Ian,
The article indicates a serious congestion/delay issue. It's worth noting
that the roundabout was retrofitted with a cut thru and currently operates
as a signalized circular intersection. From the looks of it the signal
system may not be very efficient in its current configuration.
The answer to your question is to perform a sound feasibility study with
engineers whom understand high capacity roundabout, and various signal
alternatives that may include grade separation or perhaps the counter flow
left (right in UK) intersections.
MTJ
Mark T. Johnson, P.E.
MTJ Engineering, LLC
Achieving Traffic Engineering Solutions:
Through Excellence in Roundabout Analysis, and Design
Description: MTJ
313 Price Place, #5
Madison, WI 53705
Office - 608 238-5000
Cell - 608 669 5009
www.mtjengineering.com <http://www.mtjengineering.com/>
From: Roundabout Research [mailto:ROUNDABOUTS@LISTSERV.KSU.EDU] On Behalf Of
Edmund Waddell
Sent: Saturday, October 26, 2013 8:57 AM
To: ROUNDABOUTS@LISTSERV.KSU.EDU
Subject: Re: A roundabout gone horribly wrong!
Ian:
Signals are an indication of design error. If drivers are shooting across
the roundabout in excess of 30 MPH, then it clearly wasn't designed with
sufficient entry path curvature.
The UK built most of its roundabouts decades ago. Traffic patterns have
changed and the old designers are now retiring. Those folks need to pass on
their knowledge to the current generation. Meanwhile, the current generation
of engineers has become enamored with the glamour of complex coordinated
traffic signals. It's partially the allure of something new and different.
Here in the US, we have trouble getting highway experts to objectively
evaluate alternatives via life cycle economics, and I reckon the same
problem (emotional bias) is happening in the UK.
_____
Date: Sat, 26 Oct 2013 14:21:46 +0100
From: ianenvironmental@GOOGLEMAIL.COM
Subject: A roundabout gone horribly wrong!
To: ROUNDABOUTS@LISTSERV.KSU.EDU
Whilst the world is increasingly turning the roundabouts as a safe and
efficient solution at intersections, in Britain, we continue to put all
faith in more traffic signals. There was once a roundabout in Oxford, but
it was struggling with the increasing volumes of traffic. So the engineers
decided to add some traffic signals (nice profits for the companies that are
heavily involved with many universities)...
Full story:
http://www.oxfordmail.co.uk/news/10765509.Appeal_for_traffic_lights_at____cr
ash_danger____roundabout/?action=success
Map:
https://maps.google.co.uk/maps?q=green++Road+oxford
<https://maps.google.co.uk/maps?q=green++Road+oxford&hl=en&ll=51.763187%2c-1
.196842&spn=0.002053%2c0.005845&sll=51.764171%2c-1.196024&sspn=0.004107%2c0.
011689&t=h&hnear=Green+Rd%2c+Oxford%2c+United+Kingdom&z=19>
&hl=en&ll=51.763187,-1.196842&spn=0.002053,0.005845&sll=51.764171,-1.196024&
sspn=0.004107,0.011689&t=h&hnear=Green+Rd,+Oxford,+United+Kingdom&z=19
My question is. Having made such a mess...
How do you, without gridlocking a city, put it right?
Ian
Subject: Re: A roundabout gone horribly wrong!
--047d7b2e0acd80f0ef04e9e1bf89
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Also, add the number of traffic engineers uncomfortable with roundabout
technology or just plain resistant to change, those in places of power
(civil servants, consultants, administrators etc.) who by their actions
slowed and still slow the adoption of roundabout technology. How much of
this is also gender based--the lack of women in the traffic engineering
profession? See the Lusk et al analysis (Journal of American Public
Health, July) of why cycle track has been not been addressed in the AASHTO
bicycle guides for more than two decades with panels made up of over 90%
men?
On Mon, Oct 28, 2013 at 12:33 PM, David Woolfall <david.woolfall19@gmail.com
> wrote:
> Ian's assertion of signal companies forcing a design for profit is likely
> far-fetched (how much profit could there be in a bunch of ped-poles, no
> mast arms). It does raise the curious question - have any US signal
> companies actively or covertly tried to oppose a single roundabout or even
> the now obvious proliferation of roundabouts?
>
> Ian - I dont know if you are a student or practicing engineer, but your
> tone and assertions would probably not go over well with decision makers
> for this or future projects. Any project like this in the US is thorough=
ly
> vetted with multiple engineers and agencies (and not construction or sign=
al
> contractors) having input prior to a decision on which alternative to go
> with.
> That said, if you could provide some traffic data for the A 40 or the
> other roads in the area it would be interesting to consider if an
> unsignalized roundabout is even feasible. To the northwest there are two
> roundabouts on the A-40, mostly just 2-lane entries, so there must be oth=
er
> circumstances with this location that make even 3 or 4 lane entries on the
> A40 legs impractical.
>
>
>
> David Woolfall, PE, PTOE
>
> TSIOUVARAS SIMMONS HOLDERNESS
>
> 5690 DTC Blvd.
>
> Suite 345 W
>
> Greenwood Village, CO 80111
>
> (p)303-771-6200
>
> (f) 303-771-6800
>
> (c) 303-704-5698
>
> email david.woolfall@tshengineering.com
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