis in a test fleet was equipped with one of three types of a CHMSL. The fleet traveled a cumulative 40.7 million miles during the study. The steady-burning CHMSL (the type adopted in Standard No. 108) was compared with two types of flashing CHMSLs. One flashed at a rate of 2.5 Hz whenever the brake pedal was depressed. The other flashed at 1.5 Hz, 2.5 Hz, 4 Hz or 7 Hz to relate higher braking rates to faster CHMSL flash rates. The highest flash rate occurred for all braking at greater than 0.3 g"

"Of the 48 rear end crashes experienced by the test vehicles equipped with ordinary steady-burning CHMSLs, six occurred while the
vehicles were stopping quickly. Of the 54 rear-end crashes experienced by the test vehicles equipped with CHMSLs with a flash rate proportional to the deceleration rate, four occurred while the vehicles were stopping quickly. That fewer vehicles with the hard-braking
warning were struck while stopping quickly is suggestive of the expected desirable result, but the difference between six and four rear-end accidents was not great enough to be statistically significant. In other words, the apparent reduction from six to four accidents (given the total number of accidents and test vehicles) was not great enough to outweigh the possibility that the reduction was due to chance rather than to the effectiveness of the warning.

The remaining third of the test vehicles were equipped with CHMSLs which flashed at same rate for all brake applications, regardless of deceleration rate. Of the 55 rear-end crashes experienced by the test vehicles equipped with constant-rate flashing CHMSLs, four occurred while the vehicles were stopping quickly. The accident results were the same for vehicles equipped with flashing CHMSLs with or without a distinct signal for hard braking. This suggests that the flashing action rather than the hard-braking warning (i.e., the increasing flash rate) was the source of whatever benefits the enhanced CHMSLs could provide over the performance of the ordinary steadyburning CHMSL. However, this comparison also lacks statistical significance."

"While the study provided no evidence that CHMSLs with flashing deceleration signals would be more effective than steady-burning CHMSLs, it did not rule out the possibility of an effectiveness benefit too small for statistical significance within the scope of the study. However, the study did conclude that any possible effectiveness would be limited to a small proportion of rear-end crashes."

"At the time of this study of possible CHMSL enhancements, the agency had become convinced of the effectiveness of the steady-burning CHMSL through previous studies with unambiguous results. NHTSA decided that it would not be in the interest of safety to delay a requirement for the basic steadyburning CHMSL while pursuing variants that were proving insignificant. The resulting requirement for CHMSLs permitted only steady burning CHMSLs despite the contemporary study of flashing CHMSLs."

[Smacca]

After thinking about the pros and cons of this mod stuck in traffic this evening, I was wondering what impact, if any, a flashing brake light would have on following motorists who are (negligently) distracted by their mobile phone use while driving. If someone was looking down at their phone, say on their lap or in their hand, would a flashing brake light in their peripheral vision capture their attention quicker than a solid brake light?

Maybe there is a place for a flashing brake light even in heavy traffic. I'm warming to the idea now that you have found modules with delayed, or cycle limited flashing. I note your thorough research found a study from 1981. It would be interesting to see that same study repeated today, considering the mobile phone/sat nav/in car entertainment distractions of a modern driver that surely increase the risk of nose-to-tail collisions. Of course modern cars can now stop themselves to prevent this type of low-speed collision, which would also have an impact (no pun intended) on the study's results.

[LiteIsRite]

It would be interesting to see that same study repeated today, considering the mobile phone/sat nav/in car entertainment distractions of a modern driver that surely increase the risk of nose-to-tail collisions.

Interesting point. Another facet to this, not included in my extractions from the study, is the effect of the 'novelty factor'. There was mention of the fact that when CHMSLs were first introduced (in the US, at least), there was a significant reduction in rear end collisions for a time. As more, and eventually all, vehicles were fitted with a CHMSL the reduction tapered off to the current level of (from memory) about 4%. I assume the effect of other improvements that rely on driver involvement in the braking process would be similarly diluted over time.

[noobee]

maybe look into something like this
http://archive.siliconchip.com.au/cms/A ... ticle.html
I can remember reading the article but not any details.the kits are usually found at Jaycar and Altronics.
Mick

[LiteIsRite]

Thanks for making me aware of that, noobee. Yes, I've found that the kit is available at both Altronics & Jaycar for around $40. The only problem I can see with it is they don't recommend it for manual cars as throttle changes during gear changes may falsely trigger the brake lights. Food for thought, though, and maybe someone more savvy with electronics than I can come up with a solution - perhaps something triggered by (aftermarket?) ECU outputs?

[LiteIsRite]

... or, use the clutch activation switch to somehow override the operation of the 'Quick Brake' module to reduce false activation? Link to the kit for anyone who's interested - http://www.altronics.com.au/p/k4344-silicon-chip-magazine-quick-brake-kit/

[hks_kansei]

... or, use the clutch activation switch to somehow override the operation of the 'Quick Brake' module to reduce false activation? Link to the kit for anyone who's interested - http://www.altronics.com.au/p/k4344-silicon-chip-magazine-quick-brake-kit/

Wouldnt be hard.

Just wire a normally closed relay into the power feed wire of the flasher, with the relay trigger wired to the clutch switch.

Clutch down, relay opens and breaks circuit, flasher module gets no power and therefore wont do anything.

[LiteIsRite]

Cheers, hks , I may look into this further.

[hks_kansei]

It would really rely on what the flasher unit does when it has no power to it, whether it simply lets power pass through like it's not there, or if it cuts the circuit when not powered.


Presumably it would be the first, since that means if the circuit stuffs up for whatever reason the brake lights work still.

[Mr Morlock]

The CHMSL was introduced in Aust in ? - cannot recall but it was about 30 years ago. If US did it first then it would be just about the only innovation they ever made in lighting.Aust was pretty much lock step with Europe on lighting rules. They ( US) were true laggards and positively in the Middle Ages with lighting- e.g. when the Aust Capri was exported to USA they wanted sealed beams whereas the Aus version used a QH insert- incidentally the Capri had CHMSL so it was already a legal requirement ( 1990) . Lighting innovators have been and probably still are Europe based with the Japanese following in tandem.
This subject i.e. a flashing brake light is not legal and its safety benefits are impossible to assess.
For the future the autonomous car is going to the saviour of rear end crashes when us humans are not paying attention etc

[hks_kansei]

From a very brief look (I didn't read the full legislation) it appears that the high mount brake light requirement became part of the ADRs in 1989

I'm pretty sure though that commercial vehicles were not required to until quite recently, I've seen many late model utes and vans that have no centre brake lamp at all.



Personally, I would be wary of driving any car without one. (when my GF bought her Kingswood we bought a lamp and wired it in)
To me, it's the main thing that stands out visually when a car is braking.

[and1]

Thanks, it's taken a while to get it to where it is now..

I didn't document anything when i did the board.. Though i do need to pull the bootlid off so i will take some pics when i do that.

Sounds great! Any pics or video? Had a look in your garage thread but couldn't see it. Nice build, by the way... (green with envy)