Rhondda Tunnel RSB 1m 44c

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1 Rhondda Tunnel RSB 1m 44c Special Examination - 17 April Background 1.1 Rhondda Tunnel was built in It was nearly 2 miles long and connected the village of Blaencwm in the Rhondda Valley with the village of Blaengwynfi in the Afan Valley. The tunnel suffered from water ingress and movement of the brick and stone lining throughout its operational life due to subsidence caused by coal mining above and below it. Several attempts were made to resist the movement by installing arched steel ribs around the tunnel lining but even some of these were pushed out of shape by the movement of the ground squeezing the sidewalls in and pushing the arch upwards. 1.2 The tunnel was closed to rail traffic in In 1970 the Minister for Transport made the decision not to repair the tunnel and the line was permanently closed. Land at each tunnel portal was later sold by the British Railways Board to the local authorities: West Glamorgan on the western side at Blaengwynfi and Rhondda Borough on the eastern side at Blaencwm. The majority of the tunnel passes under mountainous terrain but at the Blaengwynfi end the cover is relatively shallow and part of it passes under a corner of a playing field. 1.3 The approach cuttings at both ends were infilled by the local authorities and landscaped so that no visible trace of the tunnel remained. A series of concrete pipes were built into the infill material at the Blaencwm portal so that personnel access was still possible via a lockable hatch at the newly infilled ground level. The hatch was subject to vandalism so British Rail s Regional Civil Engineer decided to plug it with concrete which meant that inspection of the tunnel was no longer possible. In 2008 the concrete plug was removed by persons unknown but suspected to be urban explorers. BRB (Residuary) Ltd then installed a lockable steel hatch to the top of the access point. 1.4 Following the abolition of BRB (Residuary) Ltd in 2013, ownership of the tunnel passed to the Secretary of State for Transport who appointed the Historical Railways Estate (HRE) team to manage it. 2. Reasons for the Examination 2.1 Historically, the tunnel has been considered to be low risk to outside parties due to the nature of the terrain above and the very limited access. However, the risk could not be ignored due to the following facts: 1. Some of the land above the tunnel is owned by third parties and their property may be affected by any subsidence caused by the potential collapse of any parts of the tunnel.

2 2. No records were available of the tunnel s condition since the 1960s so prior to the recent inspection its current condition and the degree of risk that it presented to properties above was unknown. 3. Significant interest within the community in respect of the condition of the tunnel and ownership being transferred and potentially reopened. 2.2 The difficult access route and the unknown condition of the tunnel meant that normal examination by HRE s contractors was not possible. As part of the information gathering exercise forming HRE s Tunnels Strategy in 2014 a decision was taken to enter the tunnel via the access point with the assistance of confined space specialists who were suitably qualified to assess the potential danger and to undertake rescue operations if necessary. 3. Inspection Results 3.1Details of the findings are given in a report by Hammond (ECS) Ltd who were contracted to arrange a safe system of working and take photographs of the various forms of construction and the major defects. This was carried out over three days and I accompanied them on the third day to make notes. 3.2 Access via the narrow shaft and horizontal pipe was difficult due to the narrow diameter. The eastern end of the tunnel was wet underfoot with running water entering through the arch and sidewalls at several locations. This was seen to be flowing away via the original track drainage towards the infilled cutting at Blaencwm with no ponding in the tunnel. 3.3 Steel ribs around the arch were in poor condition but did not appear to be unsafe. However, the timber laggings that had been placed between the ribs and the stonework of the tunnel arch were in very bad condition with many having rotted and fallen. Small patches of stonework had fallen from the crown of the tunnel, probably as a result of the movement recorded in the mid-twentieth century, but did not appear to be in danger of further collapse. 3.4 Heading towards Blaengwynfi the tunnel was found to be relatively dry. Mass concrete was noted in the sidewalls, presumably having been placed in front of the original masonry. At approximately half way along the length of the tunnel substantial recesses have been built into the sidewalls with the arch correspondingly wider. 3.5 Continuing towards Blaengwynfi a timber cwg was found where the tunnel arch was at its most distorted. This structure was in two separate lengths, formed of railway sleepers built up into the shape of the tunnel arch with a central opening left for personnel access through the structure. The purpose of the structure was presumably to resist any further movement of the tunnel lining so that any falling material would not completely block the tunnel. It was noted that the timber structure was not in contact with the tunnel arch and the masonry, whilst clearly distorted in the southern haunch, did not appear to be in danger of collapse. Odd timbers had rotted and fallen but overall the cwg appeared to be stable.

3 3.6 The last 100m of the tunnel at the Blaengwynfi end is blocked off with a concrete block wall, probably constructed when West Glamorgan infilled the cutting and landscaped the area. Close to this internal wall is the only air shaft in the tunnel. This is circular and brick lined and was estimated to be 11m high above the crown of the tunnel arch. The top of the air shaft was sealed and a large volume of brick rubble in the tunnel directly beneath the shaft suggests that the chimney above ground was demolished by knocking it down the shaft. There is no visible trace of the capped shaft at ground level now although its location may be plotted from old maps. 4. Conclusions and Recommendations 4.1The condition of the masonry forming the tunnel does not appear to have become any worse since it was closed to rail traffic. The movement of the ground around the tunnel seems largely a result of extensive coal mining but since this activity has stopped the ground appears to have settled. The biggest danger to anyone entering the tunnel is the risk of being struck by loose, rotten timbers in the ribbed section. It is recommended that the tunnel is not in a condition that would prevent future similar examinations. 4.2 The western end of the tunnel where cover is relatively low near Blaengwynfi is in fair condition. It is recommended that the geology and mining history around this section of tunnel should be investigated so that the likelihood of movement and the effects of subsidence can be calculated. 4.3 It is recommended that ownership of the land above the tunnel should be checked with the Land Registry as part of it was originally purchased by the Rhondda and Swansea Bay Railway and is likely to be unregistered. 4.4 It is recommended that the shaft location should be marked at surface level and land ownership of this area should be confirmed and the capping should be investigated to ensure it is in good structural condition. 4.5 Providing the ground is found to be stable it is recommended that the tunnel should be examined on a frequency of every 6 years. The hazardous conditions in the tunnel mean that remote inspections would be preferable to having persons entering the tunnel. If regular entry were to be made into the tunnel then the rotten timbers should be removed from above head height and the steel ribs checked for stability and removed if necessary. This could be an expensive and hazardous activity in itself hence the preference for remote inspections. Lee Holland Engineer - Historical Railways Estate 14 th May 2015

4 Details of the tunnel construction Location Tunnel Construction 0m Access shaft. (NE Portal) 0m 395m Masonry sidewalls and soffit. 395m 644m Concrete sidewalls with arches and a brickwork soffit. 644m 1205m Masonry sidewalls and soffit. 1205m 1460m Concrete sidewalls with arches and a brickwork soffit. 1460m 1650m Brickwork sidewalls and soffit. 1650m 1748m Concrete sidewalls with arches and a brickwork soffit. 1748m 1955m Brickwork sidewalls and soffit. 1955m 1975m Concrete sidewalls with arches and a masonry soffit. 1975m 2134m Masonry sidewalls and soffit. 2134m 2166m Concrete sidewalls with arches and a masonry soffit. 2166m 2282m Masonry sidewalls and soffit. 2282m 2298m Concrete sidewalls with arches and a masonry soffit. 2295m 2351m Masonry sidewalls and soffit. 2351m 2381m Concrete sidewalls with arches and a masonry soffit. 2381m 2494m Masonry sidewalls and soffit. 2494m 2503m Concrete sidewalls with arches and a masonry soffit. 2503m 2526m Masonry sidewalls and soffit. 2526m 2543m Concrete sidewalls with arches and a masonry soffit. 2543m 3180m Masonry sidewalls and soffit. 3180m Block-work wall and capped ventilation shaft. (Towards SW Portal) General summary of tunnel condition Location Condition Poor condition: Very wet, open joints throughout. 0m 295m Isolated areas of missing masonry in the haunch. Severe hinging in the haunches and missing or partially collapsed masonry in the soffit in the ribbed areas only. Good condition: 295m 850m Poor condition: 850m 1054m Isolated soffit bulges and collapses in the ribbed areas only. Poor condition: 1054m 2022m Timber cog has been erected in an area where the haunch is severely hinging. Good condition: 2046m General Note The defects are concentrated in the areas where the steel reinforcing ribs are. Summary of where the tunnel is wet/damp/dry Location Condition 0m 850m Wet, with heavy water ingress through sidewalls/haunches/crown in isolated areas 850m 2691m Completely dry (tunnel lining and trackbed) 2691m 3180m Damp/Wet. Trackbed is generally dry Page 2 of 11

5 TUNNEL SURVEY NOTES Hammond (ecs) ltd Contract No: HRE823 Region: South Wales Location: Rhondda Tunnel HRE Engineer Lee Holland Structure Number: RSB 1m 44ch Date of Survey 16/04/2015 Grid Reference: SS Completed by JM, NG Location 0m 0m 295m 15m 50m 50m 61m 62m 62m 78m 78m 206m 206m 212m 212m 212m 395m 395m 644m 644m 838m 838m 850m 2691m 850m 961m 978m 1054m 1054m 2022m 2022m 2046m 2046m 2691m 2691m 3180m 3180m Comments/Defects Access shaft. (NE Portal) Generally wet with very deep open joints to the entire cross section of tunnel. The pointing material is very soft to the touch. Very deep open joints in entire cross section of tunnel. Isolated small areas of missing masonry in the haunch. Heavy water ingress through haunch and soffit. Corrugated steel sheeting fixed up into the arch to collect the water ingress and channel it down to the sidewalls. Steel reinforcing ribs. Severe hinging in the haunch. Masonry peeling away in the haunches revealing the rock behind. Several areas of partially collapsed or missing masonry in the soffit. 3no Steel reinforcing ribs. Spalling to the concrete sidewalls in isolated areas throughout its length. 6no Steel reinforcing ribs. The tunnel and trackbed is completely dry for this length. Steel reinforcing ribs. Isolated soffit collapses. Steel reinforcing ribs. Isolated soffit bulges and collapses. Timber Cog. The timber is soft, hollow and generally rotten. Severe hinging in middle of haunch. Bulge monitoring points evident. The cog has been erected to prevent the tunnel from hinging any further. Damp section. Block-work wall and capped ventilation shaft. (Towards SW Portal) Page 1 of 11

6 Photo Ref: A Entrance shaft at the NE portal Photo Ref: B General photo showing tunnel in the masonry section Page 3 of 11

7 Photo Ref: C Photo showing an example of the reinforcing ribbed section. This is where all the defects were noted Photo Ref: D General photo showing tunnel in the masonry section Page 4 of 11

the soffit Corrugated sheeting fixed into the soffit Page

8 Photo Ref: E Photo Ref: F Corrugated sheeting fixed into the soffit at 62m to contain the water cascading through the soffit Corrugated sheeting fixed into the soffit at 62m to contain the water cascading through the soffit Page 5 of 11

9 Photo Ref: G Photo showing an example of the reinforcing ribbed section. This is where all the defects were noted Photo Ref: H Photo showing the typical defect in the soffit of the arch (missing or partially collapsed masonry) Page 6 of 11

masonry) Photo showing an example of the reinforcing ribbed

10 Photo Ref: I Photo Ref: J Photo showing the typical defect in the haunch of the arch (missing or partially collapsed masonry) Photo showing an example of the reinforcing ribbed section. This is where all the defects were noted Page 7 of 11

11 Photo Ref: K A timber cog has been erected at m to prevent a tunnel collapse due to severe hinging in the haunch Photo Ref: L Photo looking through the 24m long cog section Page 8 of 11

12 Photo Ref: M Blockwork wall and shaft at 3180m towards the SW portal Photo Ref: N Photo looking up the shaft. The top includes a permanent steel shutter supported by 5no beams Page 9 of 11

arches) General photo showing tunnel in arches) Page 10

13 Photo Ref: O Photo Ref: P General photo showing tunnel in the section where the sidewalls are concrete (including arches) General photo showing tunnel in the section where the sidewalls are concrete (including arches) Page 10 of 11

Note very deep open joints in the sidewall which is typical from 0m 295m.

14 Photo Ref: Q Photo showing water cascading through the sidewall at 62m where the tunnel is very wet. Note very deep open joints in the sidewall which is typical from 0m 295m. Photo Ref: R Photo showing the typical defect in the haunch of the arch (missing or partially collapsed masonry) Page 11 of 11

REPORT OF BUILDING INSPECTIONS TECOLUCA, EL SALVADOR. Prepared by: Global Village Engineers

REPORT OF BUILDING INSPECTIONS TECOLUCA, EL SALVADOR Prepared by: Global Village Engineers 23 JANUARY, 2001 23 January 2001 Senor Carlos Cortez Hernandez Alcaldia Municipal de Tecoluca San Vicente, El