Editing Great Western Main Line (section)

=== Tunnels, viaducts and major bridges ===
Major civil engineering structures on the Great Western Main Line include the following.<ref name=":0">{{Cite book |title = Railway Track Diagrams Book 3 Western |last = Bridge |first = Mike |publisher = Tackmaps |year = 2010 |isbn = 978-0-9549866-6-7 |location = Bradford on Avon, UK |language = en-GB |pages = 1–5}}</ref>
{| class="wikitable"
|+Tunnels, viaducts and major bridges on the Great Western Main Line
!Railway structure
!Length
!Distance from London Paddington
!Location
|-
|Subway Tunnel (LU)
|{{convert|117|yd|m}}
|{{convert|0|mi|67|chain|km}} – {{convert|0|mi|73|chain|km}}
|West of Royal Oak
|-
|Spring Bridge Road Car Park Tunnel
|{{convert|121|yd|m}}
|{{convert|5|mi|70|chain|km}} – {{convert|5|mi|76|chain|km}}
|West of [[Ealing Broadway station|Ealing Broadway]]
|-
|Hanwell Viaduct
|{{convert|44|yd|m}}
|{{convert|7|mi|35|chain|km}} –  {{convert|7|mi|38|chain|km}}
| rowspan="3" |West of [[Hanwell railway station|Hanwell]]
|-
|[[Wharncliffe Viaduct]]
|{{convert|297|yd|m}}
|{{convert|7|mi|43|chain|km}} – {{convert|7|mi|56|chain|km}}
|-
|Hanwell Bridge
|{{convert|4|chain|m}}
|{{convert|8|mi|00|chain|km}} – {{convert|8|mi|04|chain|km}}
|-
|[[Maidenhead Railway Bridge|Maidenhead Viaduct]] ([[River Thames]])
|{{convert|237|yd|m}}
|{{convert|23|mi|21|chain|km}} – {{convert|23|mi|32|chain|km}}
|East of [[Maidenhead railway station|Maidenhead]]
|-
|Seven Arch Viaduct
|{{convert|68|yd|m}}
|{{convert|31|mi|19|chain|km}} – {{convert|31|mi|22|chain|km}}
| rowspan="2" |West of [[Twyford railway station|Twyford]]
|-
|River Loddon Viaduct
|{{convert|70|yd|m}}
|{{convert|31|mi|43|chain|km}} – {{convert|31|mi|46|chain|km}}
|-
|Kennet Bridge ([[Kennet and Avon Canal|Kennet & Avon Canal]])
|{{convert|4|chain|m}}
|{{convert|34|mi|77|chain|km}} – {{convert|35|mi|01|chain|km}}
|East of [[Reading railway station|Reading]]
|-
|[[Gatehampton Railway Bridge|Gatehampton Viaduct]] (River Thames)
|{{convert|99|yd|m}}
|{{convert|44|mi|00|chain|km}} – {{convert|44|mi|05|chain|km}}
|East of [[Goring & Streatley railway station|Goring & Streatley]]
|-
|[[Moulsford Railway Bridge|Moulsford Viaduct]] (River Thames)
|{{convert|147|yd|m}}
|{{convert|47|mi|27|chain|km}} – {{convert|47|mi|34|chain|km}}
|East of [[Cholsey railway station|Cholsey]]
|-
|River Avon Viaduct
|{{convert|72|yd|m}}
|{{convert|90|mi|77|chain|km}} – {{convert|91|mi|00|chain|km}}
|East of [[Chippenham railway station|Chippenham]]
|-
|[[Chippenham viaduct]]
|{{convert|90|yd|m}}
|{{convert|94|mi|08|chain|km}} – {{convert|94|mi|13|chain|km}}
|West of Chippenham
|-
|[[Box Tunnel]]
|{{convert|1|mi|1452|yd|km}}
|{{convert|99|mi|12|chain|km}} – {{convert|100|mi|78|chain|km}}
| rowspan="2" |Between Chippenham and [[Bath Spa railway station|Bath Spa]]
|-
|Middle Hill Tunnel
|{{convert|198|yd|m}}
|{{convert|101|mi|39|chain|km}} – {{convert|101|mi|48|chain|km}}
|-
|Sydney Gardens East Tunnel
|{{convert|77|yd|m}}
|{{convert|106|mi|24|chain|km}} – {{convert|106|mi|28|chain|km}}
| rowspan="3" |East of Bath Spa
|-
|Sydney Gardens West Tunnel
|{{convert|99|yd|m}}
|{{convert|106|mi|29|chain|km}} – {{convert|106|mi|33|chain|km}}
|-
|Dolemeads Viaduct
|{{convert|355|yd|m}}
|{{convert|106|mi|49|chain|km}} – {{convert|106|mi|60|chain|km}}
|-
|Arches and St James Viaduct
|{{convert|600|yd|m}}
|{{convert|106|mi|68|chain|km}} – {{convert|107|mi|20|chain|km}}
|West of Bath Spa
|-
|Twerton Viaduct
|{{convert|638|yd|m}}
|{{convert|108|mi|29|chain|km}} – {{convert|108|mi|58|chain|km}}
| rowspan="4" |Between [[Oldfield Park railway station|Oldfield Park]] and [[Keynsham railway station|Keynsham]]
|-
|Twerton Short Tunnel
|{{convert|45|yd|m}}
|{{convert|108|mi|70|chain|km}} – {{convert|108|mi|72|chain|km}}
|-
|Twerton Long Tunnel
|{{convert|264|yd|m}}
|{{convert|109|mi|03|chain|km}} – {{convert|109|mi|15|chain|km}}
|-
|Saltford Tunnel
|{{convert|176|yd|m}}
|{{convert|111|mi|57|chain|km}} – {{convert|111|mi|65|chain|km}}
|-
|St Annes Park Arches Viaduct
|{{convert|4|chain|m}}
|{{convert|115|mi|25|chain|km}} – {{convert|115|mi|29|chain|km}}
| rowspan="7" |Between Keynsham

and [[Bristol Temple Meads railway station|Bristol Temple Meads]]
|-
|St Annes Park No.3 Tunnel (or Foxes Wood Tunnel)
|{{convert|1017|yd|m}}
|{{convert|115|mi|58|chain|km}} – {{convert|116|mi|25|chain|km}}
|-
|St Annes Park or (Bristol) No.2 Tunnel
|{{convert|154|yd|m}}
|{{convert|116|mi|41|chain|km}} – {{convert|116|mi|48|chain|km}}
|-
|Main River Viaduct (River Avon)
|{{convert|108|yd|m}}
|c. {{convert|117|mi|24|chain|km}}
|-
|Main Down Viaduct (River Avon)
|{{convert|141|yd|m}}
|{{convert|117|mi|21|chain|km}} – {{convert|117|mi|27|chain|km}}
|-
|The Feeder
|
|{{convert|117|mi|51|chain|km}}
|-
|[[Bristol Harbour|Floating Harbour]]
|{{convert|3|chain|m}}
|{{convert|118|mi|16|chain|km}} – {{convert|118|mi|19|chain|km}}
|}

==== Line-side monitoring equipment ====
Line-side train monitoring equipment includes hot axle box detectors (HABD) and ''Wheelchex'' wheel impact load detectors (WILD), sited as follows.<ref name=":0" /><ref>{{Cite web |url = http://www.railwaycodes.org.uk/misc/habdwild.shtm |title = HABD and WILD equipment |website = railwaycodes.org.uk}}</ref>
{| class="wikitable"
|+Line-side monitoring equipment on the Great Western Main Line
!Name & Type
!Line
!Location (distance from Paddington)
|-
| rowspan="2" |Maidenhead HABD
|Up Relief
|{{convert|24|mi|03|chain|km}}
|-
|Up Main
|{{convert|24|mi|10|chain|km}}
|-
|Waltham WILD
|Up Relief, Down Relief, Up Main, Down Main
|{{convert|26|mi|21|chain|km}}
|-
|Twyford HABD
|Down Relief, Down Main
|{{convert|32|mi|02|chain|km}}
|-
|Basildon HABD
|Up Relief, Down Relief, Up Main
(Down Main disconnected December 2016)
|{{convert|43|mi|42|chain|km}}
|-
|Cholsey WILD
|Up Relief, Down Relief, Up Main, Down Main
|{{convert|49|mi|05|chain|km}}
|-
|Wantage Road HABD
|Up Main
|{{convert|59|mi|57|chain|km}}
|-
|Bourton HABD
|Down Main
|{{convert|72|mi|20|chain|km}}
|-
|Studley HABD
|Up Main
|{{convert|81|mi|40|chain|km}}
|-
|Twerton HABD 
|Down Main
|{{convert|108|mi|60|chain|km}}
|}