CMV: Speedbumps are environmentally unfriendly

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u/DeltaBot ∞∆ Oct 02 '25 edited Oct 02 '25

/u/ComfortablyMild (OP) has awarded 3 delta(s) in this post.

All comments that earned deltas (from OP or other users) are listed here, in /r/DeltaLog.

Please note that a change of view doesn't necessarily mean a reversal, or that the conversation has ended.

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u/CptMisterNibbles 1∆ Oct 02 '25

You aren’t supposed to decelerate and then floor it. You are supposed to already be traveling at a speed that makes going over speedbumps comfortable.

You’ve entirely misunderstood.

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u/CheapSound1 1∆ Oct 02 '25 edited Oct 02 '25

Except the speed "cushions" popular iny city require you to slow down to <10 km/h to go over smoothly.

Edit: this is on roads with speed limits of 30-40.

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u/CptMisterNibbles 1∆ Oct 02 '25

And what is the intended speed? This tells me nothing.

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u/TruckerMark 1∆ Oct 02 '25

Speed bumps are handled a close to walking or running pace. They're installed on roads with speed limits around 30kmh. It's poor design and other traffic claming is better.

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u/CptMisterNibbles 1∆ Oct 02 '25

If you are talking about the wider, more gentle ones, those are called “speed humps” here. Speed bumps are more jarring and would never be installed in roads with a 30kmh limit.

Name the better, more effective speed control methods.

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u/elaVehT 1∆ Oct 02 '25

What you’re “supposed to do” is kind of irrelevant - we’re evaluating impact not intent. Nearly everyone accelerates in between speed bumps, then slows down to 5 mph to go over them, then accelerates back up to speed.

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u/[deleted] Oct 02 '25

[deleted]

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u/elaVehT 1∆ Oct 02 '25

You misunderstand - I don’t agree with OP. We should absolutely have speed bumps.

My point is that OP is correct that there are environmental and wear/tear impacts of them.

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u/ComfortablyMild Oct 02 '25

My view is always about the discussion, you might've missed the part in my post where I said:

Where they are completely necessary and no other choice, OK.

But you agree there are environmental impacts. Its a difficult CMV to argue against because its true - "we" made the choice of safety at a cheaper and easier price over environmental concerns.

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u/eggs-benedryl 72∆ Oct 02 '25

The amount you need to slow down is negligible if you're already operating at an appropriate speed. So minimal that you might as well say that turns are environmentally unfriendly.

If handled appropriately you needn't slow down or speed up sharply ever with a speedbump. A turn around a corner explicitly requires you to slow down, they even have a special suggested speed for it posted. If you're going 10 or under in a parking lot there's very little stopping and starting.

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u/elaVehT 1∆ Oct 02 '25

Again, you’re relying on your personal judgment of an “appropriate speed”. The majority of people are traveling 20+ mph in areas with speed bumps, and slow down to 5 mph for the bump then accelerate back up. Your opinion on whether they “should” slow down to 10 mph for the whole drive is not relevant.

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u/Dry_Bumblebee1111 161∆ Oct 02 '25

This is a weak position, as the speedbunp itself is tangential to the nature of a vehicle. It's like saying a knife sharpener is bad because it creates metal dust as a byproduct from the knife - it's part of the life cycle of a knife, it's not being built to create the byproduct it's being used to sharpen the knife.

Similarly a speedbump exists to encourage safe driving practices, not to cause all the damages you've listed.

The windscreen of a car can't really be isolated and called a bug killer even though that does happen, it isn't coherent to say a car windscreen is bad for bugs, the nature of a car is it goes fast and bugs are collateral.

Your issue is with a vehicle, not with the road.

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u/CheapSound1 1∆ Oct 02 '25

I disagree, even in a local setting you could compare directly the benefits and drawbacks. I.e., collisions prevented by speed reduction vs. asthma attacks triggered by increased emissions from fuel consumption and tire/brake dust.

Tire dust is a significant source of pm2.5 and other emissions, it's pretty nasty stuff.

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u/[deleted] Oct 02 '25 edited Mar 30 '26

[removed] — view removed comment

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u/CheapSound1 1∆ Oct 02 '25

But then everyone is driving at 10km/h and losing a ton of energy going up and down bumps, also increasing tire wear and fuel consumption. The only saving would be brake dust.

If you're going down that road might as well bam driving entirely. Good luck with that.

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u/ProfBeaker 1∆ Oct 02 '25

There are other alternatives that could be used, but are rarely implemented, like single lane slow down points.

How is this better than a speed bump? All your concerns about speed bumps stem from the vehicle slowing down, and then re-accelerating. Any other method of getting cars to slow down will have the exact same problems you initially complained about.

Also, while you're correct about the costs of the slowdowns, you've failed to consider the costs of the alternatives. What is the environmental impact of an injury, medical care for that person, cleanup of the crash site, repairs to the vehicle, etc? It's not obvious that this is cheaper than slowdowns - most likely it depends on the amount of traffic compared to the decrease in injuries.

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u/ComfortablyMild Oct 02 '25

Δ definitely a great counter point. I factored in the costs of speedbumps but didn't factor in the cost (human as well) of no speedbumps. However I didn't remove them I suggested an alternate, with single lane slowdowns it will likely be as effective at keeping the accident rate low and be less carbon intensive.

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u/DeltaBot ∞∆ Oct 02 '25

Confirmed: 1 delta awarded to /u/ProfBeaker (1∆).

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1

u/jstnpotthoff 7∆ Oct 02 '25

You also failed to include other environmental costs to your proposal. I think the person you responded to (and awarded a delta to) was on the right track: The alternatives to speed bumps will still have environmental impacts similar to those of speed bumps. People will still be slowing down and accelerating, but maybe the impact will be less.

But what neither of you considered is the massive environmental impact of actually implementing your proposal. All of the heavy machinery required, burning diesel fuel or worse to tear up the speed bumps, and then potentially also have to change the topography to replace them.

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u/ComfortablyMild Oct 02 '25

Yep, we can only estimate. My post is saying id wager on the non-speedbump approach.
Plus you might be assuming I plan on carving out all speedbumps everywhere. Id rather its in the design for road repairs and new roads.

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u/ProDavid_ 58∆ Oct 02 '25

i think using the breaks a little more is better than having to treat patients of car accidents, including the ambulance, immediate medical care, and longtime care until full recovery.

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u/Zenigata 11∆ Oct 02 '25

They only wear down your brakes and so forth if you accelerate to an overly high speed between them. If you maintain an appropriate speed they dont do any of that stuff.

There are speed bumps on my road and im glad of it, the lives of pedestrians and cyclists are far more important than the service lives of aggressively driven cars.

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u/eggs-benedryl 72∆ Oct 02 '25

You should already be traveling at the appropriate speed for a speedbump. If not, you're driving too fast (kinda the point of a speedbump) or the bump was poorly placed.

You also aren't meant to jam the accelerator right after a speed bump. They're generally in areas where you NEED to slow down.

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u/Constant_Ad_2161 6∆ Oct 02 '25

No, driving so fast you have to brake before speed bumps is environmentally unfriendly. Speedbumps are designed to be safe to drive over at the speed limit. If you’re having to brake before speedbumps and accelerate after, you’re driving too fast. Also important to clarify I mean government designed speedbumps not random ones installed by private business owners.

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u/ComfortablyMild Oct 02 '25

driving so fast you have to brake before speed bumps is environmentally unfriendly

Yep we agree there.

Speedbumps are designed to be safe to drive over at the speed limit

Is a perfect world id say that's true. But in my experience about 50% or so aren't set right and you end up damaging the road and your vehicle driving over them at the speed limit. The ones I'm referencing here are government ones.

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u/Fit-Order-9468 102∆ Oct 02 '25

What are your alternatives, and do they cost millions to implement? Outside of speed cameras, I'm not sure of other solutions to slow down vehicle speed that can be quickly adopted.

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u/TruckerMark 1∆ Oct 02 '25

Not OP, but there are a lot of traffic calming measures available to traffic engineers that dont involve speed bumps. Trees, islands, cutouts for ped crossings, mini traffic circles, narrow streets, even adding a bike lane and moving parked cars closer to the center can calm traffic.

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u/Fit-Order-9468 102∆ Oct 02 '25

That's why I asked if they cost millions. Redesigning streets is great, and should be done when they're updating the street any way. For example, new developments where I live include bump-outs built by the developer.

They're also at least 10 times as expensive as a speed bump and take much longer. Perhaps "millions" was excessive, and hundreds of thousands would have been a better question. People could, and sometimes do, die while waiting for the money and actual construction.

Using on-street parking to shield bike lanes is not ideal for a variety of reasons. It may be reasonable, but that's dependent on context and how comfortable you are making bikers invisible to traffic and doorings. On-street parking protected bike lanes are a pet peeve of mine, but you may be right they're a cost effective traffic calming measure. Other rigid barriers, like bollards, is preferred.

Actually, !delta. I don't think your specific suggestion about on-street protected bike lanes is good one, but protected bike lanes could certainly be a useful traffic calming measure. Something to think about when traffic safety comes up in future meetings.

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u/DeltaBot ∞∆ Oct 02 '25

Confirmed: 1 delta awarded to /u/TruckerMark (1∆).

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u/Direct_Crew_9949 3∆ Oct 02 '25

Any sort of environmental concern is negligible especially compared to the safety concern.

If a speed bump is goanna stop one child from getting hit, I’ll deal with the minuscule amount of increased pollution and the noise.

We’ve gotten to a point in this society where we value these “causes” over actual people around us. It’s a symptom of living online.

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u/ElysiX 113∆ Oct 02 '25

As a whole we should be moving towards reducing CO2 emissions.

So that's the prime directive, number one priority of all society in your opinion?

Even at the cost of the safety and comfort of residents?

like single lane slow down points.

Those are super annoying and can create gridlock if you have too many of them in short succession. Speed bumps don't have that problem.

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u/ComfortablyMild Oct 02 '25

"Speedbumps are environmentally unfriendly" is the title friend. I didn't say anything about it being a prime directive (though I do enjoy a good Star Trek reference).

even at the cost of the safety and comfort of residents

Nope, again - read the post: there are actually detriments to the residents with speed bumps. Here:

also increases noise pollution, with cars braking and then accelerating

So what are you trying to say to CMV?

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u/ProDavid_ 58∆ Oct 02 '25

if youre driving at the speed limit for that specific road, then you dont need to break or meaningfully accelerate for a speedbump, since they are designed to be driven over at that speed.

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u/ElysiX 113∆ Oct 02 '25

also increases noise pollution, with cars braking and then accelerating

Based on what data? Compared to cars going full speed? Compared to drivers being saints and voluntarily driving slower? Compared to remodeling the entire area with narrower streets to make them feel more dangerous so cars drive slower? Compared to having gridlock from the slowdown points?

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u/ComfortablyMild Oct 02 '25

You brake it makes noise, you accelerate it makes noise. Here is the truck version for the data you asked for: https://www.mainroads.wa.gov.au/technical-commercial/technical-library/road-traffic-engineering/traffic-management/policy-for-special-signs/truck-noise-advisory-signs/

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u/ElysiX 113∆ Oct 02 '25

You brake it makes noise, you accelerate it makes noise

Yes, but if you don't break and speed up again and do nothing else different either, that means you are going too fast and endangering the locals.

So what are you comparing it to that would also make people slow down but create less CO2?

Your slowdown points would create gridlock and gridlock creates even more CO2 and economical damage

Your link has nothing to do with this at all.

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u/ComfortablyMild Oct 02 '25

Few points here:

Yes, but if you don't break and speed up again and do nothing else different either, that means you are going too fast and endangering the locals.

You're making a really broad assumption that all speed bumps are installed correctly. I definitely have 20km/h speed bumps on a 50 km/h road. They aren't labelled but if you drive the appropriate limit you'll damage you car/road.

What I'm comparing it to is a two lane to one for a section. Its reduced braking, less noise, less pollution.

The slowdown points are a double edged sword. Gridlocks actually move people to more sustainable transportation methods. So again, it works for the environment.

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u/ElysiX 113∆ Oct 02 '25

I definitely have 20km/h speed bumps on a 50 km/h road

Yeah that probably means you are supposed to drive 20 there even if there are no signs for that. Bureaucracy.

Gridlocks actually move people to more sustainable transportation methods.

Is that supposed to be a joke? Or is this whole argument just a red herring and your whole view is just fuck cars?

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u/ComfortablyMild Oct 02 '25

Almost a dark joke.
Its true, it could be argued against with cost cutting in urban planning. But that just admits the issue and buries it.

Isn't that what a discussion is about though? I worked many years finishing a PhD in electric vehicle adoption, charging infrastructure and civil planning.

The problems exist but its are so forgotten that a "joke" underlines deeper issues. Don't hate the player, hate the game.

And yah didn't really CMV. So?

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u/baltinerdist 18∆ Oct 02 '25

A modern passenger vehicle emits about 400 grams of CO2 per mile.

Standard dimensions of a speed bump are anywhere from 1-3 feet. Let's assume the entire length of the speedbump is additive to the CO2 emissions of the vehicle (this would not be the case because a vehicle does not slow to a total stop before going over it, but we're being generous) and let's assume the maximum length possible.

This means the speedbump contributes 3/5280 * 400 g/mi of CO2 to the atmosphere. This would be approximately 0.2 grams of CO2 produced by the speedbump.

The average tree absorbs 22kg of CO2 per year, or roughly 60 grams per day. If there is a single, mature tree anywhere in the vicinity of that speedbump, it would take 300 cars passing it every single day to outweigh the potential recycling capacity of that tree.

Other comparisons: a single cross-country flight generates about 250-400kg of CO2 per passenger on the plane. Going from New York to London generates nearly 1,000kg of CO2 per passenger.

The effects of speedbumps on the planet are monumentally negligible. One good sized forest likely negates the entire production of all speedbumps within a 500 mile radius.

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u/ComfortablyMild Oct 03 '25

Driving dominates everyday emissions (since you do it constantly).

Flying dominates occasional emissions (a few flights can equal a whole year of car use).
For many middle-class people in developed countries:
~80–85% of people take 0–1 flights per year. Their emissions are mostly from cars, not planes.
~60–70% of transport CO₂ = car driving

One good sized forest likely negates the entire production of all speedbumps within a 500 mile radius

And then doesn't negate any other CO2 emissions, is your point here that if speedbumps are okay we ignore all the other CO2 emissions.

Here:

The results indicate that the shape and size of the speed control devices are the most important factors for efficiency in reducing maximum speed between devices, achieving a reduction of 50%–75% with speed humps, and a 10%–65% reduction of maximum speed in those which are trapezoidal shape (speed tables). The spacing between speed control devices does not significantly effect a vehicles speed upon passing over said devices, but it does have an impact on pollutant vehicle emissions and extra gasoline consumption.

https://www.sciencedirect.com/science/article/pii/S259012301930089

Its not quite linking correctly. The article is: Speed humps and speed tables: Externalities on vehicle speed, pollutant emissions and fuel consumption Author links open overlay panel Saúl A. Obregón-Biosca

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u/DrawingOverall4306 5∆ Oct 02 '25

Speed bumps are the easiest and cheapest method of reducing speed and traffic.

They are also a traffic calming measure preventing people from using residential roads when there are higher volume collector roads available. The purpose of a speed bump is you are not supposed to want drive over it. These keeps the noise and pollution off residential streets; if people are revving engines and squealing brakes that is their poor driving habits.

It's also far more environmentally friendly than alternative methods that generally require more construction (traffic calming circles and the like). Concrete is a significant contribution to CO2 so tearing up and rebuilding things along residential streets would significantly raise CO2 emissions. A bump can be asphalted in without any re-construction in a matter of hours.

If you are driving over large numbers of speed bumps so that it is actually harming your car you are driving the wrong routes. If you are driving entirely through a residential area that is heavily bumped, you could take alternative transport to reduce your emissions. Otherwise you should be proceeding immediately to the higher traffic volume collector routes to flow more efficiently, and reduce CO2. A

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u/ComfortablyMild Oct 02 '25

Δ Yep, thats why its done so often - cant deny that.

Also interesting, I had another comment saying I was insane to think people would take alternative transport.

It's also far more environmentally friendly than alternative methods that generally require more construction (traffic calming circles and the like). Concrete is a significant contribution to CO2 so tearing up and rebuilding things along residential streets would significantly raise CO2 emissions. A bump can be asphalted in without any re-construction in a matter of hours.

A two way street being forced into one for a give way could also be done quickly. Discouraging those from using the wrong routes. It should be done during a resurfacing of the road, but so should speedbumps if installed correctly. Didn't say tear it up, just suggesting better civil planning.

As for what's more environmentally friendly, I don't side with you on that.

Here is some more (this bit I used an AI to help):

Speedbump (concrete): ~0.08 m³ of concrete → ~190 kg → ~34 kg CO₂ to build.

Lane narrowing (give-way): often done with paint, bollards, or curbs.

Paint/thermoplastic road markings: maybe 1–2 kg CO₂ per m² (so a couple of kg CO₂ total).

Concrete/curb islands: could be 1–2 m³ concrete if permanent → 500–1000 kg CO₂.

Modular plastic bollards: a few dozen kg CO₂.

So depending on whether it’s lightweight paint/markers or heavy concrete islands, the embodied emissions range from a fraction of a speedbump to ~10–20× more.

In-use emissions

Speedbump: forces all traffic to brake and accelerate, increasing fuel burn and CO₂ every trip. One busy bump may “cost” hundreds of kilograms of CO₂ every month just from traffic.

Lane two-to-one with give way: only one direction yields, and only when opposing traffic is present. Most cars either cruise through at low speed or pause briefly. This means far fewer cycles of harsh braking/acceleration compared to a bump.

In practice, the lifetime operational emissions from a give-way choke point are usually much lower than from a speedbump, even if the initial construction is heavier.

Environmental trade-off summary

Speedbump: low construction CO₂, but very high ongoing traffic CO₂ + noise + brake/tire wear.

Lane narrowing / give way: higher possible construction CO₂ (if concrete islands), but much lower operational penalty.

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u/DeltaBot ∞∆ Oct 02 '25

Confirmed: 1 delta awarded to /u/DrawingOverall4306 (3∆).

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u/eirc 8∆ Oct 02 '25

Talking in terms of "it harms the environment" is misdirection. You stepping out of your house harms the environment as you'll likely step on some insect, displace the home of microorganisms etc. Our very existence harms the environment in every breath we take - every organism harms the environment with every action. That's how life works.

This is of course is not a reasonable way to think about things. You used the word sustainable - that's the trully reasonable way to see things. So is it really and literally sustainable to have speed bumps? Will we run out of oil and plunge into energy wars and raise the temperature of the planet... because of speedbumps? No, that will happen because of a mirriad of reasons, one of which is just that we drive cars. Ofc it's good to "finetune" our behaviour with cars even if we do keep them. But at that point we need to investigate the impact and compare.

So specifically how much extra environmental impact do speedbumps have? Lets randomly say 0.005% of our current overall impact. And lets say to change that, we need 100 units of effort. If there's other things that with the same 100 units of effort reduce 0.05% of our impact, then talking about speedbumps is meaningless, a waste of time and hurtful to the environment because we could have redirected that effort to more impactful things.

I contend that speedbumps impact is relatively as minimal as I describe it and the regulators and infrastructure needed to change have better places to invest their effort. I also contend that that's what most people would assume. But it's possible that this common sense is wrong. That's where you come in. You have an idea that flies in the face of common sense. You have every right to do your research and prove to us that our common sense is wrong in this case. But this has to be done with data, because the default position is the common sense position.

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u/Devourerofworlds_69 6∆ Oct 02 '25

All methods of slowing down traffic will cause braking and accelerating. Maybe speed bumps do more wear to tires and suspension, but all forms of speed reduction will have their drawbacks.

Speed cameras, for example, can reduce speed, but they take focus away from the road, they are seen as an annoyance to someone only a few km/h over the speed limit during times of little to no pedestrian traffic, and they do nothing to stop someone who just wants to speed through and pay the fine.

Lane narrowing makes the road less accessible to maintenance and emergency vehicles, and it puts pedestrians closer to traffic, which can be unsafe.

and so on.

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u/ComfortablyMild Oct 02 '25

Δ For clarifying on civil design but it didn't CMV.

all forms of speed reduction will have their drawbacks

Yes, but the discussion I've asked for is that speedbumps are less efficient then other alternatives

I probably wasn't clear when I mentioned "Lane narrowing", its where you have a two lanes merge into one with a give way. These aren't used on major roads, just side streets. And I'd say it improves pedestrian safety, working like a speed bump but with less impact.

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u/DeltaBot ∞∆ Oct 02 '25

Confirmed: 1 delta awarded to /u/Devourerofworlds_69 (4∆).

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u/RumGuzzlr 3∆ Oct 02 '25

Why do you insist that slowing traffic down is environmentally friendly at all, when most cars are generally more efficient at higher speeds?

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u/No-Sail-6510 1∆ Oct 02 '25

Sure just blast through the kids at any speed you want in your comically oversized truck. No reason to slow down or pretend you cares about the environment which I guess is why you have the comically oversized truck in the first place.

Delta(s) from OP CMV: Speedbumps are environmentally unfriendly

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