Question: What did Harley Brinsfield do that paved the way for Subway?

Context articles: Busan Metro Line 4
Rockaway Freeway
Chris Pape
Line 2, Beijing Subway
R21 (New York City Subway car)
Subway (restaurant)
Watling Street
Harley Brinsfield
Green Line &quot;D&quot; Branch
Ridge Route

Busan Subway Line 4 ( ) is a rubber-tyred metro line of the Busan Subway network that connects part of Gijang-gun, Busan, and upper Haeundae-gu, Busan, into Dongnae-gu, Busan Korea.
 It is operated by the Busan Transportation Corporation.
 Opened on March 30, 2011, the line is a rapid transit (metro) system consisting of 14 stations - 8 underground, 1 on-ground, and 5 above-ground.
 The line color is blue.
 A trip through the entire line takes about 24 minutes.
 Unlike lines 1 to 3 of Busan Subway the trains are driverless and run with pneumatic tires on concrete track (Roll way) between two guide bars.
The Rockaway Freeway is a road in the New York City borough of Queens that was created from the old right-of-way of the Long Island Rail Road Rockaway Division in 1941–1942 as part of the project to eliminate grade crossings within New York City.
 The railroad line itself was elevated over the new automotive route, and was incorporated into the New York City Subway system as the IND Rockaway Line ( trains ) in the summer of 1956.
 Because of the large number of concrete posts supporting the elevated subway, the Freeway has consistently been hazardous for drivers.
 However, one stretch of the Freeway between Beach 73rd Street and Beach 87th Street in Hammels is difficult for drivers going in an easterly or westerly direction to avoid without going out of their way.
 A portion of the road, between Beach 67th Street and Beach 73rd Street, was closed permanently in 2005 to make way for a retail transit plaza in connection with the new Arverne-by-the-Sea construction development.
Chris Pape (aka Freedom) is an American painter and graffiti artist.
 Pape started tagging subway tunnels and subway cars in 1974 as "Gen II" before adopting the tag "Freedom".
 Pape is best known for his numerous paintings in the eponymous Freedom Tunnel, an Amtrak tunnel running underneath Manhattan's Riverside Park.
 Prominent paintings in the Freedom Tunnel attributed to Pape include his "self-portrait" featuring a male torso with a spray-can head  and "There's No Way Like the American Way" (aka "The Coca-Cola Mural"), a parody of Coca-Cola advertising and tribute to the evicted homeless of the tunnel.
 Another theme of Freedom's work is black and silver recreations of classical art, including a reinterpretation of the Venus de Milo and a full train car recreation of the icons ic hands from Michelangelo's Sistine Chapel.
Line 2 of the Beijing Subway () is a rapid transit rail line in central Beijing that runs in a rectangular loop around the city centre.
 The line traces the Ming dynasty inner city wall, which was demolished and paved over by the 2nd Ring Road and Qianmen Avenue.
 Line 2, opened in 1984, is the second oldest and one of the busiest of Beijing's subway lines and the only one to serve the Beijing Railway Station.
 All 18 stations on the 23.1 km line are under ground.
 Ten of the 18 stations offer transfers to other lines.
 Line 2's color is      blue.
The R21 was a New York City Subway car built by St. Louis Car Company in 1956-1957.
 The R21 was similar to the R17, except that it featured windows of a slightly different design.
 The cab doors are mounted the same way as the newer R62/62A subway cars, however this was not repeated on the next order for R22 subway cars which reverted to the normally mounted cab doors.
 Two different propulsion system were used, Westinghouse (WH) and General Electric (GE).
Subway is a privately held American fast food restaurant franchise that primarily sells submarine sandwiches (subs) and salads. Subway is one of the fastest-growing franchises in the world and, as of June 2017, has approximately 45,000 stores located in more than 100 countries.
 More than half of the stores are located in the United States.
 It is the largest single-brand restaurant chain and the largest restaurant operator in the world.
Watling Street is a route in England and Wales that began as an ancient trackway first used by the Britons, mainly between the areas of modern Canterbury and St Albans using a natural ford near Westminster.
 The Romans later paved the route, which then connected the Kentish ports of Dubris (Dover), Rutupiae (Richborough), Lemanis (Lympne), and Regulbium (Reculver) to their bridge over the Thames at Londinium (London).
 The route continued northwest past Verulamium (St Albans) on its way to Viroconium (Wroxeter).
 The Romans considered the continuation on to Blatobulgium (Birrens) beyond Hadrian's Wall to be part of the same route, leading some scholars to call this Watling Street as well, although others restrict it to the southern leg.
 Watling Street was the site of Boudica's defeat by the Romans and was later the southwestern border of the Danelaw.
 In the early 19th century, the course between London and the Channel was paved and became known as the Great Dover Road: today, the route from Dover to London forms part of the A2 road.
 The route from London to Wroxeter forms much of the A5 road.
 At various points along the historic route, the name Watling Street remains in modern use.
Harley Brinsfield hosted "The Harley Show, Music out of Baltimore" on WBAL and later on WFBR from about 1952 to sometime in the 1970s.
 With his second wife, Arlene Levy Brinsfield, he opened Harley Submarine Sandwich Shops, which, largely due to the publicity generated by his show, became one of the first and largest local fast food franchises pre-dating both McDonald's and Subway by many years.
The "D" Branch of the Massachusetts Bay Transportation Authority's Green Line, also known as the Highland Branch or the Riverside Line, is a light rail line in west Boston, Massachusetts.
 It branches off near Kenmore Square from the Tremont Street Subway and Boylston Street subway from downtown shared with the other light rail lines.
 It then continues west for about ten miles on a private surface right of way, grade separated from roads and highways, formerly the Highland Branch of the Boston and Albany Railroad.
 The right of way is double tracked throughout without express tracks.
The Ridge Route, officially the Castaic-Tejon Route, was a two-lane highway between Los Angeles and Kern counties, California.
 Opened in 1915 and paved with 15-ft concrete between 1917 and 1921, the road was the first paved highway directly linking the Los Angeles Basin with the San Joaquin Valley over the Tejon Pass and the rugged Sierra Pelona Mountains ridge south of Gorman.
 Much of the old road runs through the Angeles National Forest, and passes by many historical landmarks, including the National Forest Inn, Reservoir Summit, Kelly's Half Way Inn, Tumble Inn, and Sandberg's Summit Hotel.
 North of the forest, the Ridge Route passed through Deadman's Curve before ending at Grapevine.