STMP Mott MacDonald Technical Note July 2008 Platform

Transcription

Technical Note No. 10
Metro
Platform Preferences for Tramways and the
STMP
Mott MacDonald
Technical Note
July 2008
Platform Preferences for Tramways and the Metro
Issue and Revision Record
Rev
Date
Originator
Checker
A
29/07/08
T.V.
Runnacles
C.P.K.
Sherwood
Approver
C.P.K.
Sherwood
Description
First Issue
This document has been prepared for the titled project or named part thereof and should not be relied upon or used for any
other project without an independent check being carried out as to its suitability and prior written authority of Mott
MacDonald being obtained. Mott MacDonald accepts no responsibility or liability for the consequence of this document
being used for a purpose other than the purposes for which it was commissioned. Any person using or relying on the
document for such other purpose agrees, and will by such use or reliance be taken to confirm his agreement to indemnify
Mott MacDonald for all loss or damage resulting therefrom. Mott MacDonald accepts no responsibility or liability for this
document to any party other than the person by whom it was commissioned.
To the extent that this report is based on information supplied by other parties, Mott MacDonald accepts no liability for any
loss or damage suffered by the client, whether contractual or tortious, stemming from any conclusions based on data
supplied by parties other than Mott MacDonald and used by Mott MacDonald in preparing this report.
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Contents
Ch
Section/Title
Page
1
Introduction
1
2
3
1.1
Purpose
1
1.2
Differences affecting Tramway and Metro Stopping Places
1
1.3
Main Findings of this Technical Note
1
Tram Platforms
2
2.1
The Boarding and Alighting of Tramcars
2
2.2
Tram Platforms
3
2.3
Platform Locations for Abu Dhabi
5
2.4
Tram Templates
7
2.5
Tram Stop Dimensions
9
2.6
Density Guidelines for Waiting Passengers
9
2.7
Additional Factors Affecting Tram Platforms in Abu Dhabi
10
2.8
Preferences for Tram Platforms in Abu Dhabi
12
Metro Platforms
14
3.1
Historical Precedents
14
3.2
Comparisons between Tramway and Metro Platforms
17
3.3
Factors Affecting Metro Platform Preferences
17
3.4
Worldwide Platform Preferences
18
3.5
The Template Train for Abu Dhabi
20
3.6
Platform Dimensions
20
3.7
Recommendations for Metro Platforms
21
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Metro
Figures
Figure
Short title
page
2.1
A horse-drawn tram in Canada.
3
2.2
A functionally single-sided, first-generation London tram.
3
2.3
Passengers boarding and alighting from a streetcar in Toronto.
3
2.4
Passengers boarding a Frankfurt tram in the middle of the street.
3
2.5
A passenger boarding a San Francisco streetcar in the road.
4
2.6
New San Francisco streetcars at an island platform stop.
4
2.7
Dublin trams at a side-platform terminus.
4
2.8
A bi-level island platform stop in Amsterdam.
5
2.9
A side-platform stop in Sheffield combined with the sidewalk.
5
2.10
Diagram of tram tracks in the median of a divided highway.
6
2.11
Diagram of bilateral tram tracks, each side of a divided highway.
6
2.12
Diagram of unilateral alignment; both tracks to one side of a
highway.
6
2.13
Diagram of tram tracks located in a pedestrian precinct.
7
2.14
Diagram of a tram track beside a one-way street.
7
2.15
Diagram of tram tracks located on a private right of way.
7
2.16
Representative ‘supertram’ resembling the ‘30-metre template’.
8
2.17
Representative ‘town tram’ resembling the ‘45-metre template’.
8
2.18
Off-set side platforms with a ‘chicane’.
12
3.1
Side platforms at Wesminster Station, London Underground.
14
3.2
Island platform at Buchanan Street Station, Glasgow Underground.
14
3.3
Side platforms at Miromesnil Station, Paris Métro.
15
3.4
Off-side platform at Covent Garden Station on the London ‘tube’.
15
3.5
Island platform at Canning Town on London’s Jubilee Line.
15
3.6
Island platforms for interchange at Edgware Road, London
Underground.
15
3.7
3.8
One track, twin platforms, at Canary Wharf, Docklands Light
Railway, London.
16
3.9
Curved platform at Bank Station, Central Line, London.
16
3.10
Tapered platform ends at Baker Street, London.
16
3.11
Island platform in a highway median, Lafayette, BART, California.
18
3.12
Island platform station at Xiaoing, Nanjing, China.
18
3.13
Elevated side platforms at West Silvertown, Docklands, London.
19
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3.14
Elevated side platforms on the Wuhan Metro, China.
19
3.15
Narrow side platforms at Charles/MGH Station, Boston subway.
19
3.16
Expansive side platforms at Nation RER Station, Paris.
19
3.17
Metropolis ‘system train’ on the Shanghai Metro.
20
3.18
Side platform station: Saint Augustin in Paris.
22
3.19
Island platform station: Willesden Junction in London.
22
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1.
Introduction
This Technical Note considers platform location preferences on Abu Dhabi’s tramways and the
city’s planned Metro. Basically the issue comes down to a simple question of whether central
‘island’ platforms or side platforms are better from the various perspectives of tram or train
operation, capital cost, safety and passenger convenience.
1.1
Purpose
This Technical Note answers a request – made by the Department of Transport on 1st July 2008 –
for supporting information on six particular issues arising from the Consultant’s preparation of
Planning Guidelines for public transport. The Department’s question concerned platform
location preferences for Abu Dhabi’s proposed tramways, and its future Metro.
1.2
Differences affecting Tramway and Metro Stopping Places
Despite similarities between tramways and metropolitan railways, there are noticeable
differences in passenger arrangements at stopping places. Thus:
•
•
•
•
•
1.3
Many trams have low floors, so platforms are correspondingly low, whereas metro platforms
are invariably quite high;
Although trams can operate at grade, in tunnel and on viaduct, Abu Dhabi’s tramways will be
mainly or wholly at grade, so the alignment of the tram tracks relative to roads becomes a
major determinant of platform location;
It is intended that tramways will have air-conditioned shelters, whilst all Metro platforms will
be completely air-conditioned, with platform screen doors;
There will be differences in the volume of passengers to be handled. The Metro will have
over twice the capacity of the busiest tram corridor, so most infrastructure, equipment and
furnishings for the Metro must be designed on a larger scale; and
The Metro will be wholly grade separated, mainly underground. The type of underground
construction determines the preferred platform arrangement.
Main Findings of this Technical Note
For tramways the preferred locations for platforms are:
•
Side platforms for all situations, except where the tramway occupies a highway median,
pedestrian precinct or exclusive right of way. In these three situations an island platform is in
contention, and may be preferable.
For the Metro, side platforms offer a preferable engineering solution for all situations except
where tunnels are bored, in which case ‘offside platforms’ are best. Whereas these are side
platforms, when paired they function as an island platform. However,
•
In operational terms island platforms are preferable for a Metro. Their value is more evident
where passenger movements are strongly tidal, and less so where passenger flows are more
evenly balanced.
Despite these broad preferences, it must be emphasised that even where the preference is
informed by guidelines, and precedents from elsewhere – the final selection must relate to the
particular circumstances of the site in question.
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2.
Tram Platforms
2.1
The Boarding and Alighting of Tramcars
2.1.1
Interpretation
Any consideration of tramway boarding and alighting practice must define certain terms for the
avoidance of doubt:
•
•
•
•
•
•
•
2.1.2
‘Nearside’ means the side of a tram closest to the kerbside of the adjacent road, considered in
the direction of travel for both trams and motor traffic. In Abu Dhabi and other countries
where the right-hand driving rule applies, the nearside is also to the right. In the discussion
about platform locations ‘nearside’ always relates to side platforms;
‘Offside’ means the opposite of the above, and usually relates to centre or ‘island’ platforms; 1
‘Single-ended’ means a tram that can only be driven in passenger service in one direction, 2
and which must be turned, usually on a loop, at the end of each journey;
‘Double-ended’ means a tram that can be driven from either end, and is thus fully reversible;
‘Single-sided’ means a tram that passengers can only access from one side, normally the nearside;
‘Double-sided’ means a tram that can be accessed from either side; and
‘Up’ and ‘down’ with reference to tracks relates to tracks in one direction and the opposite
direction respectively. It has nothing to do with changes of elevation.
Evolution of Boarding and Alighting Practice
For the picking-up and setting-down of passengers, tramways traditionally displayed the
following features, which were largely inherited from horse trams of the 19th century (Figure 2.1):
•
•
Trams picked-up and set-down passengers in the roadway, on their nearside; and
Double-ended/double-sided trams almost invariably functioned as single-sided/single-ended
trams for the same reason.
As noted here, many older trams were double-ended and double-sided, but were functionally
single-ended/sided vehicles (Figure 2.2). By the mid-20th century purpose-built singleended/single-sided trams dominated the fleets of Europe, the former Soviet bloc and North
America. However, double-ended/double-sided vehicles became widely favoured from the 1980s
onwards, when many tramways were upgraded with centre platforms for boarding and alighting.
Of course, there were – and still are – various oddities, including single-ended/double-sided and
even double-ended/single-sided trams, but these are of no significance in the present context.
Double-sided/double-ended trams now comprise most newly-built vehicles outside the former
Soviet bloc. Although they are more expensive than single-ended/single-sided cars (more doors
and less passenger space because of their two driving positions), they are more flexible, can serve
centre platforms and require no loops at termini.
1
2
‘Offside’ is also used in this Note to indicate a particular type of metro station layout with a side platform on
the offside of the train in its direction of travel: see Chapter 3.
Most single-ended trams can be driven from the rear end, using a concealed ‘hostler’ controller, but this is
only used at depots for low-speed movement.
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Metro
Figure 2.1
Figure 2.2
Horse trams were usually single-ended and
single-sided, and invariably operated in streets
(The photograph shows a Winnipeg Street
Railway horse car operating at
Heritage Park, Calgary).
Many older electric trams were both doubleended and double-sided, but functioned as
single-ended cars. Passengers could only
access this London tram by the nearside
entrance/exit at the rear of the car (left hand
road rule).
Figure 2.3
Figure 2.4
Passengers congregate in the city centre of
Toronto, as they board and alight from a
single-ended, single-sided streetcar in Queen
Street. Note motor vehicles waiting behind
the tram.
Passengers venture into the street to board a
tram in Frankfurt am Main, Germany. The
tram is double-ended/double-sided, but loads
from the nearside when operating on-street.
2.2
Tram Platforms
Most original tramways were laid in public streets, and passengers had to venture into the
roadway to board trams. This form of boarding has become increasingly rare, because:
•
•
A practice that was acceptable a century ago when motor traffic was negligible is hazardous
now; and
Most passengers with disabilities cannot even board low-floor trams without assistance at
street stops.
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Metro
Hence platforms are now the norm on most tramways in the western world, Japan and Australia.
Figure 2.5
Figure 2.6
Evolving practice in San Francisco.
Above left: in October 1980 a man boards a single-ended, single-sided streetcar in the highway.
Above right: pictured in March 2003 is an island-platform complete with a high-level boarding
position for contemporary ‘Muni Metro’ streetcars. Nevertheless, the new streetcars feature
folding steps to serve street-level stops in the western suburbs, such as that shown in Figure 2.5.
Figure 2.7
A new tramway, complete with low-floor trams, showing the side-platform terminus at
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Connolly Station in Dublin.
2.2.1
High and Low Platforms
There was a trend during the 1970s and 1980s to equip tramways with high platforms in the
momentum to dignify them with LRT status. The need for level access to tramcars was
recognised, and for much of that period low-floor trams were not an option – the first such trams
being acquired by Génève (Geneva) as late as 1985. Several tramways rebuilt stops with high
platforms, especially in towns that were providing high-platform stations in tram subways, such
as Hannover and Köln. On many networks trams had to be fitted with folding steps to allow lowlevel boarding where platforms were lacking (the vehicles illustrated at Figures 2.4 and 2.6 are of
this type). In addition, some completely new networks featured high platforms throughout, such
as Utrecht, Tuen Mun and Los Angeles. Platform locations varied, but central ‘island’ platforms
were quite popular where space was constrained and double-sided vehicles were used.
By the early 1990s low-floor trams were dominating orders, and conversions to high-floor/highplatform operation had virtually ceased.
Nonetheless, health, safety and accessibility
requirements were making platforms ever-more necessary, even for low-floor trams. Whilst the
Consultant has not discovered any statistics, simple observation suggests that the overwhelming
majority of low-level stops have side platforms. In narrow streets this has the advantage of
allowing platforms to be combined with sidewalks. A logical exception to the side-platform
orthodoxy relates to pedestrian/tramway precincts, where pedestrian circulation may benefit
when a platform is situated centrally rather than at the side. This arrangement had been
intended in a tramway scheme for Liverpool (UK) that was shelved in 2005 for want of
Government funding.
Figure 2.8
Figure 2.9
A dual height, island-platform in Amsterdam.
A low-boarding height tram is receding from
this stop that also serves wide-bodied highplatform Sneltrams that inter-work with the
Metro.
City Hall tram stop in Sheffield designed to
give direct access to low-floor trams. This is a
side-platform stop that shares its space with
the footway (sidewalk).
2.3
Platform Locations for Abu Dhabi
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Metro
If built as envisaged, the Abu Dhabi tram system will be extensive and complex. Potentially, track
alignments will include:
•
•
•
•
•
•
Street/highway medians;
Bilateral tracks, to either side of broad boulevards;
Unilateral alignments, where both ‘up’ and ‘down’ tracks are to one side of a highway;
In pedestrian precincts;
In one-way configurations; and
On separate rights of way unrelated to any adjacent highway.
These arrangements are shown diagrammatically by Figures 2.10 to 2.15 below.
median
Figure 2.10
Tram tracks located in median of a divided highway.
median
Figures 2.11 (above) and 2.12 (below)
Tram tracks located bilaterally to either side of a divided highway (above) and unilaterally to one
side of a divided highway (below).
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median
pedestrians
pedestrians
Figure 2.13
Tram tracks located in a pedestrian precinct.
Figure 2.14
Tram track beside a one-way street.
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Figure 2.15
Tram tracks located on private right-of-way.
2.4
Tram Templates
With such a diversity of track alignments it would be inappropriate to determine a ‘one size fits
all’ policy for stop platforms. Clearly, stopping places must conform to the rolling stock to be
used on the tramway. The following tramcar parameters are becoming clear and must relate to
all stops:
•
•
•
•
•
•
Trams will be articulated and composed of several ‘modules’. There will be two basic types,
comprising 30-metre ‘supertrams’ (three or four modules) and 45-metre long ‘town trams’
(five to seven modules). Trams will operate either singly or in multiple-unit consists of 60
metres or 90 metres – according to traffic demand; 3
The passenger capacity of a 30-metre tram will be about 160 passengers, and that of a
45-metre tram will be about 245. Multiple-unit formations will accommodate the appropriate
multipliers of these capacities;
Trams will be double-ended and double-sided;
Trams will have an internal floor-height of about 350 mm, indicating a platform height of
300 mm to allow for the possible ‘settlement’ of heavily-laden trams and the ‘over-sailing’ of
plug doors (if fitted);
Trams will include Gold (First) Class accommodation and a ‘Ladies-Only’ section. It is
recommended that these compartments will be situated approximately at the centre of each
modular car; and
Tram drivers should not be responsible for fare collection. The authority to travel should be a
pre-payment system, subject to random inspection on trams and deterrent ‘supplementary
fares’ for non-possession of a valid proof of payment.
Diagrams of representative trams are shown at Figures 2.16 and 2.17 below.
Figure 2.16
A representative ‘supertram’ resembling the ‘30-metre template’
(drawing by courtesy of the Editor, Railway Gazette International).
3
Tram lengths are nominal.
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Metro
Figure 2.17
A representative ‘town tram’ resembling the ‘45-metre template’
(drawing by courtesy of Railway Gazette International).
2.5
Tram Stop Dimensions
2.5.1
Stop Length
The stops will require platforms 90 metres long, 4 although it may be sufficient to build a 45metre or 60-metre platform initially and allocate land for a 90-metre platform if it is planned to
deploy longer units later.
2.5.2
Platform Width
The width of the platforms as outlined by the Department of Transport in the first draft of its
Guidelines for the Provision of Public Transport would be generous by tramway standards, being
a minimum of five metres (5 m) for side platforms and ten metres (10 m) for island platforms.
These widths are deceptively spacious – because it is proposed to provide air-conditioned shelters
on tram platforms. These would be three metres (3 m) wide on side platforms and six metres (6
m) wide on island platforms. The topic of shelter design is being addressed in another of the
Consultant’s Technical Notes, but clearly it affects platform width, and in particular
circumstances it could determine platform type and location.
For comparison, some other planning guidelines for tramways require the following platform
widths:
•
•
•
•
4
5
Office of Rail Regulation (UK) – 3,000 mm minimum for island platforms and clear space of
1,500 mm to any obstruction (other than shelter canopies or roofs) at side platforms;
Tuen Mun LRT system (Hong Kong) – 3,000 mm for side platforms (all platforms are side
platforms); 5
LUAS tramways, Dublin – 3,000 mm for side platforms, 4,000 mm for island platforms; and
Metro North Line, Dublin (surface stops), 3,500 mm for side platforms and 7,000 mm for
island platforms. 6
Just as tram lengths are nominal: so are stop lengths. Arguably, platforms need to be longer than the longest
tram to accommodate inaccurate stopping, but they could be slightly shorter because they only need to serve
door positions. If two short trams are accommodated instead of two units in double-traction, 1.5 metres
should be allowed for the space between the two trams at the stop.
Originally the width was recommended to be 2,000 mm, but this was found to be inadequate and platforms
were widened throughout the system.
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Metro
Generally, recommendations for tram platforms in this small sample of other systems or national
guidelines are narrower than those planned for Abu Dhabi. However, none of these other
guidelines has to accommodate air-conditioned shelters. Assuming that these will be placed to
the rear of the platform, all Abu Dhabi platform widths include two metres (2 m) of space that
would not be used for passenger waiting. This means that the effective platform widths would be
three metres (side platforms) or six metres (island platforms).
2.6
Density Guidelines for Waiting Passengers
Whereas guidelines of any sort are useful, the purpose of a tram stop platform must never be
forgotten. Thus the platform must accommodate a shelter (full length in the case of Abu Dhabi),
ticket machines, passenger information displays, and perhaps concessions and staff rooms. But
above all else, it must be large enough to accommodate the likely number of passengers expected
to be waiting at any one time. This will vary from stop to stop, and will depend on the usage of
the stop and tram headways. It is considered best practice to allow for ‘two headways’; 7 this
includes some allowance for late-running or minor service perturbations. Platforms should also
be designed to cater for the peak quarter hour in the main direction of travel. Density standards
for waiting passengers on station platforms were devised long ago (amongst other pedestrian
standards) by J. Fruin, but are widely considered to remain valid today. 8 In summary, Fruin
defined the following density levels:
•
•
•
Desirable maximum – 1.08 people/m2;
‘Jam’ capacity – 2.15/m2; and
Danger level – 3.59/m2.
On this basis the desirable capacity of a tram shelter 90 metres long by three metres wide would
be 292 people. The equivalent ‘jam’ capacity would be 580. However, because full-length
platforms would be 90 metres long, it would be unreasonable to expect passengers to distribute
themselves evenly along the whole length of the sheltered area, so it could be presumed that – at
maximum – the central half would be occupied at ‘jam’ capacity, whilst the outer ‘quarters’
would be occupied at the desirable density. This would give a maximum guideline a capacity of
436 people, which ought to be adequate for most purposes. Even so, additional space may be
needed at busy termini, major activity centres (such as stadia and shopping malls) or at
intermediate stops that could be served by more than one route – where it is possible that
headways could fall to less than two minutes. Another possibility, where site conditions allow,
would be to widen the shelter along the back of its centre portion, where the most passengers
would tend to wait, although this would depend on the point or points of access. A further
consideration is whether there should be dedicated waiting accommodation for women and
holders of valid Gold Class smartcards or tickets.
2.7
Additional Factors Affecting Tram Platforms in Abu Dhabi
6
The Metro North Line will be compatible with existing LUAS tramways in Dublin, but it is designed as a
higher capacity route with underground alignment beneath the city centre.
‘Two headways’ represents the number of people who would accumulate if one scheduled departure is
missing, or if they are unable to board the first vehicle.
Fruin, J. (1971). Pedestrian Planning and Design. New York: Metropolitan Association of Urban Designers and
Environmental Planners, Inc
7
8
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Metro
It was stated above that there can be no single solution to platform location for the tramways.
However, certain factors may affect selection:
•
•
•
•
2.7.1
The environment in which the stop is set;
The advisability of changing exit sides from the tram at successive stops;
Pedestrian access requirements; and
Track layout implications.
Stop Environment
Some stops will be in the highway median, others will be in pedestrian precincts, and yet others
will be at the side of the road. Each situation invites a particular solution. For example, highway
median stops suggest island platforms so that waiting passengers are at some distance from
passing traffic. However, assuming air-conditioned shelters, this would be less of a nuisance than
at open-air stops where side platforms expose waiting passengers to noise and fumes from
passing motor vehicles – and increase their risk of injury from errant vehicles leaving the
carriageway.
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Metro
2.7.2
Advisability of Changing Exit Sides from Trams at Successive Stops
Some passengers become irritated if they cannot anticipate from which side of the tram they
should alight at their destination. However, this need not be a major issue because a well-run
system should include a public address announcement in the tram to say: “The next stop is . . .
Please exit on the right-hand side of the tram.”
2.7.3
Pedestrian Access Requirements
Pedestrian access requirements are critical. The first issue relates to the convenience of the stop and
its platform relative to its surroundings. It is a truism that wherever a tram stop is placed, it will only
suit half the potential clientèle. This is because people’s activities are usually situated on both sides of
a road, so a stop beside the road requires half the people to cross all of the road, whilst one in the
middle requires all the people to cross half the road. Median stops are liable to be far more critical
than stops beside roads because important safety issues are involved, especially on wide boulevards
with fast-moving traffic. Stop platforms for 90-metre trams will need clearly marked entry points to
deter people from dashing into moving traffic when they see an approaching tram. Signalised
pedestrian crossings or subways may be needed.
There is also the issue of crossing tram tracks. Trams are often regarded as ‘people-friendly’ vehicles,
but there are grave potential hazards in crossing tracks between moving trams. The provision of
shelters with platform-side doors should deter jaywalking across tram tracks, but a central fence to
restrict pedestrian movements to designated crossing points should be an obligatory element of the
tramway ‘furniture’. In at least one developer’s scheme (Al Raha Beach) it is proposed that access to
platforms should be by a subway (pedestrian underpass), but to equip all stops with this feature
throughout the network may not be possible (for example, because of conflicts with underground
utilities) and would certainly add significant cost to the overall tramway network.
In summary, pedestrian access to tram stops is such a major issue that it merits a separate document,
but it is worth noting here that subway access may require wider island platforms and extra width at,
or near, side platforms. A related issue that also warrants separate consideration is access for people
with disabilities, about which learned papers, official guidelines and national standards have been
published in the USA, the United Kingdom and elsewhere.
2.7.4
Track Layout Implications
Tramway designers and operators generally prefer side platforms because they enable the tracks
to be kept in a uniform alignment without the need for the ‘splays’ that are obligatory with island
platforms. Obviously, if trams have to observe a stop with centre platforms, the ‘up’ and ‘down’
lines must be separated more widely apart to serve the platform, with the implication that tram
drivers’ sightlines will be reduced and approach speeds will usually be slower. However, even
side platforms may need special geometry where lateral space is restricted: specifically platforms
may have to be offset relative to one another, with a ‘chicane’ between them, as illustrated
diagrammatically in Figure 2.18.
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Metro
Figure 2.18
A diagram (not to scale) illustrating off-set (or staggered) side platforms with a track ‘chicane’ to
accommodate tram stops in a restricted-width corridor.
2.8
Preferences for Tram Platforms in Abu Dhabi
This Section suggests preferences for tram platform locations. Again, it is important to stress that
there is no single answer to the various track alignments referred to in the Sub-section headings, and it
will be necessary to examine each site on its merits when the planning process examines individual
districts or routes.
2.8.1
Street/Highway Medians
Where the tramway is situated in the median strip of a boulevard or a broad street, either island or side
platforms would be acceptable, although passenger security may be slightly better served by an island
platform, especially if travel flows are strongly ‘tidal’. 9 The tidal flow issue relates to the size of the
waiting shelter, because a four-metre wide shelter would offer only two-thirds of the combined
capacity of two separate three-metre wide shelters. However, if the great majority of travel in (say)
the morning peak is towards the central business district, the number of passengers wishing to travel in
the opposite direction would be negligible and overall requirements may be better met by a single,
wide shelter to serve both directions of travel.
2.8.2
Bilateral Tracks, to Either Side of Broad Boulevards
By definition, island platforms are not in contention in this type of situation, except possibly
where two routes divide ‘downstream’ and it is desired to provide a ‘pocket’ for turning trams,
with the added possibility of allowing passengers to change from one route to another at the
stop.
For side platforms, the platform itself should be to the right-hand side of the direction of travel, so
that the platform is conveniently placed for frontage activities and the pedestrian sidewalk.
2.8.3
Unilateral Tracks, where Both Tracks are to One Side of a Highway
As with median tracks, platforms may either be to each side of the track, or between them. As
space may be constrained in this situation, island platforms may be preferable, or a staggered
side-platform layout (as shown in Figure 2.18) may help to save space.
9
Abu Dhabi in future will be bi-centric, with Capital City counterbalancing the Central Business District as an
employment centre. However, the two centres will be sufficiently far apart to exert minimal tidal influence on
any tram routes serving both centres. On the other hand, the bi-centric effect may help to balance peak
period flows on the Metro and the Regional Railway.
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Metro
2.8.4 Pedestrian Precincts
In pedestrian precincts the island platform layout commends itself as the most economical
solution because side platforms could obstruct access to frontages. Nonetheless, developers
favour side platforms in the only locations where tram operation in pedestrian precincts has been
discussed at the time of writing (Capital City). The reason for this is that splayed tracks would
trespass above underground utilities, so it would be imperative to keep the tracks straight
through the stopping place. Similar conditions may be found in other locations as well.
2.8.5 One-Way Configurations
By definition, side platforms would be used where the tramway operates in one direction only.
The platform should be on the side of the track furthest from any road (normally on the righthand side in the direction of travel).
2.8.6 Separate Rights of Way
Either side platforms or island platforms could be used for sections of tramway on exclusive rights
of way. There are benefits to both solutions. Side platforms avoid having to splay tracks, but
developers may have schemes to integrate island platforms with their overall plans, as at Al Raha
Beach. Island platforms would make better sense where travel is strongly tidal.
15
Metro
3.
Metro Platforms
3.1
Historical Precedents
The ancestry of the metropolitan railway – featuring underground operation beneath a city centre
– is only slightly younger than that of the tramway. The first such line was London’s
Metropolitan Railway, which opened in 1863. It was built by the cut-and-cover method, and its
trains were of main line dimensions and hauled by steam locomotives: where the original trench
was covered, the resultant tunnels contained both tracks. Side platforms were the normal
arrangement, although as the network grew, island platforms were provided at interchange
stations and termini (where they may more correctly be called ‘peninsula’ platforms, as there is a
concourse at one end).
By the end of the 19th century other major cities were building metros, and divergent practices
emerged. In Paris, the Chemin de Fer Métropolitain de Paris (opened in 1900) was at shallow
depth: it was built by cut-and-cover and was equipped with side platforms throughout. Some
early American lines were elevated, rather than underground, and they variously deployed side
and island platforms. In London, the first deep level, electrified ‘tube’ railway opened in 1890
(the City & South London Railway, now part of London Underground’s Northern Line), and this
featured island platforms at all intermediate stations. This made sense in the circumstances
because the running lines were constructed in separate ‘tubes’: moreover, the island platforms
enabled the sharing of passenger access stairs and lifts. Glasgow’s Underground, opened in 1896,
was built on the same principle.
In London the ‘tube’ network expanded rapidly in the early 20th century, whilst two additional
lines were completed in 1971 and 1999 respectively. Where underground, the tube lines were
built by ‘shields’ – manually worked ancestors of today’s tunnel boring machines (TBMs).
Stations were constructed by the same method, but with larger diameter shields. Most had/have
‘offside platforms’, or side platforms on the offside of the train (instead of the usual nearside).
Cross passages between offside platforms mean that most function as island platforms even
though they were not built as such.
16
Metro
Figure 3.1
Figure 3.2
London’s first metro lines were built by cutand-cover in the 19th century, with side
platforms. This is Westminster Station, which
defies the orthodoxy that platforms should be
straight.
A simple metro: an island platform at
Buchanan Street Station on the Glasgow
Underground before the line was modernised
in 1977. Cars only had doors (and gloss paint)
on one side.
Figure 3.3
Figure 3.4
Like the London ‘Met’, the Paris Métro was
also built by cut-and-cover, with side platforms
at stations, as illustrated by this scene at
Miromesnil Station.
Covent Garden Station in London shows
typical deep-level ‘tube’ construction. There
are separate side platforms in each tube, but
functionally it is an island arrangement.
Figure 3.5
Figure 3.6
Island platforms on the London tube lines
have been perpetuated in modern times, even
on the surface, as this view of Canning Town
Station on the Jubilee Line (opened in 1999)
indicates.
Edgware Road is an open-air interchange
station with island platforms on London
Underground’s District and Circle Lines. It was
amongst London’s earliest metro stations.
3.1.1 Non-Standard Platforms
17
Metro
It is generally presumed that there are two types of platform – island and side. In addition, it is
generally acknowledged that they should be straight-edged and that the tracks through stations
should be level (or, to be precise, graded at 1:1000 [1‰] to permit drainage). However, there are
variations worthy of note.
One oddity is the twin platform layout, with platforms to both sides of a single track. Figures 3.8
and 3.9 illustrate such platforms at Canary Wharf Station on the Docklands Light Railway. The
twin platforms can be used to allow interchange to trains in two directions as well as providing a
‘centre siding’ for terminating trains. Whereas twin platforms are relatively rare in Europe, they
are quite common in Japan, where – at busy stations – one platform is used for boarding and the
other for alighting, with train doors being opened sequentially on alternate sides.
Figure 3.7
Figure 3.8
Canary Wharf Station on London’s Docklands Light Railway is unusual because one track has
platforms on both sides of the rails in the ‘twin platform’ style.
Figure 3.9
Figure 3.10
Mind the gap! A London Underground train
illustrates the effect of a curved platform at
Bank Station on the Central Line.
Baker Street in London is a terminus. Note
how the platforms taper at their far ends to
save space.
Modern practice eschews curved platforms because they create unacceptable gaps (now outlawed
by some administrations) between train doorways and the platform edge, but they also obscure
18
Metro
sightlines for drivers (although this can be overcome to a large extent by split-screen CCTV
monitors to show drivers that all doors are closed prior to departure). These considerations did
not matter so much in the past, especially when metro trains invariably carried guards to
supervise the back end of the train.
Whereas curved platforms may be unacceptable now, end tapers were once commonplace on
metros and railways everywhere. The taper acknowledged that the density of waiting passengers
reduced towards the outer end of platforms. Moreover; a taper also allowed tracks to converge
within the station area, reducing the overall land take. Even now side platforms can be tapered
at their ends, albeit where tracks are straight, by reducing the distance from platform edge to
back-wall – with consequential reductions in land-take.
It is generally regarded as bad practice for any station (even tram stops, according to some
guidelines) to be on a slope, lest a train runs away whilst unattended. However, there are
numerous examples of stations on gradients, including Wilhelminaplein Station, recently built on
Rotterdam’s Erasmus Line where the metro alignment climbs steeply from its deepest point
beneath the Maas River. More generally, it is normal practice to situate metro stations on
‘humps’ (to slow approach speeds and accelerate departure). However, stations at the summits
of humps are usually level, but on London’s Central Line some hump gradients are within the
platform zone. 1
3.2
Comparisons between Tramway and Metro Platforms
Compared with tramways, metro platform options are more straightforward. Because the tracks
are completely segregated, the position of the highway is of no importance, at least at track level.
Similarly, there has been no almost history of single-ended and double-ended trains, or issues
about high floors versus low floors. 2 In any case, historical inconsistencies should not be
designed into a newly-built system.
On the other hand, most aspects of metro station design are more critical than for tram stops.
These largely relate to the high volumes of passengers handled by metros, which means that
passenger circulation arrangements within the station assume a high priority, and numerous
safeguards must be built into the design of stairs, escalators and internal passages to ensure that
dangerous levels of overcrowding do not accumulate when normal services fail for any reason.
However, these aspects of station design are intricate and typically codified by innumerable
regulations and guidelines: they are not generally addressed in this Technical Note, although
they will warrant separate consideration once station locations have been confirmed and
predicted passenger flows have been forecast.
3.3
Factors Affecting Metro Platform Preferences
The two main factors affecting the choice of platform locations on a metro (or a main line railway
for that matter) are construction and operation.
1
2
This situation dates from the 1930s when (unusually for an underground railway) platforms were extended to
accommodate longer trains.
Like most assertions, there are exceptions. The original trains on the Glasgow Underground were singlesided, whilst there are significant platform height differences on the London Underground between the tube
lines and the so-called ‘surface’ lines such as the Circle, District and Metropolitan lines.
19
Metro
3.3.1
Construction
Where railways are built on the surface, on elevated structure or by cut-and-cover, the most
space-saving technique is to place both ‘up’ and ‘down’ tracks together along a corridor.
Consequently the relevant stations have side platforms. On elevated alignments viaduct
construction can continue through the station, which can be constructed to each side of the
tracks. An advantage of this arrangement is that additional stations can be added to the network
in future with minimal interruption to train services.
For underground alignments built entirely by cut-and-cover, the arguments favouring side
platforms still apply – even though the overall station width is slightly greater than for an
equivalent island platform. However, where the station ‘box’ is excavated and the running
tunnels are bored, island platforms are to be preferred. This is because the normal minimum
separation for bored tunnels is ‘one tunnel diameter’, which means that the ‘up’ and ‘down’ lines
have to be separated wherever each has a separate bore.
For deep-bored metros (such as the London ‘tube’ network and Hong Kong’s Island Line) stations
must be mined rather than excavated by cut and cover. In this situation each platform has its
own tunnel, but the layout is usually that of a pseudo-island platform, with cross-passages to
connect the ‘up’ and ‘down’ platforms.
3.3.2
Operation
From an operational perspective island platforms are preferable. They are less confusing for
passengers, because (at non-interchange stations) they can confirm their route direction at
platform level. Island platforms are also more efficient at vertical movement (stairs, escalators
and lifts) than side platforms: this is not only because vertical movement arrangements can be
shared but because various national safety laws prescribe minimum stair widths, which are easier
to accommodate on a single, wide platform than on two narrower ones.
Although it is a special case, island platforms are the best solution for interchange stations, where a
pair of different lines can be brought together to afford ‘cross-platform interchange’.
3.4
Worldwide Platform Preferences
The Consultant has examined photographs of stations on several of the world’s newer metro lines
and systems to determine whether any conclusions can be drawn about platform preferences. In
summary, there is no overall unanimity about platform locations, and it makes little difference
whether tracks are underground, at grade or elevated. That said, the ‘heavier’ or high-capacity
systems make substantial use of island platforms: examples include Shanghai, Hong Kong,
Taipei, San Francisco (BART), Osaka (Line 7), and Nanjing, amongst others. Nevertheless, some
of these systems also use side platforms.
20
Metro
Figure 3.11
Figure 3.12
Lafayette Station’s island platform in a
highway median on the Bay Area Rapid
Transit system.
Passengers on an island platform at Xiaoing
Station on the Nanjing Metro.
Many light metros and lower capacity lines favour side platforms: examples include London’s
Docklands Light Railway, Vancouver Skytrain and the Wuhan Metro. The reason is that these
lines are mainly elevated, so the argument about the integrity of viaduct construction (see above)
clearly applies. On the other hand, Bangkok’s Skytrain uses island platforms.
Figure 3.13
Figure 3.14
Side platforms at the elevated West Silvertown A side-platform station on the Wuhan Metro,
Station on the Docklands Light Railway,
which is almost entirely elevated.
London.
Note how in both these cases the stations have been built around the viaduct structures, which
continue through the stations uninterrupted.
21
Metro
To some extent the choices may be arbitrary, depending perhaps on the operators’ preferences or
their consultants’ advice. However, island platforms maintain the logic that they make better use
of space, especially on lines where passenger movements are strongly tidal – typically travelling
to the city centre in the morning and back in the evening. Island platforms can concentrate other
activities, such as supervisors’ booths, disabled lifts and other ‘capital’ items. Stairs and
escalators do not have to be duplicated, but care must be taken that they are wide enough to
cope with the demands placed upon them when crowd surges occur.
3.4.1
Platform Width
Another feature that is very evident from examining images of metros worldwide is that platform
widths are becoming progressively more generous. Older metros suffer from some platforms that
would now be considered dangerously narrow, but increasing recognition of safety issues has
prompted the adoption of wider platforms on most new systems.
Figure 3.15
Figure 3.16
A side platform barely two metres wide at
Charles/MGH Station on the Boston subway.
Nation Station on Paris’s RER system was
manifestly built for ample traffic growth.
3.5
The Template Train for Abu Dhabi
Proposals for suitable trains for the Abu Dhabi Metro are taking shape and will be debated when
the Planning Guidelines for the Department of Transport are delivered. However, it is becoming
clear that the trains will comprise a maximum of eight cars, each nominally 22 metres long –
although there may be merit in acquiring 25-metre cars if they could share a common body shell
with the Regional Railway’s trains. Within reason, there are capacity advantages in making
metro trains as wide as possible, so it is recommended that the cars should be 3.2 metres wide,
which follows current practice in Singapore. Based on observations of standing practices on Abu
Dhabi’s buses, the acceptable capacity of each 22-metre car would be 140 passengers, and an
eight-car train would hold 1,120 passengers, 3 with a line capacity of 33,600 passengers per hour
in each direction. Under less congenial conditions passenger volumes could probably double
these figures, but it would be unwise to assume this condition for planning purposes. 4
3
4
These are simple calculations. Actual capacities would probably be about 90 passengers fewer after taking
into account low-density seating and usage of the Gold Class and Ladies-Only car at the middle of the train.
In Hong Kong trains of similar size carried about 2,500 passengers each during the late 1980s.
22
Metro
Figure 3.17
An Alstom Metropolis ‘system train’ of a type supplied to several metros worldwide. This
example is running in Shanghai. ‘System trains’ can be tailored to various widths, car-lengths
and interior and exterior styling options.
3.6
Platform Dimensions
The original draft of the Department of Transport’s Guidelines for Provision of Public Transport
Services included no parameters for a metro, but it did provide platform dimensions for the
Regional Railway system, which may be regarded as comparable. These were:
•
•
•
Side platform – six metres (6 m) minimum width, to include a three-metre wide airconditioned waiting area;
Island platform – 12 metres (12 m) minimum width to include a six-metre wide airconditioned waiting area; and
The recommended platform length was 175 metres to accommodate a 150-metre long train.
Several factors have changed since the original draft Guidelines were circulated. Thus, the
planned trains are longer (176 metres, or even 200 metres) and platform screen doors are now in
contention.
Assuming that Abu Dhabi Metro platforms are 200 metres long, but with an effective length of
175 metres, 5 the standing capacity of a six-metre wide side platform would be 1,134 people at
Fruin’s desirable density and 2,257 at his ‘jam’ density. A 12-metre wide island platform could
accommodate double these capacities (2,268 and 4,514 respectively). Such capacities should
adequately cope with most situations, including ‘two headways’. The island platform ought to be
able to accommodate a complete train-load, should all passengers be forced to alight from a
failed train.
5
Platform ends may be used for plant rooms. In any case, there is no point in extending the waiting area much
beyond the outermost doors of each full-length train.
23
Metro
Reference has been made to platform screen doors. The original Department of Transport
Guidelines assumed that there would be an air-conditioned waiting area to the back of side
platforms and along the central axis of island platforms. The issue of platform screen doors will
be addressed in a future Technical Note, but the Consultant now recommends their use at all
Metro stations, which means that the whole platform area can be used for waiting. In this
situation the danger of falling beneath a train is virtually eliminated, so it may be acceptable to
allow Fruin’s ‘jam density’ of passengers to be exceeded, within reason. 6
3.7
Recommendations for Metro Platforms
This review of the principles and practice of metro station construction highlights certain
conclusions that may be adopted for the Abu Dhabi Metro. Before presenting these
recommendations, it is useful to reflect on particular features of the Metro that must be
considered in station design. These include:
•
•
•
•
3.7.1
Routes that will include operation beneath high capacity roads with an abundance of major
utility pipes and cables;
A network that will service a bi-centric metropolis with a greater balance of peak hour flows
than on many metros that service a single city centre;
A long surface section along the median of an expressway road that may have to
accommodate stations after the Metro has opened; and
A section of alignment in Capital City where the two circular Metro lines will intertwine for
interchange purposes.
Preferred Platforms for Deep-Bored Construction
The first of these issues would best be met by deep-level bored construction. This means that the
Metro would be of the ‘tube’ type with stations excavated by mining. Each track would have a
side platform, although functionally the two side platforms would be an island platform linked by
cross passages.
3.7.2
Preferred Platforms for Balanced Flows
One advantage of island platforms is that they offer a particularly economical solution where
passenger flows are strongly tidal. In Abu Dhabi this would not be the case, particularly along
the southern side of the Circle Line (Line 2 in the terminology of the Consultant’s Report on
Safeguarding of Regional Rail and Metro Corridors). However, much of this length (other than in
the vicinity of Emerald Gateway) will be in deep-bored tunnel with individual side platforms
forming a ‘functional island pair’. It will be important to ensure that each platform at every
station offers sufficient capacity, both to handle normal travel demand and contingencies. This
can only be done when robust travel demand forecasts are available.
3.7.3
Preferred Platforms for Median Strip Alignments
6
If it can be argued that Fruin’s ‘dangerous density’ of 3.59 persons per square metre is less dangerous within
an enclosed, air-conditioned area. Extreme values could reach 3,770 passengers on a side platform and 7,540
passengers on an island platform.
24
Metro
The situation described in the caption is hypothetical because present plans call for no Metro
station along the 22 kilometres between Saadiyat and Yas Mall. For most of this distance the
Metro will run along the median strip of the Shahama Expressway.
It is difficult to believe that developers will fail to exploit the accessibility offered the Metro, and
that clamour will not arise for intermediate stations. If such stations are identified before track
alignments are committed, island platforms would be preferable, to save space (see Figure 3.11).
However, if the train service is already operational, side platforms would offer a less disruptive
solution.
3.7.4
Interchange Stations
Capital City (CD1) and CD2 stations are intended to offer interchange between the Circle and
Mohammed Bin Zayed Loop lines. The stations will feature tracks at two levels, so each should
have an island platform to enable cross-platform interchange.
3.7.5
Overall Preferences
This review indicates a strong preference for island platforms on the Metro, including matched
‘offside’ platform pairs on deep-bored sections that would function as island platforms.
Despite the emerging preference for island platforms, sections of Metro built in shallow trenches
by cut and cover would best be served by side platforms.
Figure 3.17
Figure 3.18
The rivals: on the left, Saint Augustin Station on the Paris Métro exemplifies a side-platform
station in a shallow metro constructed entirely by cut and cover. On the right, London
Underground’s Willesden Junction. Station has an island platform inherited from a main line
operator. Note the track splay and undesirable curved platform.
25

STMP Mott MacDonald Technical Note July 2008 Platform

Transcription

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