Ian Tindale wrote:
Stephen worheedatworheeddotf9dotcodotuk wrote:


Whilst were on about the DLR, the public enquiry into 'Capacity
enhancement' (upgrading to 3 car trains) started this week. DLR say most
of the objections have been withdrawn, so it looks likely to go ahead.


I'd have thought that it'd be more cost-effective and more satisfactory for
passengers to keep increasing the frequency of trains, instead of making
them bigger. What's the theoretical top limit for frequency of DLR trains?

Whatever they can push through North Quay Junction, which is the
bottleneck for the entire network.

Frequency enhancement was considered through doubling of Bow Church to
Stratford and remodelling of North Quay and Royal Mint Street junctions
(to remove the conflict between northbound Stratfords and southbound
Canary Wharfs at the former, and between services to/from Tower Gateway
and eastbound Banks at the latter); however, the cost was similar to the
3-car plan, but for only a 25% capacity increase rather than 50%.

That implies that the network is already at the upper limits of
frequency in the peaks for any services passing through North Quay or
Royal Mint St. Curtailing some services has also been considered (i.e
having them terminate without passing through these junctions, e.g.
Poplar - Beckton) but was considered as highly inconvenient to passengers.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Dave Arquati wrote:

Whatever they can push through North Quay Junction, which is the
bottleneck for the entire network.

Frequency enhancement was considered through doubling of Bow Church
to Stratford and remodelling of North Quay and Royal Mint Street
junctions (to remove the conflict between northbound Stratfords
and southbound Canary Wharfs at the former, and between services
to/from Tower Gateway and eastbound Banks at the latter); however,
the cost was similar to the 3-car plan, but for only a 25% capacity
increase rather than 50%.

That implies that the network is already at the upper limits of
frequency in the peaks for any services passing through North Quay
or Royal Mint St. Curtailing some services has also been considered
(i.e having them terminate without passing through these junctions,
e.g. Poplar - Beckton) but was considered as highly inconvenient
to passengers.

Was this issue part of the reason why the takeover of the NLL was
considered, to provide a completely separate route on the
Stratford-Woolwich axis that doesn't require more trains to use the
existing single-track branch into platform 4?

Dave Arquati wrote:
Ian Tindale wrote:

Stephen worheedatworheeddotf9dotcodotuk wrote:


Whilst were on about the DLR, the public enquiry into 'Capacity
enhancement' (upgrading to 3 car trains) started this week. DLR say
most
of the objections have been withdrawn, so it looks likely to go ahead.



I'd have thought that it'd be more cost-effective and more
satisfactory for
passengers to keep increasing the frequency of trains, instead of making
them bigger. What's the theoretical top limit for frequency of DLR
trains?


Whatever they can push through North Quay Junction, which is the
bottleneck for the entire network.

Frequency enhancement was considered through doubling of Bow Church to
Stratford and remodelling of North Quay and Royal Mint Street junctions
(to remove the conflict between northbound Stratfords and southbound
Canary Wharfs at the former, and between services to/from Tower Gateway
and eastbound Banks at the latter); however, the cost was similar to the
3-car plan, but for only a 25% capacity increase rather than 50%.

That implies that the network is already at the upper limits of
frequency in the peaks for any services passing through North Quay or
Royal Mint St. Curtailing some services has also been considered (i.e
having them terminate without passing through these junctions, e.g.
Poplar - Beckton) but was considered as highly inconvenient to passengers.


During rush hour trains seems to run within 2 minutes of each other.

Trying to increase that to just 90 seconds is probably going to cause
more problems with people trying to get on or off the trains themselves.

Best to look at the incomplete viaducts from the top of a 69 or 474 bus!