A dividing train is a passenger train that separates into two trains partway along its route, so as to serve two destinations. Inversely, two trains from different origins may be coupled together mid-route to reach a common endpoint. Trains on complex routes may divide or couple multiple times. The general term for coupling two or more trains along their shared route sections is portion working.
For example, the westbound Empire Builder travels from Chicago Union Station to, Washington, where its cars are divided into two trains: one continues to Portland Union Station and one to King Street Station, Seattle. On the eastbound trip, trains from Portland and Seattle are coupled at Spokane before traveling as one train to Chicago.
Dividing trains are useful where line capacity is limited, allowing multiple trains to use the same path over a congested part of a network. The common sections will often be the busiest parts of the routes.
On the initial leg of its journey, the train is driven as normal by a single crew. At a designated station before a junction, the train stops and some of the cars are detached, with passengers or goods still on board. The front part of the train then departs to run the remainder of its route. A second train is then formed from the detached cars, the points are changed at the junction, and a new crew drives the train on a different route to a second destination. Where the train is formed of multiple units – self-contained trainsets with their own propulsion and driving cabs – two or more units work in multiple on the first leg. After detachment, the second crew drives in the trailing unit's front cab.
On the return journey, the two trains may join at the same station where they divided. Special signalling is required at the station to allow a following train to enter the block currently occupied by the train in front in order for the two to couple. The British rail network uses a shunt signal to authorize this type of movement.[1]
A variety of portion working combinations is possible. For example:
For portion working to be successful, the operator may need to address many issues. For example:
Dividing trains can sometimes cause issues for unwary travellers, who may board the wrong car and thus arrive at an unexpected destination.[2]
| Route[5] | From | Dividing at | Destination |
|---|---|---|---|
| Montreal–Senneterre train | Montreal Central Station | Hervey-Jonction station | Senneterre station |
| Montreal–Jonquière train | Jonquière station |
There are several dividing train services in Japan, and each route has its own name.
The practice of portion working has been followed for a long time on the third rail network of lines in the South East of England, and has been more widely practised in continental Europe.[6] Elsewhere in the United Kingdom, the practice has been less common, because of a general reluctance to design the necessary modern signalling systems, and because of legal constraints on competition between operators.[7]
Dividing trains operate on several lines on the British railway network, mainly (although not exclusively) in the south of the country. To ensure consistent journey times, the front part of a dividing train usually becomes the rear of the returning service when it reunites.
In addition, some services detach carriages part-way along the route, and pick them back up on the return journey. This may be because a portion of the line has short platforms at a number of its stations, or because demand is much higher on one section than another.
| Route | width=150 | From | Dividing at | width=320 | Destination | class=unsortable | Remarks |
|---|---|---|---|---|---|---|---|
| Arun Valley line[8] | Front part non-stop to, then semi-fast or all-stations to | On Sundays calls at all stations to and divides there. | |||||
| Rear all stations to | |||||||
| Caledonian Sleeper[9] (Lowland) | Front part to | ||||||
| Rear part to | |||||||
| Caledonian Sleeper (Highland) | Front part to | ||||||
| Middle part to | |||||||
| Rear part to | |||||||
| Cambrian Coast Line | Front part to | Both parts call at, but use separate platforms there, and therefore must divide one stop earlier. | |||||
| Rear part to | |||||||
| Caterham line Tattenham Corner line | Front part to | Colloquially known as the "Cat & Tat". Was the most common service pattern on the branches from Purley before resignalling work made them an extension of the Brighton Main Line local tracks. | |||||
| Rear part to | |||||||
| Chatham Main Line[10] | Front part to | ||||||
| Rear part to | |||||||
| East Coastway Line | Eastbourne | Front terminates at Eastbourne | |||||
| Rear part to Ore | |||||||
| South West Main Line | Front part to | Most Dorset stations beyond Bournemouth have short platforms. During peak hours, trains divide at Southampton Central, with the front portion running fast to Bournemouth, then most or all stations to Weymouth. The rear part calls at most or all stations to Bournemouth or Poole.[11] | |||||
| Rear part terminates at Bournemouth, or runs separately to Poole | |||||||
| Front 5 carriages to | Sunday service | ||||||
| Rear 5 carriages to | |||||||
| West of England Main Line | Front part to | ||||||
| Rear part terminates at Salisbury |
| Route | From | Dividing at | Destination | Remarks |
|---|---|---|---|---|
| Amtrak routes | ||||
| Empire Builder | ||||
| Lake Shore Limited | Boston South Station | |||
| Texas Eagle | The division occurs only for the Sunset Limited's three weekly round trips. The Texas Eagle runs an additional trips per week between San Antonio and Chicago alone. | |||
| Sunset Limited | ||||
| Former Amtrak routes | ||||
| James Whitcomb Riley | Charlottesville | 1971–1976 | ||
| Floridian | 1971–1979 | |||
| National Limited | (pre-1978); (post-1978) | 1971–1979 | ||
| Lone Star | Fort Worth | 1975–1976, 1977–1979 | ||
| Inter-American | 1979–1981 | |||
| Pioneer |
| 1980–1997 | ||
| San Francisco Zephyr and California Zephyr | ||||
| Desert Wind | ||||
| River Cities | 1984–1993 | |||
| City of New Orleans | ||||
| Gulf Breeze | 1989–1995 | |||
| Crescent |