History of Services 181 - 190

Service 181 (1971 - 1998)

Operator	Year	Date	Service changes
UBC	1971	11 April	Introduced between Bt Timah Ter and Commonwealth Ave Ter under 1971 Bus Reorganisation.
		28 September	Amended to ply the extended Ganges Ave towards Bt Timah Ter.
		8 November	Extended to Upp Bt Timah Rd Ter.
	1972	11 June	Amended to ply Upp Cross St with the partial conversion of Havelock Rd to one-way traffic, skipping Upp Hokien St.
	1974	3 February	Extended to Crawford St Ter under 1974 Bus Rationalisation.
	1979	30 December	Amended to ply Jln Anak Bt towards Crawford St Ter with the partial conversion of Upp Bt Timah Rd to one-way traffic.
	1980	14 December	Extended to Woodlands Town Ter.
	1981	29 November	Amended to Woodlands Int.
	1983	4 September	Operations transferred to TIBS.
	1987	27 September	Amended to ply the extended Eu Tong Sen St towards Crawford St Ter to facilitate the first stage of road expansion along New Bridge Rd.
		1 November	Amended to ply Eu Tong Sen St towards Crawford St Ter to facilitate the second stage of road expansion along New Bridge Rd.
		13 December	Serves new staggered bus stop opposite Peninsula Plaza along Nth Bridge Rd, skipping the bus stop outside St Andrew's Cath.
	1988	28 February	Revised to operate on weekdays and Saturdays only with the introduction of Service 181#.
		20 March	Amended to ply Upp Cross St and New Bridge Rd, skipping Neil Rd.
	1990	22 July	Serves additional bus stop outside Ellenborough Mkt along Eu Tong Sen St.
	1996	4 February	Amended to Woodlands Reg Int.
	1997	TBC	First bus from Woodlands Reg Int brought forward to 0530 hrs.
		7 December	Amended to ply Sth Bridge Rd, Neil Rd and Cantonment Rd with the partial closure of New Bridge Rd to facilitate the construction of Chinatown MRT station on the North East MRT Line.
	1998	27 December	Extended to Lor 1 Geylang Ter and re-numbered Service 961.

Service 181 (since 2005)

Operator	Year	Date	Service changes
Template:SBS Transit (Current)	2005	9 January	Introduced between Boon Lay Int and Jurong West Ave 3 (Loop), operating between 0600 hrs and 2400 hrs daily.
	2006	18 June	Amended to Boon Lay Temp Int.
	2008	TBC	Last bus extended to 0030 hrs daily.
		15 June	Serves new pair of bus stops outside Blk 670A and outside Blk 678D along Jurong West St 64.
	2009	27 December	Amended to Boon Lay Integrated Transport Hub.
	2010	18 October	Designated wheelchair-accessible bus service (WAB).
	2013	TBC	Last bus extended to 0040 hrs daily.

Service 181#

Operator	Year	Date	Service changes
	1988	28 February	Introduced between Woodlands Int and Crawford St Ter as an alternate route of Service 181 via Marina Centre, operating on Sundays and Public Holidays.
		20 March	Amended to ply Upp Cross St and New Bridge Rd, skipping Neil Rd.
	1990	22 July	Serves additional bus stop outside Ellenborough Mkt along Eu Tong Sen St.
	1996	4 February	Amended to Woodlands Reg Int.
	1997	7 December	Amended to ply Sth Bridge Rd, Neil Rd and Cantonment Rd with the partial closure of New Bridge Rd to facilitate the construction of Chinatown MRT station on the North East MRT Line.
	1998	27 December	Extended to Lor 1 Geylang Ter and re-numbered Service 961#.

Service 181M

Operator	Year	Date	Service changes
Template:SBS Transit (Current)	2016	21 March	Introduced between Boon Lay Int and Jurong West St 23 (Loop) as a morning peak hour service on weekdays (except school holidays). Wheelchair-accessible at launch.

Service 182 (1971 - 1996)

Operator	Year	Date	Service changes
UBC	1971	11 April	Introduced between Bt Timah Ter and Jln Besi Ter under 1971 Bus Reorganisation.
		TBC	Extended to Benoi Rd Ter.
	1972	11 June	Amended to ply the extended Upp Cross St with the partial conversion of Havelock Rd to one-way traffic, skipping New Bridge Rd.
	1974	3 February	Amended to loop at Shenton Way from Bt Timah Ter under 1974 Bus Rationalisation.
		24 February	Amended to ply Grange Rd, Orchard Blvd and Paterson Rd towards Bt Timah Ter with the conversion of Orchard Rd to one-way traffic.
		8 December	Amended to ply Cecil St, skipping Robinson Rd.
	1976	6 June	Extended to Admiralty Rd Ter and amended to New Bridge Rd Ter.
	1979	30 December	Amended to ply Jln Anak Bt towards New Bridge Rd Ter with the partial conversion of Upp Bt Timah Rd to one-way traffic.
	1983	7 August	Operations transferred to TIBS.
	1987	6 June	Amended to the relocated New Bridge Rd Ter.
		27 September	Amended to ply the extended Eu Tong Sen St towards Marsiling Ter to facilitate the first stage of road expansion along New Bridge Rd.
		1 November	Amended to ply Eu Tong Sen St towards Marsiling Ter to facilitate the second stage of road expansion along New Bridge Rd.
		13 December	Serves new staggered bus stop outside Orchard Stn along Orchard Blvd, skipping the bus stop opposite Orchard Stn.
			Serves new bus stop outside Newton Stn along Scotts Rd.
	1988	20 March	Amended to ply Upp Cross St and New Bridge Rd, skipping Neil Rd.
	1992	19 July	Amended to ply Orchard Lk due to the closure of Grange Rd to facilitate road expansion works.
	1993	3 January	Amended to Shenton Way Ter under TransitLink Network Integration Exercise Phase 7.
	1995	7 May	Amended to ply Orchard Turn.
	1996	4 February	Amended to Woodlands Reg Int.
		10 March	Discontinued under Woodlands MRT Rationalisation.

Service 182 (since 1998)

Operator	Year	Date	Service changes
	1998	19 July	Introduced between Jurong East Int and Tuas Ter, calling at Tuas Checkpoint at selected timings only.
	2001	25 February	Shortened to Boon Lay Int.
			Last bus from Tuas Ter brought forward to 2300 hrs daily.
Template:SBS Transit (Current)	2002	26 May	Integrated with Service 183, extended to loop at Tuas Sth Ave 9 and amended to ply Jurong West St 64, Boon Lay Way, Upp Jurong Rd and PIE, skipping Jln Boon Lay.
	2004	19 January	Serves all bus stops along Upp Jurong Rd.
	2005	7 August	Serves new pair of bus stops outside and opposite Sin Lian Heng Construction along Tuas South Ave 3.
	2006	18 June	Amended to Boon Lay Temp Int.
	2007	25 November	Serves 2 new pairs of bus stops before Tuas Sth Ave 2, outside LTH Distripark, before and after Tuas Sth Ave 2 along Tuas Sth Ave 3.
	2009	27 December	Amended to Boon Lay Integrated Transport Hub.
	2013	30 September	Designated wheelchair-accessible bus service (WAB).
	2015	28 November	Shortened to Joo Koon Integrated Transport Hub.
	2016	4 January	First bus brought forward to 0545 hrs daily.
	2022	13 February	Amended to ply new road towards Tuas Sth Ave 9, skipping the Tuas roundabout.

Service 182X/182M

Operator	Year	Date	Service changes
	1998	19 July	Introduced between Jurong East Int and Tuas Ter as an alternate route of Service 182 during off peak periods, skipping Tuas Checkpoint in both directions.
	2001	25 February	Shortened to Boon Lay Int.
			Last bus from Tuas Ter brought forward to 2300 hrs daily.
Template:SBS Transit (Current)	2002	26 May	Integrated with Service 183, extended to loop at Tuas Sth Ave 9 and amended to ply Jurong West St 64, Boon Lay Way, Upp Jurong Rd and PIE, skipping Jln Boon Lay.
	2004	19 January	Serves all bus stops along Upp Jurong Rd.
	2005	7 August	Serves new pair of bus stops outside and opposite Sin Lian Heng Construction along Tuas Sth Ave 3.
	2006	18 June	Amended to Boon Lay Temp Int.
	2008	28 January	Re-numbered Service 182M.
		11 February	Serves 2 new pairs of bus stops before Tuas Sth Ave 2, outside LTH Distripark, before and after Tuas Sth Ave 2 along Tuas Sth Ave 3.
	2009	27 December	Amended to Boon Lay Integrated Transport Hub.
	2013	26 August	Amended to call at Tuas Checkpoint towards Boon Lay Int only.
		30 September	Designated wheelchair-accessible bus service (WAB).
	2015	28 November	Shortened to Joo Koon Integrated Transport Hub.
	2022	13 February	Amended to ply new road towards Tuas Sth Ave 9, skipping the Tuas roundabout.

Service 183 (1974 - 1988)

Operator	Year	Date	Service changes
	1974	3 February	Introduced between Benoi Rd Ter and Sth Canal Ter under 1974 Bus Rationalisation.
	1975	2 February	Amended to ply new slip road from Tiong Bahru Rd to Outram Rd with the conversion of Seng Poh Rd to one-way traffic.
	1978	1 June	Amended to Jurong Int and amended to New Bridge Rd Ter.
	1987	6 April	Skips abolished bus stop before College Rd along Outram Rd.
		6 June	Amended to the relocated New Bridge Rd Ter.
		1 November	Amended to ply Eu Tong Sen St towards Jurong Int to facilitate the second stage of road expansion along New Bridge Rd.
	1988	11 January	Serves merged bus stop along Ayer Rajah Rd.
		18 December	Discontinued.

Service 183 (1998 - 2002)

Operator	Year	Date	Service changes
	1998	5 July	Introduced between Tuas Ter and Tuas Sth Ave 6 (Loop).
	2001	11 February	Extended to loop at Tuas Sth Ave 9, skipping Tuas Sth Ave 6.
Template:SBS Transit	2002	26 May	Integrated with Service 182/182X and discontinued.

Service 183 (since 2004)

Operator	Year	Date	Service changes
Template:SBS Transit	2004	22 August	Introduced between Jurong East Int and Clementi Rd (Loop), operating between 0600 hrs and 2330 hrs daily.
	2005	3 October	Extended to loop at Science Pk Rd.
	2008	2 December	Designated wheelchair-accessible bus service (WAB).
	2011	17 December	Amended to Jurong East Temp Int.
(Current)	2016	26 June	Operations transferred to Tower Transit Singapore.
	2020	6 December	Amended to relocated Jurong East Temp Int and serve new bus stop before Jurong East Stn along Jurong Gateway Rd.

Short Trip 183A (2005 - 2012)

Operator	Year	Date	Service changes
Template:SBS Transit	2005	12 December	Introduced between Commonwealth Ave West (Clementi Stn) and Science Pk Rd (Loop) during morning peak hours on weekdays.
	2008	2 December	Designated wheelchair-accessible bus service (WAB).
	2009	TBC	Extended to start from Jurong East Int.
	2011	17 December	Amended to Jurong East Temp Int.
	2012	TBC	Discontinued.

Short Trip 183B

Operator	Year	Date	Service changes
Template:SBS Transit	2010	16 August	Introduced from Jurong East Int to Toh Tuck Ave (Ulu Pandan R.I. Plant) during morning peak hours on weekdays. Wheelchair-accessible at launch.
	2011	17 December	Amended to Jurong East Temp Int.
(Current)	2016	26 June	Operations transferred to Tower Transit Singapore.
	2020	6 December	Amended to relocated Jurong East Temp Int.

Service 184 (1978 - 1990)

Operator	Year	Date	Service changes
	1978	TBC	Introduced between Telok Blangah Way Ter and Boon Lay Gdns Ter.
		1 June	Amended to Jurong Int.
	1980	28 September	Amended to Bt Merah Int.
	1981	15 February	Amended to skip Telok Blangah Way and Telok Blangah Cres in both directions.
	1987	2 August	Amended to ply West Coast Highway, skipping Upp Ayer Rajah Rd and Clementi Rd.
	1990	1 July	Integrated with Service 176 and discontinued with the opening of Boon Lay Int.

Service 184 (since 1994)

Operator	Year	Date	Service changes
	1994	3 July	Introduced between Bt Panjang Ter and Commonwealth Ave West (Loop).
	1995	2 July	Operations transferred to TIBS.
	1998	TBC	First bus brought forward to 0545 hrs on weekdays.
	1999	26 December	Amended to Bt Panjang Int.
	2003	12 October	Serves the bus stop opposite Bt Timah Plaza along Jln Anak Bt with the abolition of the bus stop under the PIE Flyover.
Template:SMRT Buses (Current)	2010	23 May	Skips temporarily abolished bus stop outside Assumption Voc Inst along Upp Bt Timah Rd to facilitate the construction of Cashew MRT station along the Downtown MRT Line.
	2011	3 July	Serves additional pair of bus stops opposite Min of Defence and before Cashew Rd along Upp Bt Timah Rd.
	2012	16 December	Amended to start from and terminate at Bt Panjang Rd with the opening of Bt Panjang Temp Bus Pk and the closure of Bt Panjang Int.
	2015	1 March	Serves reinstated bus stop outside Assumption Pathway Sch along Upp Bt Timah Rd, skipping a pair of bus stops opposite Min of Defence and before Cashew Rd.
	2017	4 September	Serves additional pair of bus stops outside and opposite Ten Mile Junction Stn along Woodlands Rd.
		17 December	Designated wheelchair-accessible bus service (WAB).
	2021	23 January	Extended to Gali Batu Ter, serving 2 additional pairs of bus stops after KJE Slip Rd, Blk 632 CP, opposite Blk 632 CP and opposite Blk 635A along Woodlands Rd.
			First bus from Woodlands Rd (Aft KJE Slip Rd) brought forward to 0540 hrs on weekdays and Saturdays, and 0555 hrs on Sundays and Public Holidays. Last bus from Woodlands Rd (Aft KJE Slip Rd) extended to 2305 hrs daily.

Short Trip 184A (2000 - 2003)

Operator	Year	Date	Service changes
	2000	TBC	Introduced from Bt Panjang Int to Clementi Rd (Opp Ngee Ann Poly) during morning peak hours on weekdays.
	2003	TBC	Discontinued.

Service 185 (1979 - 1985)

Operator	Year	Date	Service changes
	1979	16 July	Introduced between Clementi Ave 3 Ter and Nth Buona Vista Rd (Loop).
		25 November	Extended to loop at Bt Merah Ctrl.
	1980	28 September	Extended to loop at Bt Merah Int.
		16 November	Amended to Clementi Int.
	1985	28 April	Integrated with Service 92 and discontinued.

Service 185 (1988 - 2003)

Operator	Year	Date	Service changes
	1988	31 July	Introduced between Choa Chu Kang Ter and Shenton Way Ter.
		25 August	Amended to ply Choa Chu Kang Ave 1 with the completion of the road junction between Teck Whye Ave and Choa Chu Kang Ave 1.
	1989	28 May	Amended to ply Commonwealth Ave.
	1990	10 March	Extended to interim terminal along Choa Chu Kang Ave 4.
		8 April	Amended to Choa Chu Kang Int.
	1991	28 April	Amended to ply Bt Batok East Ave 2 under TransitLink Network Integration Exercise Phase 4, skipping Bt Batok East Ave 3.
	1993	3 January	Shortened to loop at Jln Anak Bt from Choa Chu Kang Int with the introduction of Service 186 under TransitLink Network Integration Exercise Phase 11.
	1997	TBC	Serves new bus stop outside Lot 1 Shoppers' Mall along Choa Chu Kang Ave 4.
	1999	29 August	Operations transferred to TIBS.
			First bus brought forward to 0530 hrs on Sundays & Public Holidays.
	2003	TBC	Serves new bus stop outside Goh & Goh Bldg along Jln Jurong Kechil.
		27 July	Integrated with Service 989 to form Service 985 and discontinued.

Service 185 (since 2006)

Operator	Year	Date	Service changes
Template:SBS Transit (Current)	2006	26 December	Introduced between Soon Lee Bus Pk and Buona Vista Ter, operating between 0600 hrs and 2300 hrs from Soon Lee Bus Pk and Buona Vista Ter daily.
	2007	5 August	Serves new pair of bus stops outside and opposite Soon Lee Depot along Soon Lee Rd.
	2008	14 July	Designated wheelchair-accessible bus service (WAB).
		29 December	Last bus from Soon Lee Bus Pk extended to 2315 hrs daily.
	2009	18 May	First bus from Soon Lee Bus Pk brought forward to 0545 hrs daily.

Service 186 (1977 - 1989)

Operator	Year	Date	Service changes
	1977	7 November	Introduced between Clementi Ave 3 Ter and Tg Pagar Ter.
	1978	5 June	Amended to ply Commonwealth Ave West with the relocation of Clementi Ave 3 Ter, skipping Clementi Ave 2.
	1979	1 August	Amended to Anson Rd Ter.
	1980	16 November	Amended to Clementi Int.
	1985	27 January	Amended to Prince Edward Ter with the closure of Anson Rd Ter.
	1987	28 June	Amended to Shenton Way Ter.
	1988	8 March	Amended to ply Clementi Ave 3 with the abolition of right turning from Clementi Ave 3 to Commonwealth Ave West.
	1989	27 August	Integrated with Service 145 and discontinued.

Service 186 (since 1993)

Operator	Year	Date	Service changes
	1993	3 January	Introduced between Shenton Way Ter and Farrer Rd (Loop) under TransitLink Network Integration Exercise Phase 11.
		4 April	Extended to St. Michael's Ter under TransitLink Network Integration Exercise Phase 12.
	2000	TBC	Serves new bus stop after Shenton Way along Palmer Rd.
Template:SBS Transit (Current)	2004	TBC	Skips abolished bus stop outside Nanyang Pr Sch along Farrer Rd.
	2011	4 September	Serves new bus stop outside Botanic Gdns Stn along Bt Timah Rd.
	2012	30 September	Designated wheelchair-accessible bus service (WAB).
	2014	27 April	Serves new bus stop outside Queens Condo along Commonwealth Ave.
	2017	25 June	Amended to the relocated Shenton Way Ter.
	2023	23 July	Amended to ply temporary slip road and Mt Pleasant Rd with the temporary closure of slip road to PIE Exit 17D.

Service 187 (1981 - 1983)

Operator	Year	Date	Service changes
	1981	15 February	Introduced as a day service between Bt Merah Int and Empress Pl (Loop).
		19 May	Converted to peak hour service on weekdays and Saturdays.
	1983	14 November	Discontinued.

Service 187 (since 1988)

Operator	Year	Date	Service changes
	1988	10 July	Introduced between Bt Panjang Ter and Jurong Int.
	1989	10 April	First bus from Bt Panjang Ter brought forward to 0530 hrs on weekdays and Saturdays.
	1990	7 January	Serves new pair of bus stops outside and opposite Bt Batok Driving Ctr along Bt Batok West Ave 5.
		1 July	Amended to Boon Lay Int.
	1995	17 September	Operations transferred to TIBS.
	1996	10 March	Extended to Woodlands Reg Int under Woodlands MRT Rationalisation.
	1997	TBC	First bus from Boon Lay Int brought forward to 0550 hrs on weekdays and Saturdays.
	1998	TBC	First bus from Boon Lay Int brought forward to 0540 hrs on weekdays and Saturdays.
Template:SMRT Buses (Current)	2006	30 April	Serves new pair of bus stops outside Blk 336 and opposite Blk 334 along Bt Batok West Ave 7.
		18 June	Amended to Boon Lay Temp Int.
	2009	27 December	Amended to Boon Lay Integrated Transport Hub.
	2012	29 April	Designated wheelchair-accessible bus service (WAB).
	2016	12 March	Amended to Woodlands Temp Int.
	2021	13 June	Amended to Woodlands Integrated Transport Hub.

Short Trip 187A (2003 - 2004)

Operator	Year	Date	Service changes
	2003	25 August	Introduced from Boon Lay Int to Bt Batok Ctrl (Blk 628) during morning peak hours on weekdays.
Template:SMRT Buses	2004	TBC	Discontinued.

Service 188 (1977 - 1987)

Operator	Year	Date	Service changes
	1977	17 October	Introduced between Ulu Pandan Ter and Shenton Way (Loop).
	1979	11 February	Amended to ply the extended Shenton Way towards Ulu Pandan Ter, skipping Parsi Rd and Anson Rd.
	1980	20 January	Amended to ply Spottiswoode Pk Rd with the partial conversion of Cantonment Rd to one-way traffic.
	1981	11 October	Serves new staggered bus stop outside Tunas Bldg along Anson Rd, skipping the bus stop outside Intl Plaza.
	1987	6 April	Skips abolished bus stop before College Rd along Outram Rd.
		5 July	Discontinued.

Service 188 (1988 - 1991)

Operator	Year	Date	Service changes
	1988	10 July	Introduced between Jurong Int and Jurong West St 91 (Loop).
	1989	17 December	Amended to ply Jurong West St 72 and Jurong West Ave 5, skipping Pioneer Rd Nth.
	1990	1 July	Amended to start/terminate at Corporation Dr with the opening of Boon Lay Int.
	1991	20 January	Discontinued under TransitLink Network Integration Exercise Phase 2.

Service 188 (since 1999)

Operator	Year	Date	Service changes
	1999	7 March	Introduced between Choa Chu Kang Int and World Trade Ctr Ter.
		TBC	Skips abolished pair of bus stops outside and opposite Wishart Rd along Telok Blangah Rd.
		26 December	Operations transferred to TIBS.
	2002	TBC	Skips abolished bus stop opposite ITE Pasir Panjang along Telok Blangah Rd.
		TBC	First bus from HarbourFront Int revised to 0630 hrs on Sundays and Public Holidays.
Template:SMRT Buses (Current)	2006	30 April	Serves new pair of bus stops outside Blk 336 and opposite Blk 334 along Bt Batok West Ave 7.
	2015	22 March	Designated wheelchair-accessible bus service (WAB).
	2018	16 December	Amended to new Choa Chu Kang Int.
	2024	28 January	Serves relocated bus stop after Clementi Swim Cplx along AYE.

Short Trip 188A (July - September 2010)

Operator	Year	Date	Service changes
Template:SMRT Buses	2010	5 July	Introduced from Choa Chu Kang Int to Choa Chu Kang Gr (ITE College West) during morning peak hours on weekdays.
		13 September	Discontinued.

Service 189

Operator	Year	Date	Service changes
	1974	3 February	Re-numbered from Service 193A as a service between Commonwealth Ave Ter and Sth Canal Ter under 1974 Bus Rationalisation.
		8 December	Amended to ply Cecil St, skipping Robinson Rd.
	1975	2 February	Amended to ply new slip road from Tiong Bahru Rd to Outram Rd with the conversion of Seng Poh Rd to one-way traffic.
	1977	17 May	Amended to ply Commonwealth Ave Extension and Nth Buona Vista Rd towards Commonwealth Ave Ter.
		29 August	Amended to ply Holland Ave, Holland Dr and Nth Buona Vista Rd towards Commonwealth Ave Ter.
	1978	22 January	Amended to ply Commonwealth Ave, Queensway, Commonwealth Dr, Commonwealth Ave and Queen's Circus with the conversion of Farrer Circus into a traffic-signal controlled junction.
	1979	15 January	Amended to loop at Empress Pl and amended to ply Jln Bt Merah, Kg Bahru Rd and New Bridge Rd/Neil Rd, skipping Commonwealth Dr, Tiong Bahru Rd, Outram Rd, Cross St, Upp Cross St, New Bridge Rd and Nth Canal Rd.
		11 February	Amended to ply the extended Shenton Way towards Commonwealth Ave Ter, skipping Parsi Rd and Anson Rd.
	1980	20 January	Amended to ply Spottiswoode Pk Rd with the partial conversion of Cantonment Rd to one-way traffic.
	1982	27 May	Amended to Buona Vista Ter.
	1985	24 November	Extended to Bt Batok Ter and Marina Ctr Ter.
	1986	30 November	Amended to the relocated Marina Ctr Ter along Raffles Blvd.
	1987	27 September	Amended to Bt Batok Int.
		1 November	Amended to ply Eu Tong Sen St towards Marina Ctr Ter to facilitate the second stage of road expansion along New Bridge Rd.
	1991	28 April	Shortened to loop at Clementi West St 2, integrated with Service 366 and amended to ply Bt Batok Ctrl, Bt Batok Ave 1, Bt Batok East Ave 6 and Bt Batok St 23 under TransitLink Network Integration Exercise Phase 4.
	1995	6 May	Extended to loop at West Coast Ferry Ter, skipping Clementi West St 2.
	1996	TBC	Amended to ply PIE and Clementi Ave 6, skipping Toh Tuck Ave.
	1999	TBC	Serves new pair of bus stops outside and opposite West Bay Resort Condo along West Coast Rd.
	2000	18 June	Operations transferred to TIBS.
	2001	15 April	Shortened to loop at Kent Ridge Ter.
Template:SMRT Buses	2009	1 June	Designated wheelchair-accessible bus service (WAB).
	2014	23 November	Amended to loop at Clementi Ave 1 with the introduction of Service 201, skipping West Coast Rd and Kent Ridge Ter.
			Last bus extended to 2315 hrs daily.
(Current)	2016	29 May	Operations transferred to Tower Transit Singapore.
	2024	28 January	Serves additional bus stop after Clementi Swim Cplx along AYE.

Service 189A (2001 - 2003)

Operator	Year	Date	Service changes
	2001	15 April	Introduced between Bt Batok Int and Harbour Dr (Loop), operating at selected timings only.
	2003	4 May	Discontinued.

Short Trip 189A (since 2009)

Operator	Year	Date	Service changes
Template:SMRT Buses	2009	5 January	Introduced from Bt Batok Int to Bt Batok St 23 (Opp Midview Bldg) during morning peak hours on weekdays.
		1 June	Designated wheelchair-accessible bus service (WAB).
	2011	12 June	Extended to operate after the last bus of Service 189 daily.
	2013	TBC	Last bus extended to 0100 hrs daily.
(Current)	2016	29 May	Operations transferred to Tower Transit Singapore.
	2019	5 October	Last bus extended to 0110 hrs daily.

Service 190 (April - May 1971)

Operator	Year	Date	Service changes
ABC	1971	11 April	Introduced between Delta Circus Ter and Sth Canal Ter under 1971 Bus Reorganisation.
		25 April	Integrated with Service 193/193A and discontinued.

Service 190 (1974 - 1979)

Operator	Year	Date	Service changes
	1974	3 February	Re-numbered from Service 191A between Jln Bt Merah Ter and Prince Edward Ter under 1974 Bus Rationalisation.
		24 February	Amended to ply Grange Rd, Orchard Blvd and Paterson Rd towards Jln Bt Merah Ter with the conversion of Orchard Rd to one-way traffic.
		8 December	Amended to ply Cecil St, skipping Robinson Rd.
	1976	14 March	Serves new staggered bus stop outside The Cenotaph along Connaught Dr, skipping the bus stop opposite Singapore Cricket Club.
	1977	19 June	Amended to ply Orchard Blvd and Grange Rd towards Jln Bt Merah Ter with the full conversion of Orchard Rd to one-way traffic.
	1979	11 February	Amended to ply the extended Shenton Way, Palmer Rd and Anson Rd, skipping Parsi Rd.
		25 November	Discontinued.

Service 190 (since 1988)

Operator	Year	Date	Service changes
	1988	10 July	Introduced between Bt Panjang Ter and New Bridge Rd Ter.
	1990	16 December	Integrated with Service 179 and extended to Choa Chu Kang Int.
	1992	19 July	Amended to ply Orchard Lk due to the closure of Grange Rd to facilitate road expansion works.
	1993	3 January	Amended to ply PIE and Whitley Rd under TransitLink Network Integration Exercise Phase 11, skipping Jln Anak Bt/Upp Bt Timah Rd and Dunearn Rd/Bt Timah Rd.
		11 April	Amended to ply Victoria St, Hill St and New Bridge Rd, skipping Nth Bridge Rd, Sth Bridge Rd and Upp Cross St.
	1994	TBC	First bus from New Bridge Rd Ter brought forward to 0600 hrs on weekdays and Saturdays.
	1995	7 May	Amended to ply Orchard Turn.
	1997	7 December	Amended to ply Upp Pickering St, Sth Bridge Rd and Kreta Ayer Rd with the partial closure of New Bridge Rd to facilitate the construction of Chinatown MRT station on the North East MRT Line.
	1999	25 July	Operations transferred to TIBS.
		26 December	Amended to ply Choa Chu Kang Ave 4, Choa Chu Kang Dr and Teck Whye Ave under Bt Panjang LRT Rationalisation, skipping Choa Chu Kang Way.
	2000	20 February	Serves additional bus stop opposite Blk 333 along Kreta Ayer Rd.
	2002	20 April	Amended to ply the reinstated New Bridge Rd, skipping Upp Pickering St, Sth Bridge Rd and Kreta Ayer Rd.
		7 July	Skips the bus stop outside Orchard Emerald along Orchard Rd.
Template:SMRT Buses (Current)	2005	TBC	Serves additional bus stop outside Clarke Quay Stn along Eu Tong Sen St.
		2 July	Amended to ply Grange Rd and Orchard Lk with the partial closure of Somerset Rd.
	2006	29 October	Serves relocated bus stop outside Orchard Stn along Orchard Turn.
	2015	14 June	Designated wheelchair-accessible bus service (WAB).
	2018	10 March	Extended to Kg Bahru Ter with the closure of New Bridge Rd Ter.
			First bus from Kg Bahru Ter brought forward to 0555 hrs on weekdays and Saturdays, and 0625 hrs on Sundays and Public Holidays.
		16 December	Amended to new Choa Chu Kang Int.
	2021	15 February	First bus from Choa Chu Kang Int brought forward to 0530 hrs on weekdays.

Short Trip 190A

Operator	Year	Date	Service changes
	2000	TBC	Introduced from Choa Chu Kang Int to Orchard Rd (Dhoby Ghaut Stn) during morning peak hours on weekdays.
	2002	7 July	Skips the bus stop outside Orchard Emerald along Orchard Rd.
Template:SMRT Buses (Current)	2015	14 June	Designated wheelchair-accessible bus service (WAB).
	2018	16 December	Amended to new Choa Chu Kang Int.