Should be fun to watch the battle between DMPED, the developers, HPRB and the community if Walter Reed is given historic designation.

by Fritz on Jan 5, 2010 9:42 am  

People are going to drive what they're comfortable with. If you want people to slow down, design the road to slow them down...don't post arbitrary speed limits that are easily ignored and require speed cameras just to enforce.

At the same time, if you want people to go the speed limit, time-and-coordiante the traffic signals so that one can progress at the speed limit and not get stuck at a gazillion red lights (are you listening DDOT?!).

Lastly, the speed limits should match the function of the road. It's ludicrous that we have freeways in the District that are posted at 40 MPH, and this is a big thing that contibutes to drivers ignoring limits, not just on the freeway but once they're off the freeway. Set realistic speed limits, not arbitrary numbers.

by Froggie on Jan 5, 2010 9:55 am  

""

by Froggie on Jan 5, 2010 9:55 am  

i have heard a rumor that if DC gets a couple of more big residential developments like Walter Reed and the McMillian sand filtration site and the Howard U swap that we could be short on water supply/pressure. which i take to mean that the current infrastructure is lacking, no surprise given the number of main breaks we had last winter. the the current cold snap hasn't done nearly as much damage it appears. anyone have any real information on this?

by dano on Jan 5, 2010 10:05 am  

The "How we drive" website is showing a disturbing strain anglophilia for nanny state traffic calming measures. As Froggie points out, how is a 40MPH speed limit on a freeway (off 295) going to help save children?

Perhaps we should institute a rule that whenever someone quotes a statistic to show a measure saves children's lives, we should automatically be suspicious of their motives...

by charlie on Jan 5, 2010 10:08 am  

I agree in part with Froggie, we ought to design our roads for slowness. The problem is that people like Charlie will insist on doing the exact opposite.

by Reid on Jan 5, 2010 10:22 am  

That's great news on the Walter Read site. The campus itself would make a great school campus and ought to be preserved. It would be unfortunate to save the hideous admin building if it's the modernist monstrocity in the middle of the entrance. One could still work with it because the older buildings are oriented south, so development on Georgia avenue could screen the building.
Let's get that trolley going and make the campus a high density transit stop.

As for the water preasure, if we where at 800,000 in the 1940's, how does that work?

by Thayer-D on Jan 5, 2010 10:25 am  

@Reid; as someone who walks through DC everday, I am very aware of cars and their speed. "designing" roads to slow you down is brilliant. Look at Georgetown.

Putting traffic calming and lawn furniture in roads to slow drivers down - not so good. And last time I checked, I haven't seen many pedestrians on 295 or the Whitehurst freeway.

by charlie on Jan 5, 2010 10:31 am  

Well, as for designing the roads for slow speed, isn't DDOT already doing that by its lack of maintenance? A lot, a lot of DC roads are so uneven, that it's impossible to even get to 25 mph. Try doing 15 going down 23rd next to the State Dept. The ramps on and of I-395 in DC are mortally dangerous due to bumps. And I'm not even talking about the fact that there are plenty of intersections where lanes shift or disappear without any warning.

Seriously, on the matter of infrastructure, DC is becoming a joke like Brussels. And all of this while heavily neglected cities like London, Paris en Berlin are completely redeeming themselves with massive infrastructure upgrades. Ever ridden the Jubilee line? Wow. Try getting from DC to NY in 2.5h. You can get from London to Paris in 2h15h. BTW, London-Paris is half the distance further, and there's a a bit more water to have to cross.

by Jasper on Jan 5, 2010 10:36 am  

@ Thayer-D: The same place where a trip from DC to Chicago by train was faster in the 40s than now.

by Jasper on Jan 5, 2010 10:37 am  

@ Jasper
I guess I was assuming regular maintenance,which now-a-days might be wishful thinking.

by Thayer-D on Jan 5, 2010 10:51 am  

I'm all for lowering the speed limit on neighborhood streets to 20mph, IF, the speed limit on 295 is raised to 65mph (especially the section between South Capitol and the MD line), and the speed limits on 395 and New York Avenue by the Washington Times building are increased.

by driver on Jan 5, 2010 11:06 am  

@driver: High speeds are fine on freeways, but NY ave west of the Times building should be much lower in the 35 area. it would be nice to have some pedestrians and businesses east of... well N Capitol, really.

whatever happened with that effed up light timing at NY and Bladensburg? DDOT get that sorted out?

also, i would really like DC to implement traffic slowing outside of speed limits, because people almost always tack on 10mph to what's posted. I regularly speed on Rhode Island because the timed closer to 40-45 between Logan Circle and N Capitol.

@Thayer: good question. I am not sure how the DC water supply works, but perhaps the suburban explosion since the 40s has something to do with it. this is why i asked.

by dano on Jan 5, 2010 11:17 am  

Charlie,
Can you please clarify what sort of traffic calming you accept? What is it about Georgetown that's brilliant but any modification to a road is putting lawn furniture in your way? Yes, having smaller blocks everywhere would be good, but once big blocks are built there's not much we can do on that front. We need to look to other measures to get drivers to slow down. Among the effective measures are those that you disparage as nanny state.

And with the Whitehurst, where are you going in such a hurry? The difference between going 50 and going 25 on the Whitehurst will save you a whole 30 seconds, and that's assuming you're not just ending up at the same red light. The same can pretty much be said for 295.

by Reid on Jan 5, 2010 11:19 am  

It's pretty hard to understand the analysis in that article about traffic deaths. But at a simple level, the number of deaths they are dealing with is about 6,000 over 20 years.

The largest number of pedestrian fatalities in DC in that time period has been 24. So we've probably had a total of 400 at most in that time.

After you subtract the ones that were not speed related in any way, how many are left? Almost every time you hear about a pedestrian fatality, it's at a light-controlled intersection.

Still not seeing how changing the speed limit would have any noticeable effect. Getting people to look when they turn right, and not run red lights, on the other hand, would make a big difference.

This is not a solution to our problem.

by Jamie on Jan 5, 2010 11:34 am  

Oh as for the Whitehurst... umm, has there ever been a pedestrian fatality there? Is it even OPEN to pedestrians? Who cares? Why even discuss places where the only problem happens to be that people speed?

If there's place where people regularly exceed the speed limit, most of the time, it's because the speed limit is too low. If there is absolutely no demonstrable downside to the speed people drive on the Whitehurst Freeway (or anywhere) then why would we change anything? It's a solution without a problem.

by Jamie on Jan 5, 2010 11:37 am  

@Jamie: what do you think Georgetown would be like if people were going 45 on M st? no, the Whitehurst is not a problem other than being an aesthetic scar, and it relieves a lot of congestion on M.

in reality traffic calming helps neighborhood development by allowing a sense of safety and allowing for conversation. but it does cost outside visitors if you have to sit through an hour of traffic. its a balancing act. transit helps it all. less vehicles and potentially more people.

by dano on Jan 5, 2010 11:45 am  

Did someone suggest raising the speed limit on M Street to 45 MPH? I certainly did not. Nor do I think lowering it to 20 MPH would have any positive effects. If you could ever go more than 10 MPH on M street in the first place...

by Jamie on Jan 5, 2010 11:51 am  

Re: the Whitehurst: Both ends of the Whitehurst end in crosswalks. The road is simply no long enough to permit cars to go 65mph+ and expect them to safely slow down for the crosswalks. Do you know of any other 1/2 mile long road that has crosswalks at both ends that permits 65mph speeds?

Again, the basic question is: what the hell would be the point to increasing the speed limit? The road is only 1/2 of a mile long. Allowing people to drop the hammer for the pure thrill of it is not a legitimate public interest.

by Reid on Jan 5, 2010 11:52 am  

FWIW, this 20-mph idea would not apply to M Street. It would at most apply to roads classified as local roads, not collectors or arterials. I think M is an arterial. This would more apply to, say, N Street in Georgetown.

by David Alpert on Jan 5, 2010 11:55 am  

@David Alpert - the fact that the limit would apply only to non-artierial roads makes it even less relevant. When is the last time you heard of a pedestrian fatality that WAS NOT on a major road, typically at a light-controlled intersection?

I can't think of a single one.

I am sure they happen occasionally, but every single one that comes to mind was not like that. The most recent one: 16th Street. All the bus ones obviously not on minor roads. One in NE on Dec. 22 was at the corner of RI avenue (and actually he was on the sidewalk, two cars collided).

The bottom line is, it is crucial to understand how these kinds of accidents happen most often if your goal is to prevent them by making major changes to traffic laws. If there's no evidence that driving over 25 MPH on side streets is a major risk to pedestrian safety -- and at this point, I can't find any -- then why would you think this change would have any positive effect?

by Jamie on Jan 5, 2010 11:59 am  

@Thayer-D - the "hideous admin building" you're talking about is the main hospital. most admin offices are elsewhere.

by AJ on Jan 5, 2010 12:07 pm  

Does the Whitehurst have shoulders? Does dc295? Lack of shoulders (air cushion) is a safety concern with high speeds.
@ Jaime, I completely disagree that if there is a road where the speed limit is consistently exceeded it means the speed limit is set too low. See Connecticut Ave NW around Nebraska Ave NW. The road is designed wrong - it "allows" for speeding. Its not the speed limit thats wrong, its the street design. Although I think the speed limit is wrong. Its too high at 30 mph in an area with a lot of pedestrians including several multiunit buildings that are residences for aging/elderly. Perhaps the light timing is an issue there too. I don't know. Froggie is so right about that problem (Sherman Ave NW, NH Ave above Upshur, Irving St NW, etc.)

by Bianchi on Jan 5, 2010 12:07 pm  

I'd love to see a comparison between the streets in Georgetown and Old Town. I'd venture that the average speed on M St is close to that of King St, but M St has much more congestion, and perhaps more accidents. The difference is the "connectivity index" - King St is surrounded by multiple streets, all small, but mostly (all?) two-ways, and with small blocks. M St is the only game in town, as the Whitehurst is a detour around Georgetown, K St is too far away from M, the next northernmost east-west route is... what? R St? Macomb? Van Ness?

by michael on Jan 5, 2010 12:32 pm  

Jamie, as Bianchi said, an intersection with a lot of pedestrian traffic should not have its speed limits raised to maximum safe driving speed. The safety of pedestrians matters as well, and I don't doubt you agree.

One of the reasons those major roads are so unsafe is because of the speed of the vehicles. Whether they are legally above the limits or not is much less important. If anything, the roads should be designed to discourage speeding, rather than making it convenient.

by Neil Flanagan on Jan 5, 2010 12:36 pm  

While I haven't been arguing in favor of raising speed limits (I'm only arguing against lowering them on roads that are already 25), nobody has yet been able to support your argument that "one of the major reasons these roads are so unsafe is because of the speed of the vehicles."

Anecdotally, I can think of no pedestrian accidents that were caused because of the prevailing speed of traffic. Sure - in the 16th Street one speed was a factor - but the driver was going way above the speed limit, there was no traffic because it was late, and he ran a red light. A lower limit would have made no difference.

From reading about these events for years, the recurring theme is complex, light controlled intersections on large, multi-lane roads. Most accidents involve a turning vehicle or someone running a red light.

So, would anyone care to compile all the data on pedestrian accidents and report back on the causes and configurations of the accident site in each case?

If those who believe we should be lowering speed limits aren't interested in doing this, then promoting significant changes in laws under the pretense of improving safety is really quite irresponsible, if you don't even want to understand what the common causes of accidents really are.

It seems that a lot of people intuitively that the speed of traffic in DC has a lot to do with the pedestrian accidents. But I am struggling to find a single incident where speed was the primary cause of the accident.

by Jamie on Jan 5, 2010 12:45 pm  

Whitehurst doesn't have shoulders, but for the most part 295 does...especially south of Benning.

Connecticut Ave is, IMO, a special case, as it's functioning as a Main Street, a pedestrian street, an arterial, and a through route all at once. Gotta strike the right balance between it all...in this case, I'd stick with 30 MPH, which to me is an acceptable speed limit for built-up urban arterials.

by Froggie on Jan 5, 2010 1:00 pm  

@ Jamie: Multiple anecdotes are not data. Furthermore, lower speed limits always yield better traffic safety. Always.

Speed limits are a balance between safety and mobility. We set the speed limit at a safety level (of danger level) that is deemed acceptable.

The funny thing is that when one plane is under threat from a moron, the whole country goes beserk and demand more safety measures, while when 40.000 people die in traffic every single year, everybody raises their shoulders and whines about proven safety measures.

by Jasper on Jan 5, 2010 1:01 pm  

Bike commuters use the Whitehurst. In years past, when I worked on K Street I would take the Whitehurst from the Key Bridge. I wasn't the only one either.

by Pattrick J on Jan 5, 2010 1:17 pm  

There seems to be a whole lot of ecological inference going on here. If, in general, lowering speed limits results in fewer traffic fatalities, that DOES NOT mean that lowering the speed limit on any particular road will lower the fatalities on that particular road. In fact, lowering the speed limit could, actually make the road more dangerous, or have no effect on fatalities.

I have no doubt that if every single speed limit in the US was lowered by 10 mph, we would see fewer traffic fatalities. But to then infer that every single road in the US would have fewer fatalities, is pure fallacy.

by driver on Jan 5, 2010 1:30 pm  

"lower speed limits always yield better traffic safety. Always." Really. Jamie, if you need data to accept this relationship (between speed and safety) read Isaac Newton.

by Bianchi on Jan 5, 2010 1:34 pm  

"lower speed limits always yield better traffic safety. Always."

You know, simply asserting something without any data to back it up does not make it true. As intuitive as this may be to you, unless you can back it up with empirical evidence, it is only your own belief.

On the other hand there's a lot of easily available data that shows raising and lowering the speed limits has little effect on both the speed at which people drive, and the accident rate.

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

"Accidents at the 58 experimental sites where speed limits were lowered increased by 5.4 percent."

"Accidents at the 41 experimental sites where speed limits were raised decreased by 6.7 percent."

(Note: these data are very low confidence because of the small numbers of observations).

"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."

by Jamie on Jan 5, 2010 1:58 pm  

Here's more.

The thing is, I am in favor of any measure that can be shown to significantly increase safety. I am not someone who just wants to drive fast.

I want policies that are good for both safety and transit.

If someone can demonstrate that lowering speed limits in DC would significantly increase safety, then you'll sell me on it in a minute.

Nobody's yet been able to do that. So you can continue to make the same completely unsubstantiated assertions until you're blue in the face, but unless you can back it up with any data, it's worth nothing.

http://pubsindex.trb.org/view.aspx?id=371649

"It was found that fatal accident rates on rural Interstate highways posted at 65 mph or rural non-Interstate highways posted at 55 mph had not significantly changed after the implementation of the 65-mph speed limit."

by Jamie on Jan 5, 2010 2:02 pm  

I don't know that I trust a study (by a Republican controlled DOT) that contains the sentence "The collective judgment of the majority of motorists represents the level of reasonable travel and acceptable risk."

The 40,000 people who die every year may have had something to say about what the "reasonable and acceptable risk" was.

Now I know you'll come back and say "but how many of those deaths were caused by speed?" It's one thing to say the accident itself was caused by speed. That is a stat that is (sometimes) captured. What is rarely captured is when the speeding is the reason someone's dead. The chance of surviving a collision with a car increases exponentially when the car is going 25 instead of 35 or above. When a car hits a pedestrian, drivers are rarely held to the speed limit. As long as they were driving the "reasonable and acceptable" speed, they look for other reasons for why the pedestrian is dead.

by Reid on Jan 5, 2010 2:18 pm  

We can google too:

http://humantransport.org/sidewalks/SpeedKills.htm

by Reid on Jan 5, 2010 2:20 pm  

"I don't know if I trust that study."

Fine, show me something that refutes it.

"The chance of surviving a collision with a car increases exponentially when the car is going 25 instead of 35 or above."

Fine. But how does this translate to reducing pedestrian deaths?

If few or none of the pedestrian accidents in our city involve a car going above 25 MPH then what's the benefit?

There are around 20 people killed a year in DC by cars.

You have no idea how many, if any, of them involved a car exceeding the posted speed limit, or even 20 MPH. Probably, very few, given the circumstances (complex intersections, big roads, turning traffic) that are most common.

I don't know either, but I'm not proposing any legislation based on that assumption.

If you don't even know the cause of our pedestrian accidents, then why are you trying to change a behavior that may have nothing to do with that cause?

This is the kind of kneejerk behavior that we criticize the DC council for all the time. Enacting kneejerk legistlation to address a percieved problem without, actually, studying the problem at all.

I am amazed that so many people want to write laws that could have significant impacts on daily life for millions, without even so much as caring about whether they would do any good.

Oh yeah, I forgot - half the people here would probably vote to outlaw cars entirely if it was on the table. I guess that explains it.

by Jamie on Jan 5, 2010 2:28 pm  

@Reid:

I am not disputing that if you put a person in front of a faster-moving car versus a slower-moving car, then the result will be worse.

If I you jump off a ten story building, you'll be much more likely to die than if you jump off a one-story building. Congratulations. Let's ban any buildings over 1 story in height.

You still haven't demonstrated that people are being killed because traffic is moving too fast.

To the contrary, all evidence is that pedestrians are not accidentlly stepping in front of a fast-moving car. Rather, in most situations, someone runs a red light, is speeding way above the posted speed limit, fails to yield at a crosswalk where visibility was a problem, or failed to yield at a turn. In every case I've read about recently, the speed limit is completely irrelevant in the circumstances of the accident.

If you have something to support your position I still haven't seen it.

by Jamie on Jan 5, 2010 2:35 pm  

A number of the DC pedestrian deaths - like the one on 16th Street last week - occur when the driver is traveling at an extremely high rate of speed, often in a stolen car or fleeing from a crime they have committed.

And lowering the speed limit to 20 will help this in what way?

By the way, it was President Coolidge who ordered his driver to proceed through DC streets at a speed not to exceed 16 miles per hour.

by Mike S. on Jan 5, 2010 2:43 pm  

@ Mike S. if the road had been designed to make travelling at 45 mph extremely difficult then yes, effectively lowering the speed limit with the method of street design (instead of signs) will prevent collisions/reduce the fatality of collisions.

@Jamie; "I am not disputing that if you put a person in front of a faster-moving car versus a slower-moving car, then the result will be worse." How is this statement substantively different from "lower speed limits always yield better traffic safety. Always." What's your dispute?

by Bianchi on Jan 5, 2010 3:08 pm  

@Bianchi: I don't know how many different ways I can say this.

If the cause of the accident was not speed-related, then it doesn't matter.

Drinking arsenic is lethal. But if you find a dead person, and there's arsenic in the room, among many other possibly lethal items, would you automatically conclude they had drunk arsenic?

Most accidents take place at light-controlled intersections, involve turning traffic certainly at speeds below 25 MPH, or involve reckless driving, or pedestrian error.

If the vast majority of pedestrian accidents occur at speeds below 20 MPH, or involve someone otherwise violating laws, then how would lowering the speed limit increase safety?

Speed CAN kill, but a 6,000 lb. vehicle (or much more, if it's a bus) AT ANY SPEED can be lethal.

Your assumption is that because speed "is in the room" it's at fault. You haven't done an autopsy though.

by Jamie on Jan 5, 2010 3:15 pm  

Let me try this another way.

Google all the pedestrian fatalities you can think of from this last year, and tell me why you think lowering the speed limit on non-arterial roads by 5 MPH would have in any way affected the outcome.

I don't even remember any that occurred on non-arterial roads in the first place.

by Jamie on Jan 5, 2010 3:33 pm  

Jamie: I'll bite. I just went through the pedestrian safety related articles on GGW just for the last month or so. Each of these fatalities/injuries seems like it could have been averted if the cars had been going slower:

http://www.wjla.com/news/stories/1209/690915.html - Driver doesn't see 2 people in crosswalk at Twinbrook. Slower speeds give drivers more time to see people.

http://www.washingtonpost.com/wp-dyn/content/article/2009/12/22/AR2009122204264.html?wprss=rss_metro - Driver went over the curb, maybe because of ice or snow, kiling pedestrian. If the drivers had been going slower, they might have skidded less if ice or snow really was involved (we can't tell).

http://www.nbcwashington.com/news/local-beat/Two-Injured-in-CarPedestrian-Crash-79896402.html - Two drivers hit each other, one car gets knocked into some pedestrians. If they'd been going slower, the crash would not have thrown a vehicle so far.

http://www.washingtonpost.com/wp-dyn/content/article/2009/12/01/AR2009120102140.html?wprss=rss_metro - Man faints in front of a vehicle. If the driver had been going slower, it's more likely it could have stopped in time, or if it hit the man, might not have killed him.

http://www.washingtonpost.com/wp-dyn/content/article/2009/12/01/AR2009120101237.html?wprss=rss_metro - Driver hits man wearing dark clothes on dark roadway in poor visibility conditions in St. Mary's County. Man dies. Police say excessive speed not involved. But if the driver had been going slower, it's more likely he/she would have seen the man or the injuries would not have killed him.

http://www.washingtonpost.com/wp-dyn/content/article/2009/11/18/AR2009111804534.html?wprss=rss_metro - Driver hits man crossing street at 16th and Colesville, killing him. If the driver had been going slower, he/she might have seen the man in time to stop, or the impact might not have killed him.

We don't know all the facts about these. But it doesn't seem that people were necessarily driving recklessly. Sometimes the pedestrians were being reckless, other times probably not. But in most cases, the driver doesn't see the pedestrian in time. Slower speeds increase that chance, and increase the chance of survival if the driver does hit the pedestrian.

We can't know for sure if slower speed would have prevented some of these deaths or injuries, but it's very likely that in at least some cases it would.

by David Alpert on Jan 5, 2010 3:44 pm  

Jamie, I don't know how many different ways I can say this. If the energy transferred in the collision is reduced then predictable consequential harm from the collision is reduced. The chance of fatality from being struck by a vehicle going 25mph is significantly greater then the chance of fatality from being struck by a vehicle goin 20 mph. (Or, if its 2 vehicles, the difference between 55mph and 70mph). I've already done the lit search. It's your turn. "The vast majority" of crashes involving pedestrian death absolutely do not involve vehicles travelling at <=20mph. There are holes in your knowledge base dude.

by Bianchi on Jan 5, 2010 3:49 pm  

or more elegantly, ditto what David Alpert said.

by Bianchi on Jan 5, 2010 3:52 pm  

The problem is, you assume in each of these cases that 1) the driver was going too fast, and that 2) lower speed would have changed the circumstances. That is a really big assumption.

The first one, I have no idea what the geography is at the Twinbrook Metro, but it's almost certainly a huge intersection. It's not in DC.

The others:

-Pennsylvania Avenue
-New York Avenue
-Rhode Island Avenue
-Route 235?? This was probably a 45 mph speed limit. Totally irrelevant. You expect everyone to drive 20 MPH on all roads through the whole country?
-16th and Colesville

Do you notice a recurring theme?

BIG ROADS. BIG COMPLEX INTERSECTIONS.

I am pretty sure not one of these is on the table for a lowered speed limit under any serious proposal.

Someone find me a pedestrian accident on a side street that currently has a 25 MPH speed limit, please. I can't.

by Petworth on Jan 5, 2010 3:54 pm  

Bike commuters use the Whitehurst. In years past, when I worked on K Street I would take the Whitehurst from the Key Bridge. I wasn't the only one either.

That's insane! You'd have to be nuts to ride a bike on the Whithurst. The cars there drive, like, 60 mph.

Also I have noticed there are no non-auto users of the Whitehurst Freeway, therefore, we should raise the speed limit to 65mph.

(Same applies to North Capitol Street north of Florida)

by oboe on Jan 5, 2010 3:59 pm  

Petworth, if you're responding to me, then I am not assuming
"the driver was going too fast" or "lower speed would have changed the circumstances". I am stating what the conclusions are from the research. Outcomes are predictably - not assumed - predictably different at varying rates of speed. The assumption is that the laws of physics are constant.

by Bianchi on Jan 5, 2010 4:03 pm  

Oh, and can we stop pretending that the only relevant auto-pedestrian collisions are the ones in which the pedestrian died?

I know several friends who were rather fucked up after being hit by cars while either walking or riding a bicycle. Just because they weren't dead doesn't mean it's a win for transportation safety.

by ibc on Jan 5, 2010 4:04 pm  

Jamie: I don't assume the driver was going too fast. I said the driver probably wasn't speeding. I'm just saying that if the drivers had been going slower, the fatality might not have occurred or might have just been an injury.

Anyway, how do you define "too fast"?

We don't know if the slower speed would have changed the circumstances in all cases, but it probably would have in some.

And sure, more of the injuries/fatalities are on major roads because there's more traffic on them. But the DC crash map shows plenty of crashes on local intersections (it codes all by intersection).

Take, say, Prospect and Potomac in Georgetown which had a collision. Those are both local roads. We don't know if lower speeds there would have avoided that one, but we don't know they wouldn't, either. I bet they would have avoided some of them.

You could argue they wouldn't have avoided enough to be worth it, though I could argue that the change from 25 to 20 also doesn't inconvenience drivers so much as to not be worth it.

There's also a factor of whether residents feel safer even if there aren't crashes, or children can play in front of houses or even in the streets if cars are going slower. When many our parents were growing up, kids played in streets a fair amount in cities, which they don't do now.

by David Alpert on Jan 5, 2010 4:11 pm  

Petworth,

The first one, I have no idea what the geography is at the Twinbrook Metro, but it's almost certainly a huge intersection.

Wrong. It's a two lane road in with curb parking. There's a marked crosswalk, but no walk signal. I believe this also has one of those crosswalk signs that flash yellow when a pedestrian requests a walk.

From the article:

Police say the two women were leaving the station and headed toward Rockville Pike when a Chrysler sedan slammed into them. The 20-year-old victim went through the car's windshield into the empty passenger seat. "The other pedestrian actually went up -- flew up into the air -- and then landed back down on top of the car, on the roof area, which also caved in the back window," said Rockville police Sgt. Bill Nieberding.

My favorite bit:

The driver, identified by police as 33-year-old Hyppolite Bouopda, of Silver Spring, stayed on the scene. He was cited for failure to exercise due care to avoid a pedestrian collision. The citation carries a $110 fine and 3 points. A crisis counselor was on the scene, consoling Bouopda after the incident.

What an odd culture we live in.

by ibc on Jan 5, 2010 4:13 pm  

@ ibc, I did not intend to imply nonfatal injuries aren't relevent. I was trying to keep my point simple by focusing on the easiest-to-measure outcome, death. In agregate, total injuries, fatal and nonfatal, are mitigated at lower collision speed.

by Bianchi on Jan 5, 2010 4:18 pm  

@David, Bianchi, Reid et al: You're not going to convince Jamie of anything. Just let it go. If I may indulge into some hyperbole, its like trying to convince Iran's glorious leader that the Holocaust actually happened.

Also ibc makes a great point. My father in law nearly died a couple of years back after being hit on a rural road while riding his bike.

I find Jamie's mentality troubling because it marginalizes getting around without being surrounded by tons of steel. There will always be those who fight progress. At some point you have to cut bait and move on to someone more reasonable.

Jamie does, however, make a decent point that a 25 to 20 change in DC isn't going to significantly change things. A 40 to 25 change would. Better yet, infrastructure that allows all to get around with ease and safety should be the goal. DC, and many areas, is left with an infrastructure that was largely designed when 40mph was ridiculously fast. We need to find a way to make it work so that people have choices and safety. Debate is a great part of that, but how long can you tell shit not to stink before you realize its better just to move up wind?

by dano on Jan 5, 2010 4:20 pm  

I'm not sure how discussing the relative merits of a 5 MPH change in speed limit marginalizes getting around without being surrounded by tons of steel. Cars are, at this point, a fact of life for most people in the DC area. If you try to focus your debate on the elimination of them, you will simply alienate the vast majority of the people you need on your side to get anything done.

So if 25 to 20 doesn't do much, then what else is there to talk about?

There are very few roads in DC with speed limits above 25 today, and only a handful that are 35 or above. The only roads with speed limits above 30 that I can think of have zero or very little pedestrian traffic, e.g. Military Road and North Cap north of Michigan. I don't think there are any that are 40 or above that are not limited access.

by Jamie on Jan 5, 2010 4:29 pm  

@Petworth, "Someone find me a pedestrian accident on a side street that currently has a 25 MPH speed limit, please. I can't." See the link to DC crash map. With a few exceptions every street in DC is 25mph.

I still don't understand what the dispute is. is it That speed does not have a relationship to injury outcome in collisions? Is that the dispute?

by Bianchi on Jan 5, 2010 4:32 pm  

Those are both local roads. We don't know if lower speeds there would have avoided that one, but we don't know they wouldn't, either. I bet they would have avoided some of them.

We don't know if speed was even a factor at all, or what the vehicle's speed was.

Now, I assume that even though most of these crashes are listed at intersections, that isn't always the case. But a vehicle-accident collision at an intersection is much more likely to result from a failure of one or the other to adhere to right-of-way rules, not because a car was going 25 instead of 20. In a mid-street collision, perhaps speed is more of a factor (ped steps into crosswalk and car can't stop). But a lot of those intersections have stop signsor lights--if a driver hits a ped, either they didn't stop when they should or the ped crossed when he shouldn't.

by ah on Jan 5, 2010 4:37 pm  

dano, thanks for your comment. The surprising thing in the research is how great the difference in risk of death is between 20 and 25mph. ie there's a 5% risk of death at 20mph while at 30mph risk increases to 40%. http://www.nhtsa.dot.gov/people/injury/research/pub/hs809012.html

by Bianchi on Jan 5, 2010 4:43 pm  

@Bianchi, thanks for the link. I think you need help reading charts, first off. The data for risk of death at speeds is:

<20mph: 1.1%
20-25mph: 3.7%
26-30mph: 6.1%

Not at all sure where you got that 40% from, it's not what the chart says.

But even more interesting is the chart showing the risk of death for speed LIMITS.

1. Pedestrian injury severity as a function of speed limit

Fatal:

<25 mph: 1.2%
25 mph: 1.8%

Even more curiously, it's lower at 35mph than 30mph.

This is exactly my point. Speed Limit Does Not Equal Speed At Which Pedestrian Accidents Will Occur.

Because the speed limit DOES NOT EQUAL the likely speed at which an accident involving a pedestrian will happen. Because pedestrians are not, actually, just walking around in the road pell mell. The accidents occur most often at intersections.

by Jamie on Jan 5, 2010 4:53 pm  

Bianchi, since the internet is all about arguing and porn: 25mph is not equal to 30mph. that said, i am not going to call into question the laws of physics. yes, the faster you go the less reaction time you have to stop and the more momentum you have to do damage. the thing is, on most side streets in the district i, and hopefully most responsible folks, never hit 25, and those who speed now wont be deterred by a speed limit change that isn't posted most places. therefore a change wont in speed limit wont significantly change injury or death statistics. which may be what Jamie has been on about all day.

my point is that we should not be arguing and using up political will on a relatively rule change that doesn't appear to really do much. use it to redesign dangerous intersections. argue about the benefits of streetscaping that slows drivers. fight about raised crosswalks and contraflow bike lanes.

i really think that we are on a similar wavelength here. i just think that this blog has bigger and better uses of time than convincing Jamie that reducing speed limits on side streets is going to make the world so much better. i just don't think it will. maybe i'm wrong, but it seems that all of GGW's efforts can be better directed.

by dano on Jan 5, 2010 5:02 pm  

Jamie, the table(s) you're referencing show distributions not measurments of risk. See figure 1 under: III Vehicle Speed and Pedestrian Injury. Anymore of this nonsense and I'll have to charge your mother for tutoring services.

by Bianchi on Jan 5, 2010 5:04 pm  

Really, Bianchi. You are wrong. You must read the report to understand what you are citing.

The chart you are looking at shows the same data as Figure 2, which is Florida only, except broken out by age. The point of that chart is to show how your risk of death changes by age.

I still don't see your 40%, even looking at the highest-risk age group (65+) it's only 20% at 30 MPH.

The chart, since it's the same data as Table 2, also shows risk by accident speed. Not by speed limit. Weren't we discussing speed limits?

by Jamie on Jan 5, 2010 5:15 pm  

Oops. I was looking at a different chart. Sorry.

But still, my point is the effect of the speed LIMIT on pedestrian fatalaties. If changing the speed limit has little impact on the typical speed at which accidents occur, then it's irrelevant what happens at relative speeds.

by Jamie on Jan 5, 2010 5:20 pm  

dano, okay, risk of death at 25mph is 25% compared to 5% at 20mph. Thats a huge difference in risk. And I see your other points. I just happen to think the harm reduction between collsions at 20mph vs 25mph is significant enough to have a discussion about. Indeed the city of London thought the potential harm reduction was significant enough to change its policy (posted speed limit) in an effort to achieve harm reduction. I agree street design is far more effective then signage in achieveing reduced speed/harm reduction.
Jamie, I have been specifically discussing speed. I wrote previously that street design is a better way to achieve reduced speed then signage (see my first response to you in this thread) and again just above. And babe, distribution and probability. Look again.

by Bianchi on Jan 5, 2010 5:38 pm  

so, London saw a 42% reduction in casualties by lowing residential speed limits with both signs and street design from 25 to 20mph. Thats a huge success! 42% reduction in harm with a 5mph reduction in speed! Its easy to see how this can be achieved given the difference in risk between 20 and 25mph (5% vs 25% probability of death respectively). Whew. I'm glad we finally got that straightened out.

by Bianchi on Jan 5, 2010 6:03 pm  

"When many our parents were growing up, kids played in streets a fair amount in cities, which they don't do now."

I would suggest that this has far more to do with the complete failure of nearly every major urban school district, and the sensible decision of parents to move to areas with better schools, then the speed limit.

by driver on Jan 5, 2010 6:41 pm  

Re: the drop in fatalities in London:

Last time I checked, correlation does not necessarily equal causation...

by driver on Jan 5, 2010 6:43 pm  

How much actual enforcement in London? How sustained the change? Enforcement (very difficult, in practice) would be the biggest barrier.

Walter Reed---the maintenance on even the newer buildings has been terrible and much of the historic details have been removed from the insides--these are factors which will make it easy to question preservation issues. Huge modern buildings like the main hospital an the pathology institute (which will move to the Naval Hospital Campus) will be expensive to reuse (because of the poor maintenance) or to replace. The old buildings fit in to the surrounding neighborhood, unlike most institutional uses. There are various structures like the pool which are truly relics and despite some historic interest, probably should be bulldozed. The campus does have housing--houses for the brass and dorm type housing that perhaps could be converted to other housing uses. It would be nice to get the property back on the tax duplicate. Redevelopment probably should some how be linked to upgrading the Georgia Avenue business district, which has never really benefited from Walter Reed, because the campus has always been so self-contained.

by Rich on Jan 5, 2010 9:46 pm  

@driver, not to mention the much greater concern over child predators and the generally more sedentary nature of kids because of other forms of entertainment.

by ah on Jan 5, 2010 11:26 pm  

Preservation is mostly about exteriors. There are countless "historic" properties whose interiors have long ago disappeared but still provide a significant contribution towards the street. Interiors are easily replacable, especially in an old hospital building. What can't be replaced are those gorgeous load bearing walls with cut stone detailing which would be prohibitavley expensive to re-do. Then again, they said we'd never see the likes of farmers markets also.

by Thayer-D on Jan 6, 2010 9:36 am  

Oh, one last thing. Just so we know where Jamie is coming from:

Cars are, at this point, a fact of life for most people in the DC area. If you try to focus your debate on the elimination of them, you will simply alienate the vast majority of the people you need on your side to get anything done.

And there you have it: it really is pointless to debates someone for whom even the mildest traffic calming measures constitute and attempt to "eliminate cars."

Whether it's increasing pedestrian crosswalk signal times, adding bike lanes, or a marginal reduction in the (already universally ignored) max speed limit, anything that benefits non-auto users can only ever mean one thing: a "War on Drivers."

by ibc on Jan 6, 2010 9:45 am  

@driver, not to mention the much greater concern over child predators and the generally more sedentary nature of kids because of other forms of entertainment.

Well then, how do you explain the near-universal practice of children walking and riding their bikes to school in the suburbs, if it's not about urban decay?

:)

by ibc on Jan 6, 2010 9:48 am  

@ibc, way to pick and choose something out of my comments without any context to try to cast me as someone who thinks any change or improvement is a "war on drivers."

I was responding specifically to this:

"I find Jamie's mentality troubling because it marginalizes getting around without being surrounded by tons of steel. There will always be those who fight progress."

I have been, quite simply, trying to present a rational argument to the effect that lowering the speed limit by 5 MPH will have a negligible impact on safety of pedestrians, and therefore would result in negligible benefit for substantial cost.

So that comment, specifically, was responding to someone who sees my interest in making policies that balance the desire for safety with the desire to maintain an effective infrastructure for the cars that many of us still depend on.

Yet many seem to think that simply because I am not ready to make policies that would significantly impact the value of the infrastructure for cars, with no benefit for peds, that I am trying to marginalize others.

My mentality is one of reason. I live in the Columbia Heights and am actually a pedestrian far more often than I am a driver. I love public transit and walking and use them all very often. In fact I rarely drive around the city.

But unlike many people here, I do not view cars as the enemy. I view them as a part of our transit infrastructure that is just as important as every other part.

So you can read what you want into that comment, and take it out of context, if that makes you feel better. It was a bit of hyperbole, that was responding specifically to another bit of hyperbole, from someone who thinks that because I am not interested in making vast policy changes based only on opinion and hypothesis and not on actual fact and data, that I want to "fight progress."

by Jamie on Jan 6, 2010 9:56 am  

@jamie -You are ignoring the substantial and measurable economic costs associated with each casualty. There is significant and measurable economic loss with every preventable fatality and every preventable non-intentional injury that results in any time of loss-of-daily-activity (and loss of income). London's result of 42% decrease in casualties by getting people to drive 5mph lower on RESIDENTIAL streets is hardly economically negligible. There is a whole field of study on health related costs and epidemiological cost-benefit analysis specifically the economics asscociated with preventable loss of life and preventable loss of daily activities and the associated loss of income. You may be interested in learning more about this field of study. Oftentimes the best economic policy is also the best public health policy.

by Bianchi on Jan 7, 2010 11:14 am  

@Bianchi, really.

First, the London thing. As someone else noted, in no way does the observation they made imply cause and effect. Further, this study has little or nothing to do with the changes you are proposing.

1. Were these speed zones formerly 25 MPH? Unknown. Unlikely. They could have been 50 MPH.

2. Was this reduction in fatalities just pedestrians, or also people in cars? It was both.

3. What else has happened in the time period of analysis? Dramatic safety improvements in automobiles.

4. What is the nature of the roads where these speed zones were introduced? We don't know.

5. How much does the physical transportation infrastructure of London have in common with DC? Very little.

Second, your focus on the death rate based on speed of impact, despite your assertion, is completely unrelated to the likely impact of a change in speed LIMIT. Changing the speed limit by 5 MPH would not, in fact, mean that every auto/pedestrian collision would take place at 5 MPH slower.

How do you account for the fact that in the study you provided, the death rate was actually lower in 35 MPH zones than in 30 MPH zones? The only possible explanation is that speed limit is not directly, or possibly even remotely, related to the speeds at which most accidents occur.

I absolutely want the best policy. But nothing that you've said indicates that lowering the speed limit by 5 MPH would have positive overall benefits. You continue to ignore actual data that shows very little change in the fatality rate between <20 and 25 MPH zones, while focusing on studies and data that is not relevant to the change being proposed.

by Jamie on Jan 7, 2010 12:02 pm  

Another important economic benefit I didn't mention: "Potential reduction in the costs of treating heart disease if adults walked regularly has been calculated in the United States, saving US$5.6 billion annually if 10% of adults began a regular walking program. Vehicle danger is a disincentive to active lifestyles. Safe walking and cycling should be promoted, because their environmental, economic, and health benefits are significant. Reducing the risks of fatal traffic injury for pedestrians and cyclists is an important part of any strategy to encourage walking and cycling to combat childhood obesity." http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1854976/

by Bianchi on Jan 7, 2010 1:26 pm  

I agree with everything in that paragraph. Still at issue: whether or not 25 to 20 would increase safety. That's the argument.

There is absolutely nothing I have said that should lead you to believe I am not in favor of measures to increase safety.

Even if you're right, that would mean we'd go from somewhere between 8 and 25 per year (the range in a decade - which says, in itself, that the pedestrian accident rate is very random and heavily influenced by externalities) from between 5 and 18.

Do you really think that even if any single person in DC was aware of the pedestrian accident rate, that this change would influence their decision to walk somewhere?

The rate of pedestrian fatalities in DC is between 1 and 3 per 100,000 in the last decade.

Here are the most common causes of death in DC each year:

http://app.doh.dc.gov/services/administration_offices/schs/10_deathcauses.shtm

#1 is heart disease, at 269 per 100,000.

#4 is HIV at 46 per 100,000

#10 is hypertension, at 17 per 100,000.

Pedestrian fatalities are probably found under "accidents" at 24 per 100,000.

So right now you are between 24 and 8 times more likely to die from a random accident of some other kind, than you are to die from being hit by a car as a pedestrian.

You are between 1,200 and 300 times more likely to die from any other cause, than you are from being hit by a car as a pedestrian.

You are between 140 and 35 times more likely to be a homicide victim than you are from being hit by a car as a pedestrian.

I think that people in DC are probably worried about a LOT more things than being hit by a car when they walk down the street.

The extra pollution and traffic and stress you would cause to save 5 people each year (using the best-case scenario, which is certainly far from accurate) would probably kill more people in other ways.

by Jamie on Jan 7, 2010 2:20 pm