Advocacy & Safety - In general, traffic flow speeds are too high today.

For years, Genec has been contending (http://www.bikeforums.net/showpost.php?p=5200237&postcount=81) that, in general, traffic flow speeds are too high and driver behavior needs to change so that everyone slows down for the sake of safety. Do you agree?

Yeah I agree in the context of non-highway roadways. I believe highway speed syndrome is the cause...you know, how when you get off a stretch of high-speed highway and feel that you are just creeping along if you abide by the measly 35-45mph speed limit. People have gotten so used to driving at higher speeds, for longer stretches, on highways, that they continue to attempt to drive at those speeds on all roads. At least that's my theory. Of course the impatience/rushed factor is probably another contributor.

Really depends where you live or cycle.

I'd say so for most of metro-Phx with 45mph arterials that flow faster than that rate. But now I am visiting Austin, TX and flow is much more subdued with most roads inside the loop being 35-40mph posted and actual, a pleasure to cycle on.

Obviously for dense urban areas motor traffic flow is actually slower than cyclists.

On rural (bicycle restricted) freeways in AZ SL is 75mph resulting in 85mph traffic. Fine for straight flat freeways like I-10/8 going to CA, but for the hilly curvy freeways like I-17 this is too fast even for me (and the many who crash every day on this freeway) in a car.

Al

newer cars can often handle much greater speeds than the limit allows. better suspension, handling, less road noise, better brakes, etc. all indirectly push up the "speed comfort level". people usually drive at whatever speed feels safe, irregardless of the posted limit.

High speeds, (especially higher than posted) coupled with dense traffic, and poor driving habits (unsafe passing distances, no signals, use of distracting devices) I believe all combine to create a somewhat hostile environment to both cyclists and peds.

I think high speeds are a hazard for peds, rollerbladers, cyclists and motorists.

Is the real question: "drivers are traveling too fast for the roadways/conditions" or "roadway design speeds are too high?"

I think some drivers are definitely driving too fast for conditions. I am often a passenger in a car where a self-described "safe" driver will substantially overdrive his or her sight distance, making it hard to brake in time if stopped traffic or pedestrians were in the roadway just beyond view. I often see drivers pass at full speed perilously close to pedestrians, cyclists, disabled vehicles, etc. where this leaves no room for error on anyone's part. I believe that this behavior results in a higher crash rate than is otherwise possible, and creates a less comfortable environment for pedestrians and cyclists.

I also think some road designs are (a) overdesigned for their intended speeds, and (b) intended for higher speeds than appropriate for the surrounding land use. An example would be a mixed-use activity center centered around an important intersection, with residential on more than one quadrant and retail/commercial on more than one quadrant, often with at least one quadrant featuring a mixture of the two. The architects will design the buildings and site plan concept as "walkable" on all four quadrants. But the two roads making up the intersection will be designed by the state as 4-6 lane 50 mph thoroughfares with high-speed deceleration lanes for right turns, and long distances between adjacent intersections, making it difficult for pedestrians to get from one quadrant to another. Retailers want to locate on thoroughfares in order to have traffic exposure, and so this is where the commercial zoning goes, but the modern roads traveling through these high-intensity use areas are much faster than the traditional urban streets where high development intensity used to be located.

For years, Genec has been contending (http://www.bikeforums.net/showpost.php?p=5200237&postcount=81) that, in general, traffic flow speeds are too high and driver behavior needs to change so that everyone slows down for the sake of safety. Do you agree?

Well, I believe traffic fatalities (especially those not involving alcohol), per mile traveled, are down in the past few decades, so I'd say no.

Now, is your next question is, 'should we modify speed limits downwards so that the roads are more convenient for cyclists (who make up far less than 1% of the traffic in most areas)'? You're going to have a hard time making that contention. Outside of urban areas where cyclists are more prevalent, it's not going to happen. If you try to press the issue, you're more likely to get cyclists banned from high-limit roads than the limits dropped to accomodate us.

In non-urban areas, the better idea is to work with communities to establish bike routes that use less travelled, lower-limit roads and make them very bike friendly. But I'm not going to start riding my bike on a 55 limit road, that is engineered quite safely for 55mph traffic, and try to say that the limit should be dropped because it's not safe for me. The obvious response you're going to get is 'don't do that.'

It's not a matter of lowering speed limits, it's a matter of getting drivers to obey them, or adjusting the speed limits to fit the conditions. I'm quite comfortable cycling on 55mph roads, as long as the traffic is actually keeping at or below that speed, rather than 70+

I voted too fast...I want to take mine back from 'Too Fast'
to 'Not Too Fast'.........

The flow of traffic overall is generally slow and inefficiant in
most urban places but its the insanty that goes on in between each
stop light or 4-way that makes riding dangerous and undesirable.

I voted too fast...I want to take mine back from 'Too Fast'
to 'Not Too Fast'.........

The flow of traffic overall is generally slow and inefficiant in
most urban places but its the insanty that goes on in between each
stop light or 4-way that makes riding dangerous and undesirable.

LOL, I have to laugh as your "too fast vote" exemplifies exactly what I am talking about... poor decisions made at high speed that effects others besides motorists. :D

It comes down to this... as long as the road situation is perfectly homogeneous (cars and trucks moving at the same speed and about the same shape) motorists do fairly well... throw in a pedestrian, a few cyclists moving at different speeds, a Segway, a scooter, a motorcycle or two and then bad things start to happen. Decisions are made in split seconds regarding "the other users of the road" that may result in collisions.

Ill accept the laff-age, humbly.
What amazes me is that on the occasion I do drive my
car I go 35mph and hit all the lights green. Its really not
hard. Its comical what cars do to get around me and jump
in the gap in front of me. I can see them stop a block
ahead and by the time I get there the lite is green.
That is what Im talking about. The stoplite to stoplite drag races. :rolleyes:

It really depends on the type of road. People tend to disregad speed limits and drive at a speed that "feels safe."

In a typical urban setting, if you have a divided road, with two lanes in either direction, with a posted speed limit of 30 mph, if traffic is light, I guarantee you that the average speed will be 50+, because two wide lanes feels safe and people will naturally speed.

If you put a two lane, narrow road in the same place, 30 mph speed limit, people will go at or even under the speed limit because it doesn't feel safe to go fast.

I see that most new road construction tends to be multi lane, so I would say that speeds are tending to get higher, and higher speeds when there are intersections, is a recipe for disaster.

I see that most new road construction tends to be multi lane, so I would say that speeds are tending to get higher, and higher speeds when there are intersections, is a recipe for disaster.

That really says it all in a nutshell. Very good point Sam.

Retailers want to locate on thoroughfares in order to have traffic exposure,

This alway struck me as fairly foolish. I know that when I'm in my car, I prefer not to get out of it unless I'm at my specific destination. Impulsive shopping and driving do not mix, and yet these idiots think they do. If they want 'drop-in' shoppers, they've got to catch them once they're out of their cars and on foot.

Apart from anything else, those shopping areas (I call it 'heavy retail') beside large multi-lane roads are some of the fugliest places I've ever seen, and they're not even all that good to drive to, especially if the place you want is on the other side of the road.

I'm not really convinced that speed is the killer. It's unattentiveness on the behalf of all road users in general and ignoring road conditions that can cause problems. If everyone was paying attention 100% of the time, I would imagine that traffic accidents would decrease significantly. Of course, this is unlikely to ever occur but that's my opinion. I'd rather not see the speed limits reduced in general, and certainly not on the interstate. It's irritating to attentive drivers like me who can safely travel at or above 70mph.

As for the city where I cycle, again, I'm just extra attentive. I've had several close calls, some related to speed. But if you're paying attention, you're doing all you can.

For years, Genec has been contending (http://www.bikeforums.net/showpost.php?p=5200237&postcount=81) that, in general, traffic flow speeds are too high and driver behavior needs to change so that everyone slows down for the sake of safety. Do you agree?
Let's put it this way: ride against traffic to increase the speed differential and decrease the necessary reaction time. Then ask again.

Why ya pickin' on Gene? Pick on me, I agree with him.

But that doesn't make me afraid to ride wherever I want. You're barkin' up the wrong tree.

Vehicular cycling depends on cooperation between cyclists and motorists, just like vehicular motoring does.

I thought vehicular cycling was about "lawful" behavior. If motorists are exceeding the posted safe limit, they are not adhering to that principle.

But if you're suggesting that whatever motorists do is ok, then the same goes for vehicular cylcists, and anything goes.

Interstate or Freeways don't count... generally we don't cycle on those nor do pedestrians use them. Interstates are intersection free, have good sight lines and are banked for high speed.

My concern is surface streets... where there are intersections and where the roads are shared by cyclists and motorists.

What is the difference between getting hit at 45 mph vs. 65 mph? For a cyclist, I'm not sure there is much. I may be wrong, but it seems like you're going to be pretty dead either way.

I raise this because I actually feel much safer on some roadways where the speed limit is 60, but the lanes are very wide, there's a nice bike lane, and I don't have to ride in the door zone. There are other roads in my town where the speed limit is 30, but I'm on edge every second. And I'm not talking about freeways here. For example, on La Costa Ave., where I ride 4 times a week, traffic routinely gets up to 65 mph, but I feel reasonably safe there. On 101 in Leucadia, OTOH, I'm scared most of the time, even though cars only go 30 - no bike lane at all, parked cars everywhere, side streets galore, and lots of trees to hide your approach.

What is the difference between getting hit at 45 mph vs. 65 mph? For a cyclist, I'm not sure there is much. I may be wrong, but it seems like you're going to be pretty dead either way.

I raise this because I actually feel much safer on some roadways where the speed limit is 60, but the lanes are very wide, there's a nice bike lane, and I don't have to ride in the door zone. There are other roads in my town where the speed limit is 30, but I'm on edge every second. And I'm not talking about freeways here. For example, on La Costa Ave., where I ride 4 times a week, traffic routinely gets up to 65 mph, but I feel reasonably safe there. On 101 in Leucadia, OTOH, I'm scared most of the time, even though cars only go 30 - no bike lane at all, parked cars everywhere, side streets galore, and lots of trees to hide your approach.

If you're riding at 20 mph the difference between 45 mph and 65 mph is huge. 25 mph closing speed vs 45 mph closing speed. Getting hit with a 25 mph speed differential is at least survivable, especially since the motorist has more time to jam on the brakes before a run-over than at higher speed.

I also fear the 101 through leucadia southbound. Northbound isn't so bad, but their road quality stands out as subpar in addition to their poor cycling facilities.

If you're riding at 20 mph the difference between 45 mph and 65 mph is huge. 25 mph closing speed vs 45 mph closing speed. Getting hit with a 25 mph speed differential is at least survivable, especially since the motorist has more time to jam on the brakes before a run-over than at higher speed.

That's the main thing. At the lower speed, you've got a better chance of not getting hit in the first place.

A lot of good points here.

I also happen to think the reason we are seeing speeds increase is because traffic is getting worse! With more and more cars on the road, traffic engineers have no choice but to continue finding ways to increase vehicle average speeds. You see this all the time with traffic lights that will stay green forever on the main road unless another car (on the sidestreet) hits the sensor.

The whole traffic situation is insane.

Interstate or Freeways don't count...

I only brought them up as it is an extreme example of the excessive speeds and danger motorist put themselves in. I-17 in AZ (Phx to Flagstaff) is an example of a road with too high a volume sustaining dangerous speeds. 85-90mph is normal down quite winding steep roads (with no modern banking, etc.) Every weekend a few trailer pulling maniacs loose it and wreck. Many folks I've talked to find it uncomfortably dangerous to share this road with the typical driver on I-17. They have these concerns and are not even cyclists.

I also believe that the 65mph speeds on the many (true) urban freeways push the speeds on the surface streets. People driving 5-20mi to get across parts of town then exit onto 45mph arterials and have the 'mental momemetum' making it 'hard' for them to keep it below 60mph on roads posted at 45mph, but that should be at 35mph considering how many minor intersections there are.

But of course, except for the indirect effect on speeds and the expectation for speed, interstates or freeways don't count.

Al

I've driven I-17 about a dozen times. In many streches I've been driving significantly faster than 85-90 yet I'm not a "maniac." Perhaps some of the folks that were puttering up the hill at 53 mph thought I was a maniac though.

Conversely, I've seen one dumbass move on I-17 while I was driving a mere 45-50 mph. Luckily, I was able to avoid that person when they spun off the road.

Driving fast does not automatically equal unsafe...

In the last 5yrs? It has gotten significantly worse. Interesting you've seen someone spin off the road on I-17 in a dozen trips. I've witnessed 4 cars leave the road in the last 20 trips or so. That's very unusual to witness so many accidents on the same road.
Yeah, there is a great variety of speed on I-17 due to the many climbs. Trucks, vehicles pulling trailers, etc. do slow down up those climbs to 50mph and much less, mostly the semi trucks which simply can not go faster, mixing it up with 85mph drivers. Those same trailer pulling idiots (not the semi drivers, the boat/ATV/camper trailer pullers) then push 85mph+ down the curvy hills.

Sure a well skilled driver like yourself on low to moderate volume traffic in a decent vehicle can go fast relatively safely, but that is just not what is happening on I-17. But the average driver on I-17 is several levels of moron above those 11/12 cyclists that crashed into the car that pulled in front of them in FL. Bumper to bumper at 85mph.

Al

p.s. genec, I've driven many miles on interstates that do not have banked turns. Where are you getting your information from?
Banked turns are nice but they're totally unnecessary. I actually drive a peice of road that is banked the wrong way (old road), and I typically take this turn at about 60mph. It's not dangerous if you're paying attention.

I pull a boat frequently (5,800+ pounds with trailer) and 80-85 is perfectly fine (albeit illegal) on straight flat roads. Add some serious I-17 corners up in the hills with some good downgrades and I'll be hanging out around 55-60 mph. I don't think I've ever seen someone towing at 85mph+ in those kind of conditions.

I have many times and in two cases they went right over the edge of the road, actually the trailer started swaying madly and took them over the edge.

I generally stay in the outside late at 75mph down those hills and am passed by lots of towing vehicles. Freaks me out every time they start to wobble as they usually do.

Anyway, enough of I-17, you seem to realize it is not a road that one can just mindlessly drive at 11mph over the SL and be OK like on the more flatter interstates.

Oh, a bit on topic as I-17 is open to cyclists.

Al

I agree. One of my favorite corners (non-interstate) is banked, but the wrong way, it's off-camber. It's a bunch of fun and really challenging to drive fast.

I'm just trying to find out why genec thinks that Interstate corners are banked.
Indeed. There are some twisty bits of interstate here that I can't possibly slow down for unless there is traffic. And these are followed by a long, straight stretch. Perfect for a healthy 90mph charge.

The thing I've noticed on the bends is that some people clearly do not understand what oversteer and understeer are, and/or they don't know how the powertrain of their vehicle is going to influence which is exhibited. I saw a guy in a sport compact understeer right into a wall a few months back. Too fast, and bad technique.

I've driven I-17 about a dozen times. In many streches I've been driving significantly faster than 85-90 yet I'm not a "maniac."
so fast...

:rolleyes:

That's perimeter speeds 'round here.

newer cars can often handle much greater speeds than the limit allows. better suspension, handling, less road noise, better brakes, etc. all indirectly push up the "speed comfort level". people usually drive at whatever speed feels safe, irregardless of the posted limit.


Some people type so fast that they type whatever comes out of their head, regardless of the fact that "irregardless" isn't a word. Not to pick on you. It's a pet peeve.

You have your choice of very nice words: irrespective or regardless. Pick one. Use it. Don't combine them.

I'd agree sppeds are too fast. I'm all for 15 and 25 mph speed limits everywhere except on the interstates.

Interestingly, while the city is 'improving' the road in front of my house, folks driving the big 4WD SUVs go by at a snail's pace, I presume so that they don't damage their car/truck/whatever. Folks in their rusty Ford Escorts continue on like before, "Rocks? What rocks?"

I think we need more gravel roads.

I'd agree sppeds are too fast. I'm all for 15 and 25 mph speed limits everywhere except on the interstates.

You're living in fantasyland. There's absolutely no scientific basis for that other than a desire to make the 99% of traffic that's motorized bow to us. That won't happen, hell that *shouldn't* happen, and if you make the case that speed limits need to be at or under 25mph for safe operation of bike on road, you'll get us banned from roads.

I've driven I-17 about a dozen times. In many streches I've been driving significantly faster than 85-90 yet I'm not a "maniac." Perhaps some of the folks that were puttering up the hill at 53 mph thought I was a maniac though.

Driving fast does not automatically equal unsafe...

Forgive my ignorance, but what is the point of "driving significantly faster than 85-90" ?

I agree, and believe it's because tickets aren't expensive enough and cops are candyasses about writing them. A speeding ticket should be a significant financial and social hardship--you are after all endangering multiple other lives in a public space.

This alway struck me as fairly foolish. I know that when I'm in my car, I prefer not to get out of it unless I'm at my specific destination. Impulsive shopping and driving do not mix, and yet these idiots think they do. If they want 'drop-in' shoppers, they've got to catch them once they're out of their cars and on foot.

Apart from anything else, those shopping areas (I call it 'heavy retail') beside large multi-lane roads are some of the fugliest places I've ever seen, and they're not even all that good to drive to, especially if the place you want is on the other side of the road.

The retailers have two objectives when locating on major thoroughfares:

(1) To make themselves seen to people driving by, so people know the retailers are there.
(2) To alter people's shopping habits so they routinely shop at places that are on their commute rather than out of their way.

Of course this pattern increases congestion on important roads for commuting, making commuting less convenient, probably more so than it increases the convenience of shopping.

15 and 25MPH speed limits on most arterial roads are a probably too slow (fine for residential and high intersection areas such as downtowns), but the flip side is "what is too high?"

Should there an upper limit on roads shared with pedestrians and with businesses, with driveways; even in front of multiunit apartment structures, and with traffic lights? I am speaking of roads with limited sightlines that may or may not have bike lanes.

What should be the practical speed limit on these roads? Here there are such roads which have limits as high as 50 and 60MPH. Of course, they are often driven at higher speeds.

Roads with few intersections and few disruptions, good sight lines and with above grade or below crossing facilities, work well at higher speeds. But what about roads that don't fit this description?

I think that improving driver behavior requires more than just increased competence among drivers. I think it also requires lowering their "target risk."

According to the theory of "risk homeostasis" people adjust their behavior according to environmental conditions in order to achieve a target level of risk that they are comfortable with in exchange for whatever advantages this risk level may provide them. Make the road safer and they drive carelessly; make the road more dangerous and they drive more carefully - but the crash rate stays stubbornly similar.

Therefore, in order to drop the crash rate, it is valuable to reduce drivers' target risk. Possible ways to accomplish this include increasing their empathy toward vulnerable road users and/or crash victims or making risky behavior in public less socially acceptable (rather than celebrated as it sometimes is in our motoring culture). I think much of the reduction in DUI crashes among non-alcoholics has resulted from stigmatizing people who drink and drive as baby killers. I think we should apply similar stigma to overdriving one's sight distance, distracted driving, and drowsy driving.

It is also possible to increase the monetary risk of dangerous driving, such as increasing enforcement and fines, but I think this will be politically difficult without first building increased public support for reduced crash rates and socially responsible motor vehicle operation. Lower the target risk of those with political power so that they see themselves as more careful, law abiding drivers, and it will become easier to increase the financial risk to less responsible parties.

Note that I don't fully endorse the concept of risk homeostasis, but I believe it partially explains some safety phenomena as a contributing factor in human behavior.

15 and 25MPH speed limits on most arterial roads are a probably too slow (fine for residential and high intersection areas such as downtowns), but the flip side is "what is too high?"

Should there an upper limit on roads shared with pedestrians and with businesses, with driveways; even in front of multiunit apartment structures, and with traffic lights? I am speaking of roads with limited sightlines that may or may not have bike lanes.

What should be the practical speed limit on these roads? Here there are such roads which have limits as high as 50 and 60MPH. Of course, they are often driven at higher speeds.

Roads with few intersections and few disruptions, good sight lines and with above grade or below crossing facilities, work well at higher speeds. But what about roads that don't fit this description?

we have a posted 30mph 2 lane road in my neighborhood. (it switches to 4 lane in front of the shopping center) it is fed by a slip ramp from a 55 mph 'parkway' (we're working to get the slip ramp closed, as its impossible for kids and seniors to cross without a light).

speeds here are always high. residential along its length, with a large commercial shopping center, post office, 2 schools, several churches, and a park. most folks go 35-45 on this stretch. some targeted enforcement might help... for awhile.

in general i think speed limits on suburban and urban roads are too high. knowing that most folks drive over the speed limit anyway, and the limits are rarely enforced, it seems lowering the posted limits might lower overall speeds just a bit.

Forgive my ignorance, but what is the point of "driving significantly faster than 85-90" ?

Getting somewhere sooner rather than later.

For years, Genec has been contending (http://www.bikeforums.net/showpost.php?p=5200237&postcount=81) that, in general, traffic flow speeds are too high and driver behavior needs to change so that everyone slows down for the sake of safety. Do you agree?
In some maybe even most cases i say yes. There are of course exceptions like old 21 aka great lakes blvd. It is a 55 to 65 mph road where bikes are allowed. But do to the fact that years ago it was a 4 lane highway and is now only 2 lanes on this road bikes can safely share the road with 65mph+ traffic. The lanes are close to a extra 50% the normal width with wide shoulders nearly 1/2 the width of a normal traffic lane making up the rest. So if you simply split the lane in half and in half again and ride in that strip you have lots of room to your left and a ton to your right. Then you have roads like johnson where even 35mph is a tad fast and places like vanburen where theres a 25 mph speed limit but drivers can hit 40+ after dropping their kids off for school.

15 and 25MPH speed limits on most arterial roads are a probably too slow (fine for residential and high intersection areas such as downtowns), but the flip side is "what is too high?"

Should there an upper limit on roads shared with pedestrians and with businesses, with driveways; even in front of multiunit apartment structures, and with traffic lights? I am speaking of roads with limited sightlines that may or may not have bike lanes.

What should be the practical speed limit on these roads? Here there are such roads which have limits as high as 50 and 60MPH. Of course, they are often driven at higher speeds.

Roads with few intersections and few disruptions, good sight lines and with above grade or below crossing facilities, work well at higher speeds. But what about roads that don't fit this description?

I think even the most ardent pro-car motorist would agree that speed limits in areas with lots of businesses, no merge areas, no turn lanes, pedestrians, and bus stops would be best limited to 35mph or so.

I will always remember my driving instructor telling me that I was responsible for my vehicle at all times. If you cannot stop/ avoid / prevent a crash, you are not in control of your vehicle. The word accident makes it sound like most crashes are unavoidable. A 70 year old man on the freeway doing 80 mpg does not have the reaction time needed for a decision that could take the lives of many people. Never mind the 30 year old mother with an infant son crying in the backseat.

Road safety is about people safety. Members of your community are traveling beside you as well as visitors, friends and relatives.

I suggest the number one cause of preventative deaths is from car crashes and lifestyle choices created by the car industry and our participation in car culture.

Yes, traffic flow speeds are too high in most area's today. I say this not only as a cyclist but as a motorist also. Reducing speeds would make cycling and driving more pleasant and crashes less frequent. To believe otherwise defies the laws of physics, as increased speeds leave less reaction time. The problem is not just the high speeds, but the inadequate buffer zones most drivers leave for themselves. High speeds combined with these short buffer zones leaves little margin for error. (or anything unexpected like a cyclist moving slower than other traffic)



I will always remember my driving instructor telling me that I was responsible for my vehicle at all times. If you cannot stop/ avoid / prevent a crash, you are not in control of your vehicle. The word accident makes it sound like most crashes are unavoidable.

+1 If everyone thought like this there would be very few crashes.

"in general" is too broad...it depends on the location. I will say this; that speeds on my local arterials (aka urban freeways) are too fast for me to feel safe riding a bike on them.

Forgive my ignorance, but what is the point of "driving significantly faster than 85-90" ?



Getting somewhere sooner rather than later.

Where? The hospital? Jail?

Forgive me for not being polite ... but driving that fast is unresponsible, even if you are driving a Ferarri.

If person wants to wrap their car around an oak tree, great ... thats fun to look at. :D But unfortunately someone else would probably get taken out as well. :mad:

"in general" is too broad...it depends on the location. I will say this; that speeds on my local arterials (aka urban freeways) are too fast for me to feel safe riding a bike on them.

"In General" is "too broad" but that was how Helmet Head chose to frame my rant on the speeds of surface street arterials that may also support bike lanes, parked cars, pedestrian crossing and stop lights.

To be quite specific, I believe interstate freeway speeds generally should not be considered too high, and residential and downtown grid speeds are probably not too high, but arterials with lots of intersections and driveways, parked cars and other potential "hazards" should not be 50MPH or higher.... Especially if upon these roads a cyclist may be expected to "take a lane."

When I become King, Grand Poobah, Maximum Potentate, or Top Dog, here are the speed limits:

Residential: 15 mph
Urban - 20 or 25
Rural roads without a shoulder - 35
With a shoulder - 40
Freeway - no limit - Charles Darwin will regulate the speed.

I know for a fact that many people who drive on Ontario's 400 series highway drive a good 20km over the speed limit of 100km/h (60mph) some parts of our highways people go 140km/h~160km/h (87~100mph) and that's going with the flow.
Hwy 401 in particular has a section where people don't go slower than 130km/h (80mph).
Our 400 series is designed for 130km/h (80mph) maximum speeds in mind, but all posted with 100km/h maximums.


That being said, we had a lot of accidents and deaths on our highway this year alone because of inattentive drivers, distracted drivers, drunk drivers, drivers cutting off 18 wheelers, racing drivers who think the road is their own personal playground and in general poorly skilled drivers.

You just have to drive for the conditions and pay attention.

Where? The hospital? Jail?

Forgive me for not being polite ... but driving that fast is unresponsible, even if you are driving a Ferarri.
You are forgiven for not being polite, just as your self admitted ignorance of the subject is forgiven. I don't expect anything else from know nothing nannies. I managed to drive the Autobahns of Germany for 10 years and never ended up in jail or the hospital; just like millions of other drivers who are not so ignorant about safety and appropriate speed for the conditions

I realize that this is a global forum, but I really didn't know that there were roads in Iowa that were like the Autobahn. Huh, that's news to me.

I must be horribly mistaken ... I guess roads built like the Autobahn with their expert high speed drivers are perfectly safe.

http://www.cleanmpg.com/photos/data/501/Car_vs_Truck_crash_on_the_autobahn.jpg [link (http://www.cleanmpg.com/photos/showphoto.php/photo/2789/si/famous)]

Again, sorry for my ignorance.