myrridin

It appears that those of us who use MUP's and travel at inappropriate speeds may be used as justification to add speed limits to Dallas MUP's

https://www.nbcdfw.com/news/local-bea...106257868.html

While the report was hardly balanced (no mention that other users act in reckless manner), it didn't take them long to find cyclists going too fast for the conditions.

Brad Bedell

Here's a cross post from the jogger injured. Feel free to check my formula/math if you like.


As for speed limits. You'll still have to catch and ticket the people going too fast. You can't and won't catch them all. Even then, say a 15mph speed limit is enough to kill or seriously injure someone if they land on their head the right way. How fast was this cyclist going? Does anyone have any ideas?

Lets play a math game. Formula: F = m Dv/Dt Where F = force, M=mass, Dv=delta velocity, Dt= delta time. A quick google search gives me .0455 as a unit conversion for pound-miles per hour per second.

Say, a 200lb cyclist (180+ bike) traveling at 15mph hits a jogger who is stopped. Lets say it takes .5 seconds to 'stop' motion completely, since the jogger will give a little when hit. That's 200*15/.5 *.0455= 273lbs of force applied instantly to someone's shoulders. I'm too lazy to calculate the falling velocity of the runner when they actually are accelerated from 0 to whatever speed when they hit. I suspect it's in the neighborhood of 200lbs of force directly to the head when they impact.

Given the impact is more along the lines of .2 seconds and not .5, that force will nearly triple.

Lets do something else: A runner doing speed work. 6min mile isn't too hard for someone 'fit'. I'm not much of a runner and can run a sub 6min mile. I weigh 190lbs dressed. Lets assume it takes .3 seconds for us to crash and stop.

so 190*10/.3=6333.3...(.0455) That's 288lbs of force. More force than my first example, and with the right bad circumstances, enough to kill someone.

myrridin

The news program last night from the same station I posted the link to had people talking about a 10mph speed limit for cycles (and presumably other users). Having ridden on MUP's I don't think 10mph is an unreasonable speed to go when near pedestrians. It would be a pain to be limited to such speeds when the trail is clear and you have good sight lines. That's the problem, folks riding without regard to trail conditions.

A speed limit is not simply about reducing the lethality of a collision. It is also about giving the participants more time to respond and prevent collisions.

monogodo

When I've used the Katy Trail, I had a hard time going faster than 10mph anyway, what with having to slow to a near stop to get by joggers with headphones and dogs on leashes.

Brad Bedell

The *ONLY* way a radar will get an accurate lock is when the trail is free and clear. Of course, speed really isn't the issue, it's poor judgment of cyclists, runners and walkers. Until there is a cure for narcissism, all the laws anyone can dream up will not give us a solution.

My wife and I went for a short run yesterday morning on Katy. We stopped at Knox for a drink of water. There was a guy with his hand leaning on the edge of the water fountain. I said excuse me, he didn't respond. Wife got a drink, then I proceeded to take a drink. At this point, he seemed shocked and offended that I was drinking so close to him as he retreated.

People really don't pay attention when they are on the trail. I'm shocked this is the first time we've seen an accident this serious.

StephenH

Well, right now, if you want to get anywhere in Dallas on a bicycle, the trails are the worst ways to do it. Adding a low speed limit will just enforce that. It'll be a good way to keep newbie riders from riding, period, but won't accomplish much otherwise. It does reinforce the idea that bikes belong on a street, and is at just exactly the wrong time for the city to discover that. It would also be a way to shift the blame for virtually any bike accident on the trails to the cyclists' fault, regardless of the pedestrian actions.

If I remember right, though, the city does have a law requiring cyclists to give an audible warning when overtaking cyclists or pedestrians. Unfortunately, they don't have any law requiring people to listen to those audible warnings. That would probably be a better solution.

myrridin

I suspect that this and the desire to limit the number of cyclists on the trail are probable motivators for the folks pushing this.

I must admit that I am of two minds on this. I don't think speed limits will actually affect the speed of the cyclists who are currently riding at unsafe speeds.

I ride on a Plano MUP for at least part of my daily route. On most days I find it pleasant. Even so, I am constantly amazed by the number of people who simply do stupid things. My ride is usually before sunrise. Almost every time I pass walkers/joggers wearing dark colored clothing with no reflectors or other safety devices. Almost every user has ear plugs in their ears. While not every day I have encountered cyclists riding the trail without lights, and one without even reflectors. On weekends, I find soccer parents setting their lawn chairs and sports gear on the trail rather than in the field where it belongs. I see cyclists threading the needle between these people at unsafe speeds.

Almost everything listed above, is contrary to the park rules posted around the park.

In short, like someone mentioned above, the problem is universal. People are simply narcissistic idiots who are only concerned about their self-interest and don't care about rules designed for everyone's safety. It is the main reason I have little sympathy for cyclists complaining about drivers and wanting to change the regulations. I suspect many are the same folks who behave recklessly around pedestrians on the MUP's, particularly when the same folks talk about Idaho stops and how some "rules of the road" shouldn't apply to bicycles.

I can't find the quote, but I remember someone making the claim that it is a very rare collision that didn't have all parties contribute to the collision in some measure.

Creakyknees

Dallas area mup's already have speed limits. It's 15. Obviously it's not well posted....

Brad Bedell

I couldn't find anything in the statutes of this. Can you cite it for me?

Creakyknees

no, I'm just going from memory - when they first opened the WRT they had speed limit signs... now that I think about it I haven't even seen signposts in many years.

KD5NRH

At certain times of day, sure, but I used to ride the WRT at night. It was fairly common to go from Royal to the lake without seeing three other people on the trail.

bjtesch

I'm not in favor of speed limits. If they want to make rules, I still say no headphones, no dogs, no baby strollers. If you want to walk slowly and take your children, go to the mall. If you want to listen to music you can just stay home. If you want to jog you can jog on the sidewalk in front of your house. Actually there are good alternatives for every activity that happens on the trail, EXCEPT bicycling. I dare say you can find places to jog off of the paved roads in any part of the city, but you can't find safe places to bicycle in every part of the city.

BUT, I don't think bicyclists should ride over 15mph on the trails either. I sometimes ride on the trails near my house, and usually don't go over about 16mph. I ride on the trail because I don't want to ride on the roads. There are plenty of people with kids and dogs and so forth. They think nothing about taking the entire width of the trail without regard to whoever is around, and they WILL move right over in front of you. I ride on the trail early in the season, if I want to go short distances and I'm not in shape for higher speeds. Later in the season when I'm up for more miles and faster speeds, I don't ride on the trails anymore, I use the paved streets. There are some streets in my area that seem relatively safe for bicycling, that is until a Toyota tried to flatten me in June. I'm still recovering from that incident.

tcs

For several decades White Rock was sign posted "Cyclists Yield to Pedestrians". It's been a few years since I've been down & around - are those signs still up?

monogodo

I think you're confusing the Katy Trail with another MUP. The Katy Trail goes from Downtown Dallas north to almost SMU, and will eventually connect to WRL. About the only time I've seen it not busy is late at night.

Doohickie

Just keep your issues east of the county line, okay? I don't want any of this talk in Tarrant County.

MMACH 5

He's not confused. He was making a comparison to White Rock Trail (WRT).

monogodo

Having ridden both, there's no comparison to make, they're completely different.

MMACH 5

Not according to the city. Whatever plan they put in place to for one will automatically apply to both. (Also, I've ridden both as well and late at night, they are both basically empty.)

monogodo

I agree that both are basically empty late at night. My point was that on the Katy Trail when it's busy it's nearly impossible to go over 10mph, while at WRL, it's easy enough to do so, regardless of time of day. Yes, in spots it may be difficult, but generally it's not, or at least not as difficult as it is on the Katy.

MMACH 5

Agreed.

monogodo

Rode the Katy Trail tonight twice: once north to meet friends, then back south to home. Average speed of my entire ride north was just over 11mph at 6:45pm. Average speed heading south was just over 12.5 at 10:15 pm. The crowds weren't too bad heading north. Heading south I saw two joggers and an opossum which tried to attack me.

dougmc

They don't catch all the speeding motorists either, but we do still have speed limits.

That said, even 1 mph is enough to kill or seriously injure someone if they land on their head the right way.

That's the problem with your math right there -- the "lets say it takes .5 seconds to 'stop' " part is a guess, and really doesn't apply to reality anyways.

Accidents between pedestrians and cyclists (or just cyclist/cyclist or pedestrian/pedestrian) tend to defy analysis like this because there's so many variables. A child bumping into a pedestrian at 1 mph could make him lose his balance and fall on his head -- or if the pedestrian was aware and ready, he could stop an adult cyclist hitting him at 20 mph with no injuries to either. The devil is in the details, and trying to distill it down into a single number doesn't really help at all (and really, if you do want to distill it down into a number, the number should either be energy (joules or foot·lbs) or momentum (kg·m/s or N·s or pound·feet/s or pound·s) -- not simply force.

To be fair, you seemed to be pretty close to trying to calculate momentum -- but not quite.

As for how hard your head hits the pavement, again, it depends. The largest factors in how fast your head is going when it hits are how much you were able to catch yourself or otherwise slow your fall (humans don't fall like rag dolls in most cases) and how tall you are (or how high your head was when you started falling.) It's a complicated issue.

Brad Bedell

Doug: You are correct. There are way too many variables. I had to guess some numbers. The formula is far to variable to do much more than analyze a crash 'AFTER' it happened. Or at the least, draw up a whole series of 'what-if's'. .5 seconds is likely slow to hit the ground and was a very slow motion 'guess'. However, you understood my point. More or less, a speed limit will not make the trail safe. The 'news' and 'leaders' are trying to sell safety to citizens with an imposed speed limit; which as you pointed out isn't guaranteed. No matter how many laws they impose upon civilization, people are still going to die in freaky accidents.

Of course, it was pointed out that slower moving objects WILL increase time for people to react. IS that time enough? I don't know. For all we know the actual impact for this woman on Katy was 5mph, I've yet to be able to find that speed.

canopus 

It won't increase time automatically, it depends on WHEN the object moves into the oncoming path.

At about 10mph You can travel 15' in 1 second. If something gets in your path 10' feet out, there isn't enough time for you to react to avoid the collision. It isn't about the speed. It's about being aware of your surroundings.

Brad Bedell

No, it won't increase time automatically. But it could be the difference between hitting one's head directly on the pavement or having time to get a limb out to break the fall.

Although, I disagree on reaction time; 1 second is plenty of time to force the bike around a walker at 10mph. My avoiding a pile of bicycles catapulted directly in front of me at 30mph during a race was my only witness. Same goes for off road riding. I've had more than one rider wash out directly in front of my wheel at 10-12mph, I've yet to hit someone. But then again, that goes back to your being aware of your surroundings and riding within one's limits.