In­vis­i­ble in­vest­ment

PAUL STEPHEN scratches be­neath the sur­face of Net­work Rail’s work on the south­east­ern end of the El­iz­a­beth Line and dis­cov­ers that the money be­ing spent now will bring ben­e­fits for decades to come

Rail (UK) - - Crossrail -

RAIL scratches be­neath the sur­face of Net­work Rail’s work on Cross­rail’s south­east­ern arm at Abbey Wood.

Apart from the 26 miles of tun­nels con­structed by Cross­rail Ltd be­neath cen­tral Lon­don, Net­work Rail is re­spon­si­ble for de­liv­er­ing £ 2.3 bil­lion worth of work above ground, where the Cross­rail route utilises parts of the ex­ist­ing net­work.

This in­cludes mod­i­fy­ing 28 ex­ist­ing sta­tions, and is largely con­cen­trated on en­hanc­ing the Great Eastern Main Line be­tween Liver­pool Street and Shen­field, and the Great Western Main Line be­tween Padding­ton and Heathrow Junc­tion and Read­ing.

It also in­cludes up­grad­ing a much shorter sec­tion of track on Cross­rail’s south-eastern arm, how­ever, run­ning along­side the North Kent Line from the Plumstead eastern tun­nel por­tal to Abbey Wood, where a new ter­mi­nus sta­tion is be­ing built for Cross­rail, to act as an in­ter­change with South­east­ern’s ex­ist­ing through ser­vices.

Work be­gan in 2013 and is rapidly near­ing com­ple­tion, on what is ef­fec­tively a three­mile con­struc­tion site in prepa­ra­tion of the first El­iz­a­beth Line ser­vices, which will run on this sec­tion in De­cem­ber 2018.

For two miles to the west of Abbey Wood sta­tion, the two-track for­ma­tion of the North Kent Line needed to be widened into a four­track cor­ri­dor to ac­com­mo­date the two new Cross­rail tracks, emerg­ing from Plumstead tun­nel.

To cre­ate suf­fi­cient space, the North Kent Line tracks had to be moved five to six me­tres fur­ther south for a dis­tance of two miles, and then grad­u­ally slewed from their new po­si­tions to re­con­nect with the old align­ment, ap­prox­i­mately a mile to the east of Abbey Wood sta­tion.

The task of widen­ing the align­ment was com­pli­cated by the high wa­ter ta­ble of the sur­round­ing land, which used to be marsh­land un­til it was drained and then ur­banised by Vic­to­rian de­vel­op­ers dur­ing the 19th cen­tury.

NR’s so­lu­tion was to drive 1,800 con­crete piles up to nine me­tres into the ground, to sup­port wide con­crete bal­last slabs, placed on ei­ther side of for­mer two-track align­ment.

This was ex­pen­sive as well as chal­leng­ing, and al­most three quar­ters of the £150 mil­lion bud­get spent by Net­work Rail on this sec­tion of Cross­rail was in­vested in build­ing these earth­works and drainage cour­ses.

Find­ing ad­e­quate room for four tracks was also prob­lem­atic for NR’s engi­neers, re­quir­ing the de­mo­li­tion of sev­eral endof-ter­race prop­er­ties and the com­pul­sory pur­chase of some sec­tions of ad­join­ing gar­dens.

“The sin­gle big­gest chal­lenge has been

The sin­gle big­gest chal­lenge has been build­ing this through a hous­ing estate. Peter Hume, Se­nior Pro­gramme Man­ager, Net­work Rail

build­ing this through a hous­ing estate,” ex­plains Net­work Rail’s se­nior pro­gramme man­ager Peter Hume. “There are 2,000 res­i­dences that en­cir­cle a site over three miles long.

“You can’t see where a huge amount of our in­vest­ment has gone, as it’s been done be­low ground level to solve that drainage prob­lem.”

The project also re­quired a great deal of lo­gis­ti­cal plan­ning. Track­work had to be care­fully car­ried out in phases, in or­der to sup­port the early es­tab­lish­ment of a rail­head and tem­po­rary lo­gis­tics cen­tre at Plumstead tun­nel por­tal for en­gi­neer­ing trains, used for the on­go­ing fit-out of the tun­nels and sta­tions by Cross­rail con­trac­tor ATC.

This end of the three-mile work­site was, there­fore, com­pleted first, so that ATC could sta­ble its con­cret­ing fac­tory train at Plumstead, and an over­head gantry crane could be erected above sid­ings to sup­ply en­gi­neer­ing trains used for track­work, and all other nec­es­sary works, some of which are on­go­ing.

A £ 30m per­ma­nent de­pot will even­tu­ally be built here for main­te­nance rail ve­hi­cles, which will be op­er­a­tional in early 2019.

It was also im­por­tant to con­duct the work in stages in or­der to keep Abbey Wood open, a sta­tion used by some 4,500 peo­ple dur­ing the morn­ing peak.

With the North Kent lines moved south, both of Abbey Wood’s orig­i­nal two plat­forms have been de­mol­ished and re­built, to form two new is­land plat­forms.

The south­ern­most of these was com­pleted first, and a tem­po­rary sta­tion build­ing erected so that South­east­ern ser­vices could con­tinue to serve the sta­tion while work

What’s been car­ried out here has been so ex­ten­sive that no fur­ther work should be nec­es­sary for at least 20 years. Peter Hume, Se­nior Pro­gramme Man­ager, Net­work Rail

be­gan on the north­ern is­land plat­form, and the new sta­tion build­ing it­self, which is el­e­vated above all four run­ning lines.

Dis­rup­tion has there­fore been kept to a min­i­mum, adds Hume, apart from a se­ries of brief full-line pos­ses­sions, an un­avoid­able measure due to the close prox­im­ity of fully en­er­gised 700V DC lines to the build­ing works. The scope of the track­work means that fu­ture en­hance­ment and re­newal work should be kept to a min­i­mum, how­ever, lim­it­ing the need for any fu­ture pos­ses­sions.

“The project has taken four years. We could have shut the sta­tion com­pletely and di­verted South­east­ern trains to do it faster, but the in­dus­try view was that Abbey Wood is too busy to close. To get round that we de­vel­oped a strat­egy us­ing con­ven­tional line pos­ses­sions that al­lowed peo­ple to carry on trav­el­ling, and with min­i­mal im­pact.

“100% of the rail­way as­sets have been re­placed. What’s been car­ried out here has been so ex­ten­sive that no fur­ther work should be nec­es­sary for at least 20 years. This sec­tion of track will be main­te­nance and re­newal free for a long time.”

The sta­tion de­sign it­self had to cater for up to 20,000 peo­ple us­ing Abbey Wood in the morn­ing peak, with half of those in­ter­chang­ing to El­iz­a­beth Line ser­vices, and the rest con­sist­ing of lo­cal jour­neys.

Due to the lo­cal drainage prob­lems, a fur­ther £ 20m had to be spent on build­ing the ex­ten­sive foun­da­tions and con­crete sup­port struc­ture re­quired be­neath the el­e­vated con­course, while £ 25m is be­ing spent on the con­course it­self. The pri­mary con­trac­tor on-site lead­ing all the works is Bal­four Beatty.

The sta­tion’s dis­tin­guish­ing fea­ture is a gen­tly curv­ing roof shaped like a manta ray, formed by glu­lam (glued man­u­fac­tured tim­ber) wood pan­els in­stalled by Aus­trian firm Wiehag, that are cov­ered in zinc. Be­neath the roof, the sta­tion build­ing has been con­structed us­ing 31 tonnes of steel beams and gird­ers.

It makes a bold ar­chi­tec­tural state­ment, but the new sta­tion has also been de­signed to de­liver more func­tional im­prove­ments to the eco­nom­i­cally de­pressed lo­cal area, via its in­te­gra­tion with ad­ja­cent fly­over, Har­row Manor­way (the A2041).

This el­e­vated road has made walk­ing

around the area dif­fi­cult, and has formed a vis­ually in­tru­sive phys­i­cal bar­rier through the area since its con­struc­tion in 1975.

New stair­cases, walk­ways and a gran­itepaved con­course will dra­mat­i­cally en­hance pedes­trian ac­cess be­tween the ar­eas of Thames­mead and Bex­ley­heath lo­cated on op­po­site sides of the rail­way, while stim­u­lat­ing more than £10m in­vest­ment from lo­cal coun­cils on im­prove­ments to the sur­round­ing ur­ban area.

It has also had a re­gen­er­a­tive ef­fect on Abbey Wood, with a new su­per­mar­ket al­ready open­ing close to the sta­tion, and 1,500 homes un­der con­struc­tion nearby. Mean­while, plan­ning per­mis­sion has been granted for a public plaza, li­brary and a fur­ther 220 new homes.

The new con­course will also con­tain re­tail units to closely re­sem­ble a high street, re­in­forc­ing the sta­tion en­vi­ron­ment’s feel as a thor­ough­fare link­ing the two com­mu­ni­ties.

Now that the ex­ter­nal struc­ture is com­plete, the em­pha­sis will shift onto the sta­tion build­ing’s in­ter­nal fit-out, be­fore it is ready to open to South­east­ern cus­tomers in Oc­to­ber.

That month will also mark the end of Net­work Rail’s in­volve­ment in the project, as the Cross­rail is­land plat­form and run­ning lines are handed over to Cross­rail Ltd to be­gin dy­namic test­ing and com­mis­sion­ing, in ad­vance of the full sta­tion open­ing in De­cem­ber 2018.

Matt Steele, Cross­rail Pro­gramme Direc­tor at Net­work Rail, con­cludes: “This is one of my favourite sites as it’s an op­por­tu­nity to leave some­thing iconic and make a bold ar­chi­tec­tural state­ment. It’s also a rare chance to build some all-new rail­way.”

CROSS­RAIL.

An aerial shot of Abbey Wood sta­tion, show­ing where a level cross­ing was once situated in the area be­neath the white roof of the new sta­tion, un­til be­ing re­placed by the fly­over in the far right of the shot in 1975. Net­work Rail en­coun­tered an un­help­ful legacy from the cross­ing dur­ing the sta­tion build as it was nec­es­sary to di­vert up to 90 sep­a­rate util­i­ties to en­able the con­struc­tion of new foun­da­tions.

PAUL STEPHEN. PAUL STEPHEN. PAUL STEPHEN.

A Down South­east­ern ser­vice oc­cu­pies Plat­form 2 at Abbey Wood on March 24, demon­strat­ing the close prox­im­ity of the fully en­er­gised North Kent run­ning lines to the is­land plat­form con­structed for Cross­rail to the right. The Cross­rail tracks were due to be tamped by the end of April, ahead of the in­stal­la­tion of sig­nalling and com­mu­ni­ca­tions equip­ment. Net­work Rail’s Cross­rail Pro­gramme Direc­tor Matt Steele (left), and Se­nior Pro­gramme Man­ager Peter Hume in­spect the Abbey Wood site on March 24, less than 24 hours be­fore a full line pos­ses­sion com­menced to erect over­head line equip­ment. A high-speed cross­over has been built at the western end of the sta­tion, with the con­crete plinths for over­head line equip­ment vis­i­ble on the right-hand side. Con­trac­tors are also erect­ing sep­a­ra­tion bar­ri­ers be­tween the two Cross­rail tracks and those of the North Kent Line. This is re­quired be­cause Cross­rail utilises over­head elec­tri­fi­ca­tion and Au­to­matic Train Con­trol (ATO) that both re­quire dif­fer­ent com­pe­ten­cies for track work­ers than those work­ing with the third rail and con­ven­tion­ally sig­nalled ad­ja­cent North Kent Line tracks.

PAUL STEPHEN. NET­WORK RAIL.

The view at con­course level on March 24, prior to in­te­rior fit-out. The main tim­ber roof beams are 45 me­tres long, which is the equiv­a­lent of four Lon­don buses end to end. The new con­course mea­sures 1,500m2 (the size of six ten­nis courts). Abbey Wood sta­tion be­fore re­de­vel­op­ment be­gan in 2013.

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