Following the completion of the improvements of the 1870s, the Durham Coast Line could be operated as a through route but, having not been constructed for such a purpose, doing so it remained challenging. One major issue was that any services running between Hartlepool and Sunderland still had to ascend or descend both the 1:44 incline at Seaton Bank, and the aforementioned incline at Hesleden Bank. To alleviate this, the NER developed plans to construct a new, more direct, line along the coast. Construction of this new line between Seaham Colliery on the LS&SR, and Hart Junction on the ex-HD&R route was sanctioned in 1894–95. However its construction was contingent on the NER purchasing the Londonderry Railway's Seaham to Sunderland route and this was not agreed until 1900 when the NER agreed to pay £387,000 for it.