Chicago Subdivision

The Chicago Subdivision or Chicago Sub is a railroad line in Illinois that runs about 38 miles (61 km) from Chicago to Aurora and hosts Metra's BNSF Railway Line commuter service. It is operated by BNSF Railway as the easternmost part of the railroad's Northern Transcon to Seattle, Washington.[1][2][3][4] This line is known as the Racetrack because it is mostly triple-tracked and supports fairly fast trains. It had been operated by a BNSF ancestor, the Chicago, Burlington and Quincy Railroad, which introduced high-speed Zephyr passenger trains in 1934 and ran many of them along this subdivision from Chicago to points west.

Chicago Subdivision
Amtrak's Carl Sandburg on the Chicago Subdivision in Berwyn, Illinois. The bridge above the train belongs to the Canadian National Railway (previously Illinois Central).
Overview
Owner	BNSF Railway
Locale	Chicago metropolitan area
Termini	Chicago Aurora, Illinois
Service
Type	Freight rail Commuter rail Inter-city rail
System	Northern Transcon
Operator(s)	BNSF Railway Metra Amtrak
Technical
Line length	38 mi (61 km)
Number of tracks	3-4
Track gauge	1,435 mm (4 ft 8 1⁄2 in) standard gauge
Operating speed	70 mph (110 km/h)
Route map Chicago Subdivision mi Aurora Subdivision Mendota Subdivision Fox River Aurora original station 38.4 Aurora Transportation Center Metra yard 33.4 Eola Eola Yard Elgin, Joliet & Eastern / Canadian National 31.6 Route 59 28.4 Naperville 24.4 Lisle 22.9 Belmont 21.1 Downers Grove Main Street 20.3 Fairview Avenue 19.4 Westmont 18.2 Clarendon Hills 17.8 West Hinsdale 16.8 Hinsdale 16.3 Highlands 15.4 Western Springs 14.1 Stone Avenue 13.7 La Grange Indiana Harbor Belt Railroad 13.0 Congress Park 12.3 Brookfield 11.7 Hollywood 11.0 Riverside 10.0 Harlem Avenue 9.6 Berwyn 9.0 La Vergne Illinois Central / Canadian National Freeport Subdivision 8.5 Clyde Cicero Yard 7.0 Cicero Belt Railway of Chicago Pink CR&I Industrial Track / Norfolk Southern 3.7 Western Avenue Western Avenue Yard 1.8 Halsted Street 0.0 Union Station

The Chicago Subdivision meets the Aurora Subdivision and Mendota Subdivision in Aurora. Commuter service ends at the Aurora Transportation Center, though Amtrak trains continue southwest on the Mendota Subdivision. Triple-tracking runs from where track leading to the Aurora station and Metra Yard joins the subdivision eastward to Cicero, where multiple tracks from a yard join. It is then quadruple-tracked for the rest of the way until the turn to Union Station.[5] As of 2015 weekday traffic on the subdivision was 94 Metra commuter trains, eight Amtrak intercity trains, and 60 BNSF freight trains.[6]

After the introduction of the CB&Q Zephyrs, train speeds increased significantly around the country for the next decade or so, but the Naperville train disaster along these tracks in 1946 was one event that contributed to the federal government restricting speeds in later years. Trains that had once traveled at or above 100 miles per hour (160 km/h) were soon restricted to a maximum of 79 miles per hour (127 km/h).[7][8][9] Much of this line has a speed limit of 70 miles per hour (110 km/h) for passenger trains, while freight trains run slower.[1][2][3][4]