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Neotraditional streets vs. segragated streets in terms of traffic safety

Samminn

     
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#1
Hi everybody.

I'm new to this, what appears to be, an excellent community. Glad to join.

I'm, together with my superior here at my bureau, developing and applying for a research project which intends to determine if a neotraditional street network (pre-segregated network) with modern traffic calming remedies, can achieve the same level of traffic safety as the suburban style segregated system.

In other words answering this question: "can we apply neotraditional urban planning from the currently prevalent segregated systems planning without comprising traffic safety?"

Do you know of similar studies from elsewhere? Or can you give me advice on how to find international sources for a project such as this?

With thanks in advance
Samuel T. Petursson
Reykjavik Iceland.
 
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#2
Samminn said:
In other words answering this question: "can we apply neotraditional urban planning from the currently prevalent segregated systems planning without comprising traffic safety?"
Three lanes roads often move more traffic four lane roads and are a lot safer.
On street parking provides a safe buffer between the motorist and the pedestrian (though bicyclists have to be wary of folks opening up car doors on them (this happened to my sister a few times, people are stupid).
Landscaped Blvds are safe.
Roundabouts are seen as a way to reduce both the number and severity of crashes at an intersection.
Speed laws need to be enforced.

These recommendations do not translate well to every situation. For example, a three laned freeway would be chaos. Most planners would need to work with police and fire to ensure that enough access is allowed to reach all properties in the event of a fire.

Look at how older cities were developed with the auto in mind, places like Detroit are very similar in nature to neo-traditional communities (mostly single family, with some flats, apartments and retail along the major corridors). Be open that no matter what you do, people are still going to get in their cars and drive to Super K-martif it makes economic sense to do so.
 

chukky

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#3
DetroitPlanner said:
For example, a three laned freeway would be chaos.

.

Hmmm.Brisneyland has a fair few three laned freeways around and about - they seem to work ... whats inherently evil about them?
 

Samminn

     
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#4
How are regulations in the US or Australia? Are they very strict on how you define every street according to the well known 4 types of roads: arterial road, connecting road, collecting road and access roads (if I remember it correctly)?

Are there no big obstacles to designing large new urban areas where you apply neotraditional principles, such as on-street parking along central boulevards, short intervals between intersections and so on?
 
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#5
chukky said:
Hmmm.Brisneyland has a fair few three laned freeways around and about - they seem to work ... whats inherently evil about them?
Do you mean three lanes in each direction? I mean three lanes period, no barrier walls. Left turns off of freeway onto ramps.
 

chukky

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#6
DetroitPlanner said:
Do you mean three lanes in each direction? I mean three lanes period, no barrier walls. Left turns off of freeway onto ramps.
ah, i see, with you now.
 

ABS

     
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#9
Have a look in the Resource Directory of this website (Cyburbia) and you should find a few very good links to road and roundabout design sites.
 
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#12
DetroitPlanner said:
Three lanes roads often move more traffic four lane roads and are a lot safer.
This is only true where there are many, many driveways, and there is a threshold of about 20k ADT for 3 lane roads to work. We have a road that sees about 20-22k AADT and a 3 lane simply would NOT work, it would be backed up a long way, and you could not access it (turn into it) for 5-10 minutes at a time during peak hours.

The cities of Angola, In, and Bucyrus, OH tried this (converted a 4 lane into a 3 lane) on state routes and both are backed up horribly during peak times (and Angola's is backed up constantly. The Level of Service (LOS) for these intersections has to be D at BEST.

I do agree that many 4 lanes can be turned into 3-lanes without compromising much. That was due to overdesign of engineers in the past. I also agree, that at times a 4-lane is cumbersome, requiring several lane changes, but overall it is still a more efficient road in general.
 

jmello

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#13
ssnyderjr said:
I do agree that many 4 lanes can be turned into 3-lanes without compromising much. That was due to overdesign of engineers in the past. I also agree, that at times a 4-lane is cumbersome, requiring several lane changes, but overall it is still a more efficient road in general.
I personally cannot stand suicide lanes (center turning lanes), from a safety, aesthetic and walkability POV. I was surprised to see them so prevalent in North Carolina, even on inner-city arteries.

I would much rather see landscaped medians. However, Rhode Island DOT introduced a center lane paved with brick in Barrington, RI (one of Money's best cities) and it seems to work from both an aesthetic and safety standpoint.
 
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#14

abrowne

     
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#15
Samminn said:
Hi everybody.

I'm, together with my superior here at my bureau, developing and applying for a research project which intends to determine if a neotraditional street network (pre-segregated network) with modern traffic calming remedies, can achieve the same level of traffic safety as the suburban style segregated system.
From what I understand, neotraditional thought dictates that traffic calming consists of two simple things: narrower streets, and parallel parking.
 
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#16
ssnyderjr said:
This is only true where there are many, many driveways, and there is a threshold of about 20k ADT for 3 lane roads to work. We have a road that sees about 20-22k AADT and a 3 lane simply would NOT work, it would be backed up a long way, and you could not access it (turn into it) for 5-10 minutes at a time during peak hours.
Three-lane roads are often more ideal replacements for two-lane roads than for four-lane roads. The third lane is especially useful when a road needs to sustain moving traffic and suffers from backups created by people making left turns. In some areas, however, a third lane would be useless, due to a lack of driveways; alternately, the traffic volume may dictate the necessity of a four-lane road.
 
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#17
DetroitPlanner said:
On street parking provides a safe buffer between the motorist and the pedestrian (though bicyclists have to be wary of folks opening up car doors on them (this happened to my sister a few times, people are stupid).
Perhaps diagonal parking could alleviate the issue of doors while increasing the parking capacity of a road.
Landscaped Blvds are safe.
A median can provide pedestrians with a sort of oasis when crossing the street. The division can also protect drivers from oncoming traffic. And maybe the narrower appearance of a treed boulevard subconsciously makes people drive more slowly.
Roundabouts are seen as a way to reduce both the number and severity of crashes at an intersection.
Roundabouts can be very efficient, but they are rarely used, at least in Chicago. I have seen them used mostly as a way to make drivers slow down in residential areas. The problem that arises when they are used on a larger scale is that Americans don't seem to know how to use them. In Australia I have seen many roundabouts joining four-lane roads; in Chicago the only such roundabout I've seen is chaos (though it does in fact have five, not four, points). But if they become part of our cultural driving vocabulary, roundabouts could be extremely useful.
Speed laws need to be enforced.
Automatic speed and red-light cameras are wonderful things. Imagine that if they fined every violator, they could afford to put in more cameras, and by the time they were everywhere, speeding would have severely tapered off. (Automatic traffic-control devices, from "smart" stoplights to RFID toll collection, seem to make everything run more smoothly.)
 
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#18
abrowne said:
From what I understand, neotraditional thought dictates that traffic calming consists of two simple things: narrower streets, and parallel parking.
But sucks for street sweeping/snow plowing if you must contend with those two animals.
 

Samminn

     
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#19
nuovorecord said:
Here are a few resources that may assist you:

Iowa DOT Study on reducing from 4 to 3 lanes

Oregon publications on street design

A collection of reports for the Surface Transportation Policy Project

Michael Ronkin and Dan Burden are internationally recognized experts on safe design of streets for peds/bikes and cars.

Finally, you should check out the work Hans Monderman is doing in The Netherlands and elsewhere.

Hope these help...good luck!
Thanks a lot. This will definately help!

Good question abrowne on the concept of neotraditional street planning and its principles. The project that me and my colleagues are preparing for will focus on analysing traffic safety in two neighbourhoods. One that was developed and constructed in the pre-auto age, with only a rather vague segragation of streets into arteries, connectors, collectors and residential streets. No Cul-de-sacs and a lot of parallel parking. The other one is a typical post-autoage neighbourhood, with segragated system, pedestrians segragated from autos and no parallel parking allowed.

There is a widespread interest here in Iceland, as well as in the rest of Scandinavia and northern Europe, to break down as many barriers to designing new high-density neighbourhoods with the same sort of blending and mixing that characterizes pre-autoage districts. All in the name of a sense of community, livability, variety, thriving culture and sustainability in general. One barrier is the current viewpoint that traffic safety cannot be maximised unless segregation principles are applied. We want to examine that barrier and try to determine whether measures such as traffic calming and raised intersections can reach the same degree of traffic safety.
 

noj

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#20
Samminn,

Although (as you allude to), the issue of transport throughput in high desnity neighbourhoods is quite a big issue in the UK, unfortunately I don't have enough detailed knowledge to point you in the direction of any relevant research.

However, the following links may prove useful:

PP3: Housing

Better Places By Design - A Companion Guide to PPG3

They are both links to guidance published by the UK government, and the companion guide in partiucular has interesting sections on downgrading highways and slowing traffic to make a community more walkable and liveable.

The guidance is being taken on well here; after the usual initial reticence from Highways Engineers they are amost being forced down the route now!

Good luck.
 
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