Unfairness of "Perceived Risk"

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RobertB

Train Attendant
Joined
Apr 26, 2011
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88
Location
Union Station, Dallas
The chatter about the supposed "plot" by Bin Laden and his cronies to derail a train got me thinking about the perception of risk, versus the reality of risk. As has been pointed out already, a rail-based attack in the US would be a ridiculously low-return way to terrorize a population. Passenger rail systems are designed with so much robustness, that even in a worst-case scenario, fatalities are minimized. I'm thinking of the Los Angeles tragedy, where the engineer was too busy texting to notice the signal and telescoped into a freight. Out of hundreds of commuters, a couple of dozen died. Hugely tragic, but also a pretty impressive result given the enormous physical forces involved.

I've done a lot of Wikipedia-surfing, reading articles on rail signaling and safety considerations. In many cases, improvements were made after a terrible tragedy, and became standard practice on all modern rail lines. It's an amazing process of continuous improvement. There's a lot of erring on the side of caution. Tracks that might support higher speeds and/or more trains are restricted. Everything possible is done so that, even if *everything* goes wrong, the worst that can happen is that things come to a stop and passengers have to make alternate travel plans instead of funeral arrangements.

Now, contrast that with what we're about to do here in Texas. On the wide, open spaces of West Texas, the distances are huge. It's further from Houston to El Paso than from El Paso to Los Angeles. So the speed limits have been increasing, ever since Sammy Hagar last sang "I Can't Drive 55". The speed limit on I-10 and I-20 is now up to 80mph, and the Legislature is mulling a plan to raise it to 85. The state DOT will be required to conduct studies of the roads, but one of the criteria is "how fast are people already driving?" Here's how the Austin daily paper explains it:

The bill goes on to require TxDOT, in order to exceed the "normal" rural freeway speed limit of 70 mph, to conduct studies showing that the bulk of cars are already going faster than the existing limit. The logic is that people, absent the heavy-duty presence of state troopers handing out tickets, tend to drive at speeds appropriate to the road design and amount of traffic.
I think you can see the problem here. The drivers exceeding the speed limit do not base their decisions on engineering studies and knowledge of blind spots, reaction distance, deer populations, vehicle performance, and their tires' coefficient of friction. They just drive as fast as they want to.

I don't think anyone could possibly disagree with the following statement: If the State of Texas raises the speed limit, more people will die. It's only a question of how many.

Here's a crazy thought, in the spirit of Swift's "Modest Proposal": If passenger railroads were allowed to take the risk of accumulating a few casualties among their clients each year, could they compete with the automobile?
 
I don't think anyone could possibly disagree with the following statement: If the State of Texas raises the speed limit, more people will die. It's only a question of how many.
I disagree. Speed limits have little bearing on actual speeds on the highway.
Since the advent of the 55 MPH speed limit, speed limits have been raised incrementally many times in many different places, and I'd think that you'd be hard pressed to find an increase in highway deaths that can be traced to these increases. Over that time frame (shooting from memory), deaths/miles traveled have trended down.
 
I think you can see the problem here. The drivers exceeding the speed limit do not base their decisions on engineering studies and knowledge of blind spots, reaction distance, deer populations, vehicle performance, and their tires' coefficient of friction. They just drive as fast as they want to.
Incorrect. Most drive as fast as they are comfortable that they are in control, it's only 15% that will do faster "for the thrill of it"

On the Autobahns where there is no speed limit, most drivers top out around 85 or 90. Granted, those are roads engineered for those kinds of speed.
 
If the State of Texas raises the speed limit, more people will die. It's only a question of how many.
Eh, not necessarily true. The Autobahn's portions without a posted speed limit have about the same track record for crashes as sections with posted speed limits.

Speed limits have little bearing on actual speeds on the highway.
I suppose local law enforcement/sheriffs/highway patrol don't exist in the country you're from, nor do speeding tickets. If you aren't concerned with getting fined and having your insurance rates increase, then sure, speed limits don't mean much. But for the rest of us, the existence of traffic tickets is usually enough reason for us to not go too far above the limit. Traffic speeds will generally trend ±10 to the corresponding posted speed limit.

It would be interesting to see just how many people increase their travel speeds to 85 from 80, given the price of gas. Fuel efficiency starts to tank at that speed, and the need to stop at more frequent intervals for fuel would probably end up not saving much time versus just driving 80.
 
Although you mentioned trains versus private automobiles, it's kinda apples to oranges, as drivers don't have to worry about speed recorders in the car or inward facing cameras making sure they're following all the traffic laws.

However, when it comes to bus and truck drivers, they have to follow the rules like an locomotive engineer does, or else they get kicked to the curb. Buses and trucks (especially ones carrying HazMat) have to strictly stay under the speed limit, take curves at a slower speed, and often drive slower than the speed limit for safety reasons. Trucks and buses have had speed recorders, inward and outward facing cameras, and GPS to make sure everything is legal.

Same things applies to airplanes. They probably have the strictest safety standards in the whole industry, and even private pilots can't get away with violating safety rules.
 
Speed limits have little bearing on actual speeds on the highway.
I suppose local law enforcement/sheriffs/highway patrol don't exist in the country you're from, nor do speeding tickets. If you aren't concerned with getting fined and having your insurance rates increase, then sure, speed limits don't mean much. But for the rest of us, the existence of traffic tickets is usually enough reason for us to not go too far above the limit. Traffic speeds will generally trend ±10 to the corresponding posted speed limit.
You've obviously never driven anywhere in the DC area. If you drive at speed limit +10 on any road around here, you'd better be in the right lane with your flashers on.
 
Speed limits have little bearing on actual speeds on the highway.
I suppose local law enforcement/sheriffs/highway patrol don't exist in the country you're from, nor do speeding tickets. If you aren't concerned with getting fined and having your insurance rates increase, then sure, speed limits don't mean much. But for the rest of us, the existence of traffic tickets is usually enough reason for us to not go too far above the limit. Traffic speeds will generally trend ±10 to the corresponding posted speed limit.
You've obviously never driven anywhere in the DC area. If you drive at speed limit +10 on any road around here, you'd better be in the right lane with your flashers on.
And you've never driven anywhere outside the DC area, with logic like that.
 
Demonstrably false.

Outside of known enforcement weekends (this is in the late '90s) the average speed on I-81 was well over +10.

But, don't believe me, lets go to some real data:

http://www.ibiblio.org/rdu/sl-irrel.html

The results of the study indicated that lowering posted speed limits by as much as 20 mi/h (32 km/h), or raising speed limits by as much as 15 mi/h (24 km/h) had little effect on motorist' speed. The majority of motorist did not drive 5 mi/h (8 km/h) above the posted speed limits when speed limits were raised, nor did they reduce their speed by 5 or 10 mi/h (8 or 16 km/h) when speed limits are lowered. Data collected at the study sites indicated that the majority of speed limits are posed below the average speed of traffic. Lowering speed limits below the 50th percentile does not reduce accidents, but does significantly increase driver violations of the speed limit. Conversely, raising the posted speed limits did not increase speeds or accidents.
 
Speed limits have little bearing on actual speeds on the highway.
I suppose local law enforcement/sheriffs/highway patrol don't exist in the country you're from, nor do speeding tickets. If you aren't concerned with getting fined and having your insurance rates increase, then sure, speed limits don't mean much. But for the rest of us, the existence of traffic tickets is usually enough reason for us to not go too far above the limit. Traffic speeds will generally trend ±10 to the corresponding posted speed limit.
You've obviously never driven anywhere in the DC area. If you drive at speed limit +10 on any road around here, you'd better be in the right lane with your flashers on.
Or on I-95 between Providence and RI, where the posted speed limit is between 55 and 65 mph and people routinely drive 80-90 mph.
 
Demonstrably false.

Outside of known enforcement weekends (this is in the late '90s) the average speed on I-81 was well over +10.

But, don't believe me, lets go to some real data:

http://www.ibiblio.org/rdu/sl-irrel.html

The results of the study indicated that lowering posted speed limits by as much as 20 mi/h (32 km/h), or raising speed limits by as much as 15 mi/h (24 km/h) had little effect on motorist' speed. The majority of motorist did not drive 5 mi/h (8 km/h) above the posted speed limits when speed limits were raised, nor did they reduce their speed by 5 or 10 mi/h (8 or 16 km/h) when speed limits are lowered. Data collected at the study sites indicated that the majority of speed limits are posed below the average speed of traffic. Lowering speed limits below the 50th percentile does not reduce accidents, but does significantly increase driver violations of the speed limit. Conversely, raising the posted speed limits did not increase speeds or accidents.
That is a very interesting report. This part really strikes me:

Arbitrary, unrealistic and nonuniform speed limits have created a socially acceptable disregard for speed limits. Unrealistic limits increase accident risks for persons who attempt to comply with limit by driving slower or faster than the majority of road users, Unreasonably low limits significantly decrease driver compliance and give road users such as person not familiar with the road and pedestrians, a false indication of actual traffic speeds.
I'm sure anyone who's driven in a rural area has had experience with small town speed traps. Terrell, Texas (just outside Dallas, on Texas Eagle route but not a stop) has a spot where the road goes from 2-lane to 4-lane divided... and the speed limit *drops* from 50 to 35. (I've only gotten busted there once, though!) They successfully fought an attempt by TxDOT to raise speed limits on US 80 on the outskirts of town. But part of me still felt like there's a value to speed limits, if done right.

I guess I'll have to get off my high horse, and back on My Little Pony. ;)
 
I travel on I-81 everyday. Some cars zoom by and are obviously going 75+ while others are traveling well below 65 causing slowed traffic. Of course, this is anecdotal, but there are people who drive recklessly and there are people who are just as much a hazard by traveling much slower than traffic..
 
Demonstrably false.

Outside of known enforcement weekends (this is in the late '90s) the average speed on I-81 was well over +10.
I'd love to see a source on that. The average speed of 81 in 2005 was reported to be 69mph, and 71mph when outliers were disregarded. I travel on 81 a couple of times per week, and the traffic is always very well behaved.

But, don't believe me, lets go to some real data:

http://www.ibiblio.org/rdu/sl-irrel.html

The results of the study indicated that lowering posted speed limits by as much as 20 mi/h (32 km/h), or raising speed limits by as much as 15 mi/h (24 km/h) had little effect on motorist' speed. The majority of motorist did not drive 5 mi/h (8 km/h) above the posted speed limits when speed limits were raised, nor did they reduce their speed by 5 or 10 mi/h (8 or 16 km/h) when speed limits are lowered. Data collected at the study sites indicated that the majority of speed limits are posed below the average speed of traffic. Lowering speed limits below the 50th percentile does not reduce accidents, but does significantly increase driver violations of the speed limit. Conversely, raising the posted speed limits did not increase speeds or accidents.
Your point being?
 
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Here's a crazy thought, in the spirit of Swift's "Modest Proposal": If passenger railroads were allowed to take the risk of accumulating a few casualties among their clients each year, could they compete with the automobile?
I think the very basis of this is flawed, as those who want to drive over the speed limit are personally responsible for their own actions. Contrast this to a passenger train, where the passengers are counting on the engineer to deliver them safely to their destinations.
 
You've obviously never driven anywhere in the DC area. If you drive at speed limit +10 on any road around here, you'd better be in the right lane with your flashers on.
Beltway For the win !!

Oh how I miss fairfax..
 
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Just a couple of points.

Time is not the only factor influencing the choice of mode when travelling.

The quality of that time is also important. So you can choose between spending three hours focussing on the tallights of the car in front, or maybe a bit more than those three hours reading a book or doing some work on the laptop or enjoying the scenery or whatever.

Now if the speed limit on the road is raised any maybe another 15 minutes can be shaved off those three hours, it's still not on par quality-wise with the train.

IMHO if you want more people on trains, more important than speed is a choice of different trains at different times of day so I don't have to plan my activities around the train schedule but rather plan my activities first and use trains that fit with that.
 
IMHO if you want more people on trains, more important than speed is a choice of different trains at different times of day so I don't have to plan my activities around the train schedule but rather plan my activities first and use trains that fit with that.
 
A few comments, some from a somewhat rusty memory:

If you set the speed limit as being that at which 85% of the drivers are running at or below, it is about right for the road.

Deaths per miles driven have been trending downward ever since any records have been kept on the subject.

The only exception was during the WW2 period, during which miles driven were down due to gasoline rationing combined with of those on the road many drivers were pushing their limit due to time constraints and fatigue and tires and some other items were also rationed resulting in more on-road breakdowns at a time when full shoulder widths were not that common.

The improved safety claimed from the 55 mph speed limit was in part by giving it credit for a trend that was occurring anyway and somewhat of a dip in traffic volumes that reduced the potential for conflicts. (It is impossible to have mult-car collissions when there are not multiple cars in the area.

Traffic accidents of all types are about halved by having four lane divided roads, all else being equal. They are halved again if the road is to current geometric standards rather than the 1920's and 1930's standards to which most of the original two lane highway milage in this country was built. The are halved or further reduced if the road is limited access. Improved vehicle standards such as anti-lock brakes also help. Notice that everything on this list is speed-independent.

Thus, as general road conditions have improved with time accidents go down. As the level of experience of drivers go up accident rates go down. Use of seatbelts alone has tremendously reduced injuries and deaths and reduced the severity of injuries that do occur. Notice airbags are not on my list. They are primarily stupidity insurance against those that do not use seatbelts and increase the hazard for short people, children, and babies.

All these factors are ignored by those that go into arm waving fits about faster driving or roads that are designed for fast driving with drivers in vehicles that are safe at high speeds.
 
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