TD
The Train Describer feed provides low-level detail about the position of trains and their train reporting number through a network of berths. Usually, but not always, a berth is associated with a signal - but there are locations (such as terminal platforms at stations) where there may be more than one berth. From each berth, there are zero or more other berths which a train description may step in to. A step between berths represents movement of the train from one berth to another. Some of these steps may be one-way, some may be two-way.
To access the TD data feed, you must select and subscribe to the appropriate geographical topic(s) on the My Feeds page on the Data Feeds website (see the about the feeds page.)
See also the list of train describers page, where you will find information on specific TD's including user contributions & documentation provided by Network Rail such as S-Class data, maps and stepping data.
Topics
Train Describer messages (C-Class and S-Class) are presented on ActiveMQ topics:
The topic named 'TD_ALL_SIG_AREA' contains data from all train describers, and is not filtered. The mappings for the other topics have not been updated for a number of years and thus may contain little or no data.
| Topic | Description |
|---|---|
| TD_ALL_SIG_AREA | All signalling areas |
| TD_SE_SIG_AREA | Scotland - East |
| TD_SW_SIG_AREA | Scotland - West |
| TD_LNE_NE_SIG_AREA | London North Eastern - North East |
| TD_MC_EM_SIG_AREA | Midlands & Continental - East Midlands |
| TD_LNE_GN_SIG_AREA | London North Eastern - Great Northern |
| TD_LNW_LC_SIG_AREA | London North Western - Lancashire and Cumbria |
| TD_LNW_C_SIG_AREA | London North Western - Central |
| TD_LNW_WMC_SIG_AREA | London North Western - West Midlands Central |
| TD_WCS_SIG_AREA | West Coast - South |
| TD_ANG_SIG_AREA | Anglia |
| TD_KENT_MCC_SIG_AREA | Kent and Midlands & Continental |
| TD_SUSS_SIG_AREA | Sussex |
| TD_WESS_SIG_AREA | Wessex |
| TD_WTV_SIG_AREA | Western - Thames Valley |
| TD_WWC_SIG_AREA | Western - West Country |
| TD_WWM_SIG_AREA | Western Wales and Marches |
Message types
The Train Describer feed has seven message types, split into two classes. See individual pages for further details.
- C-Class Messages provide information about train describer berths and descriptions
- S-Class Messages provide signalling state information
| Network Rail Open Data Feeds | |
|---|---|
| Data Feeds | About the Feeds • Account States • Durable Subscriptions • Example Code ( PHP / C# / Java / Ruby / Node.js) • Advanced Uses • FAQ • Release Notes |
| RTPPM | RTPPM Feed |
| Train Movements | Train Movements Feed • Train Activation • Train Cancellation • Train Movement • Train Reinstatement • Change of Origin • Change of Identity • Change of Location • TSPEED Field • Planned Cancellations • Cancellation Codes |
| TD | TD Feed • C-Class Messages • S-Class Messages • Train Describers • TD Berths |
| VSTP | VSTP Feed |
| TSR | TSR Feed • Route Codes |
| SCHEDULE | SCHEDULE Feed • TIPLOC Records • Schedule and Location Records • Association Records • CIF Codes • How Scheduling Works • Allowances |
| Reference Data | Reference Data Feed • TOC Codes • CIF Codes • Delay Attribution Codes • Identifying Locations (STANOX, TIPLOC, NLC and 3-Alpha Codes) • STANOX Geographical Areas • Train Planning data (BPLAN) |
Cross-Midnight bug
There is a known issue with the TD feed that can cause a very small number of messages to be given an incorrect timestamp. The NR TD feed assumes that all TD events occur on the date they are received by the feed. This assumption is almost always correct but can be wrong for messages received <1s before midnight. Such messages can easily be spotted and corrected by comparing the timestamp in the message to the current time (in UTC) and adjusting by 24 hours if there is a large difference.
The impact of this is very minor, usually only 3-5 messages per day.