Tri Delta Transit

Tri Delta Transit, formally the Eastern Contra Costa Transit Authority, is a joint powers agency (JPA) of the governments of Pittsburg, Antioch, Oakley, Brentwood, and Contra Costa County that provides bus service for the eastern area of Contra Costa County, California, United States.^[1] Contra Costa County has four major public bus transportation services, divided geographically: three mostly serve destinations within the county, covering western (WestCAT), central (County Connection), and eastern (Tri Delta Transit) regions, and one (AC Transit) serves Bayside cities along the western edges of Contra Costa and Alameda counties. In 2024, the system had a ridership of 1,348,100, or about 4,300 per weekday as of the second quarter of 2025.

Tri Delta Transit

Parent	Eastern Contra Costa Transit Authority
Founded	1977 (1977)
Headquarters	801 Wilbur Ave, Antioch, California, United States
Locale	East Contra Costa County, California
Service type	bus service, paratransit
Routes	13 weekday, 8 weekend[1]
Stops	approximately 650[1]
Fleet	62 transit bus 30 paratransit 6 med vans 8 microtransit Tri MyRide [1]
Daily ridership	4,300 (weekdays, Q2 2025)[2]
Annual ridership	1,348,100 (2024)[3]
Operator	Transdev[1]
Website	trideltatransit.com

Tri Delta Transit local buses connect to the BART rapid transit system at Antioch, Pittsburg Center, Pittsburg/Bay Point and Concord. In addition, Tri Delta Transit buses connect with Amtrak commuter rail services, including San Joaquins and Capitol Corridor. Within the county, several Tri Delta Transit bus routes connect with County Connection and WestCAT.

History

The Eastern Contra Costa Transit Authority (ECCTA) JPA was formed in 1976 by the cities of Antioch, Brentwood, and Pittsburg, along with the County of Contra Costa. When Oakley was incorporated in 1999, the JPA was amended to admit Oakley on April 1, 2001.^[4]: 1 The Tri Delta Transit name was selected in May 1977 by the marketing committee of the ECCTA.^[5]

Tri Delta Transit fixed route service began on June 6, 1977, celebrated by an inaugural bus starting from Antioch City Hall (10 a.m.), traveling to Oakley (10:30), Brentwood City Hall (11), Pittsburg, and ending in West Pittsburg (2 p.m.). For the first week, free rides were offered.^[6] Initial service was provided for two local routes in Antioch and Pittsburg, which connected with express bus service serving BART.

AC Transit operated the service under contract until 1984, when it was transferred to a private operator,^[4]: 1 and ECCTA acquired its first buses; prior to that, AC Transit owned the buses it used for Tri Delta Transit.^[7] Some of the buses used in 1978 included 29-foot models, shortened from 35-foot buses at the AC Transit shops.^[8]

Dial-a-ride on-demand transit services have been provided since 1979 using contracted private operators. ECCTA consolidated fixed route and on-demand services with a single operator when the contract with AC Transit was discontinued in 1984.^[7] In 1986, Laidlaw Transit, Inc. (later First Transit, now Transdev) begin operating Tri Delta Transit.^[7]

The ECCTA headquarters in Antioch was built in 1987, consolidating administration, operations, and maintenance at a single facility; expansions in 2004 provided additional space and bus parking.^[4]: 1

Overview of fixed-route service

Tri Delta Transit Gillig BRT in Pittsburg.

Tri Delta Transit operates in eastern Contra Costa County and has stops in Antioch, Oakley, Brentwood, Bay Point, Pittsburg, Martinez, and Concord. Tri Delta Transit operates local and express routes on weekdays and local routes on weekends and holidays.

Transfers

Intra-system transfer points for the majority of Tri Delta Transit's routes include:

• Brentwood Park & Ride in Brentwood
• Oakley Park & Ride in Oakley
• Antioch BART station in Antioch
• Pittsburg Center BART station in Pittsburg
• Pittsburg/Bay Point BART station in Pittsburg
• Los Medanos College in Pittsburg

In addition to transfers within Tri Delta Transit and to BART, riders may transfer to neighboring and long-distance public transportation systems at other stations, including:

• Antioch–Pittsburg station, via Route 371
  • Amtrak San Joaquins
• Concord BART, via Route 201X (weekdays)
  • County Connection
• Martinez station, via Route 200X (weekdays)
  • Amtrak California Zephyr, Coast Starlight, San Joaquins, and Capitol Corridor
  • County Connection
  • WestCAT

Route list

Tri Delta Transit operates thirteen bus routes on weekdays, serving the cities of Bay Point, Pittsburg, Antioch, Oakley, and Brentwood, with one route each connecting to Concord (201X) and Martinez (200X). Most routes parallel the San Joaquin River, running east and west; routes designated as "express" (200X, 201X) are designed with fewer stops and operate primarily during commute hours with limited mid-day service. Several routes share the same terminal points, but take different paths to provide service to communities both north and south of California State Route 4.^[9] For example, 370 and 371 both provide service between the Pittsburg/Bay Point and Antioch BART stations.

On the weekends and holidays, Tri Delta Transit operates eight of the thirteen routes throughout the ECCTA service area including the aforementioned cities with the exceptions of Concord and Martinez. Routes numbered 37x operate all week long, with reduced service frequencies on weekends and holidays.^[10]

Tri Delta Transit bus routes^[10]

Route	Westbound Terminal	Eastbound Terminal	Weekend service	Notes / Refs.
200X	Martinez station (Amtrak)	Pittsburg/Bay Point BART	No	[11]
201X	Concord BART		No	[12]
360[a]	Los Medanos College	Antioch High School	No	[14]
361	Antioch BART	Deer Valley & Dozier Libbey	No	[15]
362	Blue Goose Park (Oakley Loop)		No	[16]
370[b]	Pittsburg/Bay Point BART	Antioch BART	Yes	[18]
371[c]			Yes	[20]
372[d]		Los Medanos College	Yes	[22]
373	Antioch BART	Brentwood Park & Ride	Yes	[23]
374	Bay Point	Pittsburg-Bay Point BART	Yes	[24]
375	Antioch BART	Slatten Ranch Center	Yes	[25]
376		Kaiser Antioch Medical Center	Yes	[26]
377		Walmart Supercenter	Yes	[27]

Discontinued Tri Delta Transit bus routes

Route	Westbound Terminal	Eastbound Terminal	Weekend service	Notes / Refs.
70	3rd & Marina[e]		No	[28]
200	Martinez station (Amtrak)	Wilbur & Cavallo Rd[f]	No	[29]
202X	Brentwood Park & Ride[g]		No	[h][31]
300	Pittsburg/Bay Point BART	Brentwood Park & Ride	No	[32][33]
300X[i]	Antioch BART	Brentwood Park & Ride	No	[j][34]
379	Antioch BART	Antioch Medical Center	No	[k][l][36]
380[m]	Pittsburg/Bay Point BART	Antioch BART	Yes	[n][37]
381[o]	Pittsburg Marina	Los Medanos College	Yes	[38]
383[p]	Wilbur and Cavallo Rd[f]	Blue Goose Park	No	[39]
384[q]	Antioch BART	Brentwood Park & Ride	No	[40]
385[r]	Antioch BART	Brentwood Park & Ride	No	[41]
386	Brentwood Park & Ride	Discovery Bay Park & Ride	No	[42][43]
387[n][s]	Pittsburg/Bay Point BART	Antioch BART	No	[44]
388[n]	Pittsburg/Bay Point BART	Antioch Medical Center	Yes	[45]
389[t]	Pittsburg/Bay Point BART[u]		Yes	[46]
390[n]	Pittsburg/Bay Point BART	Antioch BART	No	[v][47]
391[w]	Pittsburg Center BART	Brentwood Park & Ride	Yes	[48]
392	Pittsburg/Bay Point BART	Brentwood Park & Ride	Yes (no weekdays)[x]	[49]
393	Mariners Cove Dr & Pacifica Ave	Hillcrest Park & Ride	Yes (no weekdays)[x]	[50]
394	Pittsburg/Bay Point BART	Hillcrest Park & Ride	Yes (no weekdays)[x]	[51][52]
395	Antioch BART	The Streets of Brentwood	Yes (no weekdays)[x]	[53]
709	Pittsburg/Bay Point BART	Antioch BART	No	[y]
Delta Express	Hillcrest Park & Ride	Lawrence Livermore National Laboratory	No	[56]

Notes

1. Subset of legacy route 380, truncated at Los Medanos College (western terminus) and Antioch High School (eastern terminus). Limited service, with one trip each in the mornings and afternoons.^[13]
2. Adopts aspects of legacy routes 388 & 390 west of Railroad Ave (Pittsburg), 387 & 390 between Railroad and Loveridge, 380 & 387 between Loveridge and Somersville, 387 between Somersville and G, and 380, 388, and 387 east of G. Runs on Leland west of Somersville, then Sycamore and 18th east of Somersville.^[17]
3. Adopts aspects of legacy routes 380 west of Railroad Ave (Pittsburg) and 388 east of Loveridge. Generally serves neighborhoods north of SR 4.^[19]
4. Largely replicates legacy route 387, with eastern terminus moved to Los Medanos College. Serves neighborhoods within Pittsburg.^[21]
5. Operates loop service in Pittsburg via Buchanan and Harbor
6. Tri Delta Transit headquarters
7. Operates loop service via Los Medanos College Brentwood Center
8. Replaced with Tri MyRide (dial-a-ride) service.^[30]
9. Consolidated with 391 and renumbered to 373, which offers more frequent service.^[30]
10. Designed for traditional commute, operating westbound in the mornings and eastbound in the afternoons
11. Operates during school days for Antioch Unified School District^[35]
12. Renumbered to 361.^[30]
13. Replaced by new route (360).^[30]
14. Partially replaced by new route (370).^[30]
15. Consolidated into new route (372).^[30]
16. Renumbered to 362.^[30]
17. Consolidated into new routes 373 and 375.^[30]
18. Replaced by new routes 373, 375, and 376.^[30]
19. Replaced by new route (372).^[30]
20. Replaced by new route (374).^[30]
21. Operates loop service around via Bay Point
22. Operates during commute hours
23. Renumbered to 373.^[30]
24. Operates exclusively on weekends and holidays, no weekday service^[35]
25. "Early Bird Express" operated as a westbound-only route by Tri Delta Transit before regular weekday eBART service starts at 5 a.m.;^[54] eliminated starting from June 10, 2024.^[55]