Greater Greater Washington

Roads


Successful speed cameras require fair speed limits

Underlying the current discussion of speed cameras is the assumption that speed limits are rationally set, presumably by expert traffic engineers and safety officials. This assumption isn't necessarily valid, and a speed camera set up in conjunction with an irrationally low speed limit will be a problem.


Porter Street. Photo by the author.

The principal guide for setting a rational speed limit is the 85th-percentile speed of traffic. On "the theory that the large majority of drivers are reasonable and prudent, [and] do not want to be involved in a crash," the speed limit is "generally set at the nearest 5-mph increment at or below the 85th percentile speed." (See the 2006 DDOT Speed Study.)

Are there exceptions to this guideline? Yes, "an agency may choose, on the basis of one or more of these data"that is, accident or crash histories for the location"to post a speed limit that is slightly lower than the 85th percentile." [emphasis added]

Now, an example, namely Porter Street/Klingle Road between Cleveland Park and Mount Pleasant. This looks like a bit of interstate highway plunked down in the middle of the city, evidence of a long-forgotten plan to make Piney Branch Parkway into an inner-city crosstown highway. It's a four-lane divided roadway, limited access, no residences, no businesses, no crosswalks, no cross traffic, and it's no wonder that drivers speed up at this point, not because they're crazy speedsters, but because the road is clearly built for higher speeds.

The 85th-percentile speed for this road is 41 mph, as indicated by the 2006 Speed Study Map. Hence, the speed limit should be 40 mph, or maybe, if we're being conservative, 35 mph. But in actual fact, the posted limit is 30 mph, which is more than "slightly lower" than the 85th percentile. It comes as no surprise that the speed camera placed at this location has been a bountiful source of speeding tickets.

The MPD belatedly argues that "there is a lot of pedestrian and bicycle traffic accessing the park" here. But there's no bike lane, no sidewalk on the north side ("Pedestrians Prohibited" is posted), and the sidewalk on the south side is virtually covered by vegetation. These are indications that pedestrian access is, to say the least, discouraged. As for bicyclists, as one of that tribe, I can say that this is one of the most bicycle-hostile locations in the city, and not because of traffic speed, but because of road design.

So, is the 30 mph speed limit appropriate? There's no apparent justification for such a large deviation from the 85th percentile speed. In fact, just to the west of this location there are apartment houses and parked cars and driveways, and traffic speed there might be expected to be a greater concern than down where this "highway" opens up. But that's not where the speed camera is pointed, suggesting that the MPD is not really interested in the safety of residents, but in issuing lots of $125 speeding tickets.

The speed camera wouldn't matter if the speed limit were reasonable. Nobody can complain about a ticket for going much over the 85th percentile speed. The problem is not the speed camera, but the unreasonable speed limit, such that that 85th-percentile driver would, in this case, be exceeding the posted limit by a solid 11 mph.

So one has to wonder about other speed-camera locations in the District. The question is not the speed camera, but the appropriateness of the speed limit where the camera is located. Anyone defending a speed camera at a certain location should begin by confirming that the speed limit at that location is reasonable.

Jack McKay, a retired physicist, and a bicycle commuter during his working years, has been on the Mount Pleasant ANC since 2003. 

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The Benning Road bridge over the Anacostia is SIX lanes... and also 30 MPH. It's probably a lucrative speed camera at that location as well! It's a well known speed trap, so people drive 40-45, slam on their brakes just before the speed trap, and then speed up again. It's a silly game designed to tax visitors, apparently.

by Tom A. on May 21, 2012 1:10 pm • linkreport

I just checked, and the Benning Road bridge is also 41 MPH for the 85th-percentile speed of traffic.

by Tom A. on May 21, 2012 1:13 pm • linkreport

As I've said countless times (including in an official capacity with a camera up in Gaithersburg), I definitely agree that cameras must be installed where the speed limit is appropriately set. The Maryland law has just such a stipulation where cameras are installed in residential areas in Montgomery County.

If we want slower speeds: my opinion is that design-oriented treatments are the far better way to go, especially in cases where the enforcement may pose a greater risk (as I'd observed in Gaithersburg). In those cases, at the least, average speed cameras would be far more preferable than spot cameras.

Enforcement is the last resort when it comes to traffic safety. Now if enforcement is a method to fund design & construction, so be it: but we need to be honest if that's the case, dedicate a camera's funds toward its specific location, and work toward a public goal of $0 revenue per camera.

by Bossi on May 21, 2012 1:17 pm • linkreport

I think the adminstrative account at GGW just got hacked if this article has been posted.

If not, bravo for speaking the truth.

by charlie on May 21, 2012 1:29 pm • linkreport

Sigh. Cuz people would not speed if speed limits were reasonable. Sure. That's why I regularly see people trying to go 40 on short Georgetown blocks.

by Jasper on May 21, 2012 1:29 pm • linkreport

Sigh. 85th percentile is fine for something like a separated highway with zero foot or bicycle traffic. It's absolutely *not* appropriate for setting the maximum traffic speed in a place where the road is anything but a traffic sewer.

That's because, by allowing drivers to set the speed limit, you are basing the speed limit entirely on the perceived safe speed of folks who are behind the wheel of cars. Now you can increase the perception of danger, and thus slow drivers down, by increasing the amount of road "furniture" and slimming down lanes, etc... But there are times where that's not practical. And in the absence of strict speed enforcement, that gives you things like a "natural" speed limit of 40 mph on Constitution Ave through residential neighborhoods east of the Capitol. Or 55 on Pennsylvania Ave.

Frankly, the idea of an 85th percentile speed limit having relevance anywhere but on an interstate is ridiculous.

by oboe on May 21, 2012 1:30 pm • linkreport

Crap. I never knew there was a speed camera there...

In my opinion the branch of Connecticut Ave in MD that routes countless cars to and from 495 is also more of a highway than some quaint residential street and 30 mph there is also absurd.

by Emily on May 21, 2012 1:30 pm • linkreport

@Jasper-

People will certainly continue to speed, but the goal is to target the small percentage of those who do; not the greater majority driving at what feels natural. We need to redefine what feels "natural"

by Bossi on May 21, 2012 1:30 pm • linkreport

What @Jasper said.

Yes, in a world where all non-motorized traffic were banned from the roads and sidewalks of the District (or Manhattan, or SF, etc...), allowing natural driver behavior to set the speed limits would be a perfectly acceptable practice.

by oboe on May 21, 2012 1:32 pm • linkreport

It is kind of entertaining when the bus grinds to a near halt right near the speed camera on Porter, though. Everyone in the bus always looks around to see what the deal is, since there's no visible reason for the bus to slow down there.

by Ben on May 21, 2012 1:36 pm • linkreport

@oboe-

I think you might misunderstanding- while I can't speak for the author, my intent isn't to say that we should give free reign for motorists to drive as fast as they want on our six-lane arterials.

Rather, my position is that if we are serious about safety on those high speed roads: we need to be serious about road diets, traffic calming, and increasing ped/bike/transit-oriented infrastructure to drop down the natural speed.

by Bossi on May 21, 2012 1:36 pm • linkreport

Expanding on that thought:

Essentially embracing the Hans Monderman philosophy.

by Bossi on May 21, 2012 1:36 pm • linkreport

I recently got hit by a $125 camera ticket and agree that some roads with cameras need to be better designed to reflect speed.

I got tagged going 35mph on a 25mph road that goes along the reservoir up in Palisades (can't remember if it's McArthur rd or not). 25mph feels pretty slow on that road, and I usually see people put on their brakes getting close to the camera.

I fully support speed cameras and paid my fine, but this article reminded me of how annoying that ticket was.

by Lance on May 21, 2012 1:46 pm • linkreport

1. As oboe says, 85% speed is pretty irrelevant. It's true that people drive to the conditions but there are many conditions drivers ignore. The 85th percentile speed on Park Road in Mt Pleasant is 32MPH and I would consider that too fast considering pedestrian and other non-auto traffic there. The road is certainly overdesigned on Porter and the speed camera is "unfair" but I would say the speed limit is not unfair. Increasing it to 40MPH saves drivers what, a couple seconds along this stretch?

2. Using the fact that bike/ped infrastructure is inadequate/unmaintained by the city or park service isn't an argument for there not being bike/ped traffic along here. Plenty of people walk and bike along this stretch and especially do so to access the park. The fact that sidewalks are overgrown and there are no bike lanes means we should be MORE concerned about how fast cars are going since it's more likely there will be other users on the road.

by MLD on May 21, 2012 1:49 pm • linkreport

I can't believe NPS hasn't tried to cash in on Rock Creek Parkway by putting up speed cameras there. The speed limit between Virginia Avenue and the Zoo is 35 MPH, but the average speed is more like 45-55 MPH most of the time.

by Dan's High Top Fade on May 21, 2012 1:50 pm • linkreport

I think the number of annual traffic deaths in this country is a clear indicator that what "feels" safe to drivers is, in fact, not. And as others have pointed out, non-drivers disproportionately pay the price.

While I'm all in favor of road diets and other physical treatments, those are expensive and take a long time to implement. Until all our roads look like those in Amsterdam, I see nothing wrong will simply training drivers to never feel it is safe (from collisions, speed cameras, or otherwise) to drive over 30 mph in a city. Setting just a few speed traps isn't the fair way to do this- really, there should be lots of speed cameras all over the place (probably with lower fines). But resetting speed limits to the speed drivers like to drive isn't the answer.

by RichardatCourthouse on May 21, 2012 1:51 pm • linkreport

Why don't we keep porter st. at 30 mph and add bikelanes and sidewalks on both sides?

Why make it more hostile by increasing the speed limit?

by X on May 21, 2012 1:56 pm • linkreport

I think the number of annual traffic deaths in this country is a clear indicator that what "feels" safe to drivers is, in fact, not.

How many of those accidents are caused by speed?

I see nothing wrong will simply training drivers to never feel it is safe (from collisions, speed cameras, or otherwise) to drive over 30 mph in a city.

Practical and useful in some places, but not in others, as we have pointed out. Many of our roads are meant for faster, uninterrupted travel (and designed that way, such as the Rock Creek Parkway and Piney Branch Road).

by JustMe on May 21, 2012 2:00 pm • linkreport

What is 85% on the Beltway when it is not highly congested? 71 MPH? If so, should the speed limit really be 70 MPH?

by fredcorgi1@verizon.net on May 21, 2012 2:01 pm • linkreport

@ Bossi:the goal is to target the small percentage of those who do; not the greater majority driving at what feels natural.

Come on. You can't legislate on feelings. Feelings are not quantifiable.

What feels safe for me may not feel safe to you. That difference becomes larger easily when one person is in a fully equipped 4x4 SUV, and the other is on bike. The SUV driver is gonna be totally fine speeding over the uneven pavement in a straight line, while the biker will go a lot slower trying to avoid the potholes that the SUV driver can easily go over.

You can quantify countless design and engineering factors.

Another thing that matters is consistency. It is bad policy to change the speed limit from block to block.

by Jasper on May 21, 2012 2:08 pm • linkreport

@Jasper-

Unless I'm misreading- I think you just said what I was getting at? In which case: agreed!

by Bossi on May 21, 2012 2:11 pm • linkreport

Many of our roads are meant for faster, uninterrupted travel (and designed that way, such as the Rock Creek Parkway and Piney Branch Road).

I think we're sort of entering a circular logic here. Look, we take the "85 percenters" argument at face value, then what we need to do is put roads on a diet until 85 percent of the drivers are doing the speed limit that these roads are currently posted.

Raw numbers of pedestrian/cyclist fatalities are not the only salient point here. At some point, cars speeding through neighborhoods degrades the quality of life. Perhaps non-drivers get better at GTFOOMW, and so overall death rates stay the same. Perhaps parents won't let their kids play outside, because it's obviously unsafe.

Either way, it's drivers being rewarded with a few extra miles per hour (which, due to congestion, doesn't even necessarily translate to faster travel times), while residents of the neighborhoods pay for it through degraded quality of life.

"The 85 Percentile Rule" just sounds so scientific, though. Guess we'll have to let harried MD commuters settle on an appropriate level of caution as they speed past our children trying to cross the street to get to school.

(Which leads to the second question: I wonder when the wide, fairly straight roads of the suburban cul-de-sacs are going to change their posted speed limits from 20 mph to however fast I feel comfortable driving. I won't hold my breath.)

by oboe on May 21, 2012 2:11 pm • linkreport

@Jack McKay: I liked your MtP ANC flyer explanation better where you juxtapose the Porter speed camera where it doesn't appear to be needed, to the red-light camera that is woefully needed at the intersection of Park, Klingle, and Walbridge because too many cars go through the red light going westbound on Park Road. You should've brought that up as a good example of safety versus revenue generation.
As for Porter street I have to say that there are in fact a lot of pedestrians on Porter's south side and I'm not sure your characterization of it as being just a highway is acurate. That being said, walking westbound on Porter and seeing cars going around the bend at the bottom and flying up the hill is kind of scary, especially when it is wet and there leaves on the ground. It seems like it's just a matter of time before one of the cars will go airborne and go into the park. But I think some jersey barriers (or any kind of barrier there) would be great. There is a barrier where the sidewalk goes over the creek, so why not before?

by dc denizen on May 21, 2012 2:11 pm • linkreport

At some point, cars speeding through neighborhoods degrades the quality of life.

I agree, but then the roads should be designed to support quality of life. I can imagine that some parts of Cleveland Avenue could be redesigned to improve quality of life which would lead to lower speed limits. Trying to enforce 25 mph speed limits on Piney Branch Road and the Benning Road bridge doesn't help anyone except the police department's budget.

by JustMe on May 21, 2012 2:16 pm • linkreport

Why does any of that matter; point blank there is a speed limit and you should be following it period. If you can not drive without going above the speed limit you should get whatever tickets are available I have never sped on any road.

Also as I recall there are residences on Porter between Cleveland Park and Mt Pleasant; there are several apartment buildings

by kk on May 21, 2012 2:16 pm • linkreport

fredcorgi1-

Whatever 85% is of the beltway and 395, I assume it is higher - above 60 and probably more like 65. I agree that the speed limit there should be higher, at least during non-peak hours using variable speed limit signs. I'd go with 60 during peak hours and 65 during non-peak. Those roads, when not under construction, are quite safe. I drive 395 frequently late in the evening, and going about 60-62 feels about right or even a little slow. But people trying to adhere to the posted limit and people trying to go 70-75 make it less safe than it should be.

by Nick81 on May 21, 2012 2:17 pm • linkreport

On a road where drivers reap all of the costs and benefits from speeding, the 85-percentile may be an adequate way to set the speed limit. It is a rough way of ascertaining the social contract among drivers, in that most drivers object to those going alot faster than the speed that gives them comfort.

On city road where speeding gets you a ticket, then perhaps drivers are roughly paying the social cost of speeding. If speeding by 10 mph gets you a ticket, then a reasonable speed limit would be the speed at which 85% of all drive, minus 10 miles per hour.

Alternatively, if drivers at fault in a fatal collision were almost certain to face a 20 year jail sentence, then the speed at which 85% of all drivers proceed would probably be a good limit.

Perhaps the author should have started by explaining why a speed limit should be based on 85% rather than 50%.

by Jim T on May 21, 2012 2:26 pm • linkreport

I agree, but then the roads should be designed to support quality of life. I can imagine that some parts of Cleveland Avenue could be redesigned to improve quality of life which would lead to lower speed limits. Trying to enforce 25 mph speed limits on Piney Branch Road and the Benning Road bridge doesn't help anyone except the police department's budget.

Can't say I disagree with you. But of the three options--1) reconfigure the roads to slow traffic; 2) enforce current laws; or 3) do nothing--while 2 is suboptimal, I still think it's better than option 3.

by oboe on May 21, 2012 2:29 pm • linkreport

Perhaps the author should have started by explaining why a speed limit should be based on 85% rather than 50%.

Because the "consensus speed" that all the drivers can agree on and understand as a norm with provide greater consistency what what is appropriate and better expectations for how to manage the road safely than the median speed, where most of the people would feel comfortable going faster than that.

I don't think if it were legal to go 45 down piney branch road or down the Rock Creek Parkway that our quality of life would degrade.

by JustMe on May 21, 2012 2:35 pm • linkreport

On this subject, and since it's relevant, I've heard that DC intends to add speed cameras to the Southwest Freeway. Where the speed limit is 40 MPH. An excellent location example of just what is wrong with both the program and speed limits in general.

Someone (Bossi?) said it earlier...if you really want people to slow down, you don't slap up a camera or two: you reengineer the road. True, it'll take time and money (as another poster suggested), though often it can be done with just a bucket or two of paint.

My general view: with few exceptions, DC street speed limits are more or less okay...though I'd like to see the traffic signals better synchronized with the speed limit. The freeways are the ones that are underposted. There is ABSOLUTELY NO REASON why I-295 can't be at least 55 MPH, and the SE/SW Freeway could certainly be higher than 40.

by Froggie on May 21, 2012 2:37 pm • linkreport

@Lance,
That would be MacArthur alright. It is posted 25mph all along MacArthur within the District. I have a biased view b/c I live on MacArthur, but 25 makes a great deal of sense to me:
--It is a residential zone heavily populated with young families and lots of children. Within 1/2 mile of that speed camera, there are about 7 schools - 10 within a mile.
--MacArthur gets lots of cyclist traffic throughout the week (both recreational and commuter)
--That stretch along the Resevoir has a nice long straightaway that is pretty tempting to open up the gas, but its punctuated by a blind S curve at the end as you get to the Resevoir Castle and Elliott Pl. Despite a crosswalk with visible signs, I've had a few too many close calls while pushing my daughter across the street in the stroller when heading to the park.

My inclination is to side with oboe and Jasper on this one - the 85% rule makes sense in certain settings, but not on streets like MacArthur.

by Bilsko on May 21, 2012 2:39 pm • linkreport

Because the "consensus speed" that all the drivers can agree on and understand as a norm

The fact that the only "drivers" get a vote is the flaw here. A "consensus speed" should reflect a true consensus of all users of public space.

I don't think if it were legal to go 45 down piney branch road or down the Rock Creek Parkway that our quality of life would degrade.

Right, I don't necessarily disagree, but here we're just discarding the 85% rule...

by oboe on May 21, 2012 2:43 pm • linkreport

The problem really is that those roads were built "wrong" in terms of mediating the design speed vs. the operating speed _for a city_.

Another way to think about this is the link between land use context and operating speed. So while the specific context allows for higher speeds, it's probably bad public policy for those speeds to be the posted speed, since drivers who speed on those roads are likely to speed on other roads in the city where the speed limit is 25 mph.

So they have speed cameras.

Ideally, over time, the roads would be reconstructed to be more appropriate to their context, thereby reducing speeds naturally.

I've written about this for years.

Anyway, this is about speed limits in Montreal, http://ville.montreal.qc.ca/portal/page?_pageid=7657,81883593&_dad=portal&_schema=PORTAL, which follow the 20mph/32mph speed limit pioneered in Graz, Austria in the early 1990s.

by Richard Layman on May 21, 2012 2:48 pm • linkreport

Transportation departments that act on the 85% theory should paint a crosswalk wherever 85% of pedestrians would like to cross the road.

by Ben Ross on May 21, 2012 3:02 pm • linkreport

@Just me: Because the "consensus speed" that all the drivers can agree on and understand as a norm with provide greater consistency what what is appropriate and better expectations for how to manage the road safely than the median speed, where most of the people would feel comfortable going faster than that.

Your logic seems to apply if we enforce the speed limit as written. But if we only give a ticket for exceeding the limit by 12mph, why not set the limit to 12 mph below the 85 percentile (assuming only drivers are on the road).

And if we assume that bikes, walkers, and wildife are on the road, why not set the limit to the speed that people drive when they see bikes, walkers, and wildlife on the road?

by Jim T on May 21, 2012 3:11 pm • linkreport

@ Froggie: On this subject, and since it's relevant, I've heard that DC intends to add speed cameras to the Southwest Freeway. Where the speed limit is 40 MPH. An excellent location example of just what is wrong with both the program and speed limits in general.

Oh, that's no plan. They're there.

by Jasper on May 21, 2012 3:18 pm • linkreport

Richard is (of course) right. The problem in part is an innocent offshoot of good intentions. Engineers are constantly working to design and modify roadways to be safer, to be more forgiving of even unsafe driving. The unsurprising upshot of making roads more forgiving of unsafe driving is that people adjust their speeds, in particular, upwards. So the 85th percentile shifts. The other implication is now that the road is safe to drive on at higher speeds, it becomes less safe for anything else.

As for roads that briefly become suitable for higher speed driving, the problem there is that drivers leaving those areas tend not to scrub off the excess speed very quickly.

by Crickey7 on May 21, 2012 3:22 pm • linkreport

I agree with the article. Personally, the speeding on Independence Ave. SE between Pennsylvania and North Carolina Ave. is pretty bad at times and I'd like to see something done about it.

by Vik on May 21, 2012 3:40 pm • linkreport

Richard is right, and as the author notes, the road was designed at a time when urban freeways were in vogue. Perhaps part of the solution is to "degrade" the road to a more appropriate design that is conducive to its setting amidst Rock Creek Park and pedestrian/bike access to and across the creek.

by William on May 21, 2012 3:43 pm • linkreport

wrt Crickey7's point

1. The reduction in traffic deaths after the speed limit reduction imposed on interstate freeways during the Carter Administration mostly came on non-interstate roads, because people were driving slower there too.

2. While I think it's in need of an update, the Smart Transportation Guidebook has a very good discussion of right-building infrastructure in terms of land use context (the bike recommendations are specifically in need of an update though).

So they differentiate between (1) road characteristics; (2) road side characteristics; (3) desired operating speed; (4) whether the road serves community (intra-area trips) or regional (inter- through trips) needs; and (5) land use context (they list seven different types, comparable to the New Urbanist transect).

It's really a great resource.

http://www.smart-transportation.com/guidebook.html

The problem generally is that roadways aren't constructed to be differential, in terms of achieving desired operating speeds. They are all built the same way, and therefore able to accommodate extremely high speeds (depending on the width and presence of parked cars). E.g., a camera on Florida Ave. NE clocked a car going 90+ mph.

And cars, except maybe the SmartCar, are engineered to go very fast as well.

The issue is to not plan for the convenience of the automobile driver, but for what's best for the city.

That being said, I have a tendency to speed between Taylor Street and Michigan Ave. on North Capitol, or on Military Road west of Georgia Ave., for the same reasons.

The roads are built to accommodate high speeds (on N. Capitol it's because it was built in anticipation of building I-70/I-270 along the Metropolitan Branch Railroad). They are wide, concrete, not asphalt I think in both places, with limited traffic, and limited cross streets.

by Richard Layman on May 21, 2012 3:45 pm • linkreport

@ Bossi:In which case: agreed!

Upon rereading your post: correct!

I'll also throw in another point that many ignore. In my neighborhood in Sprawlia, the speed limit is set at 25. However, if there road's emtpy, you can easily "feel" that driving 35, perhaps even 40 is safe. Yes, that is poor design, but hey, the road's there and not gonna change.

However, 25 is really what the speed limit should be, because the road is NOT empty. People walk, jog and bike along the road, some with their dog. Kids wait at the bus stops to be picked up. The road is curvy. You can not see what's around the curve. Going 35-40 give you no time to stop if someone's crossing the road, or some kid is running home without paying attention. Likewise, pedestrians can not stop and yield to cars they don't see coming. Especially in the dark.

Not to mention what happens when going more than 25 during heavy rain. Slip and slide guaranteed!

by Jasper on May 21, 2012 3:50 pm • linkreport

What about overall LOS? Can a higher speed limit based on 85th percentile when the road is clear actually contribute to LOS degradation in heavy traffic? One example of what I mean is the GW pkwy NB, from say 395 to Spout Run. Posted limit is 40 but everyone goes 55-60. From my observations, the effect that this has is that it becomes much more difficult for cars to merge in and traffic becomes less tolerant of speed fluctuations, so you get a very abrupt accordion effect. I think that if the limit was a strictly enforced 40mph all the way to the Beltway, you'd see fewer backups during rush hours and average speeds would increase.

Same goes for 395/695...all the criss-crossing becomes difficult at high speeds and the system quickly breaks down into gridlock (for lack of a better term) rather than a slow but steady flow of cars. Seems like lowering the speed limit (or better enforcement of already low speed limits) could lead to higher average speeds for a lot of roads, particularly the commuter routes.

by MM on May 21, 2012 4:01 pm • linkreport

Meanwhile the city is using speed cameras to enforce the 50 mph limit on 295, certainly improving the quality of life of all the people use that interstate highway to jog, walk their dogs, ride their bikes, and let their kids play kickball in the street.

This weekend they positioned a speed camera car at the end of a row of busses on Maine Ave SW just before the USDA office. Never mind that nearly all of the buses were idling in clear violation of DC law, the police don't care about that. You see, enforcing laws on commercial vehicles takes time and requires officers to learn a whole new set of regulations (local and federal DOT). Its much easier to sit an officer in a car and let the camera click away all afternoon.

How about this for a deal. The MPD can only activate the speed camera mounted on the weigh station on 295 on days in which the weigh station is actually open and being used to enforce commercial vehicle regulations.

by dcdriver on May 21, 2012 4:36 pm • linkreport

"Your logic seems to apply if we enforce the speed limit as written. But if we only give a ticket for exceeding the limit by 12mph, why not set the limit to 12 mph below the 85 percentile (assuming only drivers are on the road)."

Absolutely - many drivers drive as if they are "entitled" to travel 11 MPH over the speed limit.

by Fred on May 21, 2012 4:38 pm • linkreport

If these cars want to be treated as vehicles, with equal access to the roads, they should start following the traffic laws just like everyone else -- regardless of whether they feel it is safe to disregard the law. And the drivers should start wearing helmets

More seriously, the presence of speed cameras seems to undermine two of the three justifications cited in the 2006 DDOT-commissioned study for establishing a floor on appropriate speed limits, namely: (1) drivers will ignore unreasonably-low limits and (2) "if the limits are unreasonable, enforcement becomes indiscriminate" (I assume that they mean arbitrary). The third justification is that speed should be set at a level that ensure smooth traffic flow. I really do not know how that applies when you're talking about stretches of road that connect residential communities and include a number of intersections.

The speed limits won't be ignored (for long) if cameras are installed, and I don't believe that you can make a credible claim of indiscriminate/arbitrary enforcement if the systems automatically issues tickets to those traveling X MPH over the posted speed limit. Sure, you might have issues with people slamming on the brakes right before a camera, but the answer to that concern might be to install more cameras to cover a greater stretch of pavement.

Couldn't you conclude that with cameras, the first two justifications for mandating a floor on the appropriate speed limit disappear? Then, can't the speed limit be set as low as the City wants, as long as it is not creating a hazardous condition (due to speed differential) or traffic flow problems? In that case, couldn't the title of your piece be "Speed Cameras Justify Unreasonably Low Speed Limits"?

In short, I don't see how the 2006 DDOT Speed Study gets you anywhere. Who cares what kinds of norms people developed during the Wild West days (ie 85% of traffic speed), when speed limits could be violated with very little likelihood of penalty.

by todd on May 21, 2012 4:42 pm • linkreport

This is an issue that's frustrated me for a long time: we need to be cognizant of the designed speed of roads, and what kind of road character we want to have in a given context, before throwing up cameras and calling it a day. MoCo is definitely guilty of this: they installed a camera on Randolph Road in front of Wheaton High School to "make it safer" for peds, but a mile east at Georgia Avenue they're building a grade-separated interchange that will make it harder to walk but easier to speed.

by dan reed! on May 21, 2012 4:47 pm • linkreport

Put a sign at each end of Porter that says "Speed Limit 25MPH CAMERA ENFORCED". Problem solved. If you want to speed and pay the fine after that, that's your prerogative, but at least it might stop all the whining about people not knowing what the limit is and speeding because it feels "natural."

by MLD on May 21, 2012 4:52 pm • linkreport

Absolutely - many drivers drive as if they are "entitled" to travel 11 MPH over the speed limit.

Which is why the debate over recently defeated legislation that would've set the minimum speed limit to 20mph was so ridiculous. "You can't even drive 20 mph if you wanted to!" we heard.

Meanwhile, a posted speed limit of 25 in this town is effectively 35 mph. So 20 would have been 30.

by oboe on May 21, 2012 5:11 pm • linkreport

Put a sign at each end of Porter that says "Speed Limit 25MPH CAMERA ENFORCED". Problem solved. If you want to speed and pay the fine after that, that's your prerogative, but at least it might stop all the whining about people not knowing what the limit is and speeding because it feels "natural."

Yes, but expect public opposition to their presence, a feeling that $125 fines aren't appropriate, and the possibility that the entire idea of speed cameras is one big scam.

I think the speed camera, the speed limit, and the fines are entirely appropriate on Connecticut Avenue in Chevy Chase. I don't feel that way universally. In part because I think it's clear that MoCo has a better traffic design and policymaking apparatus than DC does.

by JustMe on May 21, 2012 5:18 pm • linkreport

If these cars want to be treated as vehicles, with equal access to the roads, they should start following the traffic laws just like everyone else --

Yes, just like everyone else. Just like the pedestrians who cross against the lights or in the middle of the street. Just like the bikers who zip in and out of traffic, fail to stop at stop lights and don't signal their turns.

Just like the bikes that have to be registered, oh wait. Or have to have license plates so that the police can ticket them by camera, oh wait. Or have to have liability insurance, oh wait. Or require that riders pass a test of basic skills and traffic laws before getting a license, oh wait.

by dcdriver on May 21, 2012 6:00 pm • linkreport

The whole 'people should be able to have stuff because they want it' philosophy is really funny.

Grow up, folks! Speed limits aren't just about the cars on the road.

by Capt. Hilts on May 21, 2012 6:06 pm • linkreport

@dcdriver:

I'm pretty certain todd was using sarcasm by utilizing the same mode of argument that motorists routinely--and illegitimately--use against bicyclists whenever the issue of bicyclists' non-adherence to a poorly suited law is the topic of conversation.

I hope that Jack's article might serve as a useful reminder to motorists that, when it comes to sharing our roadways and public spaces, legal technicalities shouldn't be the end all and be all. We ought always to focus on the public ends that our laws are seeking to advance and whether the existing laws do a good job of delivering.

by Ted on May 21, 2012 6:28 pm • linkreport

I'd like to know more about the Parkway and why it was scrapped.

by Michael on May 21, 2012 8:57 pm • linkreport

And why is the SE/SW freeway 40 mph. I never knew that thill I saw the new photo enforced signs and the sipped camera minivan near 7th street on the eastbound side. It's a freeway, if traffic is too heavy to do 55 you can't do 55.

by Mike on May 21, 2012 9:07 pm • linkreport

I agree 40 is way too low for SE/SW freeway. With the new cameras they're putting in, DC will be making some serious coin. Or there will be a lot of accidents when people slow down suddenly for the camera.

by DB on May 21, 2012 10:14 pm • linkreport

I just checked, and the Benning Road bridge is also 41 MPH for the 85th-percentile speed of traffic.
by Tom A. on May 21, 2012 1:13 pm

It's not just the Bridge. The roadway leading to the bridge and also the entrance to 295 under the bridge is wide enough for a speedway. If I"m not mistaken, it's actually 8 lanes across. There is basically nothhng on either side of the road except a gas station or two on one side and the trestle for the Metro overhead on the other.

I got a $125 fine for doing 41 mph. There are so many problems with this that I don't know where to start. First, I find it improbable that I WAS doing 41 mph. When I saw the flash, I looked at my speed. I know I probably hit the brake reflexively, but I was at 36 or 37 mph. I might even believe I was doing 40, but I don't think I slowed that quickly to have been doing more. Now, if I was doing a tick under 41 mph, no ticket should have issued. The law doesn't provide for rounding up. Being charitable I might say the camera rounded up. I did a calculation based on my wheelbase and also the graphically-pictured 5 foot hashmarks, and I estimated i was doing about 38 mph, traveling at least a foot and half less between the two frames than ticket necessitated.

Mostly, though, the speed limit there is 10 or even 15 mph below what it ought to be set at.

For what it's worth, I have always thought the same about Porter St, even when they used to post speed trap radar cars in the days before speed cameras. IT's tolerable when police enforce the rules, because they can use sensible discretion to pull the one driver traveling faster than the others, perhaps driving a little recklessly. The cameras have no such discretion.

by Fischy (Ed F.) on May 21, 2012 10:45 pm • linkreport

I'm generally in favor of speed cameras but I think even the most ardent speed camera supporter has to agree that there are locations that would benefit far more from the installation of a speed camera than the portion of Porter noted in the article. That portion has limited access by non-vehicles and limited use by non-vehicles.

The entire speed camera campaign (of which I'm generally a supporter) would benefit from being extra cautious in protecting the image of cameras. That image is benefitted when they are placed in high ped/bike areas saving lives and tarnished when the city's fairly small number of cameras are placed in places that conveniently/coincidrntally generate a lot of tix but don't have a lot of non-vehicular traffic. Maybe they're not placed there as money generators but you could certainly see how someone would think that.

The solution is to blanket the city with cameras so road portions with few non-vehicles that with road designs that allow cars to safely travel at higher speeds (i.e., making it feel like the limit is too low) don't seem unfairly singled out...and slash the amount of the fine.

by Falls Church on May 21, 2012 10:51 pm • linkreport

Let me say that I agree fully with the assertion that the road ought to be redesigned so that it isn't a chunk of freeway in the city. The median should be wide and tree-lined, not that guard rail barrier. The north (westbound) side should be a single lane, and the curb lane converted to sidewalk and bike lane. The south (eastbound) side should be narrowed, and a bike lane incorporated. Then 30 mph could well be an appropriate speed limit.

That's my next project. The problem, of course, is that this redevelopment would be expensive.

by Jack on May 21, 2012 11:54 pm • linkreport

Nobody likes fast-moving cars, to be sure, especially when you're on foot or on bicycle. But is speed really the great threat to public safety that is commonly supposed?

Nationwide, 70% of traffic deaths do not involve speeding. Here in DC, in 2007 (the numbers which happen to be at hand), of 44 traffic fatalities, just 8 involved speeding. Why are we so focused on the 20%, and ignoring the 80%?

Maybe it's because we don't have a good way to deal with the more serious causes of traffic collisions and deaths, namely driving under the influence of alcohol or drugs, and distracted driving. What the world needs is a good drunk-driver detection camera.

by Jack on May 22, 2012 12:20 am • linkreport

Yes! Finally an article that states an obvious. Too many roads in the metro DC region are posted with speed limits slower than they should be!

I understand the need for safety, but the cameras are about making money for the governments involved, and safety is just a side benefit.

As tickets drop as people slow down, the proof will be that the cameras are about money when the governments around here start dropping speed limits some more. You watch, they will NOT adjust them up as needed, but down, with some excuse or another.

by Ray B on May 22, 2012 12:29 am • linkreport

If you live in the city you hate fast moving cars. If you don't, you don't. I say to hell with the people who don't, but I really hate fast moving cars.

by Bama on May 22, 2012 12:36 am • linkreport

Is the speed limit clearly marked?

Then its not a trap.

If a driver cant read and follow the instructions set forth by a large speed limit sign, then they shouldnt be driving.

Now, if the speed limit is 50, suddenly drops to 30 (and the road design stays the same) and the camera is posted right at the sign...then yes, thats a trap.

by JJJJJ on May 22, 2012 1:25 am • linkreport

Speed limit is clearly marked and there is a sign that says "Photo Enforced". Really, there shouldn't be any complaints here about entrapment.

by William on May 22, 2012 7:02 am • linkreport

If you live in the city you hate fast moving cars. If you don't, you don't. I say to hell with the people who don't, but I really hate fast moving cars.

It depends where the cars are, no? There are probably plenty of fast-moving cars going down the Rock Creek Parkway or New York Avenue near the 9th Street Bridge, but the speed of those cars is hardly my or anyone's concern, because those are not residential and pedestrian areas.

The existence of fast moving cars somewhere, sometime in the city doesn't keep me up at night. In my own neighborhood, or where I shop/work, sure. But I'm not going to make myself over into a "concerned citizen" about fast moving cars somewhere that doesn't affect me (or most anyone else).

by Tyro on May 22, 2012 8:12 am • linkreport

Yeah I have no problem with fast-moving cars in places where there is actual separation and you are away from areas where there are actually people.

The two areas most mentioned here as being problem spots are this spot on Porter and the Benning Road bridge. The difference with these areas is that they are points in between actual residential and commercial spots. There's absolutely NO reason for us to want to raise the speed limit on what amounts to ~2000ft of road space. Raising the limit from 25 or 30 to 40MPH would allow drivers to traverse that section of road 20 seconds faster. 20 seconds is nothing, and certainly not worth making these places more inhospitable to pedestrians, bikers, etc.

by MLD on May 22, 2012 8:22 am • linkreport

I got a $125 fine for doing 41 mph. There are so many problems with this that I don't know where to start. First, I find it improbable that I WAS doing 41 mph...

That speed camera has been there for 3 years at least, and besides missing the "photo enforced" sign, you also missed all the other drivers hitting the brakes just before they got there. Even the cops and the buses do that.

Welcome to urban driving. Tickets, speeding and otherwise, are a cost of doing business.

I do not think the speed limit is too low there -- there are bus stops and schoolchildren nearby.

by goldfish on May 22, 2012 8:39 am • linkreport

Nationwide, 70% of traffic deaths do not involve speeding.

That statement is just splitting hairs about the labels that go into police traffic reports. The fact is that 82 percent of fatal crashes in urban areas occur at speeds above 30 mph. As the saying goes, on urban streets and suburban arterials - speed kills.

Source: Traffic Safety Facts 2009, p. 54.
http://www-nrd.nhtsa.dot.gov/Pubs/811402.pdf

by Laurence Aurbach on May 22, 2012 8:57 am • linkreport

Regarding comical camera locations: last week, I had occasion to head out of the city via 9th St. to 395 several times. In the three-lane, one-way tunnel--which doesn't allow pedestrians or cyclists--feeding onto a pair of interstates, there was a camera and car set up around the bend. It was there for pretty much a whole week, generally at deeply silly times; do you really need a camera car at 9 pm on a Wednesday, when there's all of a dozen cars going through that tunnel on one light cycle?

Just like @Falls Church said, the district must be smarter in where it places cameras. I'm also a big supporter of the program in principle, but obvious cash-grab placements on freeways and at interstate entrances, particularly during low-throughput hours, make it unnecessarily challenging to defend.

by worthing on May 22, 2012 9:16 am • linkreport

Why no discussion on the timing of lights? Or did I miss that. I actually drive at the speed limit in the city (not on the highway!) but I there are many spots where it "pays" to speed... there are many sections where if you speed ~10mph over the limit you hit all the green lights perfectly, but if you follow the speed limit you get stuck at light after light.

I like speed camera's in neighborhood streets (se/sw freeway is idiotic), but if speed flows can be altered with better light timing, that should be implemented (Maine ave, Independence ave is where I always notice this).

by wd on May 22, 2012 9:44 am • linkreport

@ MM:Seems like lowering the speed limit (or better enforcement of already low speed limits) could lead to higher average speeds for a lot of roads, particularly the commuter routes.

Traffic math proves this easily - it's just solving a bunch of derivatives, but few people are willing to believe it.

Back home, most of the busy part of the highway system has variable speed limits all over the place. They slow down traffic coming into a traffic jam, allowing the jam to dissolve itself. However, it took years, and years of massive ticketing to make this clear to people.

The problem is that people do not understand that their actions do not stand on their own. Traffic truly works like a hive. Your sudden breaking may cause a traffic jam at that point 5 minutes later. Now, when avoiding a pothole, that's fine, but when you had to suddenly brake because you were tailgating, or you forced someone else to brake because you changed lanes without signaling, then it's not fine. Your better behavior could have avoid a traffic jam.

by Jasper on May 22, 2012 10:12 am • linkreport

@ MM:Seems like lowering the speed limit (or better enforcement of already low speed limits) could lead to higher average speeds for a lot of roads, particularly the commuter routes.
Traffic math proves this easily - it's just solving a bunch of derivatives, but few people are willing to believe it.

Agreed. People find this hard to believe, because they don't want to believe it. But you don't even need traffic math. Any school aged child knows that in a fire, you're supposed to proceed in a deliberate and orderly manner for the exits, not have everyone running pell-mell.

Of course, if you apply this obvious rule to traffic, someone's sure to pull up some study of grade-separated highways from the 70s to show that letting people drive as fast as they want equals optimal traffic throughput.

by oboe on May 22, 2012 10:52 am • linkreport

@ oboe:some study of grade-separated highways from the 70s to show that letting people drive as fast as they want equals optimal traffic throughput.

If that were the case, there would be more countries with no speed limit on the highways. I only know of one [and it's awesome to average 100mph for a couple hours]. Also, those highways are in pristine condition and that costs a lot of money.

by Jasper on May 22, 2012 10:58 am • linkreport

Just for the record . . . while I object vehemently to that ridiculous speed camera on Porter, I'm not in the cars-uber-alles category. At this point in the year, I've got 1000 miles on my car (one of the first Priuses in the city), 1120 miles on my bicycle. That's what it's about: balance. Not all for one, nothing for the other, but a reasonable balance.

One problem we have in Mount Pleasant is an absence of safe bicycle routes into Rock Creek Park. Mostly we use the Zoo, but of course they have a noxious habit of locking the gates at the Harvard Street exit. Klingle Road? Extremely bicyclist-hostile. Park Road? Suicidal.

This miserable Porter/Klingle crossing is an ugly remnant of the days when cars ruled. It really should be thoroughly reconstructed for proper balance among automobiles, bicycles, and pedestrians. Then the speed camera might become irrelevant.

by Jack on May 22, 2012 3:44 pm • linkreport

Last night at about 7:30pm, MPD mobile speed camera in the 9th St tunnel.

Now the 9th St. tunnel is safe for children to play kickball...

by dcdriver on May 22, 2012 4:04 pm • linkreport

This miserable Porter/Klingle crossing is an ugly remnant of the days when cars ruled. It really should be thoroughly reconstructed for proper balance among automobiles, bicycles, and pedestrians. Then the speed camera might become irrelevant.

Absolutely. And while that should be the end goal, we can't do that overnight. Until then, drivers (including myself) need to be trained to drive in a way that's appropriate for an urbanizing area.

I guess one of the things that galls me about this whole conversation is that we need to slow the cars down now, then we see more bike and pedestrian traffic. Not the other way around.

by oboe on May 22, 2012 4:07 pm • linkreport

@ Jack:an absence of safe bicycle routes into Rock Creek Park

Actually, it's kinda hard to get into Rock Creek Park at all on a bike. At the Potomac side, you have to find your way through a spaghetti of ramps, and at the first couple of entry/exit points, bike access gets messed up quite a bit during the one-way times.

by Jasper on May 22, 2012 8:31 pm • linkreport

What we can all agree on: Speed limits should be set at a level that makes sense.

What we don't agree on: What method for setting speed limits makes sense.

I'm with oboe that the 85% rule relies too much on the wisdom of crowds, who we all know aren't really that wise. If "whatever 85% of people do should be legal" is true than I guess that should include the Idaho stop and underage drinking.

We should instead set an engineering metric. Speed determines stopping distance. Different roads will require different stopping distances because of crosswalks, intersections etc.. and we should set the speed limit on what engineers determine the stopping distance is that drivers will need to avoid xx% of all crashes where xx is far closer to 99 than 90.

by David C on May 22, 2012 8:37 pm • linkreport

No one has yet discussed the constiutionality of these speed cameras. The law is designed so that the state does not have to meet their burden of proof. They make the vehicle owner responsible for the ticket, whether or not they are driving the vehicle or not. If the same speed camera caught a photo of a vehicle speeding and hitting a pedistrian, the photo alone would not be enough to convict the owner of the vehicle. The state would also have to prove who was driving the vehicle. Other states get around this issue by making speed camera tix an "administrative" fine, akin to a parking ticket. In DC, however, the code specifically states that speed/redlight camera tickets are, "moving violations." This also means they will appear on your driving record and your insurance rates will be adjusted accordingly. These cameras are a complete revenue generating scheme as evidenced by the placement of the cameras and the slow posted speeds on major highways and have nothing to do with safety, at least in the District.

by steve on May 25, 2012 8:26 am • linkreport

Vehicle owners are also somewhat responsible if someone else wrecks their car and hurts someone.

The truth of the matter is...the cameras dramatically increase compliance with speed limits and wrecks and injuries go down.

by Capt. Hilts on May 25, 2012 9:08 am • linkreport

I recently got hit by a $125 camera ticket and agree that some roads with cameras need to be better designed to reflect speed. I got tagged going 35mph on a 25mph road that goes along the reservoir up in Palisades (can't remember if it's McArthur rd or not). 25mph feels pretty slow on that road, and I usually see people put on their brakes getting close to the camera.

I got hit at that same exact spot. I was going 39mph. It's ridiculous that it's 25 mph at that stretch of that road...there's no residences alongside the road (it's the Potomac on one side and the lower part of the hill where Gtown Univ. campus is located. There is absolutely NO REASON for it to be 25mph there other than the city wants my money.

by LuvDusty on May 25, 2012 12:21 pm • linkreport

@LuvDusty

That's not the part Lance was talking about there. All of MacArthur has houses along it.

Also, the place I think you are complaining about (Canal Road) is 2000ft of road between two areas that do have plenty of pedestrian activity. Maybe the road could be 35mph and you could speed up before slowing down in residential parts. That would save you all of 15 seconds along that stretch. So just slow down and enjoy your 15 seconds of delay. Or do you really make so much that $40 for 15 seconds seems like a good tradeoff?

by MLD on May 25, 2012 12:30 pm • linkreport

@ Capt. Hilts

You stated, "Vehicle owners are also somewhat responsible if someone else wrecks their car and hurts someone.
The truth of the matter is...the cameras dramatically increase compliance with speed limits and wrecks and injuries go down."

With all due respect, you are completely wrong. A vehicle owner may bear some responsibility in a civil case brought about by the injured party, but there is no way to hold the vehicle owner criminally responsible, which is why I was comparing it to speed/redlight cameras.

Also, the truth of the matter is, people speed until they come upon a known speed camera, abruptly slow down and then return to their normal cruising speed. Why, b/c these cameras are a revenue generating scheme as evidenced by putting 4 cameras on I-295 and then posting a 45-50 mph speed limit on a 4 to 6 lane highway! Maybe, just maybe I would support them if they were placed in residential neighborhoods.

Also, how much regular traffic enforcement does MPD do? Make a mental note of how often you see a car pulled over by MPD at a traffic stop. The answer is hardly ever. Why is that? B/C it doesn't generate enough revenue. Now all I see are cops in cars sleeping while the camera does all the work.

by Steve on Jun 5, 2012 9:13 am • linkreport

MPD don't often pull people over for speeding because of safety issues.

Yes, the number of traffic incidents goes down with slower speeds. Fact. As a pedestrian it is safer to cross Connecticut Ave. where there are cameras than up in Kensington where there are not. As you have stated, people obey the law where there is enforcement.

by Capt. Hilts on Jun 5, 2012 9:42 am • linkreport

Why, b/c these cameras are a revenue generating scheme as evidenced by putting 4 cameras on I-295 and then posting a 45-50 mph speed limit on a 4 to 6 lane highway!

I don't drive I-295 often enough to comment, but given the amount of unfounded complaints you hear by drivers about the (perfectly reasonable) 45 mph speed limit on the SE/SW freeway, I'm skeptical.

by oboe on Jun 5, 2012 9:49 am • linkreport

the truth of the matter is, people speed until they come upon a known speed camera, abruptly slow down and then return to their normal cruising speed.

For me that isn't true. On DC-295 I got enough tickets under the railroad tracks that I now get on the freeway at the speed limit and don't speed up until after I'm well past that spot.

by David C on Jun 5, 2012 10:04 am • linkreport

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