Loop routes

Loop routes (or circular routes) are a unique form of bus routing. As its name suggests, a loop route only has one terminus, unlike bidirectional routes or unidirectional routes with no return trips. Buses leave the terminus and complete their route by returning back to the same terminus. Loop routes provide continuous bus service along a longer stretch of road compared to an ordinary bidirectional route. Technically, passengers can pay a fare for the full route, ending up at the bus terminus. However, some exceptions do exist, and passengers may be required to alight at the looping point.

The point where a loop service turns back towards its starting point (and merges with its own forward route), is known as a looping point. After the looping point, buses resume their return route back to the bus terminus. Looping points can be named after street names (e.g. Changi North Crescent) or places of interest near the looping point (e.g. Singapore Zoo). However, not all loop routes have a defined looping point.

Some special cases do exist with loop routes. For example, some bidirectional trunk routes operate like loop routes, and drivers do not park their buses nor get a layover at the bus terminal. Some loop routes have multiple looping points, and some have looping points within restricted areas.

Some loop services have their Electronic Display Systems (EDS) programmed with both directions of the loop route, and bus drivers will switch the directions on their EDS at the looping point. Some other services, e.g. 4 and 116, have an EDS display of both the terminus and the looping point, hence eliminating the need for switching the EDS. On older buses, drivers have to manually flip their side destos by removing them out of the desto holder and putting them back in. This was because both sides of the desto was printed with route details. This practice was phased out with the retirement of square destos. Rectangular destos were featured in Volvo B10M Mark IV and air-con double decker buses.

1. Normal loop routes
Let’s say Bob is at point A and needs bus connections to point B and C. With a normal bidirectional route passing through point B, Bob will not be able to head for point C. Similarly, with a normal bidirectional route passing through point C, Bob does not have bus connections to point B. Such loop routes solve the problem often by using different sections of road in their forward journey and return journey.

The examples are:
 * Service A1 (Orchard Road)
 * Feeder Services

2. Looping at bus interchange
Some loop routes loop at bus interchanges, without having any layover there. This is usually because they need to quickly return to their terminus without introducing unnecessary layovers, or to avoid the need for setting up a driver’s kiosk there when the bus company does not operate any other routes into that interchange.

The examples are:
 * Service 17 / 18 / 60 / 69 (Bedok Interchange)
 * Service 78 / 173 (Clementi Interchange)
 * Service 965 (Sengkang Interchange)

3. Point loop routes
Let’s have a service from point A and looping at point B. Because of geographical limitations (e.g. no space for a bus terminus) or for various operational reasons when the bus should return to point A as quickly as possible, the service will be operated as a loop route. Point loop routes routes are characterized by a single looping point (e.g. a roundabout / three point turn) and heavy duplication of their forward and return journeys. Most loop routes in Singapore fall under this category.

The examples are:
 * Service 24 (Medway Drive)
 * Service 35 (Tanah Merah Ferry Terminal)
 * Service 81 / 82 (Serangoon)
 * Service 84 (Punggol Road End)
 * Service 98 (Jurong Island Checkpoint)
 * Service 158 (Tanjong Rhu)
 * Service 183 (Science Park)
 * Service 926 / 927 (Singapore Zoo)

4. Area loop routes
Let’s have a service from point A and looping at point B. Because of geographical limitations (e.g. no space for a bus terminus) or for various operational reasons when the bus should return to point A as quickly as possible, the service will be operated as a loop route. Area loop routes do not loop around a point, but over an small area instead, using multiple turns at various junctions. They are characterized by heavy duplication of their forward and return journeys. Most loop routes in Singapore fall under this category.

The examples are:
 * Service 4 (Changi North Way)
 * Service 24, 27, 34, A1, 53 and 858 (Changi Airport)
 * Service 70M / 107M / 111/ 162M (Suntec City)
 * Service 95, 96 (NUS)
 * Service 179, 199 (NTU)
 * Service 182 (Tuas South Avenue 9)
 * Service 401 (East Coast Park Service Road)
 * Service 502, 518 (City)

5. Clockwise/Anticlockwise loop routes
In some situations, a loop route will be required to connect points A, B and C. An ordinary loop route going through A, B and C in order may face some problems. For example, there may be high passenger demand from B to A, as well as from C to A. This creates overcrowding on the route, as well as unnecessary travel time for passengers at B. Also, although passengers at B will be able to alight at C, passengers at C will not have bus connections to B. This is when clockwise and anticlockwise loop routes are launched, one routed as A→B→C→A and the other routed as A→C→B→A, to cater to the needs of different commuters.

6. Two-part loop routes
Some loop routes are actually two loop routes combined into one, and the route stops at the original terminus midway through the route. Both the first and second leg serve different areas (A→B→A→C→A). This system allows passengers to travel between the areas served by both legs of the route. This is most commonly seen in intratown/townlink routes. To differentiate between the two legs of the route, SBS Transit used to implement a red/green plate system for the two legs.

7. “Infinite” loop routes
This variant of loop routes allow passengers to remain onboard the bus at the bus terminus. The passengers can wait onboard until the bus departs on its next trip. The distance fare will be accumulated for both stretches of route (return and forward trip) once the passenger taps out, or a passenger pays a cash fare equivalent to the distance he traveled. This form of loop route technically allows passenger to stay onboard for as long as they like, as the fare will only be charged upon alighting (A ↺ B ↺ A)

Examples are:
 * Timothy North service 213, before assuming a bus terminus at the Jeremy Hub.

8. Looping point within restricted areas
Some routes loop within restricted areas where a pass is needed to enter. Such is the case for Changi Airfreight Terminal (Services 9, 19 and 89 in total), where only workers with a valid entry pass can enter the restricted area. For card-paying passengers, their ride will be suspended upon tapping out at the Police Pass Office, and resumed upon boarding the same service as they alighted (at another bus stop near the Police Pass Office after buses exit the restricted areas). For cash paying passengers, they will have to pay again upon boaring if their ticket expires within the restricted area. (A→B→C→B→A).

9. Loop routes not operating from bus terminals
These routes are implemented without bus terminals and originate / terminate from various enroute bus stops.

10. Loop routes operating like trunk routes
Some routes are designated as loop routes but operate like trunk routes. They have a terminus at either end and have a short layover at the looping terminus, usually without any driver’s kiosk.
 * Service 63 (Rumah Tinggi)