Bus and Driver Scheduling

Bus and Driver Scheduling are an integral part of bus operations. Bus operators in Singapore rely on the adherence of schedules to meet service standards laid out by the Public Transport Council, and to maximize the efficiency of bus services.

Public Transport Operators (PTOs) are faced with many challenges in the area of bus operations, such as meeting service requirements for various bus routes, and the pressure to maximize the use of their resources (be it bus drivers or vehicles). In urban cities with large-scale bus operations such as Singapore, bus planning is of great importance, since large amounts of money can be saved if the available resources are employed efficiently, or wasted if not.

Scheduling flowchart

Scheduling flowchart

Bus and driver scheduling are important in the day-to-day management of resources. A simplified diagram is shown on the right to illustrate what goes on within bus operations. A dedicated scheduling department is responsible for the complex job of managing overall movement of buses on a day-to-day basis, by ensuring that buses need to be where they should be, since buses can ply multiple bus routes in a day. This translates to vehicle scheduling, where buses are assigned to various bus routes, and every single bus has a fixed timesheet to follow throughout the day. Because buses can be taken out of revenue service for various reasons (such as breakdown or scheduled maintenance works), every revenue service bus starts its day by being allocated to a shift, which will be fully explained later.

After vehicle scheduling is done, driver scheduling is needed to generate daily duties for bus drivers. Drivers are allocated to various working shifts, during which they will be in charge of the operations of their respective buses in adherence to the published timesheet. Finally, driver rostering constructs duty rosters for individuals bus drivers, including overtime work, rest days and holidays. These four aspects of bus and driver scheduling are closely interlinked and key to the daily operations of bus services. However, emergency situations allow for impromptu changes in vehicle and driver scheduling, which will be discussed later on.

A – Vehicle / Driver Scheduling:

Bus operations rely on vehicle scheduling to assign buses on various bus services on a daily basis. This is done by arranging bus deployments in shifts, where every shift will be allocated to a driver. The shift dictates the scheduled movement of a particular bus for a duration of time, and every shift is given a reference code which differs between bus operators. Commonly used shift durations are summarized below. Note that SBST uses single-letter notations but SMRT uses double-letter notations.

SBST SMRT Shift Duration
A AM Morning shift 5-6am till 2-4pm.
P PM Afternoon shift 2-4pm till 11+ pm.
S S1 Split shift 5-7am till 8-9am, Split Break, 3-4pm till 6-7pm.
E S2 Extended shift 5-7 am till 9-10am, Split Break, 12-1pm till 6-7pm.
T TQ Three-quarter shift 6-7am till 6-7pm.

A and P shifts are the most commonly-used shifts. The A or AM shift takes care of morning shift operations, while the P or PM shift continues off from the AM shift, and ends after revenue services ends for the day. The AP shift is a common designation for a bus that operates for the whole day (hence covering the working hours of two bus drivers). Drivers are split into AM shift and PM shift, as explained above. Both A and P shifts have a designated mealbreak times, lunch for A shift and dinner for P shift.

S shift, or split shift, is where a regular seven to eight-hour shift is split into two parts: morning and evening. This form of split-working-day arrangement is common during weekdays to accommodate additional drivers during the rush hour, where more buses are deployed. Drivers are on the job during the peak periods only, and receive a unpaid break-time (Split Break (SMRT) & Swing Break (SBST)) in-between shifts similar to E shift. Due to the lengthy nature of such breaks, drivers can return home during their long breaks or rest at the bus depot. Despite the odd working hours, split shifts provide more opportunity for overtime pay. Some split-shifts end as late as 9pm or later.

E shift, or extended shift, is used by SBS Transit and usually tied to bus services with high student demand and matches the operating hours of various education institutions (though not exclusively), and also has the longest working hours. The benefits of the extended shift caters not only to peak hours, but also for the pre-peak afternoon hours where additional buses are needed. This eliminates the need for more AM/PM shift buses which potentially drain resources during generally low-demand periods (such as 9am-12pm and 8pm onwards). In SMRT practice, S2 (which is explained later) achieves the same effect, and are used more frequently in scheduling than SBST.

T shift (SBST), also known as TQ shift (SMRT), refers to three-quarter shift, starting at around 6-7am and ending at 6-7pm.  T shift is usually given out on weekends where bus services experience stable demand for the day but substantially less demand at night, hence the T shift fits well with regular commuting patterns. Also, day-operating services such as Service 115 use the T shift on a daily basis. All T shifts include a mealbreak (lunch), but only the longer-duration ones come with a coffee break in the afternoon.

It is worth mentioning that mealbreaks that we discuss about are referring to paid mealbreaks, i.e. lunch or dinner breaks incorporated into part of the driver’s working schedule and hence included in his or her paid working hours.

Shift hours diagram

Shift hours diagram

SBS Transit:

SBST uses the A/P/S/E/T notation to denote shifts. Shifts are organised as: (Reference Number) (Shift Duration), without the inclusion of the bus service number. Reference numbers are used in the A/P/S/E/T order, starting from one, until the last shift.

For illustration purposes, let’s consider SBS Transit Service 4, with six buses in it’s fleet (as of 2013).
The weekday deployment is as follows: 4AM4PM / 1S / 1T .
Hence, the weekday shifts are: 1A, 2A, 3A, 4A, 5P, 6P, 7P, 8P, 9S, 10T

Notice that the numerical order adheres to the APSET notation. 1A and 4P use the same bus, same for 2A & 6P, 3A & 7P, and 4A & 8P. Collectively, 1A to 8P can be referred to as 4 A/P, which means that 4 buses operate on Service 4 for the entire day. Subsequently, 9S and 10T refer to one S-shift and one T-shift bus respectively. Hence, service 4 has 10 shifts every day.

Let’s use another example, SBS Transit Service 156
The weekday deployment is as follows: Hougang 7AM8PM / 7S; Bt Batok 4AM-4PM / 1S 1E

Because service 156 is dual-depot controlled, the APSET notation will be continued in numerical order after completing all the shifts of the first depot.

Hence from Hougang Depot, the weekday shifts are:
1A, 2A, 3A, 4A, 5A, 6A, 7A, 8P, 9P, 10P, 11P, 12P, 13P, 14P, 15P, 16S, 17S, 18S, 19S, 20S, 21S, 22S

Continuing on, Bukit Batok Depot shifts are:
23A, 24A, 25A, 26A, 27P, 28P, 39P, 30P, 31E, 32S

Collectively, Service 156 has 7 – 8 A/P buses from HGDEP and 4 A/P buses from BBDEP. Including E and S shifts, this service has a total of 32 shifts in a day, corresponding to a total of 32 drivers deployed on this route on weekdays.

There are exceptions to the numerical order used in this notation. Duty numbers with 80 and 90 correspond to drivers who are allocated to drive at least two different buses during the course of their shift rather than sticking to one bus for the whole day’s shift, a practice known as “jumpbus”. For deployment nomenclature, visit the Bus Deployments Overview article.

SMRT Buses:


SMRT uses a slightly different method of denoting shifts, using AM, PM, S1, S2 and TQ to denote shift duration. Shifts are organised as: (Service Number)(Shift Duration)(Duty Number). Reference numbers are two-digit numbers than run in numerical order, with exceptions (later explained). For AM and PM shifts, similar duty numbers usually denote same vehicles, e.g. 189AM01 and 189PM01 use the same bus (but different drivers on the AM and PM shift respectively). Combined, they are referred to as 189AP01.

Although SBS Transit uses the letter S to designate S shift, SMRT employs a more complicated designation involving S1 and S2. There are distinct differences between these two shifts, the main one being that S1 has more trips for the AM portion, while S2 has more trips for the PM portion.

S1 shift working hours are usually between 6am to 11am/12pm, followed by 4pm to 7pm/8pm. They almost always never come with a paid mealbreak (some rare exceptions have a lunchbreak included, such as Service 171 which ends its morning portion at 1pm). The S1 shift is usually heavier on the morning portion and less on the evening.

In contrast, S2 working hours are usually between 6am to 9am/10am, followed by 1pm to 7pm/8pm. They always come with a scheduled lunch break (lunchtime varies between shifts) and an afternoon coffee break. The S2 shift is usually less heavy on the morning portion but heavier on the evening portion. It is also the longest duration shifts in SMRT bus planning, commonly exceeding 9 hours. Before SMRT actively cut down on driver operating hours, its split shifts routinely exceeded 10 hours, and the longest ones exceeded 11 hours.

Another quirk in SMRT shifts is the use of the number 5 in the first digit of the duty number to denote a crossover slot. For example, duty 911S150 is used for an Intratown 911 bus that does crossover trips to Feeder 901 during Weekdays AM Peak. Although the crossover service is not reflected in the duty number, S150 is an indication of a crossover bus (since S1 is the shift and 50 is the duty number). The use of ‘5’ in the first digit always refers to a crossover slot, but not exclusively, due to the large number of crossover trips involved in SMRT bus planning.

As an example, we use SMRT Service 169.
The weekday deployment is as follows: 11AM11PM / 9 S1 / 3 S2 (as of 2013)

Hence, the shifts are as follows:

  • AM: 169AM01 169AM02 169AM03 … … 169AM11
  • PM: 169PM01 169PM02 169PM03 … … 169PM11
  • S1: 169S101 169S102 169S103 … … 169S108 + Additional 169S190
  • S2: 169S201 169S202 169S203

Hence in total, service 169 has 34 shifts operating in total on a weekday. 169S190 is a BSEP slot: regardless of service, BSEP Buses in SMRT are assigned a duty number of 9x. In the above case this case the duty number is 90, operating on S1 timesheet.

It is worth noting that buses from other services perform crossover trips on Service 169. Because a shift denotation can only reflect its parent service, it is difficult to estimate the full number of buses on a route unless the crossovers are known. In the case of service 169, duties 857S150, 963S159 and 971ES201 perform crossovers to this service during weekdays. Also note how the 5x duties denote crossover slots (as mentioned previously).

Here are some case examples of duty numbers:

  • 854AM14: Service 854 bus, #14 on the AM shift. Does one trip of Express 854E on weekday mornings.
  • 971ES102: Service 971E bus, #02 on the S1 shift. Does crossover trips on Service 962 (not reflected in duty number).
  • 167S154: Service 167 bus, #54 on the S1 shift. Does crossover trips on Express 854E followed by Premium 531 on weekday AM peak hours.
  • 854S201: Service 854 bus, #01 on the S2 shift. Does one trip of Express 854E on weekday mornings.
  • 945S201: One of the duties spanning the most number of bus services, namely 188, 530 and 941 during AM Peak and 945 during PM Peak. This shift has since been modified to exclude 941.

Peak hour bus routes are operated solely on S-shift buses. For example SMRT Service 177 runs of 4 S1 buses, with a duty code of 177S150, 177S151, 177S152 and 177S153. All four buses cross over to Service 925 (hence the 5x duty number).

Bus schedules are part of the internal operations of bus companies and are not available to the public, and all schedules available to bus enthusiasts are based on physical spottings of timesheets on various buses. By understanding how shifts work, one can easily appreciate the massive complexity that goes into planning daily bus operations. SMRT NightRider services had previously operated on a dedicated fleet using the PM timesheet designation (i.e. NR1PMxx), which has since been replaced by crossover buses from trunk services.

B: Timetables

Bus companies issue timetables for respective shifts. When a driver is in charge of a particular shift for the day, he or she will need to follow the timetable issued by the scheduling department. Hence. the timetable dictates bus movements throughout the duration of the shift.

SBS Transit and SMRT issue different forms of timetables to drivers, as we will explore below.

SBS Transit:

Service 83, shift 14S

Service 83, shift 14S. Click for larger image

Here is a sample timesheet published by SBS Transit. At the top left hand corner, it is introduced that this is the 14S timetable for Service 83, a loop service. All timings are indicated in bold so it’s easy to see whats going on. Here, the page is divided into two parts, with the morning split shift timings at the top and afternoon split shift timings at the bottom.

This particular shift starts at 5:14am from Hougang Depot (HGDEP), and downroutes to bus stop 65151 (the 9.9km mark) where it does a partial trip of Service 83 from that bus stop to Punggol, reaching the interchange at 5:44am. After performing five more complete rounds of service 83, the bus returns to Hougang Depot at 11:59am, concluding the morning shift. “SWING 1159 1602” implies that the driver takes a split break from 1159hrs and must report back to the depot at 1602hrs.

For the afternoon shift, the bus departs the depot at 1602hrs and reaches Punggol Interchange at 1624hrs, thereby immediately starting a trip of Service 83, and returning back to T1 at 1724hrs for a six-minute break, departing again at 17:30hrs. After it’s third trip of the PM shift, the driver leaves Punggol Int at 1936hrs and returns to the depot at 1958hrs, concluding the shift for the day.

A PDF copy of the timesheet is available at the bottom of the article.

SMRT Buses:

SMRT buses uses a more complicated timesheet, which may be confusing at first but easy to read after some practice. The following timesheet is an old version and SMRT has since revised its timesheet layout.

911S201 timesheet

911S201 timesheet. Click for larger image.

Here we have a sample timesheet from 912S201, an Intratown 912 bus running on the S2 split-shift on weekdays. The “Block” is used to divide the timetable and is of little importance. We will go through the timetable starting from the top left. If you have noticed, this is an S2 timetable, which is equivalent to a E shift in SBS Transit.

The first entry shows the bus at Woodlands Depot at 5:54am, and at Woodlands Regional Interchange at 6:03am. This implies the first morning downroute from the depot. the 0 and 9 on the left column simply means that the bus has 9 minutes to get from the depot to the interchange, and there is no layover time after reaching the interchange.

Below, the second set of entries shows the bus doing two full rounds of Intratown 912. On the leftmost column, 912 stands for the service number, 0 refers to the layover time in minutes (upon completing the route), and 72 refers to the runtime in minutes. Notice that the bus starts the trip at 6:03am, right when he reaches the interchange, hence the layover time is zero. The second left column indicates the various distances that correspond to the bus stops written in the center column. Since our timetable is dated in 2007, the numbers would be in fare stages, but all recent timetables have their distances written in kilometers. After two consecutive trips, the bus arrives at Woodlands Interchange at 8:28am, where it will go out of service and return to the depot at 8:36am. Notice how the shift does not incorporate any layovers at all, from leaving the depot until returning to the depot, a duration of 2.5hours. This is reflective of the rigor involved in driving Intratown routes during the peak hours, to cater to the large increase in demand during peak hours.

Upon arriving at the depot, the driver takes a split break until 12:09pm, where he departs the depot returns to Woodlands Interchange at 12:17pm, immediately starting another round of 912 until 1:28pm. After the completion of the 1328hrs departure of 912, he gets an 11 minute break. The rest of the timetable can be inferred from the above information.

Finally, note that there is a paid mealbreak from 17:03hrs to 17:30hrs. As explained under section A, all S2 shifts come with a mealbreak, while S1 rarely or never comes with a mealbreak.

A PDF copy of the timesheet is available at the bottom of the article.

C: Working Hours

Bus driver working hours are entirely dependent on the shift that they are allocated to. Depending on shifts, bus drivers report to either a bus depot or a bus interchange to start their shift. Most AM shift drivers would collect their buses from the depot at the start of their shift, while PM drivers would take over buses from their AM counterparts at the interchange, driving them back to the depot at the end of the day, and the cycle repeats.

Currently, both SBS Transit and SMRT Buses employ a six-day work week, with the basic working hours per week spread across six days. SMRT employs a 44-hour basic working week, and that for SBST is likely to be around the same. Drivers who exceed the basic working hours get paid an overtime rate of 1.5 times the usual pay. Overtime pay is capped at 72 hours per month, in line with Ministry of Manpower regulations. The basic pay for Singaporean bus drivers is around $1,600 per month. After factoring in overtime, allowance and incentives, pay for Singaporean bus drivers can go up to $2,500 on average. This was further increased up to $3,500 with a newer wage model introduced in late 2013, which added more promotion ranks for well-performing bus drivers and trains them for more supervisory roles.

Working hours for bus drivers are entirely dependent on the schedule, and does not factor in unscheduled delays such as traffic congestion; drivers are not paid extra for being late, even for reasons beyond their control. However, drivers do get overtime pay for emergency pullovers and/or unscheduled emergencies which extend their regular working hours (such as Rail Bridging Services and other extra duties after working hours)



Sample SBS Transit timesheet – sv83: 14S (PDF)
Sample SMRT Buses timesheet – 912S201 (PDF)

Please note that timesheets have been phased out and do not represent actual shifts currently in operation. SMRT has since revised their timesheet to a slightly different layout, but retains most characteristics as the example presented above.

Back to Bus Articles

5 thoughts on “Bus and Driver Scheduling

  1. Error: S S1 Split shift 5-7am till 8-9pm, rest, 3-4pm till 6-7pm.
    Correct: S S1 Split shift 5-7am till 8-9am, rest, 3-4pm till 6-7pm.

  2. For the SBS Transit shift number part on service 4,
    should be “1A and 5P use the same bus” and not “1A and 4P use the same bus”.

  3. how is the shift pattern of a smrt bus captain? is it like after 5 mornings get 1 off then followed by 6 afternoon then 1 off. correct me if i m wrong.

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