77Univega

Fellow posters:
Is there any agreement within the vehicular cycling community as to when the speed limit of a given highway is so high that it is too dangerous for bicyclists to share the traffic lane with motorists?

I grew up next to a two-lane road with a 65 mph speed limit where (I think) it would be criminal for bicyclists to expect the motorists just "go around" them.

I have been absent for a couple years; this question may have already been introduced but I cannot narrow it down via the search feature.

Helmet Head

I don't know of any agreed upon "maximum speed limit" for sharing.

When you say "share the lane", what do you mean? If the lane is wide enough to be safely shared side-by-side by car and bicyclists, then the passing motorists are not going around, but going beside the cyclist. They might have to adjust slightly to be closer to the center line on a 2 lane road, but no big deal, regardless of the speed limit.

On a road with the outside lane too narrow to be shared, the cyclist must take the lane, and being far enough left is important so that motorists approaching from behind notice him sooner than later, and can plan accordingly. That is, they must cross over into the oncoming lane to pass, or, yes, slow down to the cyclist's speed.

In any case, it's not criminal for a cyclist to ride on any road, though it may be citation if it's on a road where drivers of slow moving vehicles are prohibited.

-=(8)=-

It depends......The 65mph highway you mention , I dont think I would even ride
on and agree that someone who thinks they have a right to make cars swerve around
them is lacking in common sense but other highways in the states I live have 35mph
posted on certain sections and cars still go 55-60 . I dont think we will ever see
the enforcement that is required to make any highway travel as safe as we would like it
to be.

maddyfish

I ride several 55 mph two lane roads fairly often. I ride in the right tire track. I move left to the center is somebody comes up and rides right behind me measuring to see if they can slide by me.
I guess I never understand what all the worry is about, seems like there is much more to wory about when riding through interesections than all the worry about riding on roads with too high speed limits.

genec

It is not just an issue of speed, but also of traffic density and room.

I have toured in various places around this country and used hiways all over with no problem... but in every case, the density of traffic was such that the drivers could see me in advance, and there was so little oncoming traffic that I was easy to pass; this was even on narrow roads and mountain grades.

Increase the traffic density, and it is harder to pass you... and the choice then seems to become more difficult for motorists... to the point where they start making bad decisions and even blaming cyclists for "forcing them off the road." At that point you are at risk.

No one in their right mind for instance would try to take the lane on a busy multi laned interstate... even slow motorvehicles are at risk in those conditions.

So as the traffic speed and density approaches that of a busy interstate, it is time to consider other routes or other means of getting to your destination.

When local surface streets approach the speed and density of near interstate traffic... and there is no room to ride at the side (where a bike lane might exist) then even "sharing the lane" becomes risky business and "taking the lane" is impossible.

On the other hand, very heavy traffic that is "slowed to a crawl" by just by the over crowding of the road, can offer a opportunity for cyclists to proceed.

The critical factors are heavy, fast moving traffic, and little room. Imagine a "fire triangle..." change any of the aforementioned factors: speed, density, or room; and you "put out the fire." Speed alone is not a problem.

AlmostTrick

It sounds like you're talking about unsharable lanes, where cyclists must ride centered in the lane to make motorists "go around them" safely.

If traffic is light, motorists have plenty of time and space to change lanes, no matter the speed difference. This seems pretty safe to me. In heavy traffic, the motorists are often going slower, and there often will be someone on your tail going your speed. This also seems pretty safe to me, although not as pleasant as light traffic. What seems least safe to me is when traffic is moderate, with packs of high speed tailgaters coming up from behind. While I wouldn't consider it "criminal" I avoid biking in these conditions as much as possible.

gcottay

I could well be wrong. It has happened before.

It seems to me that high speed limits change smart riding behavior depending on the situation. If the road is wide enough for lane sharing, motorized speeds make little difference. If the road is narrow enough that lane taking is required, the difference can be huge, especially when site lines are not good or traffic is heavy.

Wide lanes make all the difference!

genec

Perhaps the biggest problem is when road engineers look at densely packed roads and then choose to increase the speeds to "increase the flow."

Without any other change to the road, the engineers have done nothing but "fan the flame."

LittleBigMan

With the pardigm being "get traffic to flow as efficiently as possible" (which means motor traffic flowing as fast as is practical,) we cyclists aren't really considered equal players in this game. Whether we're talking bike lanes, extra wide lanes, or what-not, we're not the primary concern of planners. We're sort of an after-thought, and we tend to get leftovers.

On the other hand, considering the size of the table, leftovers can be quite a large meal, sometimes.

Bekologist

wow. stunning.

to address the OP: I think a reasonable standard for expecting bicyclists to share lanes is when median motor vehicle traffic speed is less than 2.5 times the speed of the average bicyclist.

This is not for you or me or anyone that actually rides a lot, where 6 to 7 times speed differential is sometimes encountered on a regular basis and isn't phased by it.

I think society's expectation for safe lane sharing for the mass of bicyclist skill levels (kids, elderely, disenfranchised, out of shape, etc) is less than 2.5 times the speed of the average bicyclist.


that's my opinion. when road designs exceed that 2.5 ratio speed differential, more elaborate bike infrastructure should be considered.

genec

The funny thing is the biggest leftovers tend to be at the biggest table... Have you ever considered how wide a freeway shoulder is?

I know this sounds a bit off kilter... but back in the mid 80s I toured from the west coast to Texas and a good portion of the way was on interstate... the nice wide shoulder was a great "bike lane." OK, there were some "issues," and I would not tout this as a regular thing. But the point is, that the shoulders of limited access freeways are indeed usually fairly flat or at a moderate slope, nice and wide and well marked. (and where I rode, these were the only road.)

Now consider, the US builds a lot of Interstate... and a lot of it is thruway across cities.

Now here is the tricky concept: why not build a bike freeway system using that same concept, on the same thruway, but either above or below grade as needed. There might even be enough existing shoulder to use part of the existing roadway. Think of the inertia preserving thing it could be... with cyclists not have to stop every few blocks or so for a light or sign or other intersecting traffic. A limited access freeway for bikes... paralleling the regular freeways, which go where you need to go...

Locally such a bikeway exists... and it was done quite nicely. So certainly such an example exists.

******************************************

Getting back to your first comment... indeed, we are often (always?) being treated as an afterthought. Imagine if our "priority" was moved up just a bit... Wouldn't that be a treat?!

San Rensho 

First of all, there is no agreement about anything among the vehicular cycling (VC) community.

If you want my opinion, I try to ride on streets where my speed can come close to matching the actual average speed of traffic. The posted speed limit is a guide but definitely not controlling. Its the actual conditions at the time I am riding.

If the street is narrow and has one lane in each direction, I am going to take the lane, so I would ride on a residential street where the average speed is below 30 mph. But I would not risk my life on, for example, an airport perimeter road that is narrow, two lanes and limited access where even if the posted speed is 40 MPH, people are going 60.

Two narrow lanes in each direction, I will ride on streets where the average speed is a little higher, approaching 40 MPH, because cars can easily go in the left hand lane to pass and I won't be holding up traffic.

So about 40 mph is the max average traffic speed I will bike in.

noisebeam

Like this?
https://www.americantrails.org/nation...RT/CAP-AZ.html

This follows I-10 basically. From Tuscon to Phoenix to Lake Havasu (CA/AZ border). 336mi total.

Of course not a bike freeway system, but a single freeway.

Al

LittleBigMan

Interesting thoughts, Gene.

genec

It's a start... but I really am thinking more about areas within cities, where the freeways now exist. Those would serve a lot more cyclists needing to go to the same locations that those automotive freeways now serve.

BTW as an aside, AZ is one of those places where I spent quite a bit of time on the interstate... actually being pulled over by an AZ highway patrol just outside of Tucson in a rather humorous encounter... he eventually pointed the way to the frontage road into Tucson. From Tucson on east, there is actually quite a bit of farm hiway that is interconnecting... and Tombstone and Bisbee (especially Bisbee) is worth the visit.

mattotoole

Road engineers do not do this.

If speed limits are adjusted, they're set at the 85th percentile -- the speed below which 85 percent of the traffic is actually travelling. That's rare though. All roads have a design speed, and most are governed by statute, according to the type of road.

genec

I know what is supposed to happen.

The 85th percentile rule for instance encompasses 24 hours a day and does not take into account all users of the road, such as cyclists. Also road design speeds may have nothing to do with the current speeds on that road... look at roads that were laid out 40 years ago for 30MPH traffic that now have speed limits of 50MPH. (these exist in my area... )

I also know of roads that have been built recently that are signed for 60MPH, as there was no development on the road, but since, the roadside has filled with homes, and businesses, and speeds have not been adjusted accordingly.

Also the fallacy of the 85 percentile rule is it assumes drivers are driving in a safe and reasonable manner while using the road.

Mr. Underbridge

Sure it does...it assumes 85% of them are, which is what makes it a non-fallacious line of reasoning. The question is, is that percentile high or low? Around here, way more than 15% of the driving populace seems to be mentally ********.

genec

Right... so those motorists are using the 2 second rule and are spacing themselves in manner prudent to safe driving?

And yeah I agree with your assessment of a few drivers...

noisebeam

Establishing Speed Limits - A Case of Majority Rule
https://www.azdot.gov/Highways/Traffic/Speed.asp

Al

John E

That is the real problem -- speed limits for everyone are dictated by the fastest 15 to 20% of motorists. Exacerbating the situation is the skewed-right (long upper tail) distribution of motor vehicle speeds on most roads, because there is a physical lower limit (0 mph), but no corresponding upper limit. A road on which most motorists consider 40mph prudent will often be posted at 50mph, because the 85th percentile rule will make a 40mph limit unenforceable.

PJones0012

In Houston posted speed limits are just a suggestion.

StrangeWill

If the speed limit is 65, I want a wide shoulder, or I'm taking an alternate route. I'm not sharing a lane, I want to have a shoulder thats practically a car width (preferably a large truck carrying the space shuttle width), that is MY space. Stay the hell away you fast moving cars.

Example of wide:
https://maps.google.com/?ie=UTF8&ll=3...&t=h&z=19&om=0

Alternate route: The bike path next to it. (I take the bike path because it's fun, shhhh!) Though I've taken 76 before for a few miles with no problems.

Mainly: I'm not trusting my life with the kinds of people that drive on that road, I can't trust them when I'm behind 2000lbs of steel, let alone being a total of 130lbs of human and aluminum. I will not share nor take the lane at those kinds of speeds, I value my life more than I value my beliefs in cycling. Especially when the driver is going to get a slap on the wrists if they hit me because that "idiot cyclist was in the middle of the road".

Thats my favorite kind of traffic!

tdister

Riding on the shoulder of an interstate? I'd be more worried about my hearing than anything else. Car tires often start to get really loud at 55 mph and up in my experience. Maybe an ipod wouldn't be so bad under those circumstances?

77Univega

Quote:

Originally Posted by San Rensho

First of all, there is no agreement about anything among the vehicular cycling (VC) community.

If you want my opinion, I try to ride on streets where my speed can come close to matching the actual average speed of traffic. The posted speed limit is a guide but definitely not controlling. Its the actual conditions at the time I am riding.

If the street is narrow and has one lane in each direction, I am going to take the lane, so I would ride on a residential street where the average speed is below 30 mph. But I would not risk my life on, for example, an airport perimeter road that is narrow, two lanes and limited access where even if the posted speed is 40 MPH, people are going 60.

Two narrow lanes in each direction, I will ride on streets where the average speed is a little higher, approaching 40 MPH, because cars can easily go in the left hand lane to pass and I won't be holding up traffic.

So about 40 mph is the max average traffic speed I will bike in.

Thank you. Of all the responses, this one actually answers my question as I intended it to be interpreted.