Advantages of broad gauge The Broad Gauge Society was formed in 1980, to promote research into the 7ft 0¼in gauge railways of Britain in the 19th Century. It also requires less land width. 08. Countries like India, Russia, and Argentina use broad gauge extensively. Why does this difference in railway Jan 8, 2024 · As of December 2023, the electrification effort has covered a total of 61,508 Route Kilometers, representing 93. Advantages of the New Gauge. It explains that there are three main gauges used: broad gauge (1676 mm), meter gauge (1000 mm), and narrow gauge (762 mm and 610 mm). This happened when the broad gauge 'Bristol and Gloucester Railway' entered Gloucester to terminate at a temporary station made by adding a platform to the north side of the narrow gauge Birmingham and Gloucester Railway terminus. Which of the following is/are advantages of the Uni-gauge system? Hard. Broad and narrow gauge rails first met at Gloucester in 1844. Nov 16, 2020 · Recent Developments and Future Prospects of Manufacturing of Broad Gauge Railway Sleepers Using Waste Materials in India composite sleepers have prominent advantages in performance design and The Great Western Railway had gradually come to dominate Cornwall’s railway network but during the final decade of the 19th century the ‘Battle of the Gauges’ was won by the standard gauge. Out of all gauges near 5 ft already in use, George Stephenson chose 4'8½" for the Liverpool and Manchester Railway and many other railway projects in Europe were modelled on that. [8] [9] In Australia, where the states of Victoria and South Australia have this gauge (as did Tasmania in the 19th century), it is known as broad gauge. b) Metre/Meter Gauge (M. 676m, the gauge is called broad gauge. Almost since the beginning of the hobby 'O' gauge has been a popular gauge to work in. This width is greater than the standard gauge (1,435 mm). a. The diameter of the wheels is 1524 mm and the flanges project 32 mm below the top of rail. Rapid transit lines are mostly on standard gauge, although some initial lines use 1,676 mm (5 ft 6 in) broad gauge. However, at Didcot Railway Centre the Great Western Society has recreated a section of broad gauge railway using materials recovered from a disused railway near Burlescombe in Devon together with the relocated Didcot Transfer Shed built in the 1850s to trans-ship goods between broad and standard gauge trains. 001 mm or 0. Solve any question of Life Lines of National Economy with:-Patterns of problems > [5] [6] [7] In Ireland it is also common to hear it referred to as standard gauge or broad gauge when distinguishing it from the various 3 ft narrow-gauge railways of the island. imo the advantages of standard gauge have been vastly overstated. Efforts are being made to convert non-broad gauge lines to broad gauge. Higher CCEA has approved electrification of remaining unelectrified broad gauge (BG) routes of Indian Railways Upon completion of electrification of the proposed routes, Indian Railways broad gauge network will be 100% operational on electric traction Significant benefits in the areas of Safety, Capacity, Speed, Energy Security & Sustainability Mixed gauge track - which used three rails to accommodate both broad and narrow gauge trains as depicted in the photo of Taplow station - was initially laid on baulk timbers; but this gave way to the use of cross sleepers, which was said to need less timber than the equivalent baulk road. R. Electrification offers benefits like: Reduced operating cost. About the Broad Gauge Society. This gauge is, therefore, used for Broad gauge, also known as wide gauge, is a track width in rail traffic that is wider than standard gauge. The broad gauge railway line on the west coast is known as the Home » advantages of broad gauge advantages of broad gauge. As of 2015, only a few out of more than sixty tram systems in Russia are not broad gauge: 1,000 mm in Kaliningrad and Pyatigorsk, 1,435 mm (4 ft 8 + 1 ⁄ 2 in) in Rostov-on-Don. In Indian railway, the following gauges are used: a) Standard Gauge or Broad Gauge – Gauge width 1. The Society has an database of images, some 2,000 photographs and drawings of broad gauge subjects, which can be found in hundreds of publications and archives. Advantages: Lower • Wide measurement range: Ultrasonic gauges are available for measurement ranges as broad as 0. Some lines, like the Nilgiri Mountain Railway, remain operational due to their heritage status. Subject: Science and tech. Let’s start with broad gauge. What were the advantages of broad gauge? What would the implications have been if broad gauge had been chosen for nationwide use and the 4 ft 8½ in abandoned? Apr 9, 2023 · Broad Gauge. The locos had a top speed of some 80 mph. , from London to Maidenhead on the Thames, opened on 4th June 1838. Section: MSc. 672 m. View solution > 4. The uni-gauge system will be highly beneficial to rail users, the railway administration, as well as Aug 9, 2023 · As on 01. The perceived difficulties in safely integrating Standard-Gauge and Broad-Gauge infrastructure at anything other than low speeds, has resulted in a dichotomy of the two gauges, where integration is seen as a lesser option than a choice of either single gauge. Wiki User ∙ 10 y ago Broad and narrow conflicts. A broad-gauge railway is a railway with a track gauge (the distance between the rails) broader than the 1,435 mm (4 ft 8 + 1 ⁄ 2 in) used by standard-gauge railways. Jan 17, 2025 · Breaking railway gauge, or changing the width between the rails, can offer advantages such as improved safety by preventing incompatible trains from entering a section of track, and facilitating the use of specialized equipment or rolling stock on specific lines. To sum up, the PPG thickness gauge has the advantages of high precision, fast measurement speed, wide range, clear display, strong durability, etc. 435 meters) over the usual broad gauge (B G) of 5 feet 6 inches (1. . This led to all the broad-gauge lines being converted to standard-gauge with the last trains to be run on broad-gauge running on 20th May 1892. Resolution can be as fine as 0. 2015 Social Sciences Secondary School 29 votes, 17 comments. The different gauges can broadly be divided into the following four categories: Broad Gauge, Standard Gauge, Metre Gauge, Narrow Gauge. Broad Gauge: A broad-gauge is also known as a wide gauge or large line. true. The definition and characteristics of broad gauge tracks, as well as their advantages, disadvantages, and variations in track width, are discussed in this section. 02/12/2021 Nov 28, 2024 · Projects like “Mission 100%” aim to convert all railways in India to broad gauge by eliminating narrow and metre gauge tracks. Another negative is that almost always the loading gauge is wider than smaller rail gauges, so it needs bigger stations, tunnels, bridges, etc. It is also called the India gauge. The first completed section of the G. 08 mm (0. 7 Km/day during 2023-24. 762 meters. However, when DMRC attempted Nov 29, 2024 · Indian Railways is advancing rapidly in electrifying its Broad Gauge railway lines. Railway Electrification offers benefits like: Reduced operating cost. Train 18). This enabled the Erie to carry wider and larger items than it's standard-gauge competitors, but made it difficult to interchange with them. The perceived benefits of a common gauge for freight logistics have seen an increase Hopefully this web-site will help you glimpse some aspects of the Broad Gauge railway, its history and operation, - along with the activities of the 'Broad Gauge Society', formed to research, archive, model, and sometimes to re-create this amazing railway. But on that same country, there are broad gauge high speed rail at up to 300kmh, and works with no issue. com Broad gauge are a type of railway track with a wider distance between the rails compared to standard gauge and narrow gauge tracks. The advantages of broad gauge relate to heavier loads and higher speeds. It is theoretically easier to procure rolling stock internationally, but manufacturers can change the train's gauge much easier than cities can change their track. The Society is the only known group that is entirely dedicated to Brunel ‘s broad gauge. Sep 20, 2023 · Project Uni gauge seeks to standardize the rail gauges in India by converting most of the Meter gauge and Narrow Gauge tracks to Broad Gauge track. 435 meters. The 'battle of the gauges' was to be temporarily resolved by laying a third rail inside the broad gauge tracks from lines running on the standard gauge. , and it can't run on standard gauge dual track because the station platforms would hit the sides of the train. Broad Gauge The countries using the Broad Gauge are India, Pakistan, Bangladesh, SriLanka, Brazil, Argentine, etc. Until 2014, 21,801 KM of broad gauge network was electrified. 83% of the total Broad Gauge route (65,556 RKMs) in the Indian Railways network. If you have not worked to such fine measurements before, do not worry - all the critical dimensions for wheels and rails van be set using gauges available from the Broad Gauge Society. This means that waveform setup is instantaneous and fully automatic. [10]: 168 [11] Oct 4, 2020 · There are mainly four types of railway gauge used in India, which are: Broad gauge, Narrow gauge, Standard gauge (for Delhi Metro), and Meter Gauge. . Why is the Conversion to Broad Gauge Important? Converting tracks to broad gauge has several advantages: Increased Speed and Safety: Broad gauge tracks enable faster trains with better safety features. Broad gauge of 1,520 mm ( 4 ft 11 + 27 ⁄ 32 in ) , more known as Russian gauge , is the dominant track gauge in former Soviet Union countries ( Jan 8, 2024 · Total Broad Gauge (BG) network of 61,508 Route Kms have been electrified upto December ’2023 which is 93. Project Uni- gauge seeks to standardize the rail gauges in India by converting most of the Metre Gauge and Narrow Gauge tracks to Broad Gauge track. Small stretches of the network that remain on metre and narrow gauges are also being converted to broad gauge. ) maximum, depending on material and transducer selection. The distance between the two tracks in these railway gauges is 5 ft 6 in (1676 mm). Annual field trip to location with a broad gauge relevance Nov 27, 2024 · Indian Railways (IR) has taken up electrification of Broad Gauge (BG) Railway lines in a Mission mode. As the name suggests, the narrow-gauge railway is essentially distinguished by a smaller gauge width of just 750 mm. ) minimum to 635 mm (25 in. Jan 11, 2025 · In fact the only advantages I can think of are low marginal benefit low-floor width you've mentioned, and the ability to share equipment with other similarly gauged systems, and as others have mentioned it's probably better for Cincinatti to be able to share with the larger standard gauge world than for them to share with broad gauge Pittsburgh Tender For Construction Of New Broad Gauge Line Track Between Sindhanur Excl 84820 And Hirekotangal Incl 115500 30 68 Km Under Ginigera Gin Raichur Rc New Line Project 165 57 Km In. Oct 14, 2020 · There are 3 major types of gauges in railway. TDR : 36927689 Aug 28, 2024 · For instance, NDC’s ultrasonic gauge (BETA LaserMike) UltraScan Pro can measure a broad product range to meet the majority of wall thickness measurement requirements. Gooch set out to design a much larger loco that would demonstrate to Parliament the advantages of broad gauge. The coaches were massively wide and tall. This rail gauge is used in flat terrains and heavily populated areas with heavy traffic. 676 metres. The narrower gauge enables tighter curves to be taken, especially in valleys and in generally difficult Most of the metre gauge and narrow gauge railways have been converted to broad gauge. Broad widths have a distance of 1676 mm, and their operating speed is high. The G. Bid Submission date : 19-07-2023. The broad gauges that had appeared in many places were gradually scrapped because interoperability was more important than the additional cargo. Nov 20, 2024 · Broad Gauge . South Asia primarily uses the broad gauge for its passenger rail services and the fastest broad-gauge train presently in the region is the Indian Railways' Vande Bharat Express (a. , raichur, Karnataka Tenders. 724 m of a vehicle moving on a broad gauge(B. Broad gauge: 1. When the clear horizontal distance between the inner faces of two parallel rails forming a track is 1. Although the last main-line 'Broad Gauge' trains ran in May 1892, that is no reason to assume that interest in this period, or railway, has faded away. In 1848 the loco ‘Great ritain’ ran between Paddington and Didcot averaging 67 mph. 02. The distance between the rails is 1. Please explore . Sleeper number on the track can be specified by the sleeper number per kilometre of the track. ব্রডগেজ মিটারগেজ ডুয়েলগেজ ও In 1845, four years after the GWR was completed, a Gauge Commission was created to report on whether all railways should be built to "one uniform gauge". c) Narrow Gauge (N. Indian Railways therefore took the bold decision in 1992 of getting rid of the multi-gauge system and following the uni- gauge policy of adopting the broad gauge (1 676 mm) uniformly. G) – Gauge width 1. Newsletter issued six times a year. Many tramway networks initially built to narrow gauges (750 mm or 2 ft 5 + 1 ⁄ 2 in or 1,000 mm or 3 ft 3 + 3 ⁄ 8 in metre gauge) were converted to broad gauge. Dipayan Dipayan 05. The sleeper density in India is 18, whileas, in the USA, Sleeper Density is 23-25. Magazine, ‘Broadsheet’, issued twice per year. Types of Gauges in India. 676 m. (ii) When the prospects of revenue are very bright. [5] [6] [7] In Ireland it is also common to hear it referred to as standard gauge or broad gauge when distinguishing it from the various 3 ft narrow-gauge railways of the island. Nov 27, 2021 · The wheelbase is 4. Its wider track permits the use of larger equipment, and that means more freight or passengers can be carried. Narrow gauge: 0. The gauge is equipped with “Snap Technology” for automated ultrasonic waveform setup. Project Uni gauge seeks to standardize the rail Nov 19, 2024 · Each gauge is tested and calibrated for accuracy, durability, and ease of use, delivering real-time data with high reliability. Benefits of Membership Specialist society relating to broad gauge railways in the UK. Project Uni gauge seeks to standardize the rail The different gauges can broadly be divided into the following four categories: Broad Gauge, Standard Gauge, Metre Gauge, Narrow Gauge. 393 Advantages Disadvantages of Broad Gauge jobs available on Indeed. I'm guessing the reason for india to use standard gauge, was to reduce costs. Their performance was incredible for the mid-19th century. It has broad application prospects and market demand, and has been widely used in manufacturing and other fields Sep 24, 2023 · The standard gauge railway line allows for increased capacity for standard gauge railway line through the addition of an extra track on the current line. Jul 6, 2023 · If the sleeper density is M+ 7, and the length of the broad gauge rail is 13 m, it infers that there are 20 sleepers per rail length. The advantages of narrow gauge are the opposite of these two disadvantages: cheaper lines, and tighter curves are possible. The broad gauge network was eventually converted—a progressive process completed in 1892 A broad-gauge railway is a railway with a track gauge (the distance between the rails) broader than the 1,435 mm (4 ft 8 + 1 ⁄ 2 in) used by standard-gauge railways. Complete load data anthology and shotshell encyclopedia. Brunel however, stated that he would consider an even wider gauge if he was starting again. W. (S G) of 4 feet 8 and half inches (1. only completed its full conversion to standard gauge in 1892. It is a fact that Standard Gauge provides a safer, speedier and more comfortable system for which well-developed and proven technologies are available. Electrification Milestones. 003 in. Feb 4, 2022 · Broad Gauge. Sep 10, 2024 · Meter gauge refers to railway tracks with a distance of 1,000 mm (3 ft 3 3/8 in) between the rails. advantages of broad gauge. Aug 29, 2019 · George Stephenson originally used 4 ft 8 in so where did 4 ft 8½ in come from? IKB favoured broad gauge, initially 7 ft and then 7ft ¼ in. This gives it a number of advantages over railways with normal gauges (1435 mm). The distance between the two tracks in these railway gauges is 1676 mm (5 ft 6 in). Tender Amount : 6317659793. During one of the trial runs, the Vande Bharat Express achieved a peak speed of 180 km/h (110 mph). Haulage of heavier freight trains and longer passenger trains due to higher haulage capacity of Electric Locomotives; leading to increased throughput. Broad gauge is also called wide gauge or large line. Thus, where lines will carry a lot of traffic, and tight curves aren't required, broad gauge is a technically better choice. Since 2014-15, Indian Railways has completed electrification of about 45,200 Route Km on Broad gauge (BG) network. It would not be wrong to say that any gauge Project Uni gauge is an ongoing exercise by Indian Railways to standardize most of the rail gauges in India at 1676 mm (5 ft 6 in) broad gauge. Calculate the extra wide of gauge required by using rule 1 and 2, where the radius of the curve is 165 m. com. Broad gauge tracks are wider than the standard gauge, with common sizes including 1,524 mm (5 feet), 1,600 mm (5 feet, 3 inches), and 1,676 mm (5 feet, 6 inches). 2023, total 59,524 km length of Broad Gauge (BG) rail line has been electrified. Broad gauge. Historically 'O' gauge referred to a track gauge of 11⁄4" or 32mm but is now almost universally taken to mean mod-els built to a scale of 7mm to the foot or 1:43. Which type of gauge is used in hilly areas? (From a drivers perspective) The issues of difference between Standard and Broad gauge is virtually nonexistent apart from a few select locations where they interact, one in particular being the North Melbourne flyover and into Southern Cross, but it is more of an issue due to the change of who owns/controls the lines. 676 meters) available on Indian Railways. Around 60% of the world uses the standard 1,435mm gauge today while the other 40% uses either a narrow or a broad gauge. It handles 85% of the total goods traffic in tones-km. 676 metres, the rapid rail transport system in Delhi, the high-speed rail line between Mumbai and Ahmedabad In 1845 a Royal Commission on Railway Gauges was created to look into the growing problem, and this led to the Regulating the Gauge of Railways Act 1846, [13] which forbade the construction of broad gauge lines unconnected with the broad gauge network. ADVANTAGES. 435 m width. Advantages of broad gauge include better stability, higher speed potential, and greater load Sep 22, 2018 · The distance between the inner faces of a pair of wheels is called the wheel gauge. Context: While the predominant railway network in India is Broad Gauge (BG) with a width of 1. Oct 9, 2023 · Rail Gauge Debate. Speed: The broad gauge metro will be capable of operating at a higher speed, with the potential for even higher speeds based on its design capabilities. There is substantial jump in electrification from about 1. But what it's ussually prefered is legacy compatibility. Prototype can be of Standard, Broad or any of the narrow The Nazis had plans for a broad gauge railway, with almost 10' track gauge. 54, usually rounded off to 1:43. 42 Km/day during 2004-14 to about 19. Project Uni gauge is an ongoing exercise by Indian Railways to standardize most of the rail gauges in India at 1676 mm (5 ft 6 in) broad gauge. Oct 9, 2023 · News: This article discusses the advantages and disadvantages of the Broad-Gauge railway network vis-à-vis the Standard Gauge railway network. Complete answer: Indian Railways' Project Unigauge is an ongoing effort to standardise most of the country's rail gauges to 1676 mm (5 ft 6 in) wide gauge. Historical Significance: Introduced to reduce construction costs. G). Mixed gauge track - which used three rails to accommodate both broad and narrow gauge trains as depicted in the photo of Taplow station - was initially laid on baulk timbers; but this gave way to the use of cross sleepers, which was said to need less timber than the equivalent baulk road. In 2024, approximately 97% of the network is electrified, which was shared by Union Minister Ashwini Vaishnaw in a Lok Sabha response. 5. 0001 in. 000 m. 676 meters, the rapid rail transport system in Delhi, the high speed rail line between Mumbai and Ahmedabad, and more than a score of metro rail systems in parts of the country are coming up on Standard Gauge (SG) of 1. What is the current status of railway gauge in India? The predominant railway network in India is Broad Gauge (BG) with a width of 1. Suitability of Broad Gauge: Broad gauge is suitable under the following conditions The different gauges can broadly be divided into the following four categories: Broad Gauge: width 1676 mm to 1524 mm or 5’6” to 5’0” Standard Gauge: width 1435 mm and 1451 mm or 4’-8⅟2” Metre Gauge: width 1067 mm, 1000 mm and 915 mm or 3’-6”, 3’-33/8” and 3’-0” Narrow Gauge: width 762 mm and 610 mm or 2’-6” and 2 Standard Gauge or Broad Gauge? Revisiting the Metro Rail Debate The decision to choose the standard gauge for metro systems in Mumbai, Bangalore and Hyderabad, despite many disadvantages, has to be reviewed, given the needfor integration of the new lines with the existing rail networks. Current Status: Most meter gauge lines are being converted to broad gauge under the Project Unigauge initiative. Difference between Broad Gauge Metro and Standard Metro System Download scientific diagram | Advantages and disadvantage of alternative standard-gauge options from publication: Quantifying the Economic Benefits of changing the Gauteng to Durban Railway Nov 19, 2024 · Each gauge is tested and calibrated for accuracy, durability, and ease of use, delivering real-time data with high reliability. Broad gauge of 1,520 mm (4 ft 11 + 27 ⁄ 32 in), more known as Russian gauge, is the dominant track gauge in former Soviet Union countries (CIS states, Baltic states, Georgia, Ukraine) and Mongolia. k. Jul 24, 2003 · In spite of the argued advantages of larger-gauged trains, the bitter reality is that no one has yet to propose any independent system (aside from operations like BART) where the advantages of “broad-gauge” would overrule the practical advantages of “off-the-shelf” technology in stock and mass production. (From a drivers perspective) The issues of difference between Standard and Broad gauge is virtually nonexistent apart from a few select locations where they interact, one in particular being the North Melbourne flyover and into Southern Cross, but it is more of an issue due to the change of who owns/controls the lines. The narrow-gauge railway proves its worth. M RAVIBABU ased on the Delhi Metro Rail Corporation's May 5, 2020 · For a broad gauge to be worth it, it would need to be substantially wider, say like the old GW 7ft gauge, with a substantially bigger structure gauge to match. G) – Gauge width 0. Dec 22, 2024 · Track Width: The broad gauge track measures 1,676 mm (5 ft 6 in). So you could get 4 containers on a wagon, 2 wide and 2 high. [13] This video contains detailed and simple concept of Railway, Bridges and Tunnels RBT as per HSBTE syllabus under NITTTRRailway Bridges and tunnels RBT - lectu Dec 6, 2024 · He was wrong. Project Uni-gauge is an ongoing exercise by Indian Railways to standardize most of the rail gauges in India at 1676 mm (5 ft 6 in) broad gauge. Broad gauge connects major ports with interior towns and industrial centres. Metre gauge: 1 meter. 1) Indian Railways have become more Broad Gauge: Almost all major rail routes are broad gauge routes. The rails were laid in concrete, so didn't have ties in the traditional sense. It would not be wrong to say that any gauge Feb 5, 2015 · What are the advantages of unigauge? (Answer in points) - 78841. The Gauge The line at Dawlish was originally laid as "Broad Gauge" where the distance between the tracks was 7ft ¼ inch instead of "Standard Gauge" at 4ft 8 ½ inch which was standard in most other parts of the country and the world. 676 meters. [13] Jun 14, 2021 · Whereas in Broad Gauge, trains would be able to operate only upto speeds of 160 kmph in India, though with a slightly better speed in some other railways. [10]: 168 [11] May 1, 2018 · This document discusses railway track gauges used in India. 2. While the standard gauge in Germany has a width of 1,435 millimetres, broad gauges are generally wider and vary depending on the region and country. Even the Chinese are willing to build broad gauge trains, specifically for the Sri Lankan market. You also need wider curves than narrower gauges. In some places, the broad gauge is considered the standard rail gauge. Our digital gauges come equipped with features like data logging, intrinsically safe designs, and broad measurement ranges to meet diverse application needs. Jan 8, 2024 · Total Broad Gauge (BG) network of 61,508 Route Kms have been electrified upto December ’2023 which is 93. 83 % of total Broad Gauge route (65,556 RKMs) of Indian Railways. from broad gauge to narrow gauge "The Erie was built as a broad-gauge line, having 6 feet between the rail as opposed to the standard 4 feet 8 1/2 inches. 5 Benefits of Adopting BG (1 676 mm) as the Uniform Gauge. That's why in Spain most high speed lines are standard rather than iberian (broad) gauge. Apply to Boilermaker, Quality Assurance Analyst, Fitter and more! May 23, 2024 · Lines in some parts of Australia were built to 63-inch (160-cm) gauge and later converted to standard, but broad gauge tracks theoretically offer significant advantages to railroads and to customers. Broad gauge; Metre gauge; Narrow gauge; I will tell you more details about each of them in the upcoming sections. However, specific projects, such as the rapid rail transport in Delhi, the high-speed line between Mumbai and Ahmedabad, and several metro rail systems in different parts of the country, are adopting Standard Gauge (SG) with a width of 1. Virtually every transit agency in the US (and Europe) has some type of nonstandard equipment already, and a broad gauge doesn't add too much complexity to equipment overall (in fact it's possible to convert trains between gauges in overhaul shops). Several witnesses to the Commission thought that a gauge somewhere between the two gauges would be best. Oct 9, 2023 · In India, the primary railway network operates on Broad Gauge (BG), with a width of 1. advantages of broad gauge Nov 28, 2024 · Indian Railways nears 97% electrification of broad gauge network, 45,200 km route electrified since 2014 Vaishnaw highlighted that around 45,200 route kilometers of the Broad Gauge network have Oct 8, 2023 · While the predominant railway network in India is Broad Gauge (BG) with a width of 1. Since the fiscal year 2014-15, around 45,200 kilometres of Broad Gauge tracks have been electrified. Suitability: Broad gauge is suitable under the following conditions: (i) When sufficient funds are available for the railway project. See full list on cargo-partner. jmc feo oldxeo zlktby oyhiok swhae xnyvz kfhz ppky ydhlk jmiazckc qim joadzvg drxjcq zhqrw