page_title: Pont-y-Cafnau
section_title: Design
hierarchical_section_title: Pont-y-Cafnau / Design
caption_attribution_description: Pont-y-Cafnau
context_page_description: The Pont-y-Cafnau is a 14.2-metre long iron truss bridge over the River Taff in Merthyr Tydfil, Wales. The bridge was designed by Watkin George and built in 1793 for his employer, the Cyfarthfa Ironworks, to support both a tramway and an aqueduct to carry limestone and water into the works. A Grade II* listed building and Scheduled Ancient Monument, the Pont-y-Cafnau is the world's earliest surviving iron railway bridge.
context_section_description: The present bridge was designed by Watkin George. George had been trained as a carpenter, but in 1792 became the chief engineer of the ironworks and a partner in the business. The bridge is composed of two cast iron A-frame trusses supporting a rectangular 2-foot by 6-foot-2-inch cast iron trough. This lower trough carried the Taff Fechan leat and acts as a girder supporting the plates acting as the railway sleepers, into which the rail chairs are integrally cast.  Wooden uprights were attached to the iron risers that passed through the apex of each of the A-frames and these supported the upper trough carrying the Taff Fawr leat. Reflecting its designer's roots in carpentry, the members composing the trusses are joined by dovetail and mortise and tenon joints commonly used in wooden structures.
caption: Pont-y-Cafnau, showing detail of joints
exif: {"Image Make": "Panasonic", "Image Model": "DMC-TZ10", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Ver.1.1", "Image DateTime": "2012:11:23 12:28:42", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "642", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 50, 53, 48, 0, 0, 14, 0, 1, 0, 22, 0, ... ]", "Image Tag 0xC6D2": "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ... ]", "Image Tag 0xC6D3": "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ... ]", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail Orientation": "Rotated 90 CW", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "11764", "Thumbnail JPEGInterchangeFormatLength": "9132", "Thumbnail YCbCrPositioning": "Co-sited", "EXIF ExposureTime": "1/60", "EXIF FNumber": "9/2", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "400", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2012:11:23 12:28:42", "EXIF DateTimeDigitized": "2012:11:23 12:28:42", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "86/25", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "139/5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2858", "EXIF ExifImageLength": "3646", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "11240", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0/0", "EXIF FocalLengthIn35mmFilm": "169", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "High gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}