Rail systems in France, Iberian peninsula and Great Britain that progressively emerged during the 19th had take topographic and political discontinuities into account, reinforced in the case of Spain by the choice of a different track gauge. The continuity of train services had also to suffer from many other technical disruptions such as different loading gauges, axles load, electrification system, length of train and of course different railway signalling and circulation rules. The traditional divisions went through a dramatic technical and political evolution during the nineties. On both borders, the development of high speed rail service was contemporary with realisation of the Single European Act (SEA). Since 1994 London is connected with Paris and Bruxelles and the first Spanish line between Madrid and Sevilla opened in 1992 will be connected soon to the French high speed offer. But practically, the systems are far from being continue and unified. The current situation can be explained by the lasting technical heritages as well as by recent political decisions. In fact, the attention of the three countries to their mutual interfaces is quite different. A comparative approach will pinpoint the local balances of territorial and technical differences and their recent evolution. UK and 2 Ireland decided to stay out the Schengen Agreements and maintained an identity control on travellers that locally reinforced the barrier effect. Due to the advantages of the new transport offer, the custom controls have been displaced at the departure stations (St Pancras International or Paris-Nord). It also produced the interesting figure of the intermittent custom installation in Calais-Fréthun or Lille-Europe. On the contrary, Spain always claimed its choice to reduce its access restriction to the rest of Europe. The UIC standard gauge has been introduced in the Iberian peninsula to ease the access to the French network. If in former national-led systems the disruptions of technical and politic lines were obvious and generally overlapped each other, the new European integration context seems to alienate this divide. High speed train offers and their recent evolution introduce a new differentiated way of managing the border effect. The presentation successively will detail and analyse the international contexts of the French-Spanish and French-British borders. A further point will present a more general and conceptual approach in how political and technical discontinuities in transport influence each other and create through a co-evolution process symbiotic configurations. Although the expression of the rail border effects are quite different in the two cases, the management of discontinuities shows a common tendency to accommodate with the transport expectations and a spread out of the former disruption at the border all along the network.