Interstate 370

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Interstate 370 is a 2.54-mile long spur from I-270 into the city of Gaithersburg. The route links the Inter County Connector (ICC) and Shady Grove Metro station with Interstate 270 and Rockville.

Opening of Maryland Route 200 (ICC) on February 23, 2011, from near the Shady Grove Metro station east to MD 97, resulted in a reconfiguration of the Interstate 370 southward curve toward Shady Grove Road. Built where the freeway turned south is a trumpet interchange joining I-370 with the west end of the ICC. This shortened I-370, which was previously 3.13 miles in length. Old I-370 leading south to the metro station was redesignated as part of 0.52-mile unsigned Maryland Route 200A, though an end shield remained along the route in June 2012.

Interstate 370 East
Sam Eig Highway eastbound at Fields Road and the transition to I-370. The surface arterial begins nearby at Great Seneca Highway (MD 119) and intersects Fields Road at a traffic signal adjacent to I-370. Washingtonian Boulevard to Rio Center and Washingtonian Center in Gaithersburg is the first exit eastbound. 06/20/12
Interstate 370 commences and travels through a 1998-constructed diamond interchange with Washingtonian Boulevard. The freeway quickly encounters Interstate 270 as it curves eastward.
Completion of the western leg of the Intercounty Connector (ICC) toll road resulted in the placement of a new sign bridge along Sam Elg Highway. Hosted on the assembly is the original Interstate 270 overhead and a dynamic message sign with the toll schedule of MD 200 Toll east to U.S. 29 and Interstate 95. These rates vary depending upon time of day. 06/20/12
A pair of lanes depart ahead for Interstate 270 southbound for Rockville, Bethesda, Silverspring, Washington, and Northern Virginia. Interstate 270 carries up to 12 lanes on the drive southward to the Capital Beltway (Interstate 495).
Sign changes made after the ICC opened green out the Interstate 370 destination of "Metro Station". I-370 still provides a route to Shady Grove Station, but not directly. 06/20/12
Interstate 370 eastbound at the cloverleaf ramp onto Interstate 270 northbound for the city of Frederick, Hagerstown, and other points north and west. The loop ramp here is the only non-directional ramp within the Interstate 270 and 370 junction. 09/25/04
The pull through panel for Interstate 370 at I-270 was replaced with a MD 200 Toll advance sign for the forthcoming connection with the ICC. An Interstate 95 greenout covers a MD 97 shield. Note that there is no control city for MD 200 east. 06/20/12
Eastbound at the Interstate 270 northbound ramp gore point. Interstate 270 ends at the confluence of Interstate 70 and U.S. 15 & 40, 23 miles to the northwest at Frederick. 06/20/12
Interstate 370 eastbound expands to four lanes with the on-ramps from Interstate 270 as it passes under Industrial Drive. A pair of ramps depart ahead for MD 355 (Frederick Road) and Shady Grove Road eastbound. MD 355 constitutes the former routing of U.S. 240 between Frederick and Washington, D.C.
Again "Metro Station" was greened out along the Interstate 370 pull through panel due to the creation of the ICC. 06/20/12
MD 355 (Frederick Road) northbound travels into downtown Gaithersburg and the historic district just beyond its interchange with Interstate 370. 06/20/12
The right lane departs for the Shady Grove Road eastbound off-ramp. Shady Grove Road comprises a busy surface arterial between MD 28 (Key Stone Avenue) and Interstate 270 northeast to MD 355 (Frederick Road) and the Midcounty Highway at Redland. 06/20/12
Curving to parallel Shady Grove Road, one mile ahead of MD 200 (Intercounty Connector) on Interstate 370 east. The ICC opened fully between I-370 and Interstate 95 on November 22, 2011. 06/20/12
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2 photos
A directional ramp (Exit 2) claimed the third eastbound lane for MD 355 (Frederick Road) and downtown Gaithersburg before the freeway was expanded to six overall lanes to MD 200.
Interstate 370 crosses over Frederick Road below as the MD-355 northbound ramp departs and merges with the westbound off-ramp to MD 355. 1.5 miles separate Interstate 370 from MD 117 (Diamond Avenue) via Frederick Road. 09/25/04, 06/20/12
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2 photos
An end advisory sign for Interstate 370 was posted just beyond the MD 355 northbound off-ramp for the freeway's original end at the Shady Grove Metro Station. 09/25/04, 01/02/01
The lone Interstate 370 eastbound reassurance shield was posted near the Oakmont Avenue underpass between MD 355 and Shady Grove Road. All Maryland Interstate highways double as snow emergency routes. Therefore in almost all cases reassurance shields are accompanied by these snow route signs. 09/25/04
A new end sign for Interstate 370 takes the place of the only eastbound reassurance shield ahead of the Oakmont Avenue underpass. Interstate 370 was truncated 0.59 miles from Shady Grove Station with the opening of the Intercounty Connector. 06/20/12
Spanning the MARC Brunswick Line & CSX Railroad, Interstate 370 travelers approach the half mile mark to MD 200 Toll and the original southward turn of Interstate 370. The forthcoming toll road uses cashless tolling via E-ZPass transponders or video tolling. 06/20/12
A look at the original Interstate 370 freeway configuration and half-mile guide sign for the Shady Grove Road parclo interchange. Shady Grove Road travels less than one mile east of MD 355 to interchange with Interstate 370. 09/25/04
Separate ramps now split from Interstate 370 for Shady Grove Road (Exit 3A) and unsigned MD 200A (original I-370) south to Shady Grove Metro station. 06/20/12
Exit 3B consists of a trumpet interchange between the unsigned MD 200A freeway south and the joint end of Interstate 370 and beginning of MD 200 Toll (Intercounty Connector). 06/20/12
Maryland Route 200A / Former Interstate 370 South
Turning southward along unsigned MD 200A from Interstate 370 east; traffic merges in from the left ahead of a loop ramp to Shady Grove Road. 06/20/12
Originally separate ramps served Shady Grove Road east and westbound from Interstate 370 east. Reconfiguration of the freeway southward from MD 200 resulted in those ramps gaining full access to either direction of Shady Grove Road at a traffic light. 09/25/04
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2 photos
MD 200A continues south directly to Shady Grove Metro station as the loop ramp to Shady Grove Road departs. Shady Grove Road westbound returns to intersect Frederick Road and the rest of Gaithersburg. Eastbound continues 1.1 miles to Midcounty Highway and 1.7 miles to MD 115 at Redland and Airpark Road. 09/25/04, 06/20/12
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2 photos
An end shield remains for Interstate 370 at the on-ramp from Shady Grove Road. The four-lane freeway reduces speed as it enters the Shady Grove Station of the Washington Metro transit system ahead. 06/20/12, 01/02/01
Interstate 370 motorists are provided with three options on what to do when entering the Shady Grove Metro Station parking area. The Kiss & Ride lot to the left is for drivers dropping off passengers for the Metro trains and short term parking. 09/25/04
Lots 1 and 2 provide daytime parking for commuters traveling into Washington. Both roadways loop back out onto Interstate 370 westbound. 09/25/04
Maryland Route 200A / Former Interstate 370 North
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2 photos
Leaving the Shady Grove Metro Station on unsigned MD 200A northbound. The six-ramp parclo interchange with Shady Grove Road quickly faces drivers. Redland lies to the east and MD 355 (Frederick Road) to the west. 09/25/04, 06/20/12
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2 photos
Unsigned MD 200A partitions with the off-ramp to Shady Grove Road; MD 355 lies 0.75 miles to the west. The pull through panel for Interstate 370 was replaced and now connections with I-370, I-270 and MD-200 are touted along the connector. 09/25/04, 06/20/12
A one-piece assembly of Interstate 370 west to Interstate 270 represented the first westbound shield of the formerly 3.13-mile long Interstate. Shady Grove Road passes over the freeway in the distance. 09/25/04
Drivers exiting Shady Grove Station continued northwest along Interstate 370 and next met MD 355 (Frederick Road) northbound. This exit occurs beyond the MD 200 Toll trumpet interchange now and this overhead is no longer posted above unsigned MD 200A. 09/25/04
MD 200A quickly approaches the off-ramp to MD 200 Toll (Intercounty Connector) from the Shady Grove Road overpass. Separate ramps bring drivers from Shady Grove Road onto Interstate 370 west and MD-200 east. 06/20/12
Traffic defaults onto the loop ramp for Interstate 370 west to Gaithersburg and Interstate 270. MD 200 Toll begins to the east through the suburban communities of Olney, Rossmoor, Colesville, and Fairland. 06/20/12
A historic look at the original Interstate 370 curve northwest toward the MD 355 (Frederick Road) interchange. MD 355 represents the original U.S. 240 alignment through Gaithersburg and beyond. U.S. 240 initially followed Interstate 270 once the freeway was completed. But the redundancy in the numbering led to officials decommissioning the US highway. 09/25/04
A state-named shield, the only that was posted for Interstate 370, at the Crabbs Branch Way underpass. Six lanes of freeway now travel straight in this scene. 09/25/04
Interstate 370 West
Reassurance marker for Interstate 370 posted at the Crabbs Branch Way overpass. This is the only shield along the westbound mainline. 06/20/12
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2 photos
Changes made between Interstate 370 and MD 355 (Frederick Road) add an exit number (2) and expand access to both directions of the state highway. Previously there was no direct access from Interstate 370 west onto MD 355 (Frederick Road) southbound. 09/25/04, 06/20/12
Frederick Road travels 1.5 miles north from Interstate 370 to intersect MD 117 (Diamond Avenue) at the Gaithersburg Town Center. Downtown Rockville lies 3.3 miles to the south via MD-355. 06/20/12
Interstate 370 continues one mile west to meet Interstate 270 at what was a previously unnumbered exit but now is Exit 1. 06/20/12
Interstate 370 bends northwesterly alongside Muddy Branch on the half mile approach to Interstate 270. 06/20/12
Passing under the Industrial Drive over crossing, one-quarter mile east from the directional cloverleaf interchange with Interstate 270. The northbound off-ramp for Frederick, Hagerstown, and Gettysburg departs first. 06/20/12
Interstate 370 westbound transitions into the unnumbered Sam Eig Highway beyond Interstate 270. Ramps for Interstate 270 north and south depart quickly as Interstate 370 passes above the Interstate 270 mainline. 06/20/12
Attached to the Interstate 270 northbound to Interstate 370 westbound flyover is the end sign for Interstate 370. Traffic to Interstate 270 southbound for Washington D.C., Rockville, and Northern Virginia departs from the left. The right side panel indicates the freeway end at Fields Road. 06/20/12
The Interstate 270 southbound ramp sinks below the eastbound Interstate 370 travel lanes to combine with the eastbound off-ramp. Interstate 270 southbound interchanges with Shady Grove Road and MD 28 (Montgomery Avenue) as it leaves Interstate 370. 06/20/12
A diamond interchange accessible from I-270 via Exit 9B, joins Sam Eig Highway with Washingtonian Boulevard just west of I-370.
Washingtonian Boulevard parallels I- 270 and Fields Road between I-370 and Omega Drive adjacent to the interchange at Shady Grove Road. The arterial was built for the Rio Center and Washingtonian Center in Gaithersburg. 09/25/04
The Interstate 370 freeway ends at the Fields Road intersection west of the Washingtonian Boulevard overpass. Sam Eig Highway quickly encounters signals at both Fields Road and Diamondback Drive ahead. Otherwise the arterial ends in 0.75 miles at the Great Seneca Highway. 06/20/12
Access to Washingtonian Center from the Interstate 370 (Sam Eig Highway) mainline is provided via Fields Road. The interchange between Sam Eig Highway and Washingtonian Boulevard was completed in 1998. 06/20/12
Interstate 370 scenes
Fields Road northbound at Interstate 370 east and the Sam Eig Highway. The eastbound beginning of the freeway is allocated a pair of turn lanes. However ground level traffic signals preclude turning on red. 06/20/12
Diamondback Drive departs the Sam Eig Highway just west of the intersection with Fields Road. Washingtonian Boulevard meets Interstate 370 to the right. 06/20/12
The Interstate 370 trailblazer posted on Fields Road north at Sam Eig Highway was removed. 01/02/01


Photo Credits:

01/02/01, 09/25/04, 06/20/12 by AARoads

Connect with:
Interstate 270
Route 200 - Intercounty Connector

Page Updated 07-17-2012.

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