GOSPEL Electrification
 

The line between Barking and Gospel Oak is due to be
re-opened at the end of this month. I have assumed all
along that the entire electrification project and attendant
rebuilding work will be completed by then. Certainly I have
not seen statements from TfL or Network Rail warning of
further weekend closures after the line is re-opened to
allow more work to be done.

At present on much of the route the stanchions to support
overhead wiring are not yet in place. I don't know how long
it takes to install these stanchions or to string up overhead
wiring, but it seems quite possible that this work will not be
completed within the next 24 days.

Does anyone know whether or not the original plan was to
complete the project fully by the end of February?

Stanchions are now being installed but in a piecemeal
way that seems to flout common sense. A complete one
was erected at Leyton Midland Station several weeks ago
and then left in isolation. A few weeks later a second was
installed. That too was not followed up. Now a single upright
column has been erected.

I admit openly I do not understand this methodology.

Paris Shows The Way!
 

Robin9 wrote on 14 Feb 2017 at
16:30 ...
British politicians, particularly those in London, love to
pretend that they are concerned about traffic congestion
and the consequential air pollution. They persist with policies
which have been proved not to work, and refuse to listen
to people who drive in traffic day after day and have a
real understanding of the main cause of the problem.

It seems that in Paris someone in authority is less bigoted
than our politicians:

http://tinyurl.com/jxlb4kc

How refreshing! I am deeply envious.

Ealing have been doing that for several years, e.g. the traffic lights
at the T-junction outside Acton Town station (opposite the entrance to
the LT Museum Depot) were replaced by a mini-roundabout and a zebra
crossing about 5 years ago.

--
Richard J.
(to email me, swap 'uk' and 'yon' in address)

Paris Shows The Way!
 

On 2017-02-14 23:01:46 +0000, Richard J. said:

Ealing have been doing that for several years, e.g. the traffic lights
at the T-junction outside Acton Town station (opposite the entrance to
the LT Museum Depot) were replaced by a mini-roundabout and a zebra
crossing about 5 years ago.

Luton airport for years had a terrible congestion problem on a Monday
morning. This started happening soon after a set of traffic lights was
installed at the approach roundabout.

"Get rid of them" said us regulars.

"No" said the airport.

And on it went.

Eventually they did get rid of them, and the problem went away.

The problem with traffic lights, of course, is that they block traffic
movement during the "overlap" between two phases - replace with
something else e.g. a roundabout and traffic can move all of the time.
What you replace it with does require some thought as roundabouts don't
cope well with unbalanced flows, but lights on all approaches to a
junction basically waste time. If lights are needed to balance flows,
not having lights on one branch of the roundabout works quite well -
during the "overlap" time, traffic can then flow from that branch.

Neil
--
Neil Williams
Put my first name before the @ to reply.

Paris Shows The Way!
 

On Wed, 15 Feb 2017 00:10:31 +0000
Neil Williams wrote:
On 2017-02-14 23:01:46 +0000, Richard J. said:

Ealing have been doing that for several years, e.g. the traffic lights
at the T-junction outside Acton Town station (opposite the entrance to
the LT Museum Depot) were replaced by a mini-roundabout and a zebra
crossing about 5 years ago.

Luton airport for years had a terrible congestion problem on a Monday
morning. This started happening soon after a set of traffic lights was
installed at the approach roundabout.

Putting traffic lights on roundabouts has always struck me as a ridiculous
thing to do. Its as if the traffic planners didn't quite understand the
purpose of a roundabout or how it worked and assumed it was no different
to a 4 way junction. Once you've added the lights the roundabout is now
completely redundant and you'd probably get better traffic flow if you did
replace it with a simple junction.

What you replace it with does require some thought as roundabouts don't
cope well with unbalanced flows, but lights on all approaches to a
junction basically waste time. If lights are needed to balance flows,
not having lights on one branch of the roundabout works quite well -
during the "overlap" time, traffic can then flow from that branch.

Roundabouts generally work pretty well on their own. Stirling corner on the
A1 has intermittent lights. The only time serious queues build up is when they
switch the damn things on.

--
Spud

Paris Shows The Way!
 

On 2017-02-15 09:38:59 +0000, d said:

Putting traffic lights on roundabouts has always struck me as a ridiculous
thing to do. Its as if the traffic planners didn't quite understand the
purpose of a roundabout or how it worked and assumed it was no different
to a 4 way junction. Once you've added the lights the roundabout is now
completely redundant and you'd probably get better traffic flow if you did
replace it with a simple junction.

Roundabouts work very well where there is a reasonably balanced traffic
flow on all 4 (or more) arms. They fail badly where the traffic is
highly directional, e.g. towards a city centre.

Consider a typical 4 arm roundabout with arms A, B, C and D positioned
at noon, 3, 6 and 9. If at certain times of day you have a very large
flow from arm B (3 o'clock) to arm D (9 o'clock), it is basically
impossible to get out onto the roundabout on arm C (6 o'clock) because
there is a constant traffic flow preventing this. There are a number
of roundabouts in Milton Keynes where this causes peak time queueing,
particularly as the A421 passes through eastbound in the morning peak
and westbound in the evening peak.

The way to prevent this is to place traffic lights on all but one of
the arms, having no lights on an arm that is not a "blocking" flow but
does have reasonable demand. In the example above, putting them on all
but arm C would allow continuous traffic flow, but would regulate arm B
such that those on arm C could get out and queueing is prevented.

This has an advantage over a traditional traffic light junction as
traffic is always flowing - when the lights are on amber or all on red
for the "overlap", C can flow. With a traditional junction there is
dead time, which with certain designs of junction can be as much of 25%
of the time - reducing overall capacity of the junction. With the
roundabout, this doesn't happen.

Neil
--
Neil Williams
Put my first name before the @ to reply.

Paris Shows The Way!
 

In article , d () wrote:

On Wed, 15 Feb 2017 00:10:31 +0000
Neil Williams wrote:
On 2017-02-14 23:01:46 +0000, Richard J. said:

Ealing have been doing that for several years, e.g. the traffic lights
at the T-junction outside Acton Town station (opposite the entrance to
the LT Museum Depot) were replaced by a mini-roundabout and a zebra
crossing about 5 years ago.

Luton airport for years had a terrible congestion problem on a Monday
morning. This started happening soon after a set of traffic lights was
installed at the approach roundabout.

Putting traffic lights on roundabouts has always struck me as a ridiculous
thing to do. Its as if the traffic planners didn't quite understand the
purpose of a roundabout or how it worked and assumed it was no different
to a 4 way junction. Once you've added the lights the roundabout is now
completely redundant and you'd probably get better traffic flow if you did
replace it with a simple junction.

What you replace it with does require some thought as roundabouts don't
cope well with unbalanced flows, but lights on all approaches to a
junction basically waste time. If lights are needed to balance flows,
not having lights on one branch of the roundabout works quite well -
during the "overlap" time, traffic can then flow from that branch.

Roundabouts generally work pretty well on their own. Stirling corner on
the A1 has intermittent lights. The only time serious queues build up is
when they switch the damn things on.

If you made any attempt to understand traffic engineering, there are
conditions when roundabouts really don't work. If traffic levels are high
and flows unbalanced then some arms can't get out onto the roundabout unless
traffic lights are installed.

--
Colin Rosenstiel

Paris Shows The Way!
 

wrote in message ...
On Wed, 15 Feb 2017 00:10:31 +0000
Neil Williams wrote:
On 2017-02-14 23:01:46 +0000, Richard J. said:

Ealing have been doing that for several years, e.g. the traffic lights
at the T-junction outside Acton Town station (opposite the entrance to
the LT Museum Depot) were replaced by a mini-roundabout and a zebra
crossing about 5 years ago.

Luton airport for years had a terrible congestion problem on a Monday
morning. This started happening soon after a set of traffic lights was
installed at the approach roundabout.

Putting traffic lights on roundabouts has always struck me as a ridiculous
thing to do. Its as if the traffic planners didn't quite understand the
purpose of a roundabout or how it worked and assumed it was no different
to a 4 way junction. Once you've added the lights the roundabout is now
completely redundant and you'd probably get better traffic flow if you did
replace it with a simple junction.

bit difficult to do when the roundabout is above a motorway junction

tim

Paris Shows The Way!
 

On 2017-02-15 10:46:24 +0000, tim... said:

bit difficult to do when the roundabout is above a motorway junction

There are plenty of cases where it isn't, e.g. the roundabout in Slough
made famous by "The Office" which was indeed removed and replaced with
a signalled junction.

OTOH, traffic signals on roundabouts often do make sense to solve a
specific problem involving unbalanced flows without reducing the
capacity of the junction.

Neil
--
Neil Williams
Put my first name before the @ to reply.

Paris Shows The Way!
 

On 2017\02\15 10:26, Neil Williams wrote:
On 2017-02-15 09:38:59 +0000, d said:

Putting traffic lights on roundabouts has always struck me as a
ridiculous
thing to do. Its as if the traffic planners didn't quite understand the
purpose of a roundabout or how it worked and assumed it was no different
to a 4 way junction. Once you've added the lights the roundabout is now
completely redundant and you'd probably get better traffic flow if you
did
replace it with a simple junction.

Roundabouts work very well where there is a reasonably balanced traffic
flow on all 4 (or more) arms. They fail badly where the traffic is
highly directional, e.g. towards a city centre.

Consider a typical 4 arm roundabout with arms A, B, C and D positioned
at noon, 3, 6 and 9. If at certain times of day you have a very large
flow from arm B (3 o'clock) to arm D (9 o'clock), it is basically
impossible to get out onto the roundabout on arm C (6 o'clock) because
there is a constant traffic flow preventing this. There are a number of
roundabouts in Milton Keynes where this causes peak time queueing,
particularly as the A421 passes through eastbound in the morning peak
and westbound in the evening peak.

The way to prevent this is to place traffic lights on all but one of the
arms, having no lights on an arm that is not a "blocking" flow but does
have reasonable demand. In the example above, putting them on all but
arm C would allow continuous traffic flow, but would regulate arm B such
that those on arm C could get out and queueing is prevented.

This has an advantage over a traditional traffic light junction as
traffic is always flowing - when the lights are on amber or all on red
for the "overlap", C can flow. With a traditional junction there is
dead time, which with certain designs of junction can be as much of 25%
of the time - reducing overall capacity of the junction. With the
roundabout, this doesn't happen.

I'm amazed part-time lights at roundabouts are allowed. It seems obvious
to me that every time a blown red bulb faces traffic already on the
roundabout, you will have traffic joining the roundabout seeing a green
light and thinking it has the priority, and the traffic on the
roundabout seeing no light and thinking it has the priority.