"Pitt et al. (1990) examined about 1,000 urban crashes with pedestrians younger than 20 years of age taken from NHTSA's Pedestrian Injury Causation Study (PICS) data. They found that, compared to crashes with vehicle travel speeds of 10 - 19 mph, the risk of serious injury (or death) was 2.1 for speeds of 20 - 29 mph, 7.2 for speeds of 30 - 39 mph, and 30.7 for speeds of 40 mph or more."
Presumably from the title it's about a car hitting a pedestrian... I doubt there's been much significant innovation in that kind of safety since the 90s.
Features to prevent/alert to collisions, sure, but I'd assume this is about hitting someone when going X speed; surely that's pretty similar now and then.
There are also changes that increase pedestrian harm, like the arms race in the height of front ends of SUVs[1] and trucks.
Recent trends in vehicle purchases also increase pedestrian harm, as the popularity of sedans has waned in favor of SUVs and trucks. These days 72% of vehicle sales are for SUVs and trucks[2], and the trend is expected to continue into the future.
Saying "72% of vehicle sales are trucks and SUVs" in the context of pedestrian safety is highly disingenuous when a huge slice of that is crossovers that are mostly sold globally and conform to European requirements for pedestrian safety.
Hitting one's head on the windshield is/was the source of a lot of the pedestrian injury and fatalities and modern safety requirements try and prevent this outcome.
Would you rather get hit by a'21 CRV or a '95 LeBaron? CRV seems like the obvious choice.
Of course there's a lot more big trucks to hit you on the roads in 2021 but improvements in pretty much every smaller class of vehicle do a lot to balance that out.
Looking at the data I don't see any clear trend that pedestrians are at more risk today than in the past.
I actually bounced off a car with modern safety maybe 10 years ago or so, trashed a good jacket but I wasn't even shaken enough to bother getting looked over at an Urgent Care, I continued walking to lunch. Not a high speed collision of course, it was a quiet inner city street and I looked the wrong way (one way street, I looked where cars should be if it was a two way street, oops), but I suspect a 1970s car would have been markedly worse for a pedestrian.
One key trick other than the pop-up headlamps going away, was a gap between the bodywork and harder internal surfaces. As I understand it that goes something like this:
Think about a large steel panel such as a car bonnet (hood?), obviously it's no comfort blanket, smacking into that isn't a good idea, but it will bend and absorb lots of energy during impact. Now, think about an engine block, that's not going to bend at all. In a desire to give a more stream-lined look, older cars would mount that large panel almost touching the engine block and other large stiff elements, because why not. Well, dead pedestrians is why not. If you add a gap that gap absorbs lots of energy that otherwise is going to cause injuries to a pedestrian. I can't prove it, but I credit that for the difference between walking away with a damaged jacket and spending the rest of my working day in A&E being told I'm not dying so can't cut to the front of the queue, but I'm also not OK and so mustn't leave yet.
A pedestrian will never actually get into the "hard parts" of a car even on an old car. But the "soft" internal bodywork that holds the radiator, headlights and front sheet-metal are more than enough to cause bad injuries.
You're exactly correct that all that empty plastic in the top front of modern cars and crossovers is there to protect pedestrians (hood designs have been revised to facilitate this as well).
Crumple zones (or their British English equivalent if there is one) are a definite change from "classic" designs but my feeling is they were mostly in place by the 90s... but I could be misremembering.
Braking distances have gotten much better as tires and ABS have improved. A kid darts out from between two cars and people hit them at speeds much lower than they used to.
On the other hand the height and shape of the average car has changed to make them less pedestrian friendly.... but any one of these vehicles also sold in Europe includes a bunch of measures to lessen damage to pedestrians.
So I feel very comfortable saying a study from the 90s is not relevant because too much has changed on both sides of the equation.
I think that is a good point, as materials and pedestrian safety features of cars have changed. Seems unlikely the relationship between speed and severity would change too though.
Reporting would change too. People don't report crashes where there's no damage other than a hood and some grill plastic (such a crash may have broken a hip back in "the day"). This is even more true now that cars with nonzero amounts of pedestrian safety features have made it to the bottom of the market where people don't have the luxury of being able to mindlessly report everything to insurance and the guy who got hit and has only a minor injury looks at the situation and doesn't see a potential payday.
https://one.nhtsa.gov/people/injury/research/pub/hs809012.ht...