having tried once already:
High Speed Lines
HS2 extended to Glasgow via Manchester Airport, Preston, Kendal & Carlisle, to Dundee via an 'Glasgow avoider' and to Belfast via a tunnel. Also a spur direct into Liverpool & Manchester city centres, as well as a Liverpool-Manc. Airport-Manchester line
Separate HSL to Nottingham, Sheffield, Leeds, Newcastle, Edinburgh, Dundee and Aberdeen, including Leeds-Manchester and Edinburgh-Glasgow lines
Spurs from Liverpool & Crewe (approx) to Dublin via a Holyhead-Dun Laoghaire tunnel
HS3 to run Euston-OOC-Heathrow-Reading-Bristol-Cardiff-Swansea-Fishguard-Rosslare-Dublin/Cork, and include a Bristol-Birmingham link
Irish HSL to run Cork-Dublin-Belfast
Assist with the French with the LGV Picardie & the Belgians with a Calais-Ghent-Antwerp HSL, speeding up London-Paris & London-Netherlands
Connect HS1 to HS2 via north London (NoL International trains to call at Stratford International), and connect HS3 to HS2 via a Stratford-OOC line
Reopenings
Yorkshire
Middlesbrough-Scarborough via Whitby West Cliff
Northallerton-Battersby
Northallerton-Cross Gates via Ripon, Harrogate & Wetherby
York-Hull via Beverley
Selby-Driffield
Church Fenton-Wetherby
Harrogate-Pateley Bridge
Pool in Wharfedale-Menston via Otley
Laisterdyke-Low Moor
Garforth-Castleford
Wakefield-Barnsley via Royston
Low Moor-Mirfield via Heckmondwike
Leeds-Mirfield via Birstall, Heckmondwike
Horbury West Curve
Methley Junction-Glasshoughton
Brockholes-Holmfirth
Sheffield-Manchester via Woodhead
Beeston Junction-Morley Top
Deepcar-Stocksbridge
Clowne-Staveley
Staveley-Bolsover
Chesterfield-Sheffield via Woodhouse Mill
Greater Manchester
Rose Hill Marple-Macclesfield
Stoke on Trent-Congleton via Biddulph
Macclesfield-Stoke on Trent via Leek
Gorton-Fallowfield
Altrincham-Glazebrook
Timperley-Warrington Bank Quay Low Level
Buxton-Matlock
Northwich-Sandbach
Stalybridge-Diggle via Lower Arthur
Rest of the Country
Walsall-Stourbridge Junction
Wolverhampton-Coleshill Parkway
Kenilworth-Berkswell
Kings Norton-Birmingham New Street via Moseley
Leamington Spa-Rugby
Leamington Spa-Weedon Bec via Daventry
Aylesbury Vale Parkway-Leicester
Rugby-Leicester via South Wigston
Bedford-Market Harborough via Northampton
Northampton-Peterborough
Bedford-Cambridge
Grimsby Town-Spalding via Louth
Boston-Lincoln
Skegness-Lincoln
Horncastle-Woodhall Junction
Saxilby-Retford avoiding Gainsborough Lea Road
Grantham-Lincoln
Lincoln-Shirebrook
Melton Mowbray-Kings Lynn via Spalding
Kings Lynn-Hunstanton
Penrith-Workington via Cockermouth & Keswick
Hereford-Gloucester via Ross on Wye
Pontypool-Ross on Wye via Monmouth
Monmouth-Chepstow
Preserved Lines
Skipton-Grassington & Threshfield
Skipton-Embsay
Bolton Abbey-Ilkley (Embsay & Bolton Abbey)
Ingrow East-Halifax (Keighley & Worth Valley)
Northallerton-Hawes Junction (Wensleydale Railway)
Malton-Pickering (NYMR)
Hartlebury-Bewdley
Bridgnorth-Shrewsbury
Buildwas Junction-Wellington/Telford (Severn Valley/Telford)
Rawtenstall-Bacup
Heywood-Castleton (East Lancs)
Sheffield Park-Lewes (Bluebell)
Bishop's Lydeyard-Taunton (West Somerset)
Llangollen-Ruabon
Corwen-Bala
Corwen-Ruthun(Llangollen)
RAPID TRANSIT
Tyne & Wear Metro
Northumberland Park-Newbiggin/Blyth/Morpeth
Monkseaton-Seaton Delaval
Airport-Darras Hall
Byker-Percy Main via St Anthonys
St James-Throckley
Gateshead-Prudhoe
Metro Centre-Consett
Pelaw-Durham
South Hylton-Shiney Row
East Boldon-Tyne Dock
Manchester Metrolink
St Werburgh's Road-Fallowfield
Eccles-Wigan via Tyldesley
Tyldesley-Leigh
Roe Green-Bolton
Radcliffe-Bolton
Victoria-St Peters Square (2XC)
Rochdale-Bacup
Oldham-Greenfield
Oldham-Ashton under Lyne
East Didsbury-Stockport
Pomona-Glazebrook
Trafford Park-Trafford Centre
Merseyrail
Edge Hill-Albert Dock (via old tunnell)
Edge Hill-Kirkdale (Inner Circle)
Bootle New Strand-Hunts Cross (Outer Circle)
Bidston-Wrexham Central
Kirkby-Wigan Wallgate
Ormskirk-Preston
West Kirkby-Hooton
Ellesmere Port-Runcorn North
Liverpool South Parkway-Liverpool John Lennon Airport
Hawarden Bridge-Chester