Concrete sleeper

A concrete sleeper is a railroad tie made out of steel reinforced concrete.

History

In 1877, Joseph Monier, a French gardener, suggested that concrete reinforced with steel could be used for making ties for railway track. Monier designed a tie and obtained a patent for it, but it was not successful.

Concrete sleepers were first used on the Alford and Sutton Tramway in 1884. Their first use on a main line railway was by the Reading Company in America in 1896, as recorded by AREA Proceedings at the time.

Designs were further developed and the railways of Austria and Italy used the first concrete ties around the turn of the 20th century. This was closely followed by other European railways.

Major progress was not achieved until World War II, when the timbers used for ties were scarce due competition from other uses, such as mines.^[1] Following research carried out on French and other European railways, the modern pre-stressed concrete tie was developed. Heavier rail sections and long welded rails were also being installed, requiring higher-quality ties. These conditions spurred the development of concrete ties in France, Germany and Britain, where the technology was perfected.

Interest in concrete railroad ties increased after World War II following advances in the design, quality and production of pre-stressed concrete.

Types

Concrete sleepers can be of one piece of uniform dimensions, or of variable dimensions. Concrete sleepers can also consist of two separate blocks connected by a steel tie rod. Exceptionally, the concrete can be poured as two separate longitudinal slabs as has been used in Namibia.

Slab track consists of a continuous concrete roadbed without division into separate sleepers, and these are most often used in tunnels.

Austrak has developed a concrete Timber Replacement Sleeper that can be inter-dispersed with timber sleepers. These sleepers have a similar profile to the timber but have the benefits of concrete - especially when it comes to holding gauge.

Advantages

• Do not rot like timber sleepers.
• Extra weight makes track more stable, particularly with changes in temperature.
• Withstand fire hazards better than wooden sleepers.
• Longer life than wooden sleepers.
• Less maintenance means lower ongoing costs and less track closures.
• The date (or at least the 2-digit year) of manufacture is usually molded into the top surface.

Under Sleeper Pads

Concrete sleepers lack the elasticity of wooden sleepers and therefore ballast tracks with Concrete sleepers usually have a much quicker degradation of the ballast when loaded. This is especially true in bends and turnouts/swithces. To reduce the wear on the ballast and in some cases offer vibration isolation pads are fitted to the base of the sleeper. The pads are usually manufactured of poluretahane foams with a stiffness tailored to meet the elasticity requirements of the track.

To reduce the wear of the ballast only, the best material to use is a very stiff semi-plastic polyurethane foam which mimics the plastic behaviour of wooden sleepers (the ballast stones are pressed into the surface of the sleeper, increasing contact area) typically these pads are 7–10 mm thick.

In order to achieve vibration isolation as well the elastic layer needs to be softer and in many cases thicker as well. A vibration isolation of 5-12 dB can be achieved, but the results will depend on many factors such as axle load, velocity, subsoil stiffness, ballast thickness, ballast quality and more. Therefore it is very difficult to predict the results exactly.

Disadvantages

• When trains derail and the wheels hit the sleepers, timber sleepers tend to absorb the blow and remain intact, while concrete sleepers tend to shatter and have to be replaced.
• Concrete sleepers are heavier and need stronger people and even special tools to carry them.
• Gives more retentivity to the track.
• Cost more, especially initial cost.
• Unsuitable for change of gauge, unless this is already taken into account.
• Concrete turnout sleepers may take too much time to make, so use timber if in a hurry.

Alternatives

Sleepers made of recycled plastics, which are less brittle than concrete, where reported to be under development in 2007.^[2] Fibre glass is also an option.

Characteristics

Gauge and weight

• 1,680 mm (5 ft 6 ⁵⁄₃₂ in) - 300 kg

Axleload

• Fortescue - 40t^[3]

Sharp curves

• Special sleepers may be necessary on extremely sharp curves, such as the new triangle at Newmarket, New Zealand on the 1,067 mm (3 ft 6 in) gauge of radius 95 m (312 ft). Here the sleepers are extra heavy, about 250 kg, and may include gauge widening with transitional gauge widening.^[4]

Guard Rails

• Special measures are needed to support guard rails.

Manufacture

Concrete sleepers are made upside down in moulds, several sleepers long. Pandrol clip bases or other fittings are inserted into the moulds. Pretensiled steel wire are installed in these moulds, and then the concrete is poured. It takes several days for the concrete to cure, after which the sleepers are removed from the moulds and cut into individual sleepers. The bottom of the mould is marked with the logo of the manufacturer and a datestamp.

Occasionally sleepers are made with conduits for track circuit wiring, or extra fixtures for guard rails.

Sleepers can be made using a Long Line method or a Short Line method; each method has its advantages and disadvantages.

Ingredients and components

• Portland cement made into suitable concrete.
• Steel wire usually galvanised, and pre-tensioned.
• Railclips such as Pandrol.

Transport

When transported in small piles, pieces of timber are interposed between the layers of concrete sleepers.

Installation

The sleepers are laid either using manual methods or using various sleeper laying machines.

Oldest

• 

The 597 mm (1 ft 11 ¹⁄₂ in) gauge Lynton and Barnstaple Railway (1898 to 1935) in North Devon, experimented with concrete sleepers at a number of locations along the line. Currently unknown why experiment was not continued.

Some concrete sleepers can now be seen on display at Woody Bay Station www.lynton-rail.co.uk

Chaired bullhead concrete sleepers have been around since at least the 1950s.^[5]

Turnouts

Concrete sleepers for turnouts are much longer than normal sleepers, have gaps for switch motors, have sleepers individually designed, and are generally made by a small number of specialist manufactures. If a turnout is needed in a hurry, it may be made with timber sleepers which can simply be drilled to suit.

Problems

German rails have experienced cracking of their sleepers on high speed lines.^[6]

Examples

Pakistan

• Line: Karachi - Lahore main line.
• Gauge: 1676 mm gauge.
• Cost per km: Rs33·85m
• Rail: UIC-54 rails
• Number per km: 1,640
• Fastenings: Vossloh

United states

On November 8, 2011, the US Federal Railroad Administration (FRA) put into effect new regulations on concrete ties, with notices published by the FRA in the April 1 and September 9, 2011 U. S. Federal Register. The FRA notices say that the need for the new rules was shown by the derailment of an Amtrak train near Home Valley, Washington on April 3, 2005, which according to the U.S. National Transportation Safety Board was caused in part by excessive concrete tie abrasion. To be counted as a good tie under FRA regulation 213.109(d)(4), a concrete ties shall not be deteriorated or abraded under the rail to a depth of one-half inch or more. Limits on other types of concrete tie deterioration are also given.

List of plants

Angola

(Three plants needed)

• North - Bengo Province
• Centre - Liangongo - Benguela
• South - Caraculo^[7]
• South - Namialo - concrete sleeper plant. ^[8]

Australia

(clockwise)

• Townsville Austrak - 1067 mm - defunct^[9]
• Mackay Austrak - 1067 mm - defunct^[9]
• Rockhampton Austrak - 1067 mm^[9]
• 610 mm are also made for cane tramways.
• Mittagong - 1435 mm
• Taree - 1435 mm
• Denman - 1435 mm
• Mittagong^[10]
• Grafton^[10]
• Wagga Wagga (Bomen) Austrak - 1435 mm
• Geelong (Avalon) Austrak - 1435 mm & 1600 mm
• Port Hedland Austrak - 1435 mm
• Wedgefield Austrak - 610 mm, 1067 mm, 1435 mm^[11]
• Wickham - 1435 mm
• Katherine Austrak - 1435 mm - defunct^[9]
• Tennant Creek Austrak - 1435 mm - defunct^[9]
• Austrak - Australia's largest manufacturer of concrete railway sleepers^[12]

Azerbaijan

• Sleeper Factory Baku ^[13]

Bangladesh

• Chhatak^[14]

Botswana

• Gaborone - Kwena Concrete Works^[15]

Bulgaria

• Svishtov ^[16]

China

• China United Railway Logistics^[17]

Congo-Kinshasa

• Due 2012 ^[18]

Ethiopia

• Dire Dawa - 1000 mm^[19][20]

Germany

• 1435 mm^[21]
• DW Schwellen Güsen sleeper production plant - see http://www.thosti.com.de/guesen-sleeper-production-plant.html and http://dw-schwellen.de/unternehmen/werke/guesen/index.html
• DW Schwellen Neuss sleeper production plant - see http://dw-schwellen.de/unternehmen/werke/neuss/index.html
• DW Schwellen Augsburg sleeper production plant - see http://dw-schwellen.de/unternehmen/werke/augsburg/index.html

Ghana

• Huni Valley - 1435 mm/1067 mm dual gauge (?)^[22]
• Number: 2 m
• Cost: Euro 85m
• Cost each: Euro 42.5 per sleeper.
• Cost of plant: Euro 7
• Jobs: 130
• Output: 400,000 per annum
• Output: 1096 per day (about 0.5 km of track).
• Makers: Kampac and Rail.One
• Gauge: possibly dual gauge 1435 mm/1067 mm

Greece

• Sleeper Factory Trikala - Strotires ^[23]

India

• ^[24] First use in 1977^[25]
• Hindustan Prefab Limited^[26]
• PCM Group - 3 plants - first in 1991^[27]
• Patil Group - 8 plants - first in 1971^[28]
• Nandgaon, Maharashtra
• Madhepura^[29]
• Kathua^[30]
• Vishal Nirmiti^[31]

Iraq

• Abu Ghraib^[24]

Kenya

• 2005 - proposed^[32][33]

Korea, North

• Rahung^[34]

Korea, South

• Pusan^[35]

Libya

• Khoms^[36] by Walterbau,^[37] Germany.
• Ra's Lanuf - for Russian contract

Malawi

• plant supplied earlier by same maker as plant for Mozambique (Nacala). ^[38]

Malaysia

• Malaysia - 1000 mm - proposed^[9]

Mozambique

• Namialo for northern line of Caminhos de ferro do Moçambique (CFM) of Nacala to the Malawian border. ^{[39] [40]}
• Dondo^[41]
• Sena - 600 per day

Namibia

• Tsumeb^[42][43]

New Zealand

• Te Rapa, Hamilton, North Island ^[44]

Poland

• Goczalkow sleeper production plant ^[45]

Romania

• Metabet
• Dunapref -Blejoi ^[46]
• Dunapref -Giurgiu ^[46]

Russia

• Viazma^[47]

Saudi Arabia

• Ha'il - Transport in Saudi Arabia 32.5T axleload - 1435 mm^[48]
• Rail. one^[49]
• PCM Strescon Overseas Ventures Ltd, Manufacturers of Heavy Haul Concrete Sleepers with capacity of 100,000 sleepers a month^[50]
• Hofuf sleeper production plant ^[51]

Sierra Leone

• Racegroup^[52]

South Africa

• Infraset^[53][54]

Sudan

• Sudan - north Khartoum, producing 1,200 concrete sleepers a day.^[55][56] by Shanghai Hui Bo Investment Co (SHIC) ^[57]
• Cost of factory - $5m^[55]

Switzerland

• Tribeton^[58]

Syria

• Sleeper Factory Homs ^[59]

Tanzania

• Tanzania called tenders in 2008 for sleeper plant.

Thailand

• Wihan Daeng in Saraburi Province^[60]

Turkey

• Sleeper Factory Denizli ^[61]

United Kingdom

• Trackwork Moll Ltd. ^[62]

Damaged or obsolete sleepers

Damaged concrete sleepers cannot be repaired. Old concrete sleepers can be used for things like retaining walls, else they might be crushed to recycle gravel and the steel reinforcing. ^[63]

Inventors

• 1877 Joseph Monier, France
• 1912 Bonnet (diagram)^[64]

• 1929 Stent^[65]

• Timms

See also

• Sleeper
• Ladder track - longitudinal sleepers
• Tubular Modular Track
• Bi Block sleepers^[66]
• Cement in Africa
• Ballast

References

Concrete sleeper research URL http://ro.uow.edu.au/

External links

Media related to Concrete sleeper at Wikimedia Commons

• Concrete Sleeper Manufacturers Association
• ARTC