London to Aylesbury Line

The London to Aylesbury Line is the main railway line between London (Marylebone) and Aylesbury, going via the Chiltern Hills; it is operated by Chiltern Railways. The line is unique in the UK railway network for being the only route where National Rail trains use track owned by London Underground (LUL). This section is approximately 20 miles (the total mileage of the passenger section of the line is about 39 miles, meaning over 50% of the line is owned by LUL) between Harrow on the Hill and Mantles Wood, just north of Amersham.

The line operates modified timetables during autumn, as a result of the heavily wooded section between Amersham and Rickmansworth. Trains need to take more time to brake due to the amount of leaves fallen on the line. [ [http://www.chilternrailways.co.uk/news/press-releases/new-train-simulator-helps-drivers-deal/ New train simulator helps drivers deal with autumn leaf fall] - Chiltern Railways]

The line is part of the former trunk route, the Great Central Main Line.

History

The route towards Aylesbury opened in stages between 1868 and 1899:
# The Metropolitan & St. John’s Wood Railway (later the Metropolitan Railway) opened a branch from Baker Street to Swiss Cottage in 1868.
# The Aylesbury & Buckingham Railway connected Verney Junction with Aylesbury in 1868. The route would become part of the Met in 1891.
# In 1879 the Met was extended from Swiss Cottage to Willesden Green.
# In 1880 to Harrow.
# In 1885 to Pinner.
# In 1887 to Rickmansworth.
# In 1889 to Chesham.
# Then in September 1892 the Metropolitan connected to Aylesbury via Amersham making the Chesham route a branch line.

The Great Central Railway decided to build a mainline called The London Extension from Annesley Junction north of Nottingham to London via the Metropolitan Railway. It was the last mainline to be built in Britain until High Speed 1. The line was completed in 1899. In 1903 the line between Harrow and Canfield Place (near Finchley Road) was built, thus bypassing the Met. The route was a major trunk route and many prestigious trains ran such as "The Master Cutler" and "The South Yorkshireman".

The line beyond Aylesbury is now closed to almost all passenger services: The service to Verney Junction was withdrawn in 1936 as London Transport wanted to focus more closely to London. The permanent way is now lost.

The line (from Harrow) was electrified in stages. In 1925, 4 rail electrification reached Rickmansworth and Watford and the Metropolitan Railway planned to electrify the line up to Aylesbury by 1935. However, when the Met was absorbed into LT the plans were put on hiatus. Electrification of the final leg of the Met finally got underway in the late 1950s but LT decided later to electrify only up to Amersham. This could be easily seen as colourlight signalling was fully installed up to Aylesbury and platform extensions up to Stoke Mandeville. In 1961 LT withdrew the Metropolitan Line from Aylesbury and now it goes only as far as Amersham.

The mainline services to the North were withdrawn in 1966 as the Great Central Main Line was seen as a duplicate of the Midland Main Line by Dr Beeching. Now only freight services to Calvert and specials to and from Quainton run (the specials only run on certain Bank Holidays). The track remains in situ from Calvert west to Bicester Town and intermittently east to Bletchley.

Intercity 125 trains have been used on the line albeit rarely during the 1980s. [ [http://www.citytransport.info/Share.htm Track Sharing & Route Sharing ] ] This is probably because of a lack of availability of stock for the line due to the regular failure of the Class 115.Fact|date=May 2008

Route description

From Marylebone the line runs into a series of tunnels, until Finchley Road, where the line becomes overground and runs parallel to the Metropolitan and Jubilee Lines. It is actually possible to see the Metropolitan Line before entering the first tunnel after Marylebone station. This is because the tunnels used by these two lines run only a few yards apart. At Neasden Junction, the Chiltern Main Line diverges to the west, while the line still runs north parallel to the underground lines, passing Wembley Stadium.

The line then joins Metropolitan Line tracks a few yards south of Harrow-on-the-Hill station and shares this track with London Underground's Metropolitan Line unique express services to Amersham from London Baker Street. This section runs parallel to the slow Met Line to Northwood and Watford. The line goes under the M25, north of Rickmansworth. At Chalfont & Latimer station, the Chesham branch diverges and Amersham is the final Metropolitan Line stop.

After Amersham, the line returns to Network Rail control and runs north to Aylesbury, running parallel to the A413 road for the majority of this section. At Aylesbury, the Princes Risborough line joins and is where major maintenance work on trains is done. Beyond Aylesbury, the line is singled and becomes freight only and runs through Quainton Road railway station to Calvert, where there is a waste depot. Beyond Calvert, there is a junction, one goes east and joins the Varsity Line, while the mainline goes north and becomes the dismantled Great Central Main Line.

As a result of going through the Chiltern Hills and being built in stages, the line has very steep gradients and very harsh curves. This is one of the main reasons that the GCR built a new line (the Chiltern Main Line) to Woodford Halse in 1906.

Towns/Villages served

The line serves the following stations:

*London Marylebone
*Harrow on the Hill
*Rickmansworth
*Chorleywood
*Chalfont and Latimer
*Amersham
*Great Missenden
*Wendover
*Stoke Mandeville
*Aylesbury
*(Quainton)

Map

Operation

Passenger services are provided by Chiltern Railways. From Marylebone to Neasden Junction the track is shared with the Chiltern Main Line, and from Harrow to Amersham the track is shared with London Underground's Metropolitan Line, and is used by their "fast" services. As a result, all Chiltern trains must be fitted with the tripcock braking system to run on Underground lines. Marylebone Signalling Control Centre controls all the signals on the line between Marylebone and south of Harrow, and also from north of Amersham to Aylesbury. Marylebone is able to see all train movements throughout the line but does not control the signals on the Metropolitan Line section. These are operated by London Underground signal cabins at Harrow, Rickmansworth and Amersham. The Network Rail controlled section of the line is fully equipped with ATP, the only line in Britain to have this bar the Chiltern Main Line and the Great Western Main Line. As a result all Chiltern trains must be equipped with ATP equipment.

Line Speeds

Marylebone-Harrow on the Hill

After departing Marylebone, the speed limit rises to 50mph for Sprinter-class multiple unit trains (of which the Class 165s and Class 168s are qualifying derivatives) and 30mph for all other types of train. Beyond Canfield Place, near Finchley Road, the line speed remains at 30/50 until a point near Willesden Green, where the line speed for Sprinter-class trains rises to 60mph. The line speed remains 30/60 as far as Neasden Junction, where the Chiltern Main Line diverges to the west. Passing Neasden, the line speed rises to 30/75 as far north of Northwick Park where the speed drops to 30/60mph. Shortly after this, the line speed drops to 40mph for all trains as the line enters London Underground control. The drop is due to the curve at Harrow.

Harrow on the Hill-Amersham

The line speed stays at 40mph through Harrow until after the junctions north of Harrow. At this point the line speed increases to 60mph as it runs parallel to the Metropolitan slow lines to Watford (This is the maximum limit on the LU controlled section of the line). [ [http://www.chilternrailways.co.uk/uploads/publications/638.pdf Chiltern Railways Q&A] ] The line between Harrow and Rickmansworth used to have a limit of 75mph for Turbo trains until the early 2000s but this has dropped since the London Underground A Stock was limited from 70mph to 50mph to improve reliability. The limit stays at 60mph until Moor Park, where the speed drops to 50mph. Just south of Rickmansworth, the line speed drops dramatically to 25mph caused by the very harsh curve and numerous points. After Rickmansworth, the speed increases back up to 60mph until Amersham, where the speed increases to 70mph. All speed limits between Harrow and Amersham are for passenger trains only. Freight trains are not permitted to run on LU track except when the line is closed.

Amersham-Calvert

As the line passes back into Network Rail control the speed increase to 30/75mph until south of Aylesbury where the speed reduces to 35mph (due to Moorgate Control). Speed limits have risen by 25 mph in some places due to major track improvement work in the early 2000s. After Aylesbury the line is singled and speeds drop to 30mph until the end of the line at Calvert.

ervices

Off peak services consist of:

*2tph (trains per hour) Marylebone — Aylesbury (operated by Chiltern Railways)
*4tph Baker Street — Amersham (operated by London Underground)

Future

*Following completion of a major track work project in December 2006, journey times on the line were cut by about 10 minutes. Currently major track replacement work is underway on the London Underground parts of the line. The goal of this project is to increase the maximum speed limit on that part of the line.
*In the long term, it is hoped to reopen the line beyond Aylesbury to allow passenger services to reach Milton Keynes, Bedford and even Cambridge via the Varsity Line. [ [http://www.eastwestrail.org.uk/ East-Wast Rail] ] This is under consideration as a result of expected heavy growth of the Aylesbury Vale area. A new station called Aylesbury Vale Parkway is under construction, the station opening in December 2008. [ [http://www.chilternrailways.co.uk/news/press-releases/new-aylesbury-vale-parkway-station-to/ New Aylesbury Vale Parkway station to open in 2010] - Chiltern Railways]
*The reopening of the Great Central Main Line towards Rugby and Leicester may happen as a result of expected high passenger growth on the West Coast Main Line and Midland Main Line [http://www.cwn.org.uk/business/a-z/c/chiltern-railways/images/train-route.gif] . The West Coast Main Line is expected to be at full capacity by 2015. [ [http://news.bbc.co.uk/1/hi/help/3681938.stm BBC] ]
*There is a proposal to build a high speed line (HS2) via the Chiltern Main Line to the North. If this is undertaken, Aylesbury will also be connected as a branch line of the HS2. [ [http://www.greengauge21.net/assets/GG21_HS2.pdf Greenguage21 proposal for a High Speed Two] ]

References