Head-on collision scenario.

Let’s say you’re headed down a two lane road at 45 miles per hour in your everyday driver. There’s a row of oncoming traffic headed in the opposite direction. You are about to over take a biker on a ten speed who’s riding close to the shoulder in your lane. One of the oncoming cars veers into your lane. You’re left with three options.

Veer left and risk a multiple car pile up of the head-on nature. Injury and possible death very likely.

Hold your lane and take the hit. That amounts to about a 90 mph collision, surely an injury or death is likely.

Veer right to escape all vehicular contact but square up with the biker. 80% chance of killing the biker and 100% chance of a lifetime disability.

What’s your initial reaction?
Then add your most significant other to your car as a passenger. Does your answer change?

That 45mph collision will only be like a 45 mph collision.

Oh, and the biker dies.

I’m not sure I can make this decision consciously. If I see the car headed right for me I’m going to steer right, I believe, due to long training almost instinct. This is true regardless if whether there is a biker there or a cliff I’m falling over.

That’s not how it works - the kinetic energy involved is closer to a 63 mph collision against a wall, but with two cars both having their own crumple zones … not sure how it compares.

That’s really strange I was just thinking about this exact scenario a few hours ago and wondered what I would do. At first I thought, other than the biker it would be better for everyone if I swerved, then I realzed I don’t think I could not swerve. Sorry biker, sucks, to be you, hope you’re wearing a helmet. Sounds crass, I know, but what am I suppose to do? I have to think about myself and my 8 year old daughter in the back seat. If hitting a biker means she doesn’t get into a head on collision at 45mph I’ll probably take that option.

To make matters worse, what if, right before the head-on crash, the oncoming car moves back into his lane. Maybe he was going around something and knew exactly what was going on (knew you were there) or maybe he was drifting over, saw you and moved back over. Now you’ve hit the biker for no reason and he, the person who caused it, probably doesn’t even know it happened or if he does, he’d be wise (from a legal stand point) to just keep driving.

How do you explain to the police that it wasn’t your fault because you were avoiding some guy that swerved into your lane?

I commute by bicycle every day. In my state, Pennsylvania, there’s a minimum passing distance of 4 feet for a car to overtake a bicycle; many states have similar laws. The law basically exists to avoid the presented scenario. Sometimes cars need to take evasive action, and sometimes bikes need to avoid road debris or potholes without warning. Given the above scenario, I would not be attempting to overtake a bike in my lane without enough distance between us.

If the swerving car were coming very fast and very far into my lane as I was passing the bike rider, I think instinct to steer hard to the right would be impossible to ignore.

At 45 MPH, just hit the brakes. If you’ve got time to swerve, on any even remotely modern car you’ve got time to get most of the way from 45-0. Reducing speed and thus the energy involved in a collision should almost always be your first instinct in these sorts of situations. Swerving has the opportunity cost of not braking, and so unless you’re pretty darn sure you can avoid the collision altogether you should brake instead.

I’m not saying the crash would be fun, but the fact that you should be able to slow most of the way down and what Arrogance Ex Machina said about inelastic collisions, it should be plenty survivable. I don’t know what a court of law would say, but I’d say intentionally splatting the biker just to avoid what is a relatively minor crash with modern safety equipment would be pretty questionable.

Under reasonable conditions a car decelerates at 15 feet per second per second or 10 miles per hour per second. That means it takes 4.5 seconds to stop from 45 mph not counting reaction time. In that time you will have traveled about 150 feet. It takes nowhere near that long in either distance or time to swerve around something.

I wouldn’t swerve into the biker, no damn matter what. I’ve got some armor, and seat belts and an airbag. He’s got jack.

I stand on the brakes and try to angle into the oncoming car. I don’t want to hit him nose-to-nose, but off-center a little, so some of the energy will be lost in shoving the two cars past each other and into a spin. Let the fenders take as much of the damage as possible.

(I’m also going to be watchful of the guy behind me. I figure he’s gonna plough into my butt once I stamp on the brakes. Accordion city.)

I see a bicyclist. (a bike = motorcycle to me )
I go super alert automatically.
Happened just this evening. Lone bicyclist on 55 MPH, curvy road. Another car crowding me as he wanted to go faster. I slowed so as to either be able to stop or slow to the bicyclist’s speed at about the same time I would be able to see far enough to safely pass him.

At that point, it was clear enough so I scooted past him, not legally but safely. The guy behind me followed along even though the safe zone was closing fast due to oncoming traffic. The next place I could see ahead for a safe but illegal pass I slowed and dropped the right wheels of the pavement and he zoomed by.

The cop was not where he usually is so the zoom guy did not get the ticket I was hoping he would get but, ‘Oh Well.’

If I was in a position where I could not have made these decisions, I would have been driving too fast for conditions IMO.

In this part of AR, the paved 55 MPH roads with a passing place only every 5 to 15 miles apart are many and we have way many bicyclists all the time weather permitting.
Also all the people going home and know the roads very well and run them as fast as they can which is really fast in some places, those people really really don’t like to be held up. Not my problem you say. Well maybe but I seem to make better time and drive safer if I am not getting crowed and driving like I like and at the speeds I like.

After about a mile or two, if we both are still on the same road, I will have caught up to them and just sit back a safe distance and let them see that if they could drive better, they might could get away. snerk I know the roads too & if the wife is not in the car with me, they get the lesson.

If I am on a motorcycle, well, no contest there.

I’m going on 71 and still ride a chopper, kick start, hard tail without a sprung seat & it really chaps their hide that they can’t catch or get away from that old fat biker dude on the ugly old bike. Bawahahahaha

Now if I have no reason to be extra alert and an on coming fool starts a pass on the other side of the hill and the first I know of this is at about 100 feet with him right beside the 18 wheeler. Well yeah, the ditch is my friend.

As a driver, it is my duty to be aware of the type of road I am on, the traffic and what escape possibilities I have at any given time. My speed and what not should be adjusted accordingly. I am not anywhere near 100% on this. But I do think about these things in advance and make A plan for this & that because sometimes I will only have reaction time to use so a predetermined plan is good. Especially when life & death are on the line. Do not like to be figuring it out during, as it is usually ‘do it’ time.


A car travelling at 45MPH has the same forces on it if it hits a wall or another identical car going 45MPH in the opposite direction. The crumple zones really don’t enter into the equation.

I think most people would brake as hard as possible, then both drivers would instinctively swerve to try and avoid direct contact. The final collision speed would be slower than 45 mph for each, and the force of impact would not be that of a 90 mph collision, but whatever the final speed of contact was.

It really depends, because the OP left out some detail. He didn’t mention the distance between the two approaching cars, which is a key factor. Also, GreasyJack said most of the way from 45-0, under a threshold braking situation. If both motorists threshold brake, it will lessen the speed in the eventual impact, even if not zero, and they’ll likely survive (AMHIK). I also think he wanted to avoid possibly killing the cyclist.

I also understand what Greasy is saying about turning vs braking. If you’re swerving, you can’t fully commit to braking, so unless you’re absolutely sure you can dodge in time (and hit the cyclist), partially getting out of the way would still result in a collision.

Without knowing the distance, though, it depends what details we choose to add.

For most cars these days, the deceleration rate is closer to 25-30 ft/second^2. That means in about one second of braking you can go from 45-25 and you can be stopped in just a bit over 2 seconds.

And you don’t even need to stop, just slow enough that you’re behind the bike and then swerve, or speed up so you’re ahead of the bike and swerve. Unless this is a long assed train of bikes - they just don’t take up that much room.

I’m going to try to stop my car as quickly as possible while maneuvering (not swerving) as much as possible out of the way of the oncoming car. Assuming that the biker keeps going, he will end up in front of me very soon and I will have more room to maneuver toward the shoulder. I will not sacrifice the biker to save myself. Even with a carload of kids I’m not going to take out an innocent person on purpose.

For the sake of the op, braking is not an option. You are left with the three scenarios as laid out in the first post.

Also, since this isn’t GQ we don’t need to bicker over the actual force of the head on collision. Just knowing that it “may” kill you or the other driver is the point I was trying to make.

It’s a variation of the Trolley Problem. Given the three options, I will take “Hold your lane and take the hit.” Same answer if my whole family is in the car. I’m not taking out the biker. Trying to avoid the collision by driving into oncoming traffic seems no better than taking the hit.

In reality, brake and dodge right when I can. Under the “no other options rule” and my wife being in the car, the biker gets it. Sorry, dude. But it’s her or you, and you are always going to lose that one.

So at about 14:30n this afternoon I was on my way to a Doc app. and was slowing from 55 to 45 where myself & the other drives were doing the same because the sign said so.
Side street on my left with a red pickup sitting still with a left turn blinker going. Car ahead of me clears the pickup, traffic coming towards is 2 cars that have not cleared.

After they cleared the red pickup, I still had not but was real close. Too close for that truck to even go straight across much less make a left.

The next only takes 2.5 seconds at most.
Red truck lunges fwd. & starts going for the lane across from me going the opposite direction. Also starts his turn towards me.
I think, " You GD idiot, I say loudly, "You Fxxxxx idiot and having checked the on coming traffic, seen that at his rate of ingress made a swerve to the left a better deal & so was ding that with minor tire complaint.
He stops violently 7/8th of the way into my lane, I have instantly, it seemed, that I checked the right lane for trouble just ahead to the turn into a popular local store. ( The street the pickup was on had no connection by street to the store, it was just my side of the store parking lot. )
I also rechecked the on coming lane, realized I could still safely turn right 7 stay on the road without going foo the road. So I was already swerving back into my lane as I had by then passed in front of the red pickup.

I though a few choice things and checked my mirrors to make sure there was no excitement behind me that I might be need to comment on later.
then I thought of this thread and went back over the event to see if I did what I said I would do.

First though, 2.5 seconds is a long time during a traffic incident.
I feel I did the right things, looked in the right places & made the best choices in this instance. I was actually surprised at how much conscious thought I actually had in those 2.5 seconds.

For almost 71, I did real good.

If I had been on a motorcycle I don’t think the red pickup would have stopped because I would not have registered in that guys mind as a potential problem. I pay read good attention when on one of my bikes but due to this particular set of circumstances, I might not have. I hope with my extreme vigilance & looking for others having even to possibility to do stupid stuff, I could have already been slow enough that the red pickup could not have hit me even if he was trying.

I wonder if having gone over this thread just yesterday made a difference in the outcome of today’s incident?