A zigzag is a pattern made up of small corners at variable angles, though constant within the zigzag, tracing a path between two parallel lines; it can be described as both jagged and fairly regular.
From the point of view of symmetry, a regular zigzag can be generated from a simple motif like a line segment by repeated application of a glide reflection.
The origin of the word is unclear. Its first printed appearance was in French books in the late 17th century.
Examples of zigzags
Lightning and other electrical hazards are often depicted with a zigzag design, with long downward strokes and short backward ones.
A railwayzig zag, also called a switchback, is a method of climbing steep gradients with minimal need for tunnels and heavy earthworks. For a short distance (corresponding to the middle leg of the letter "Z"), the direction of travel is reversed, before the original direction is resumed.
A location on railways constructed by using a zig-zag alignment at which trains have to reverse direction in order to continue is a reversing station.
Advantages
Zig zags tend to be cheaper to construct because the grades required are discontinuous. Civil engineers can generally find a series of shorter segments going back and forth up the side of a hill more easily and with less grading than they can a continuous grade which has to contend with the larger scale geography of the hills to be surmounted.
Disadvantages
Zig zags suffer from a number of limitations:
The length of a train is limited to what will fit on the shortest stub track in the zig zag. The Lithgow Zig Zag stub was extended at great cost in 1908, only to be completely deviated in 1910.
Operation of the Zig Zag Railway was suspended in 2012 for an indefinite period, following accreditation issues with the New South Wales Government. The railway was aiming to resume services in October 2013, but was then severely damaged during the 2013 NSW Bushfires. There is currently no fixed timetable for reopening but estimates given for getting an engine back on the tracks range from six to 12 months from January 2015. It is hoped to restart in 2016.
History
Construction and abandonment
The Lithgow Zig Zag line was constructed as part of the Main Western line and opened on the 19 October 1869. Between Lithgow and Clarence, the Main Western line needed to climb the western flank of the Blue Mountains, overcoming a vertical distance of 550ft (170m). The alternative eventually decided upon required the use of two railway zig zags known as Top Points and Bottom Points, where all trains had to reverse. The line had a ruling grade of 1:42 (~2.38%) on three inclines known as the Top Road (above Top Points), Middle Road (between the two zig zags) and Bottom Road (below Bottom Points). The line included several short tunnels and some viaducts.
) Zig Zag Railway back on track with $3.6 million restoration ...The Blue Mountains' historic Zig Zag Railway is now back on track thanks to a $3.6 million restoration of its locomotive workshop ... Zig Zag Railway CEODaniel Zolfel said..
) Zig Zag Railway back on track with $3.6 million restoration ...The Blue Mountains' historic Zig Zag Railway is now back on track thanks to a $3.6 million restoration of its locomotive workshop ... Zig Zag Railway CEODaniel Zolfel said..
Lithgow’s historic Zig Zag Railway has had a bumper reopening with tickets selling out a month in advance for rides on its iconic heritage steam trains ....
SYDNEY, May 28 (Xinhua) -- The heritage-listed Zig Zag Railway in the Australian state of New South Wales (NSW) welcomed back steam enthusiasts on Saturday after local volunteers spent more than a decade refurbishing the track to its previous glory.
The historic Zig Zag Railway in the New South WalesBlue Mountains reopens to the public today after undergoing a full restoration. The first passenger trip in more than 10 years is sold out ....
The Zig Zag Railway has been closed since 2012 following multiple disasters. Today more than 900 visitors celebrated the return of the heritage-listed attraction ... .
The popular Zig Zag Railway in NSW's Blue Mountains is set to reopen just two weeks from now with a trial run along the seven-kilometre route through the Blue Mountains on Saturday – complete with a historic steam locomotive ....
A long-dormant scenic railway in Sydney’s Blue Mountains has got the safety seal of approval and been given permission to carry passengers for the first time in over a decade ....
He is known as the father of Chinese railways and the father of China’s modern engineering ... He designed and built a zig zag section to overcome the steep slope near Chinglongqiao RailwayStation.
Amidst great excitement in Darjeeling on Monday, a narrow-gauge railway line transported G-20 delegates in three vistadome coaches using a steam locomotive ... – To gain altitude, it uses six zig zags and five loops.
