Here are several plain facts about buses and trucks:
-Literally ALL modern city buses and motor coaches have flat fronts.
-A good majority of school buses in North America, however, have nose fronts (where there is a bulge in front of the driver in which the engine is contained). Flat-fronted school buses exist, but are far less common (back in 1989 when I was 10, I was quite surprised the first time I saw one; the next year, I got the chance to ride on one and I recall other kids gleefully remarking on how it was a different kind of bus; however, they didn’t seem to catch on).
-The cabs of tractor trailer trucks in North America used to be fairly common in two different styles: either with a long nose front or a cube-shaped cab with a flat front (two examples of the latter, both dating to the 1980s, are the vehicle mode of Autobot leader Optimus Prime in the original Transformers cartoon and the contraband-laden truck in the opening scene of “Beverly Hills Cop”). However, I don’t remember the last time I saw saw a flat-fronted tractor trailer truck in any North American context (oh wait - I do. A beautiful example, implied to be Optimus Prime, was showcased near the end of “Bumblebee”, the 2018 Transformers iteration, which was set in the 80s).
-In Europe, however, trucks with the cube-shaped cab are standard (the cab also generally seems a bit smaller than on North American trucks).
Are there practical differences for the prevailing styles of front that I have enumerated specifically being applied to each of the specific types of vehicle on which they prevail? Or is there an element of tradition/fashion/preference in any case? If flat fronts are good enough for all other kinds of bus, why not school buses and derivatives? Why are roughly cube-shaped truck cabs cool in Europe but ancient history in North America?
The “flat fronts” to use your term, offer excellent visibility for the driver. This is great for bus drivers so they don’t take off and run down somebody who’s in front of the bus and invisible. It’s great for truck drivers who may need to meander through narrow roads. The truck version of this is called “cabover”, for reasons I’m getting into shortly.
The “nose fronts” (“conventional”) are cheaper to assemble. The engine has to go somewhere; in the case of a freight truck, it’s somewhere under the driver (hence “cabover”). I recall one truck’s entire cabin area had to tilt away to allow access to the engine.
So in North America, where much trucking happens across large, highspeed highways with little concern of pedestrian interference, a truck that’s cheaper to purchase is dandy when perfect, low visibility isn’t so much of a concern.
And that’s an important distinction between “flat front” trucks and buses. Most city buses with that sort of front have the engine at the rear of the bus, where I imagine it’s fairly easy to service (just open up the access panel at the back of the bus). OTOH, there’s no equivalent to the “rear of the bus” on a semi tractor (truck), hence the need to have the engine below the driver’s compartment.
The cube type you are referring to are called cab-over trucks. The cab over the engine, not behind the engine. One of the first vehicle I ever drove was my father’s 1963 Ford Falcon van, it had the flat front and the engine was between the front seats. One of the first diesel trucks I ever drove was a cab-over International truck. Making turns are different in these, you have to wait to you are physically farther into the intersection before turning. I rode the flat front buses to school back the the 60’s, these are still the most popular style where I live now.
Engines make for poor crumple zones. Anything that doesn’t distort, deform or drop off is just transferring kinetic energy further along the chain–usually to the squishy things inside.
Which is a very long way of saying, “The engine in front doesn’t provide meaningful safety benefits.”
It’s that way because it’s cheap. A rural bus service for the kids (I presume you rode in some yellows as any right-thinking non-urban Canadian did) gets cheap buses, not good buses.
If they were at all interested in safety, those yellow buses would have seat belts and a roof that wasn’t a single sheet of formed aluminum.
Only a couple dozen kids across the US are killed each year in bus accidents, and the cost of retrofitting school buses with seat belts is $7,000 to $11,000 per bus so it’s unlikely to change.
Seat belts wouldn’t necessarily make buses safer. On the contrary, some believe they would increase the number of serious injuries. Shoulder harnesses aren’t practical in buses as currently designed, and lap belts are likely to cause more head and abdominal injuries because in a collision the wearer is jerked forward from the waist.
I wonder if there’s a regional or urban/rural divide then? Here in Bellevue, WA I’ve noticed most school buses seem to be of the flat front, city bus style. It’s a wealthy, mostly suburbs city so that would make sense. Expensive buses that are safer with lots of intersections, etc.
When I was going to elementary school on a bus I noticed the elementary school buses had a nose while the high school buses were flat. I figured it was helpful in keeping a kid who couldn’t rtead yet from getting on the wrong bus.
In Europe, there are strict limits on the overall length of a truck (exceptional loads aside). A longer tractor unit means a shorter trailer and a smaller payload. There are a few American style trucks around but they are mainly for show.
If you put an American truck driver into a modern European truck they would be lost. No gear lever (or two), Only two pedals, No mirrors (CCTV instead). They would be disappointed at the lack of dials and gauges and the high level of visibility and comfort.
Of course, they won’t be going anywhere without a card for the tachograph and at least 35 hours of mandatory study on the complicated laws of driving and rest time and load security.
Engines and associated equipment, as has been said, are much easier to get at for servicing and repairs when they’re not under the cab.
Cab-over vehicles will have a shorter turning radius. In some areas this is more important than in other areas – it might explain the flat-front school buses in city areas but not in rural areas, if that’s actually what’s happening and not just an occasional case.
These same length limits were a big deal in the USA in the 1950s & 60s. Which led to lots of US long-haul intercity trucks being cab-over.
As the interstate highway system came into being they rescinded length limits and went to gross weight limits instead. Cab-overs instantly became non-competitive for long-haul as they were more expensive to build and less comfortable to drive. By the early 1970s they were gone except for a few old units still in use.
Although US cities are generally easier to navigate any given size truck around than are UK/EU cities, there are still plenty of areas in the urbanized US where a cab-over single unit truck has maneuverability and capacity advantages over a conventional. So they’re still seen in that role.
Increasingly most of the 20-30 foot box trucks seen in the US are made overseas. The US is a big single market, but not so big compared to the entire rest of the world. So lots of Diahatsu or Nissan or whatever trucks are sold in the US and most are cabover because that’s what the world wants.
There has been a lot of work done to streamline European trucks, hardly surprising given the cost of fuel here.
The length limit mandates cabovers, but nearly all have wind deflectors on the roof and side wings to bridge the gap between tractor and trailer as well as rounded corners. The latest developments are the ‘teardrop’ shaped trailers.
Other ideas like flaps at the rear of the trailer have been tried but proved impractical.
Fairings under the van between aft of the kingpin back to the leading edge of the tires are also becoming popular. They also don’t have the small drawback of needing to be opened and closed and moved out of the way each time the van is opened to load or unload. Some are shaped like this
but many more seem to form a lateral wedge shape starting narrow behind the kingpin and widening to full trailer width at the rear.