Changes

[[File:Sterns_20180325.jpg|thumb|300px|right| The telegraph pole at Sterns (spring)]]'''Sterns''' is situated between [[Hampton Loade]] and [[Bridgnorth]] at the foot of [[Eardington Bank]], at approximately [[Gradient profile and mileages|milepost 147]]. It is at a place where the [[River Severn]] approaches close to the railwayat almost 90 degrees before turning away southwards towards Bewdley, and is notorious as a maintenance trouble spot due to the ground regularly slipping towards the river on numerous occasions over the history of the railway. During the last Ice Age, the valley of the River Severn was scoured out by glacial action and bands of different types of material were deposited at varying depths. This subsequently resulted in the formation of 'slip-planes' where the different layers can slide over each other, particularly when placed under a load such as the presence of a railway line and especially after periods of heavy rain. Slip-planes exist throughout most of the valley but have resulted in areas of major instability at [[Jackfield Halt|Jackfield]] and Sterns.<ref name=Sowden>[[Bibliography#Books|Sowden (2012)]] pp. 12-14.</ref> The slip plane causing the movement in this area is located at a depth of around 20 metres below the ground surface.<ref name=BranchLines202406>[https://www.svrlive.com/bljun24 Branch Lines June 2024, ''More concerns at Sterns'']</ref> The line of telegraph poles adjacent to the railway at Sterns vividly illustrates this; one the ground movements that have taken place. One post which stood next to the track until shortly before 1979<ref>SVR News 52 p26</ref> has been carried a significant distance towards the river by ground movements slips since that time and is now only just visible in the trees towards the river. The post is mentioned in the Railway's [[From The Window]] booklet as one of the items to see during the journey and it carries a yellow flash to make it more visible.__TOC__<br clear="all"/>

SVR News and newsletters regularly refer to repair work at Sterns. Some examples are as follows:.===1976-77===*Over the winter of [[Severn Valley Railway Timeline 1970-1979#1977 | 1976-77]], intense cold followed by heavy rain resulted in the line dropping 2ft 6" and moving 4ft nearer the river. Permanent way work in progress at [[Borle Viaduct]] was halted while repairs were carried out at Sterns. Remedial work enabled the line to re-open in March with trains passing Sterns at the slowest possible speed, repairs there being completed some three weeks later<ref>SVR News 43, 44</ref>.  ===1994-95===*In [[Severn Valley Railway Timeline 1990-1999#1995|1994-95]] ten feet of river bank was washed away, triggering further slippage. 3,000 tons of rock was deposited on the river bank as a temporary measureto protect the bottom of the embankment from further erosion and to 'toe-load' the slip area. A large ditch was also dug alongside the line on the uphill side<ref name=Sowden/>. *===2007===In the [[2007 Storm Damage|Summer 2007 storm damage]], the first severe thunderstorm did not affect Sterns, but . However further slips began in the following weeks as the wet weather continued, both at the area normally affected and further to the north by Sterns Cottage, the house alongside the line on the side nearer the river.  Part of the solution involved building a 150 foot long piled concrete retaining wall alongside Sterns Cottage, the house alongside the line on the side nearer the river. This required 75 24-foot long vertical piles reinforced by 37 42-foot long angled soil-nails and covered by a concrete cap<ref name=Sowden/>. <gallerymode=packed heights=200px style="text-align:left">Sterns_20160514.jpg| The cap of the 150 foot retaining wall alongside Sterns Cottage</gallery> ===2014===In mid-February 2014 evidence emerged that further subsidence was taking place when a significant dip in the line appeared at the north end of the Sterns area close to Sterns Cottage. A 'stop and proceed with caution' restriction was put in place until repairs could be completed over the following months. A large concrete sleeper wall was built at the toe of the slip and packed behind with approximately 150 tonnes of ballast. This was topped off with around 200 tonnes of graded stone in order to help to stabilise the slip and drain the water from the embankment. Full-time staff, with the help of [[Other rolling stock visiting the SVR|hired in plant]] completed the repairs to the line<ref>SVR Live April 2014</ref>.<gallery mode=packed heights=200px style="text-align:left">Sterns_20140316.jpg|Dip in the line seen from the DMUSterns_2_20150228.jpg|Evidence of 2014 repair work is still visible in 2015</gallery> ===2020-2023===Following [[Severn Valley Railway Timeline 2020-2029#2020|extensive flooding in February 2020]] land movements were again observed. A comprehensive drainage network was proposed to collect rainwater and transport it to the river in an efficient manner before it could get down to the slip planes and exacerbate the problem.<ref>[https://www.svrlive.com/bljun20 Branch Lines, June 2020] (Retrieved 26 June 2020)</ref> Contractors Walsh Construction completed this water management work by 29 July as planned, with the final item being the lining of the existing drainage ditch with concrete canvas. The work was funded by £120,000 from the [[Severn Valley Railway Charitable Trust Ltd|SVR Charitable Trust]].<ref>[https://www.svrlive.com/blaug20 Branch Lines, August 2020] (Retrieved 3 August 2020)</ref> <gallery mode=packed heights=200px style="text-align:left">Sterns_20200808.jpg|Lineside view of the drainage ditch and repair works uphill from it, looking northSterns_Drone.jpg|Aerial view of the repair works looking south (River Severn to the left)</gallery> In spring of 2022 Walsh and SVR staff undertook a further project. A deep area of ballast had developed from successive tamping over the years. 300 cubic metres of embankment comprising around 150 tonnes of ballast and 650 tonnes of fill material were replaced with around 400 tonnes of Leca (lightweight expanded clay aggregate) and 40-60 tonnes of ballast, at a total cost of £81,209.<ref>SVRH Report and accounts up to 2 January 2023</ref> This reduced the weight on the embankment, thereby lessening the progressive movement.<ref>[https://www.svrlive.com/blfeb22 Branch Lines, February 2022] (Retrieved 7 March 2021)</ref> Both projects were hoped to mitigate the problems, but neither was intended to provide a lasting solution. Electronic 'tilt monitoring' equipment was fitted in February 2021<ref>[https://www.svrlive.com/blmar21 Branch Lines, March 2021] (Retrieved 7 March 2021)</ref>. Following the insolvency of the provider this was taken out of use in 2023.  ===2024===With ground movements continuing to cause concern to the Railway, new tilt monitors were installed in February 2024, together with blue 'ground-alignment markers', to monitor movement in the near-surface soils. In June 2024 specialist contractor 'Ground Investigation Specialists' drilled through the rock to a depth of 23 metres to install new boreholes to monitor the movement more accurately.<ref name=BranchLines202406/> <gallery mode=packed heights=200px style="text-align:left">Sterns_ground-alignment_markers_20240502.jpg|Ground-alignment markers, May 2024Sterns_borehole_drilling_20240605.jpg|Borehole drilling, June 2024. The 'moving telegraph pole' is to the left.

*In February 2014, evidence of further subsidence appeared with a significant dip in the line. Repair work was undertaken over the following months.<ref>SVR Live April 2014</ref><gallery>Sterns_20140316.jpg|Dip in the line in 2014 seen from the DMU</gallery> *Following [[Severn Valley Railway Timeline 2020-2029#2020|extensive flooding in February 2020]] land movements were again observed. A comprehensive drainage network was proposed to collect rainwater and transport it to the river in an efficient manner before it could get down to the slip planes and exacerbate the problem.<ref>[https://www.svrlive.com/bljun20 Branch Lines, June 2020] (Retrieved 26 June 2020)</ref> Contractors Walsh Construction completed this water management work by 29 July as planned, with the final item being the lining of the existing drainage ditch with concrete canvas.<ref>[https://www.svrlive.com/blaug20 Branch Lines, August 2020] (Retrieved 3 August 2020)</ref> ==Speed restrictions==The section of line through Sterns was for many years under a strict 5mph speed limit, with the drainage improvements and earthworks in 2013/14 finally allowing for the limit to be increased to 15mph (although further ground movement led to the reinstatement of a lower temporary speed limit soon after). A consequence of this speed restriction is that northbound trains are made to work harder as they are prevented from ‘taking 'taking a run’ run' at Eardington Bank.