Traffic Calming vs Bicycles



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Alex Rodriguez <[email protected]> wrote in message news:<bbl6jt$kr6

> Depends on the problem. Roads are meant to allow fast and efficient flow of traffic, otherwise why
> bother building a road. When you add a speed bump, you have just taken a step backwards. You
> analyze the problem. See what is causing the problem, and then formulate solution. Many times the
> people deciding on the solution, speed bump, have no formal training in traffic enginerring.

In the particular instance of the speed humps I mentioned in my post, the section of the street that
the humps are going into has these characteristics:

It's minor suburban arterial -- important enough to have a stripe down the center and a 25 mph speed
limit. It is lined with average suburban single-family homes (one story and two story ramblers built
in the 1960s, for the most part) with only slightly inflated values because of their location. The
surrounding neighborhood is mostly the same sort of homes. Lots of families live in the
neighborhood.

It has a high school and elementary school on one end. You have lots of small children walking to
school on the road. There are parents taking their kids to school on this road. There are also
some high school students walking and riding their bikes, and a fair number of inexperienced high
school drivers.

At the other end, about a quarter of a mile or so away, you have a major arterial and the Microsoft
Corporate Campus. Cars do not generally use the street to get to MS, though, because the only
access/egress from the campus at this street is for non-motorized means. However, when the more
major arterial to and from Microsoft gets clogged at rush hour, people are likely to take this minor
suburban arterial.

The neighborhood is well-organized politically, having a history of having fended off other
measurers that would mitigate Microsoft commuter traffic but add to the burden of their
neighborhood streets.

The neighborhood wants people to slow down on the street. The concern for pedestrian safety,
particularly for children, I think, is merited. Speeding on the street is rampant.

Mr. Rodriguez, if you think speed humps are a bad idea on this street, what are the alternatives
you'd propose?

Warm Regards,

Claire no sig this afternoon
 
=v= I've heard of elevated tables and walkways made of brick, but an entire street? That's a new one
on me. Not very bike- friendly, I agree. I agree that a bicycle advisory board or somesuch seems to
be needed. <_Jym_
 
> I have doubts about any traffic engineer who thinks adding a bump, or hump to a roadway is a
> good idea.

=v= For an engineer, what counts is results, and well-placed speed hump gets results. I've seen
entire neighborhoods revitalized thanks to a few speed humps and bollards.

=v= There is some confusion due to people confusing speed humps with speed bumps, and that
confusions been worsened by people making poor-quality speed bumps and mislabelling them
"humps." <_Jym_
 
>Jym Dyer [email protected]

wrote:

>I've heard of elevated tables and walkways made of brick, but an entire street? That's a new
>one on me.

---snip---

Perhaps brick streets are unusual in the Western U.S. but in the Midwest (and the East I think)
streets were routinely paved with brick well into the 30's and 40's. That's why they are called
"paving bricks". <g>

>Not very bike- friendly, I agree. I agree that a bicycle advisory board or somesuch seems to
>be needed.

If the grading and maintenance is done properly, brick streets really aren't a whole lot harder on
bicycles and cyclists than most concrete or asphalt surfaces. They are definitely "slippery when
wet" though.

Regards, Bob Hunt
 
"Hunrobe" <[email protected]> wrote in message news:[email protected]...
> >Jym Dyer [email protected]
>
> wrote:
>
> >I've heard of elevated tables and walkways made of brick, but an entire street? That's a new
> >one on me.
>
> ---snip---
>
> Perhaps brick streets are unusual in the Western U.S. but
in the Midwest (and
> the East I think) streets were routinely paved with brick
well into the 30's
> and 40's. That's why they are called "paving bricks". <g>
>
> >Not very bike- friendly, I agree. I agree that a bicycle advisory board
or
> >somesuch seems to be needed.
>
> If the grading and maintenance is done properly, brick
streets really aren't a
> whole lot harder on bicycles and cyclists than most
concrete or asphalt
> surfaces. They are definitely "slippery when wet" though.

Bricks might be a good idea. The old downtown neighborhoods in Wilmington, NC have brick streets,
and they look lovely. They're plenty smooth for cyclists. I don't know if they're old and
maintained, or restored, or entirely new, but they're really neat.

I do think bricks might be a good traffic calming measure. In my old neighborhood, one of the main
streets through the residential area had bad pavement for many years. No potholes, the pavement was
just incredibly rough. Traffic moved pretty slowly -- even though there was a lot of it, with many
harried drivers. The drumming of the lousy pavement kept speeds down. This was immediately apparent
when they finally repaved it. Speeds increased to the ridiculous level of the surrounding busy
streets. People definately noticed, and complained. What the city finally did was put bike lanes in,
and reflectors and botts dots on the white lines. I know bike lanes are controversial here, but they
*do* calm traffic by visually narrowing the roadway. Sanity has been restored to this street.

Here's another rough pavement anecdote. A year or so ago I was living in the Eagle Rock area in
Los Angeles. The main drag, Eagle Rock Bl., was being repaved then after many years of neglect.
This road is a typical southern CA four lane commerical strip, where traffic would normally cruise
at 40-50 MPH (despite the legal limit of 35 MPH). However, the city did such a terrible job that
travelling at such speeds is uncomfortable. The pavement is uneven, with lots of little dips and
rises. It isn't even that comfortable on a bike! However, it does keep the speeds down -- to 30
MPH or so.

Anyway, rough pavement works. Bricks are appropriately rough, and look nice too.

Visually narrowing the roadway works too. I can't cite any studies right now, but if you looked at
some traffic engineering journals I'm sure you'd find all you'd need.

Speed bumps definately have their problems. Those wide slopey ones are no trouble for bikes, and do
work to calm traffic -- but don't ever buy a house next to one. You'll be driven nuts by cars
driving over them all night, their speed winding down, their supensions whomping over the bump, and
their engines gunning as drivers accelerate away in anger. These were tried in my old neighborhood
too, but were promptly removed after complaints from the residents (not from drivers).

Matt O.
 
"Jym Dyer" <[email protected]> wrote in message news:[email protected]...

> =v= For an engineer, what counts is results, and
well-placed
> speed hump gets results. I've seen entire neighborhoods revitalized thanks to a few speed humps
> and bollards.
>
> =v= There is some confusion due to people confusing speed
humps
> with speed bumps, and that confusions been worsened by
people
> making poor-quality speed bumps and mislabelling them
"humps."

Consider the engineer-language alternatives -- "raised pavement feature," or "speed attenuating
device," perhaps?

Matt O.
 
"Matt O'Toole" <[email protected]> wrote in message
news:[email protected]...
>
> Visually narrowing the roadway works too. I can't cite
> any studies right now, but if you looked at some traffic
> engineering journals I'm sure you'd find all you'd need.

I'm not sure whether this is a permanent or transitory effect. There are many visually narrow
roadways in Europe (physically narrow, too) where cars are driven at speeds I would have considered
imprudent from an American perspective.

> wide slopey [speed bumps] are no trouble for bikes, and do work to calm traffic

The wide slopey ones that are no trouble for bikes are often referred to in the traffic engineering
literature as "speed tables" rather than speed bumps. They have almost no effect in residential
areas because you can traverse a speed table in a car at 25mph; thus, putting one on a street where
the current speed is 35mph works well, but putting one on a street where the average speed is 25 and
you want to lower it to 20 doesn't. Most of the physical roadway alterations that work can be
grouped into "vertical deflection" and "horizontal deflection" devices. Speed bumps and speed tables
are vertical deflection; roundabouts and choke points and curves are horizontal deflection. The
greater the vertical or horizontal deflection
(e.g., steep speed bumps or tight radius traffic circles or, in your example, poorly-maintained and
bumpy road surfaces) the greater the effect. A knowledgable traffic engineer can "tune" the
device to get the desired result. In my experience, most public works departments don't have an
incentive to hire and pay for knowledgable traffic engineers.
 
"Robert Chung" <[email protected]> wrote in message news:[email protected]...

> "Matt O'Toole" <[email protected]> wrote in message
> news:[email protected]...

> > Visually narrowing the roadway works too.

> I'm not sure whether this is a permanent or transitory
effect. There are
> many visually narrow roadways in Europe (physically
narrow, too) where cars
> are driven at speeds I would have considered imprudent
from an American
> perspective.

People who drive any stretch of road frequently, tend to push the envelope. So they wind up going
faster and faster. But the narrowing still makes them go slower than they would otherwise. Whatever
the general tendency is, narrowing produced the desired result in my first example, and has not
changed since AFAIK.

Matt O.
 
On 04 Jun 2003 16:43:53 -0700, Jym Dyer <[email protected]> wrote:

>=v= There is some confusion due to people confusing speed humps with speed bumps, and that
>confusions been worsened by people making poor-quality speed bumps and mislabelling them "humps."

As not a native of your continent or an english speaking language, could you elaborate on the
difference between the two?

Jasper
 
On Wed, 04 Jun 2003 16:48:23 GMT, "Bob" <[email protected]> wrote:

>Basically, you can get as many engineers on this problem as you want to. There's no way that the
>cities involved are going to change the structure of the roads, and they probably can't do it even
>if they wanted to. There aren't many solutions other than adding a speed bump.

4 way stops suck. That's what traffic lights were invented for.

Jasper
 
On Thu, 5 Jun 2003 07:20:42 +0200, "Robert Chung" <[email protected]> wrote:

>The wide slopey ones that are no trouble for bikes are often referred to in the traffic engineering
>literature as "speed tables" rather than speed bumps. They have almost no effect in residential
>areas because you can traverse a speed table in a car at 25mph; thus, putting one on a street where
>the current speed is 35mph works well, but putting one on a street where the average speed is 25
>and you want to lower it to 20 doesn't. Most

It should be easy to modify it to be a 20 mph device, rather than 25, no? A matter of making it a
bit steeper or higher.

Jasper
 
On Thu, 5 Jun 2003 07:20:42 +0200, "Robert Chung" <[email protected]> wrote:

>The greater the vertical or horizontal deflection
>(e.g., steep speed bumps or tight radius traffic circles or, in your example, poorly-maintained and
> bumpy road surfaces) the greater the effect. A knowledgable traffic engineer can "tune" the
> device to get the desired

I think I would have to disagree slightly with this. It's not the amount of deflection, it's the
RATE of deflection. Consider a one foot change in pavement height (vertical deflection). Make this
hump 20 feet wide and traffic doesn't slow down much. Make it 3 feet wide and it slows down a lot!
Maybe as much can be tuned by tweaking the rate of deflection as by tweaking the amount.

larry To reply by e-mail, be polite. Rudeness is unnecessary.
 
"Jasper Janssen" <[email protected]> wrote in message
news:[email protected]...
> On 04 Jun 2003 16:43:53 -0700, Jym Dyer <[email protected]> wrote:
>
> >=v= There is some confusion due to people confusing speed humps with speed bumps, and that
> >confusions been worsened by people making poor-quality speed bumps and mislabelling them "humps."
>
> As not a native of your continent or an english speaking language, could you elaborate on the
> difference between the two?

Take a look at http://www.trafficcalming.org for pictures. The main difference is the length and
height. A speed bump is 3 or 4 inches high and only a foot or so across. A speed hump is 10 to 14
feet across and may be higher. At the right speed, speed humps give you a gentle rolling motion in a
car. A speed bump will always jar your suspension because it has a much sharper profile.

-Buck
 
[email protected] (Hunrobe) wrote:
> >Jym Dyer [email protected] wrote:
>
> >I've heard of elevated tables and walkways made of brick, but an entire street? That's a new
> >one on me.
>
> Perhaps brick streets are unusual in the Western U.S. but in the Midwest (and the East I think)
> streets were routinely paved with brick well into the 30's and 40's. That's why they are called
> "paving bricks". <g>

Cobblestones in NYC can be nasty to ride on, especially on a skinny tire road bike.

> >Not very bike- friendly, I agree. I agree that a bicycle advisory board or somesuch seems to be
> >needed.
>
> If the grading and maintenance is done properly, brick streets really aren't a whole lot harder on
> bicycles and cyclists than most concrete or asphalt surfaces. They are definitely "slippery when
> wet" though.

It depends, though. The HRG (West Side bike path) has areas in some intersections that are paved
with brick. The bricks were laid parallel to the direction of the path, with just enough gap between
the bricks to cause a problem for 23c tires, if you hit them just right. In the rain, those sections
can be a little scary.

--
z e l d a b e e @ p a n i x . c o m http://NewsReader.Com/
 
On 4 Jun 2003 15:49:12 -0700, [email protected] (Claire Petersky) wrote:

>Mr. Rodriguez, if you think speed humps are a bad idea on this street, what are the alternatives
> you'd propose?

Radar activated spike strips.

--
Scott Johnson "Always with the excuses for small legs. People like you are why they only open the
top half of caskets." -Tommy Bowen
 
"Larry Schudt" <[email protected]> wrote in message
news:[email protected]...

> On Thu, 5 Jun 2003 07:20:42 +0200, "Robert Chung"
<[email protected]>
> wrote:
>
> >The greater the vertical or horizontal deflection
> >(e.g., steep speed bumps or tight radius traffic circles
or, in your
> >example, poorly-maintained and bumpy road surfaces) the
greater the effect.
> >A knowledgable traffic engineer can "tune" the device to
get the desired
>
> I think I would have to disagree slightly with this. It's
not the
> amount of deflection, it's the RATE of deflection.
Consider a one foot
> change in pavement height (vertical deflection). Make this
hump 20
> feet wide and traffic doesn't slow down much. Make it 3
feet wide and
> it slows down a lot! Maybe as much can be tuned by
tweaking the rate
> of deflection as by tweaking the amount.

Ah, an engineer amongst us. You are correct, sir.

Matt O.
 
"Larry Schudt" <[email protected]> wrote in message
news:[email protected]...
> On Thu, 5 Jun 2003 07:20:42 +0200, "Robert Chung" <[email protected]> wrote:
>
> >The greater the vertical or horizontal deflection
> >(e.g., steep speed bumps or tight radius traffic circles or, in your example, poorly-maintained
> > and bumpy road surfaces) the greater the
effect.
> >A knowledgable traffic engineer can "tune" the device to get the desired
>
> I think I would have to disagree slightly with this. It's not the amount of deflection, it's the
> RATE of deflection. Consider a one foot change in pavement height (vertical deflection). Make this
> hump 20 feet wide and traffic doesn't slow down much. Make it 3 feet wide and it slows down a lot!
> Maybe as much can be tuned by tweaking the rate of deflection as by tweaking the amount.

You're right, of course. Traffic engineers occasionally describe deflection devices in terms of the
accelerations (vertical or horizontal g forces) that they impose, and tune by that.
 
On Thu, 05 Jun 2003 12:15:06 -0400, Top Sirloin <[email protected]> wrote:

>Radar activated spike strips.

Dammit. I was gonna propose that.

Jasper
 
On 06 Jun 2003 05:02:49 GMT, [email protected] (Hunrobe) wrote:

>Of course if it's not done right brick paving can be hell to ride on and especially hellish if it's
>also wet. I think there may even be a race somewhere over in Europe that's rather well known for
>that. Roubaix something or other...

De kasseien, de kasseien!

Actually, those aren't bricks, I think. Natural stone of some kind, cut into small (~half a foot)
squares, with rounded tops that are highly polished to remove all traction whatsoever in the
event of rain.

Jasper
 
> Perhaps brick streets are unusual in the Western U.S. but in the Midwest (and the East I think)
> streets were routinely paved with brick well into the 30's and 40's.

=v= I should clarify: I've heard of brick streets (and grew up on them), but this is the first time
I've heard of using them in the name of "traffic calming." <_Jym_
 
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