Dash cam for other project

[Udontno]

Hello. This is my first post, so I hopefully won't step on any toes here. I have project that I think would be best suited to a dash cam, but used somewhat atypically. I need to document vehicle speeding issues on a 2-lane state highway in front of my home in a residential neighborhood, to try to persuade the local council to request the state to do a "traffic safety study" that could lead to signage changes, lower limits, more enforcement, etc. The state does not permit individual residents to make such a request.

As support for my request, I want to tabulate vehicle speeds for an hour duration each time during peak traffic volume, on several different days. I already have an inexpensive but reasonably accurate hand-held radar speed gun. I want to video the traffic as I measure speed, and simultaneously voice record the speeds and brief descriptions of individual vehicles on the recording. WIth that done, I hope to be able to view the audio later and put together a spreadsheet of vehicles and speeds.

The reason I think a dash cam might be my appropriate choice is that many of them seem to have a second (rear view) lens so that video may be simultaneously recorded from two perspectives 180-degrees apart. I believe that would help minimize the risk of failing to identify a particular vehicle in 2 way traffic. I plan to mount the camera on a fixed tripod, while holding the speed gun by hand.

What I think I should look for in the camera is: some way to use external power (I do see that there is a forum section devoted to that); an audio input jack so that I can use a mic to voice record (to minimize traffic noise); and the ability to mount on top of a tripod (it appears that some dash cams are only designed to hang underneath a support). It would be a plus if the camera was not terribly vulnerable to a little bit of rain, although that may be asking too much. Finally, while I don't mind spending a little for the right camera, this is intended to be a limited time endeavor, so price and/or resale value will be a consideration.

I will appreciate any advice or recommendations you may offer. Thanks!

 

[Nigel]

I think I would chose or place two clear markers on the road and use the video time (displayed accurately on many video players) to measure how long they take between the two markers, just using a single video channel, if you want it very accurate or want to time over a short distance then you can count the number of video frames between the two. That would be better evidence than spoken evidence where you can say whatever you want! The timing can be checked by the experts, as long as you have an accurately measured distance, but the distance can often be checked using Google maps, in which case they can completely validate your values.

Possibly an action camera would be a better choice, the better ones are often waterproof and can often take a microphone, although you may not have any use for that afterwards while you might have use for a dashcam.

I don't think you need 2 channels unless you want to record license plates and you don't have front plates in your area, in which case a 2 channel dashcam would be useful, but I don't see why you need license plates for this survey, and I don't see why you need to catch every vehicle.

If you do want a 2 channel dashcam with external microphone, then the Viofo A139 is a good choice, not the cheapest of dashcams, but there are very few with an external microphone input. If you are going to put it to use in a car afterwards then the A139 Pro is recommended, the basic A139 is now a little outdated. These will happily sit flat on a surface, with the lens adjusted to be horizontal. They don't have a tripod mount, but their sticky pad will stick to any tripod that you can remove the screw from, or screw it down far enough for it to not be in the way, which is most. They are not waterproof, but I don't think a few splashes would be a problem, they tend to get fairly warm so will dry fairly fast. Don't use them in heavy rain without protection. As for power, they will run off a USB powerbank, or for a very long session, a 12V car battery if you have an adaptor - the optional hardwire kit might be sensible if you don't mind the cost.

If you are doing this at night then you will not be able to read plates unless you provide some lighting, such as car headlights shining on the plates of the cars. In which case you will want that A139 Pro since it is one of the few dashcams with good HDR that can read plates at night. Again, I'm not sure why you would need to read the plates. You could just use a couple of torches with narrow beams that are going to light up the sides of the cars as they go past, then it is easy to measure the time between the torches. Could use infrared (IR) torches so that they can't be seen if you measure using an interior IR camera.

 

[Udontno]

Good and welcome observations, thanks.

This state does use tags on front and back of vehicles, but we get a large influx of tourists in Summer from states that use only the rear. I do not plan to do this at night. The most egregious speeding periods are 6 AM - 7 AM and 4 PM - 5 PM weekdays, which generally correspond to to and from work traffic. The reason I want license plate numbers (beyond my OCD is that some of the speeding vehicles of most concern to me are commercial tri-axle dump trucks (which max out at 80,000 lbs GVW with a full load) and (believe it or not) local district school buses. I regularly see both types of vehicles blast through our 30 MPH zone at 50 - 60 MPH. In addition to my asking local council to request the state study, I plan to write polite letters to the operators of those trucks and buses complaining about their drivers' lack of speed discipline, and pointing out the potential liabilities they incur as a result. I think having the license plate numbers to accompany those complaints would add some impact. It also gives me additional corroboration of each vehicle I identify on the audio. Another reason for wanting the 180-degree view is that there is a traffic signal controlled intersection not far past my house, and the state of that signal has obvious effects on traffic speed. I might want to try to note those effects in my worksheet.

I will investigate the A139. I have a large number of 12V 7 AH batteries taken out of computer UPS boxegs at my disposal that would probably make good external power sources. Once I get some hands on with my set-up, including knowin what my cone of sight needs to be from the camera lens(es), I can probably rig some kind of small canopy for the camera to better shield it from weather. Thanks again for your reply!

 

[Nigel]

Another reason for wanting the 180-degree view is that there is a traffic signal controlled intersection not far past my house, and the state of that signal has obvious effects on traffic speed.

Because dashcams are very wide angle, if you want them o see as far as your eyes can see then you will want 4K resolution, and it still won't see quite as far.

I plan to write polite letters to the operators of those trucks and buses complaining about their drivers' lack of speed discipline, and pointing out the potential liabilities they incur as a result. I think having the license plate numbers to accompany those complaints would add some impact.

I doubt you will make much impact with that, normally it takes a change in the road layout so that the drivers actually feel that they are driving too fast.

If it was here then I would suggest that for any that you catch multiple times, you upload the videos to the police and let them take the appropriate action, but that requires that your police have an interest. One issue here is that since you would be setting up fixed surveillance cameras, you would need to comply with the data protection rules for CCTV cameras and audio recording. I don't know your rules, but it might be worth checking.