The area covered by the two lines combined developed considerably serving collieries and the iron and zinc smelting industries, and the L&OR system was extremely busy in conveying minerals up until 1914.
A number of extensions to the system were made, even after takeover by the Great Western Railway in 1873 for management purposes and in 1883 as full amalgamation.
Passengers were carried on parts of the network, but were never dominant except at Porthcawl, which declined as a harbour and arose as a holiday and residential location.
In the first half of the eighteenth century the area was entirely rural, but coal outcropped in the ground and was used by farmers, and some was taken away for sale by pack animal.
[3] Even the earlier, small-scale iron and coal industries around Maesteg, and further south along the Cefn Cribwr ridge, created a demand for ship-borne transport to market.
[4][5][6][7][3] As well as conveying mineral products down to Porthcawl for shipping transport away, it was to bring limestone (used for fluxing in iron making) up from Cornelly, and also to a certain extent timber for mine use.
The line was to use stone-block sleepers and cast iron fish-bellied edge rails,[8] and the track gauge was to be 4 ft 7 in (1,397 mm) and its length would be 17 miles (27 km).
There were already a number of tramroad connections to works in the Tondu and Maesteg area, and the opening of the line, giving easy access to the dock at Porthcawl, encouraged the establishment of further metal foundries and collieries, in many cases served by private tramroads in connection with the DL&PR and in other cases purely internal and private.
It then continued through Commercial Street to Bethania Street and along Llwydarth Road to the Cerdin (Cross Inn); thence to the Llwyndurys weighing house at Pontrhydycyff (Llangynwyd), after which it ran across the main road, and continued behind the modern Maesteg Comprehensive School to the old Gadlys Woollen Mill, where its embankment can be traced across Nant-y-Gadlys.
The broad gauge connection, known as the South Wales Junction Branch Railway, was constructed almost immediately, and may originally have been intended as a transhipment siding.
The act authorised the re-incorporation of the company with a capital of £200,000, with powers to purchase the Bridgend Railway for £3,000, and to enter into working arrangements with the SWR.
The short South Wales Junction Branch Railway at Stormy was removed after the opening of the LVR, the only connection with the SWR then being at Bridgend.
The LVR line and the South Wales Railway (now GWR following amalgamation) route were not immediately adjacent and there was no connection between them, and the stations were not close together.
[5] The Bridgend Railway route fell into disuse and later became used as a roadway; this was also the fate of parts of the DL&PR in the upper Llynfi valley.
[6][21] Mining output and the ironfounding businesses in the Llynfi and Ogmore valleys continued to grow, and indeed it was obviously outstripping the limited capacity of Porthcawl harbour to handle it.
Much larger and better protected from prevailing winds, it cost £250,000 to build, and was engineered by R. P. Brereton, sometime the principal assistant of Isambard Kingdom Brunel.
The project would have been extremely expensive, although the London and North Western Railway encouraged it and would no doubt have contributed to the cost in order to get the access.
[5] On 16 May 1873 the L&OR agreed with the Great Western Railway (GWR) that the latter would take over the working of their line, which by now extended to 27 miles (43 km), reaching 26 collieries.
Now capable of handling vessels of 2,000 tons, it had become an important gateway for mineral products and incoming necessities, including timber for the mines, and a shipbuilding business had been established.
The construction involved driving a tunnel 1,594 yards (1.458 km) in length, and making a large single span bridge crossing the River Afan at Cymmer.
For some decades the little harbour enjoyed considerable success, but the increasing size of sea-going shipping and the difficult seaward access eventually militated against it in competition with larger and better equipped ports elsewhere.
It served a colliery at Gilfach Goch, but at the time was separated from the OVR network, and it was worked by the GWR; the line was broad gauge.
[5][3][10] Now that the South Wales Main Line was standard gauge, the possibility opened up of taking Ogmore Valley minerals to Cardiff, or Penarth, where better shipping facilities existed.
However, as a result of a general depression in trade, the scheme was long delayed, and it was not until 25 October 1876 that a branch line was finally opened to Blaengarw at the head of the Garw Valley.
The poor approach to Porthcawl Dock, together with its inadequate facilities, once more made it impossible for the site to compete economically with other South Wales ports, especially as larger steamships were coming into use.
[3] When the Vale of Glamorgan Railway was being constructed, ready for its opening in 1897, it had sought running powers to Tondu, but these were refused, and exchange sidings had to be built at Coity Junction.
[27] The mineral wealth of the Rhondda Valley proved immensely lucrative to the Taff Vale Railway, and later others, in conveying coal to Bristol Channel ports for shipment.
[28][12] On 31 August 1897 the Port Talbot Railway and Docks Company opened its mineral line through Maesteg, on a sinuous west to east alignment crossing over the L&OR route.
As a south to west curve, it was used by limestone traffic between Cornelly Sidings and the Abbey steelworks, and by morning and evening residential passenger trains between Swansea and Porthcawl.
On 26 October 1992 the line between Bridgend and Maesteg was reopened by British Rail and Mid Glamorgan County Council for passenger trains.