These are good questions concerning traffic flows over two unrelated connections of Conrail in the late 1980's and early 1990's. In each case, the commercial decision as to routing of traffic is a customer decision; notwithstanding marginal considerations or "inducements", the commercial routing decision is always the customer's. The circumstances of the D&H and the B&M arrangements were different and unrelated to each other...
As to CR and CP, with CP's acquisition of D&H, CP acquired a more direct route via Albany for traffic destined to points between NY and DC, including newsprint (and other commodities) from on-line origins in Quebec. CP+D&H substantially increased its length of haul on this and other traffic, placing CR in a very difficult - if not quite impossible - competitive situation. The impact of CP's acquisition of D&H was not difficult to foresee. Prior to the assimilation of D&H by CP we enjoyed a long-term and mutually productive business relationship on traffic over Adirondack Jct. After these changes had taken effect CR and CP continued to maintain a cordial business relationship on operational matters for many years.
The B&M (GTI) was a very important connection of CR's, for which we (CR) identified an opportunity to improve service, to our mutual benefit. CR had completed a clearance improvement project, a TCS project, and had fully installed welded rail across its Boston Line east of Selkirk, NY. On the other hand, the B&M had limited clearances through their Hoosac Tunnel, plus a great deal of track and signal work to be completed, if their route were to become fully competitive.
CR acquired trackage rights over the P&W in Worcester, enabling finished vehicles in enclosed multi-levels to reach Ayer on the B&M. Other traffic was moved by CR between Selkirk and Ayer under a haulage arrangement, eliminating torturous reverse movements and delays at Rotterdam Jct. while expediting traffic with preblocking to CR points (WB) and to GTI (B&M, MEC) points (EB). Service on all traffic improved significantly. As a haulage arrangement, and consistent with shipper-specified routing, the haulage traffic remained in B&M's account while on CR between Selkirk and Ayer. In this case, it was a simple matter of two roads cooperating to share their respective natural advantages, to their mutual benefit - and that of their customers!