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Railway Transport in Qatar

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Abstract

The article presents the railway infrastructure projects currently carried out in the State of Qatar with specific focus on the Doha Metro Project. The types of designed structures, such as viaducts and tunnels with a closer look at the construction of the trackbed are described in more detail. The last part of the article contains key information about both the Tram Network project in Lusail and the Long Distance Lines for the passenger and freight trains.
Robert Wojtczak - Railway transport in Qatar
Conference “Problemy budowy i naprawy podtorza kolejowego”, Jelenia Góra, 10/2016
The article presents the railway infrastructure projects currently carried out in the State of Qatar with
specific focus on the Doha Metro Project. The types of designed structures, such as viaducts and tunnels
with a closer look at the construction of the trackbed are described in more detail. The last part of the
article contains key information about both the Tram Network project in Lusail and the Long Distance
Lines for the passenger and freight trains.
Introduction
Qatar is one of the smallest countries in the world. Its area is comparable to one of the smallest
voivodships in Poland - opolskie. It is also the richest country in terms of per capita income. Number of
residents is about 2.6M, 1.5M live in a capital Doha. It may be little confusing as almost 90% of all
residents are people who came just to work. Native Qataris are merely about three hundred thousand.
Thanks to income from huge natural gas resources, Qatar’s development rate is one of the highest in the
world. It can be noticed in the large amount of on-going constructions of residential and commercial
buildings as well as in construction of road and railway systems. All investments are being done at a
great speed because of the football World Cup in the year 2022.
Qatar Railways as a company was created in 2009 and construction started in the year 2012 The Qatar
Railways is constructing the metro system in Doha, a tram network across the new township of Lusail
and a long distance rail network connecting the GCC countries. The first phase of Doha Metro will be
open to public by the 2020. It will consist of 37 stations, 3 lines and 85km of tracks.
1. Doha Metro map
Metro
At the initial stage a detailed geological study was carried out.
During the geological study, it was noticed that limestone formations had irregular structures and many
there were empty spaces caused by karstic effects, which is unfavourable for tunnelling. Waterbed was
observed at the depth between 5 and 15 meters. The water had large quantity of sulphates and chlorides
and was found corrosive for steel and concrete. Average water temperature reached as high as 28ºC.
Doha Metro network will be constructed in two phases. Phase 1 will be finished by 2020and Phase 2 by
2030. Phase 1 will consist of 3 lines; red, green and gold. Red Line or the coast line will consist of 18
stations and will connect to the Hamad International Airport, Gold Line with 11 stations and Green Line
with the same number of stations is called the historic and educational lines respectively. Also an
operational line will be built and it will become a part of Blue Line in Phase 2. All three lines connect on
two level station Msheireb that is the heart of the entire system. There are also four stabling yards and
depots planned, one for Green and Gold Lines and two for Red Line. One of them is situated below
ground. Figure 2 shows Phase 1 lines in appropriate colours, lines of Phase 2 are shown in grey. Table 1
shows length of lines and number of stations for Phase 1.
2. Doha Metro network diagram (Phase 1 and 2)
Line
Length
No. of Stations
Red
42 km
18
Green
22 km
10
Gold
16 km
10
Operational
4 km
0
Table 1. Length of lines and number of stations in Phase 1
Despite extension of all lines, another line Blue Line in Phase 2 - will be constructed. The line will go
along the city centre. The second phase of Green and Gold will be constructed as well with another big
stabling yard. Table 2 shows line lengths and station numbers designed for Phase 2. Table 3 shows
lengths of different structure types and percentage share is shown in Figure 3. Two-thirds of the whole
lines length in Phase 1 take double bore tunnels made by TBMs followed by cut & cover structures
(14%) and viaducts (12%). The longest structures in Phase 2 are as follows viaducts (45%), TBM
tunnels (44%); lengths of other structures are relatively short. After finishing all Phase 1 and 2 lines
percentage share will look this way TBM tunnels 52%, viaducts 32%, cut & cover 10%, at-grade
4% and ramps and troughs 2%.
Line
Length
No. of Stations
Red
27 km
12
Green
63 km
31
Gold
21 km
11
Blue
20 km
9
Table 2. Length of lines and number of stations in Phase 2
Tunnels
Cut & Cover
Ramps, Troughs
At-grade
Phase 1
56 km (x 2)
12 km
2 km
4 km
Phase 2
57 km (x 2)
9 km
2 km
5 km
Phase 1 + 2
113 km (x 2)
21 km
4 km
9 km
Table 3. Structure types in Phase 1 i 2
3. Percentage share of different structure types
Each line has been designed as two tracks 4.0 m apart outside TBM tunnels and nominal 15.7 m within
them. Along underground platforms the distance between tracks is 17.5 m to achieve island platform
width 14.4 m. Trains will be powered from a third rail located at the side of the track. The length of one
train is 60 m (3 wagons of 20 m each) or 120 m (2 short 60 m trains), axel load is 16 t.
Track consists of rail 60E1 type welded into CWR, resilient fastenings and prefabricated concrete slab.
Because of sand storms, it was decided not to use ballasted tracks. Such solution could not be
economically justified as the ballast would get contaminated quickly and it would require frequent
maintenance works.
Because of structure that takes load from track, and thus trackbed type, metro lines can be divided into
sections:
- tunnels,
- cut & cover structures (stations, switch boxes i shallow tunnels),
- elevated sturctures (viaducts),
- ramps,
- troughs,
- at-grade sections (in small cut or fill). Figure 4 shows structure heights of the mention structures.
4. Doha Metro structure types
All tunnel sections in Phase 1 have been finished by September 2016 and currently track and utility
works are being carried inside and outside tunnels. Track geometry has to be checked. In some sections
it will be required to adjust track geometry in plan and profile despite the assumed 100 mm tunnel
construction tolerance bigger inaccuracy occurred in some places. For such sections new so called
wriggle alignment has to be developed.
Boring tunnels is done by TBMs (Tunnel Boring Machine) of EPB type (Earth Pressure Balance).
However this is a relatively slow process (about 13 m per day) this is very efficient method for big cities
active all the time. Metro tunnels in Doha are of 6170 mm internal diameter and thickness of tunnel
elements (tubings) is 330 mm. Tubings are placed in correct positions automatically by the machine just
after another section is bored. They have a protection layer from outside to protect tunnels against high
level of ground water and its high aggressiveness. Additionally, a fluid mixture of cement and other
additives is injected between tunnel and ground. In the bottom of tunnels C25/30 concrete layer is
constructed, so called first stage concrete. Then the matts of special anti-vibrating properties are laid on
the concrete. On the matts the concrete slab for the track is constructed. The whole compound is so
called mass-spring system. A proper stiffness required for the system is provided by the matts.
The new Guinness record in September 2015 was established in Doha there were 21 TBMs working
simultaneously on one project. Figures 5-6 show tunnel cross-sections.
5. Metro tunnel cross-section
6. Tunnel cross-section slab track detail
Special formulas have been developed to optimize track position within tunnels. It gives the horizontal
and vertical shift according to track cant value and position of emergency walkway. For the safety
reasons, both walkways are designed on inner side i.e. in the left tunnel the walkway is on the right side
and in the right tunnel it is on the left side. If the walkway is on the outer side of curve then formulas to
calculate horizontal shift SH and vertical shift SV are as follows:
SH = 85 0.75 ∙ C,
SV = 1675 + 0.75 ∙ C,
if it is in the inner side of the curve: SH = 85 + 0.75 ∙ C,
SV = 1675.
In the formulas above, C is cant in mm and shift is also measured in mm. It is easy to notice that on
straight section of tunnels a track axis is shifted by 85 mm horizontally and 1676 mm vertically from the
tunnel axis. Maximum applied cant is 100 mm and the horizontal shift for that value is 160 mm. It
means that load from track is situated non-centrically to the tunnel axis. It doesn’t cause any problems to
the tunnel performance.
Tunnels constructed by cut & cover methods are at places where track vertical profile is designed
shallow below the ground level. It is assumed that safe TBM tunnelling can be done only if there is
enough ground above the machine approximately one tunnel diameter. In cut & cover tunnels the slab
track lays on 0.6 m concrete layer via special self-compacting concrete thin layer. Prefabricated slab
track is equipped with anti-vibrating layer. Figure 7 shows a typical section of cut & cover structure.
7. Cut & cover structure cross-section
Connections between tunnels and at grade or viaduct sections are done as ramps (Figure 8) and troughs.
Track slab and additional layers are similar to cut & cover section. On concrete bottom slab of 1 m
depth it is another concrete layer laid and the track slab.
8. Concrete trough cross-section
Ramps (Figure 9) are constructed as parallel retaining walls filled with granular material compacted to
value 1.0. Top layer is 20 cm of cement stabilized sand. On that layer 35-40 cm of reinforced concrete
layer is laid and then the track slab is placed. It is very important that the layers between walls are
properly compacted. Top layer of stabilized ground should have Ev2 modulus of 120 MPa.
9. Ramp structure cross-section
Track components are also similar on elevated structures sections (Figure 10) but the slab is placed
directly on the viaduct structure. Standard span length is 32 m and the longest span constructed during
Phase 1 was 80 m long. There are plans in Phase 2 to build the other Gold Line partially in the median
of one of the main streets. This will require constructing four viaducts over two level road crossings 140
m long each.
10. Track on viaduct section
For the at-grade sections the slab track is placed on 35 cm deep concrete layer (Figure 11). The
protection layer is 50 cm thick and should be compacted to value 1.0 and the Ev2 modulus should be not
lower than 120 MPa. Ground subsoil should have compaction level minimum 0.95 and modulus 45
MPa. And for drainage reasons it should also be finished with 5% inclination away from track.
11. At-grade cross-section
Assumed designed speed is 80 km/h in tunnels and up to 100 km/h outside. Due to constraints caused by
existing infrastructure, both underground and overground, at some places the design speed couldn’t be
achieved. Short distances between stations, like in metro projects, also were a constraint in achieving
speed 100 km/h outside tunnels in some places. On a few sections the speed had to be lowered to 60
km/h. However it didn’t impact the commercial speed as most of restrictions were close to stations were
trains would go with lower speed anyway. Figure 12 shows a part of train performance analysis between
5 stations along Red Line. Average distance between stations is about 1.3 km and average running time
between stations is 90 s. Average speed (commercial speed) on the analysed section is 58 km/h,
including stations dwelling time of 30 s. The graph shows clearly that the design speed was chosen
properly and increasing it to 100 km/h wouldn’t bring almost any benefits.
12. Curvature and train permormance graph for a section of Red Line
Tram Network in Lusail (Lusail Light Rail Transit)
Writing about metro in Doha one shouldn’t forget about the tram network in Lusail, also under
construction. Both networks, however separate in terms of track connections, have a couple of common
station. The LLRT network is designed as 4 lines of total length about 30 km including 8 km of
underground sections. The tunnels are constructed as cut & cover structures. The stations are designed
in three configurations with island platforms, with side platforms and with shifted side platforms.
Totally, there are 31 stations, 8 stations are constructed underground. It is planned to expand the
network by another 11 km and 10-15 stations in the next phase. Trains will be powered by catenary
system in tunnels and from the third rail situated between running rails outside tunnels.
Because of crossings with roads at the same level and other existing restrictions, the design speed of 70
km/h had to be lowered along some sections. Expected commercial speed will be about 29 km/h.
Average travel time betweemn stations will be 1-2 min. It is expected that the network patronage will be
around 50000 passenger trips per day.
Lusail itself is the very interesting and impressing project too. It is a new city for 200000 people and is
being constructed north of Doha. It will have residential and commercial areas, offices, schools,
hospitals and shopping centres.
Long Distance Network
The planned long distance passenger-freight network will not only connect the capital with other cities
but also with other GCC (Gulf Cooperation Council) countries such as Saudi Arabia, Bahrain, Kuwait,
UAE and Oman. There are five main lines to be constructed: freight line from Mesaieed to Ras Laffan,
passenger-freight from Doha to Dukhan, Doha to As Shamal and Doha to Saudi Arabia, as well as
passenger high speed line from Doha to Bahrain through undersea tunnel.
Construction of these lines is also divided into phases. Phase 1 includes construction of 143 km double
track sections, over 30 turnouts in main tracks, one passenger station, three freight stations, one
intermodal station and about 100 structures (including 60 bridges). Additional 350 km of double track
lines is planned in the further phases. Big part of the line crossing metropolitan areas will be constructed
in tunnels drilled by TBMs of inner diameter of 9 m. The whole network will conform to the speed of
220-270 km/h for passenger trains and 120 km/h for freight trains. All the works will be divided into
four phases and should be finished by 2030.
Summary
In the last few years Qatar is developing rapidly, which is manifested by construction of modern
transport systems including railway networks. At the same time the scope of intense design and
construction works includes three different railway transport systems metro, trams and long distance
network. This article focuses on metro project and describes particular types of construction depending
on position of track along the terrain. As the majority of sections is constructed in either tunnels or on
viaducts and given Qatar’s nearly homogeneous geological conditions, challenges regarding trackbed do
not seem to be the crucial ones. However they should never be underestimated.
Source materials
[1] Qatar Railways Corporation own materials.
[2] Qatar Rail, Alignment Design Specifications Long Distance, Metro & LRT, 08/2016.
[3] Kretschmer M, Jantschke M. The Doha Metro Tunnelling in special dimensions. Tunnel, 05/2012.
[4] www.railabstudio.com/Railab_PL.pdf, 2015-08-30.
Railway transport in Qatar
The article presents the railway infrastructure projects currently carried out in the State of Qatar with
specific focus on the Doha Metro Project. The types of designed structures, such as viaducts and tunnels
with a closer look at the construction of the trackbed are described in more detail. The last past of the
article contains key information about both the Tram Network project in Lusail and the Long Distance
Lines for the passenger and freight trains.
Doha Metro; Qatar Railways; tunneling
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