This happens rather frequently for the first few bus stops from the bus interchange, the discrepancy is rather huge. This can be easily solve when you align the timing with the bus interchange. Very funny error.
I don’t think this can be resolved quite easily. For I believe the ‘exact’ departure time from the interchange or terminal are subject to at least one human factor:
a. the ‘actual’ time the bus captain drive off from the bus interchange.
The arrival time at the very first stop likely to be from an ‘ideal’ bus departure time table.
I may understand wrongly though.
@goondu, you are somewhere right there.
“Bus Timing” vs “Bus Arrival” = not the same.
“Bus Timing” is frequently referred to Bus Timetable Frequency like 6-8 mins, 10-15mins etc like those you have seen on the Bus Stop for Bus Service Information according to the respective Peak/Off-Peak hours data row table.
“Bus Arrival” is when the Bus Captain updated their Bus Stop “stage” system (as when he/she is reaching the stop) and it will send to their own Bus Provider’s system (SBST, SMRT, GoAhead, TT, etc). Internally within the each of Bus Provider’s system (Ops Side), the Bus Provider’s Ops Team also keep track on their bus assets on the movement (location, speed, etc) with GPS from the bus to their internal system (not visible to other Bus Providers). The Bus Stop “stage” data will send to LTA system for consolidation and also available in their Public Facing API as Bus Arrival API via LTA DataMall.
OneMap Routing is based on “Bus Timing” when you selected PT mode while when you clicked on OneMap Bus Stop icon for Bus Arrival timing is based on LTA DataMall Bus Arrival API.
And also of cos the latency/delay from actual data update internally to API is one of the factors.