San Diego Trolley

The planning for the San Diego Trolley began in 1966 under the auspices of the Comprehensive Planning Organization (CPO), an intergovernmental agency of 13 cities and San Diego County.[9] San Diego's streetcar system had been replaced with buses in 1949. In 1966 the local bus company, San Diego Transit, was facing a financial crisis and public takeover. The CPO developed a mass-transit plan to address the long-range transportation issues of the metropolitan area, and that plan recommended a heavy rail "rapid transit" system, similar to the BART project then under construction in the San Francisco Bay area.

Little progress was made in the decade 1966–1975. CPO continued to research options for addressing the region's transportation needs. Several prominent stakeholders submitted their own mass-transit master plans for the region. The alternatives studied in the decade included:

• Restoration of the 1949 streetcar system for $1.3 billion
• BART-like system featuring 417 stations on a system of 284 miles (457 km) for $2–5 billion
• Elevated system featuring automatic rapid transit vehicles for $1 billion
• Short demonstration light-rail line (Airport to Downtown), for $20 million
• Express bus system on freeways

The debate between rail rapid transit and light rail was conducted without reference to any specific right-of-way or railroad tracks. The CPO's 1975 Regional Comprehensive Plan described a $1.5 billion rail-rapid transit system in San Diego featuring a system of 58 miles (93 km) and 11 lines. However, by this time, it was widely acknowledged by public officials that a BART-like rapid transit system would be much more expensive than light rail. Rail rapid plans were stalled due to high costs. Proponents of the rail rapid system were concerned about the low speed of at-grade streetcar systems. Operating deficits were also a concern. A 1974 CPO study concluded that a streetcar system would incur operating deficits of $1.9 million annually. It was also understood that any BART-like system would incur substantial deficits.

San Diego Trolley
System diagram
UCSD West/Pepper Canyon UCSD East/Voigt Drive VA Medical Center Executive Drive Nobel Drive University Towne Center Balboa Avenue Clairemont Drive Tecolote Road Morena/Linda Vista Old Town Transit Center Fashion Valley Transit Center Washington Street (via ) Middletown Hazard Center County Center/Little Italy (via ) Santa Fe Depot Mission Valley Center (via ) America Plaza Courthouse Rio Vista Civic Center Fifth Avenue Fenton Parkway closed 1986 San Diego Square City College Park & Market Stadium Seaport Village Convention Center Mission San Diego Gaslamp Quarter Grantville 12th & Imperial Transit Center San Diego State University Transit Center Storage & Maintenance Yard Alvarado Medical Center Barrio Logan Harborside 25th & Commercial Pacific Fleet 32nd & Commercial 8th Street 47th Street 24th Street Euclid Avenue Bayfront/E Street Encanto/62nd Street H Street Massachusetts Avenue Palomar Street Lemon Grove Depot Palm Avenue Spring Street Iris Avenue La Mesa Boulevard Beyer Boulevard 70th Street San Ysidro Transit Center Grossmont Transit Center Amaya Drive El Cajon Transit Center Arnele Avenue Gillespie Field Santee Town Center

The creation of the Metropolitan Transit Development Board (MTDB) in 1976 with a clearly stated mission initially did not resolve differences between the many stakeholders. However, MTDB did analyze previous transit studies, and determined that the guideway system should satisfy the following principles:

• Corridor should extend a long distance and offer high-speed operation
• Low capital cost designs should be adopted, to keep the costs within an affordable range
• Construction should be at-grade with mostly exclusive right-of-way
• Operating deficits should be minimized

A feasibility study completed in 1975 identified the unit costs of guideway options, including the estimation of ‘typical section’ per-linear-foot costs for six guideway types: (1) cut-and-cover subway; (2) tunnel bore; (3) ‘aerial line’; (4) open-cut line with retaining walls; (5) sidehill berm cut line; (6) at-grade line. In addition, the MTDB's enabling legislation explicitly required the guideway system to satisfy the following criteria, consistent with the principles adopted by the Board: priority consideration shall be given to technologies available and in use; guideway system shall be capable of being brought into operation incrementally; transportation rights-of-way of public entities shall be utilized to minimize construction costs. The adoption of the principles effectively required either a ‘light rail vehicle’ capable of street running (to avoid grade separation), or a commuter-rail like design terminating at the Santa Fe Depot.

The MTDB's enabling legislation also provided a dedicated funding source for guideway construction that would expire in 1981. Urgency was created since the dedicated funding would revert to the State highway fund if not expended on mass-transit guideway construction. In 1976–77, considerable planning efforts were completed. MTDB's 1977 "Guideway Planning Project: Phase I Report" identified many alignment options: Interstate highways I-5, I-8, and I-805; State Routes 94 and 163; railroad rights-of-way owned by Santa Fe (AT&SF) and by Southern Pacific/San Diego & Arizona Eastern (SD&AE); local arterials El Cajon Boulevard, 4th/6th/Genesee Avenues, and Highland/National/3rd/5th Avenues.

This report dismissed the use of local arterials for line-haul purposes, due to the cost of aerial or tunnel guideways. "A guideway extending from El Cajon easterly (parallel to I-8) to the vicinity of I-5/Santa Fe Railroad, then southerly through Centre City to San Ysidro parallel to I-5 and SD&AE" was recommended as the first increment. As planning intensified, Phase II of the "Guideway Planning Project" was under way, with efforts initially focusing on the El Cajon Line with the higher ridership potential. However, nature intervened.

On September 10, 1976, Tropical Storm Kathleen destroyed parts of SD&AE's Desert Line, at the time a part of the Southern Pacific (SP) system.[9] The hurricane caused $1.3 million worth of damage ($5.84 million adjusted for inflation), primarily in the eastern part of the state. Through freight service to Arizona was suspended and San Diego became an isolated portion of the SP system. SP petitioned for abandonment of the SD&AE on August 9, 1977, of all tracks west of Plaster City, while the MTDB guideway planning project was ongoing. Due to the apparently immediate availability of a right-of-way in the South Bay Corridor, the transit planning refocused on the SD&AE (SP) Tijuana line, making it the effective ‘minimum operable segment’.

At the same time, the San Diego County Board of Supervisors became concerned about the freight service on the SD&AE. Direct freight service to the East was seen as vital to the county's economic interests and the continued viability of San Diego as a deep-water port. With an eye towards preserving freight service and future transit right-of-way, San Diego County commissioned its own internal study effort, "Feasibility of Using Existing SD&AE ROW for Commuter Service", to examine using a portion of the SD&AE tracks for light rail or diesel passenger service sharing track with freight services. Part of the motivation for considering the SD&AE was to "operate the freight service at a profit through changes to work rules, relief from property taxes, and sharing of costs with the transit operation".

By late 1977, two major transit investment studies were under way focusing on the same corridor: the MTDB-sponsored "Guideway Planning Project", and San Diego County's "SD&AE ROW Feasibility Study".

1. The Base Case: MTDB described the base case as a modified bus network that retained the same number of total vehicles as the present San Diego Transit system.
2. MTDB's All-Bus Improvement Alternative: This "low capital cost" system would have introduced high-occupancy vehicle lanes on freeways and invested in higher capacity buses and express routes.
3. MTDB's Rail Improvement Alternative, San Diego County's "Light Rail Electric": This "medium capital cost" has electric light-rail transit replacing buses in the South Line corridor and would re-deploy the buses on feeder services.
4. MTDB's Fully Separated Rail Freight Service Alternative: MTDB examined the possibility of an exclusive double-track South Line on the SD&AE right-of-way. Under this freight rationalization proposal, freight trains would operate over the parallel Coronado Spur south to Imperial Beach, and via 2 miles (3.2 km) of new right-of-way and 5 miles (8 km) of "shared corridor" parallel operations on dedicated tracks to reach Tijuana.
5. San Diego County's "Leased Diesel" Option: The county saw the leased diesel (equivalent to present day commuter rail) as the lowest initial cost option with the least time required to begin service. Facilities would be designed to be convertible to light rail when more funds became available.
6. San Diego County's "Light Rail Diesel" Option: The county was interested in the self-powered diesel rail cars for its lower capital costs, however, noted that the vehicles were not then approved by the California Public Utilities Commission for one-person operation.

The original San Diego Trolley alignment later named the "South Line" known today as the "Blue Line"

In 1978, the MTDB successfully negotiated with SP to purchase the SD&AE for $18.1 million, including the $1.3 million required to restore the hurricane-damaged freight line. This was a dual-intent decision, to preserve both rail freight services to the Imperial Valley, and to preserve available right-of-way for future transit use. In light of cheaper light-rail options identified in the MTDB and San Diego County studies, more expensive options such as a proposed $325 million rail-rapid transit line on a new right-of-way to the border seemed less competitive. There was agreement that using the SD&AE right-of-way and light rail technology was more economical and practical than a new rail-rapid transit line.

Construction of the San Diego Trolley proceeded incrementally. The initial construction of new track focused mainly in downtown San Diego. The work on the SD&AE railroad track is best described as ‘rehabilitation’. The MTDB replaced 40% of all ties, cropped and welded the jointed rail, constructed electric catenaries, and installed an absolute block signal system. To control costs, the San Diego Trolley ordered only 14 cars, and did not install ‘mimic’ boards or the on-train location equipment until after the East Line was completed in 1989. No new sidings were initially installed on the SD&AE segment, which had three passing sidings between San Diego and San Ysidro. Service started at 15-minute headways using the rehabilitated single-track line.

San Diego Trolley opened in 1981 with 13.5 miles (21.7 km) of operations on the South Line. Additional vehicles were purchased in 1983, and the South Line was mostly double-tracked by 1984, largely on the strength of demand for more frequent headways. The business plan's incremental building and funding approach was vindicated. The East Line opened to Euclid Avenue in 1986, and was extended to El Cajon in 1989 and Santee in 1995. Service was extended northward to Old Town in 1996 and then eastward in Mission Valley in both 1997 and 2005.[10]

The transit center at 12th & Imperial, in the southeastern portion of downtown San Diego, has historically been used as the transfer point between the various lines, and is located adjacent to the Trolley's maintenance facilities. It is a recognizable landmark in the neighborhood, as it includes a grey clocktower with red clock. It is located two blocks east of the main entrance to Petco Park and is the station serving that facility.

On September 2, 2012,[11][12] MTS realigned trolley operations to allow for "more efficient travel" and to solve several issues with the previous operating layout. The Green Line was extended from its former western terminus in Old Town south to 12th & Imperial Transit Center's Bayside Terminal, eliminating the need for the Special Event Service Line, which previously ran on a similar route. The Orange Line's western terminus was extended to Santa Fe Depot while its eastern terminus was shortened to El Cajon Transit Center due to the line's low ridership to and from the Gillespie Field station. The Blue Line's northern terminus was temporarily shortened to America Plaza until the completion of the Mid-Coast Trolley extension project.[13][14] Not only does this plan ensure every line will stop or pass through downtown, but it also creates two universal transfer points, one at the 12th & Imperial Transit Center (at the east side of downtown) and the other at the America Plaza/Santa Fe Depot (on the west side of downtown).

On September 24, 2009, MTS approved the purchase of 57 new model Siemens S70 cars, at a total cost of $205 million.[15][16] The cars began arriving in late September 2011 and are custom made model S70s. In 2012, the order was increased from 57 to 65 of these 'streetcar length' S70s.[17][18] The new vehicles are nine feet (2.74 m) shorter than the existing S70 vehicles on the system, making them the equivalent size of the older SD100 "Boxed Shaped" cars, allowing for three car operation in the downtown area. In order to run these trolleys on the older Orange and Blue Lines a platform and tracks renovation project was begun in 2010,[19][20] starting with Blue Line stations south of Old Town, working its way southbound.

The project entailed raising the station from a track level (0-inch or 0-millimeter) or 4-inch (102 mm) raised platform to a 6-inch (152 mm) raised platform and placing a special "safety tile" with a smooth surface in the center, on the curb to allow for the wheelchair ramps to deploy without being damaged, as the existing "safety tile" contains rivets all the way throughout it. Some stations, primarily south of 12th and Imperial on the Blue Line, continued to board at track level through early 2015, and major re-construction was needed before low-floor trolleys could operate at these stations. Such improvements included brand new station platforms, station structures, rails, switches, signals, and overhead wires.[15]

In addition to new LRVs, San Diego Trolley also slowly retrofitted the SD-100s LRVs with new paint, door sensors & switches, wheelchair lifts, route display signs, and interior & exterior lighting. The oldest model U2 trolleys had very little that can be done to improve their functionality or operation as they lacked the overhead equipment compartments found in the SD-100s and S70s, and were planned to be entirely phased out and retired by 2015. Eleven of the U2 cars were sold to the upstart Metrotranvía Mendoza in Mendoza, Argentina;[21] another 29 had been retired by early 2013,[1] and the rest of the U2 trolleys were retired from service in January 2015.[22] Six U2 cars have been preserved: car 1019 at the Rockhill Trolley Museum, cars 1003 and 1008 at the Orange Empire Railway Museum, as well as cars 1017 and 1018 at the Western Railway Museum; car 1001 has been retained by MTS and was restored for use on the Silver Line.[23]

The project cost around $660 million.[18][24] The new LRVs began arriving in late September 2011 and began running on the Green Line on October 3, 2011.[25] Additional new LRVs began operation on the Orange line in January 2013.[26] The final phase of the project began July 25, 2013 with a groundbreaking ceremony to kick off the construction to modernize the remaining unrenovated stations on the portion of the Blue Line south of downtown San Diego.[27] The low-floor Siemens S70 trolleys began operation on the Blue Line on January 27, 2015,[28] which coincided with the retirement of the last of the original U2 trolleys.[22] The project, including remaining station and track renovations, was completed in late 2015.[24]

Following the World Health Organization's proclamation of a pandemic, the COVID-19 pandemic in March 2020, MTS began installing handwashing stations at all platforms.[29] Cleaning crews have been stationed at major hubs throughout the network to frequently disinfect vehicle surfaces, seats, and ramp buttons.

Trolley service operates on three daily lines: the Blue, Green, and Orange Lines, and travels through 53 stations and 53.5 total miles of double-track rail.[1] A fourth line, the heritage streetcar Silver Line, operates more limited weekday and weekend service, in a clockwise 'circle-loop' around downtown San Diego only.[2]

Line	Opening[1]	Length[1]	Stations[1]	End Points	Operation
Blue Line	1981	15.4 mi (24.8 km)	18	America Plaza San Ysidro Transit Center	Daily
Green Line	2005	23.6 mi (38.0 km)	27	12th & Imperial Transit Center Santee Town Center	Daily
Orange Line	1986	18.0 mi (29.0 km)	19	Courthouse Arnele Avenue	Daily
Silver Line	2011	2.7 mi (4.3 km)	9	Clockwise loop through 12th & Imperial Transit Center and around downtown San Diego	Mid-day on Selected Days

E Street Station of San Diego Trolley.

Trolley of Blue Line arriving at E Street Station of San Diego Trolley.

San Diego Trolley at America Plaza Station.

San Diego Trolley Inside.

The San Diego Trolley system has 55 stations serving its four Trolley lines.[30]

Fourteen of the Trolley system's stations operate as transfer stations, which allow passengers to transfer between lines. There are two universal transfer points (i.e., allowing transfers among all four lines) in the system in downtown San Diego: the 12th & Imperial Transit Center station, and the America Plaza/Santa Fe Depot stations. Six Trolley stations are end-of-line stations. Of the 53 San Diego Trolley stations, 37 stations are within the city limits of San Diego, serving various neighborhoods in San Diego; the other 16 stations are located in the cities of Chula Vista, El Cajon, La Mesa, Lemon Grove, National City, and Santee.

Most of the stations in the San Diego Trolley system are 'at-grade' stations. There are 8 aerial stations, mostly on the newer Green Line. There is just one Trolley station in the system that is underground – the SDSU Transit Center station – also on the Green Line.

About half of San Diego Trolley stations offer free park and ride lots. Most Trolley stations offer connections to MTS bus lines.

The San Diego Trolley's three main lines operate regular service between 5am and midnight, seven days a week. Limited service on particular segments is provided before 5am and after midnight, however; but there is no rail service between 2am and 3:30am.[31] During these hours when there is no passenger service, freight trains of the San Diego and Imperial Valley Railroad operate on the trolley's right of way.

Service on the Blue Line operates every 15 minutes, seven days a week, with service every 7.5 minutes during weekday rush-hours; late-night service on this line runs every 30 minutes.[31] The Green and Orange Lines operate service every 15 minutes on Monday-Saturday mid-days, but every 30 minutes on weekend mornings, on Sundays, and during evenings.[31]

The fare for a standard one-way Trolley ticket is $2.50, and one-way tickets are good for two hours from the time of purchase. Kids below 6 ride for free with fare-paying rider; limit is 3.[32] Transfers between trolley lines are free, provided it is to complete the one-way trip;[32] but round-trips are not allowed on a one-way ticket.[32] Transfers to MTS/NCTD buses, the Coaster and the Sprinter are also not allowed with a standard one-way Trolley ticket. However, a 24-Hour Pass (good for 24 hours from first boarding) is unlimited use, and allows unlimited travel on the San Diego Trolley system, as well as most MTS & NCTD bus systems, and the north country Sprinter light rail service for next 24 hours.[32] A RegionPlus 24-Hour Pass allows unlimited service on all of the above named systems, as well as MTS Premium buses and the Coaster commuter rail, for 24 hours upon first boarding.[32]

The following table shows San Diego MTS fares,[32] since 09-01-2019.[33] (in US dollars):

Fare collection is based on a proof-of-payment system. The San Diego Trolley is a barrier-free (no turnstiles), self-service system. Patrons must have proof of fare (ticket or pass) before boarding. Self-serve ticket vending machines are located at each station. Compass Card (see below) users must "tap" at a Compass Card validator (located at various points around each Trolley station, and on MTS buses) or on the Compass Card target on a ticket vending machine before boarding a trolley. Random fare inspections are performed by roving transit enforcement personnel. Based on frequent security inspections, nearly 98% of the 37 million patrons have proper fares.[1]

The Compass Card is a form of electronic ticketing used on public transport services within San Diego County. It is administered by the San Diego Association of Governments (SANDAG)[34] and is valid for travel on a number of different transit systems within San Diego County including MTS buses, the San Diego Trolley, North County Buses, the Coaster commuter rail line and the SPRINTER (a light rail line in north San Diego County). The card and fare collection systems are manufactured by Cubic Transportation Systems, and SANDAG administers the Compass Call Center (CCC), a central call center for all agencies.[35]

The Compass Card is an orange or yellow, credit-card-sized contactless smartcard which can hold a transit pass, such as a Day Pass, a 14-Day Pass, etc. The Compass Card card must tapped on an electronic Compass Card validator when entering and transferring within the system in order to validate the fare. Compass Card readers are integrated in bus fareboxes, and standalone readers are located just outside the paid-area of Trolley and rail stations.

As of the Fourth Quarter (Q4) of 2013, the average weekday ridership on the San Diego Trolley system was 119,800,[37] making it the fourth busiest Light rail system in the United States. Taking overall track length into consideration, the San Diego Trolley transported 2,239 daily passengers per route mile in Q4 2014, making it the twelfth busiest Light rail system on a per mile basis over this time period. Weekday ridership on the Trolley has been relatively high since Q3 2013 (see table at right).

In all of 2014, the San Diego Trolley provided 39,731,900 unlinked passenger transits according to the American Public Transportation Association (APTA).[37] MTS reported that there were 39,694,197 trips on the Trolley in Fiscal Year 2014 (FY 2014), a 34% increase over Fiscal Year 2013.[38] Of the Trolley's three lines, the Blue Line has the system's highest ridership with 15,094,878 riders during FY 2014, followed by the Green Line with 13,673,926 FY 2014 riders, and the Orange Line with 10,896,289 FY 2014 riders.[38] The Silver Line, operating only mid-days just four days a week (and with some service interruptions during the year), carried 29,104 passengers around the downtown loop in FY2014.

The following ridership data for the San Diego Trolley was obtained from the American Public Transportation Association's (APTA) Ridership Report Archives:[39]

According to figures from APTA, previous to 2014, the San Diego Trolley achieved the highest level of ridership in 2007, when there were 36,386,100 unlinked passenger transits on the system over that entire year.[40] The Trolley system's highest average weekday ridership of 124,300 was achieved in Q3 2007[45] – this corresponded to 2,323 passengers per route mile daily.

SANDAG is Currently Under construction On an extension of the Blue Line[46] from the Old Town Transit Center 11 miles (17.7 km) to the University City community, which will serve major activity and employment centers such as the University of California, San Diego (UCSD) campus and University Towne Centre (UTC) shopping center.[47][48] This is part of the "Mid-Coast Corridor Transit Project".[49] Construction began in October 2016,[50] and the Mid-Coast extension is slated to be completed and in operation by Summer/Fall 2021.[47]

After the Mid-Coast Trolley extension project is completed, the Blue Line will be extended north from its current northern terminus at America Plaza to run through 5 existing stations (up to and including the Old Town Transit Center), 8 new stations (Tecolote Road, Clairemont Drive, Balboa Avenue, Nobel Drive, VA Medical Center, UCSD West/Pepper Canyon, UCSD East/Voigt Drive, and Executive Drive), and then terminate at University Towne Center, near Westfield UTC in the University City/UCSD area.[47]

MTS began work in March 2011 on a study to evaluate the feasibility of reconnecting Balboa Park, the San Diego Zoo and Downtown San Diego through a fixed-guideway, electrified streetcar line – the final study on the subject was published in October 2012.[51] The project study corridor runs between the City College Trolley Station area, and Balboa Park in the vicinity of the San Diego Zoo.[52] An alignment similar to the proposed one was last served by a streetcar system in 1949 on lines 7 (Park Boulevard-University Avenue to East San Diego) & 11 (Park Boulevard-Adams Avenue to Kensington).[53] The Committee evaluated what types of streetcars to use for this proposed line, the possible options including the recently ordered 57 Ultra Short 2011 S70s in the "Modern Streetcar" category, and the restored PCC Streetcars from the Downtown Silver Line in the "Vintage Streetcar" category.[54][55] The major construction issue was how to cross I-5 without having to reconstruct the entire bridge. The estimated cost for construction of this line was $68.2 million, with each trolley car estimated to cost between $850,000 (for a restored PPC trolley car) to $3.6 million (for a modern trolley car). Four cars are anticipated for service on this line. No funding sources were identified. No further action on this proposal has taken place since the October 2012 release of the study.

Since 2009, SANDAG has proposed a plan that would bring trolley service to San Diego International Airport. On January 19, 2013, mayor Bob Filner endorsed the idea, which spawned a renewed city interest in the project. In January 2013, SANDAG took steps to bring about a proposed extension to the Airport; MTS also had this idea in consideration for many years. One scenario of the plan would be an extension of the existing Orange Line from downtown to the southern portion of the Airport along Harbor Drive that would connect the Airport's terminals to trolley service. Another proposed scenario would bring service to the northern portion of the Airport and connect with the Blue and Green Lines at Washington Street and/or Old Town in the near or distant future. The California High-Speed Rail line is also planned to terminate on the north side of the airport (in Phase 2, which has no timetable yet). There is no projected completion date for this proposed airport extension.[56]

A dedicated local bus line (Route 992) currently provides a connection between the airport terminals and downtown. There is also the Trolley → Terminal Shuttle service, which takes passengers from the terminals to within 1 block of the Middletown station on the Green Line.

The Purple Line is a new San Diego Trolley line proposed by SANDAG, the San Diego Association of Governments, that would run from San Ysidro Transit Center at the United States–Mexico border to Kearny Mesa with a possible extension to Carmel Valley. It would run along, or close to I-805 and I-15.

In April 2011, the San Diego Association of Governments (SANDAG) released a draft of its 2050 Regional Transportation Plan, which was approved by the SANDAG Board of Directors on October 28, 2011. An inland Trolley line from San Ysidro to Kearny Mesa, though not yet called the Purple Line, was included in the plan.[57][58][59]

In April 2019, SANDAG approved the final version of a November ballot initiative to increase the countywide sales tax by a half cent which further detailed future transit plans and specifically mentions and estimates the cost to build the proposed San Ysidro-Kearney Mesa trolley extension the Purple Line.[60]

The San Diego Association of Governments (SANDAG) released a draft of its 2050 Regional Transportation Plan in April 2011, which was approved by the SANDAG Board of Directors on October 28, 2011.[58][59] Significant expansion of 156 new miles of Trolley service is proposed in the 2050 RTP,[58] as well as the creation of three new streetcar lines serving Downtown San Diego.

In addition, in April 2019, SANDAG approved the final version of a November ballot initiative to increase the countywide sales tax by a half cent which further details future transit plans and named the proposed San Ysidro-Kearney Mesa trolley extension the Purple Line.[60]

The following Trolley and streetcar projects were included in the 2050 Regional Transportation Plan. The Plan's projected date of completion of each project is shown, but these dates are highly speculative since no specific commitments are being made in this plan, with the exception of the Blue Line Mid-Coast Extension which is currently under construction.[57]

A related project to these is the plan to build an Airport Intermodal Transit Center on the northeast side of Lindbergh Field by 2035,[63] which would include direct Trolley service access (from the Green Line, and from the Blue Line as well after the completion of the Mid-Coast Transit project) to San Diego International Airport. (Note: This is unrelated to the separate proposal to extend the Orange Line along Harbor Drive to the terminals on the south side of Lindbergh Field.)

Other Trolley projects in the 2050 Regional Transportation Plan involve more grade separations (from street crossings) for the Blue and Orange Lines, and the creation of more Express Lines on existing track.[57]

Below are the floor plans of the system's three different models of light rail vehicle, as shown on the website of the MTS.[4][17]

	Floor plan
Model U2 71 units (originally; now: 1 in operation) Car nos.: 1001–1071 First purchase: 1979
Model SD100 52 units Car nos.: 2001–2052 First purchase: 1993
Model S70 (Full Length) 11 units Car nos.: 3001–3011 First purchase: 2004
Model US-S70 (Streetcar Length) 65 units Car nos.: 4001–4065 First purchase: 2009/2012
Model US-S700 (Streetcar Length) 45 units Car nos.: 5001–5045 First purchase: 2018