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{{Technology Infobox
| image=FileSmart Barrier plaza.jpg|250px
| name=Combine Smart Barrier
| affiliation=Combine
| type=Mechanic wall
| usedby=
| entity=func_movelinear
| designer=*Viktor Antonov (early and final versions)
*Eric Kirchmer (final version)''Half-Life 2 Raising the Bar''
| hidei=
| hideu=yes
| hideg=
}}
The '''Combine Smart Barrier''', also known as the '''Combine Mobile Wall''', is a large mechanized wall that uses powerful drive systems in tandem with heavy metal blocks to slowly expand outward and destroy existing structures in the way. Smart Barriers are seen surrounding the Citadel (where they make up the "City 17 Inner Wall"), certain areas of Nova Prospekt and City 17, notably on the Trainstation Plaza during Combine occupation of Earth and around the Overwatch Nexus.
==Overview==
Standard operation is to lift and force a set of blocks outward, before allowing them to drop, and then alternating with another set. During this procedure a metallic groaning is heard, presumably from the drive mechanisms. It is unknown whether the Combine are using this method to simply destroy existing structures, or whether to gather raw materials as well. Either way, they are also used as blockades, blocking off alleyways and even entire streets as necessary. Gordon Freeman narrowly escapes being crushed by Smart Barriers shortly before getting into the Nova Prospekt Depot.
As its name suggests, the Smart Barrier seems to be self-operated and will sometimes get into movement when a being passes nearby, crushing them if they were to remain in the way.
==Behind the scenes==
*As seen in the WC mappack and suggested by the Development of Half-Life 2 game|''Half-Life 2'' leak sound files, the City 17 Inner Wall was originally to be stationary, much higher and made out of concrete. The Manhack Arcade was at some point to be located nearby, before being replaced by Vance Headquarters|Captain Vance's Headquarters, where Gordon was to go look for Vance while Alyx was to be left hurt in the WC mappack.html">Skyscraper.WC mappackDevelopment of Half-Life 2 game|''Half-Life 2'' leak files
*An early version, only existing as concept art, was made of cubes.
*An early prototype version, featured in the WC mappack as a http//developer.valvesoftware.com/wiki/Brush brush, was named "Sensor Gate". It can be found in the WC mappack maps "sensor_gate_004.vmf", "combine_gallery_002.vmf" or "d1_garage_01.vmf". It is always accompanied by an early Combine Watchtower (Watchtowers are often seen near Smart Barriers, but also Combine Barricade|Barricades), often featuring a Metrocop inside. By default in open state, it shuts itself when the player approaches it, also reacting to a nearby presence with its "sensors", much like the final version.
==Gallery==
===Pre-release===
FileCombine techno.jpg|Concept art for an early version.
FileCitadel walls.jpg|Concept art for the City 17 Inner Wall.
FilePlayable leak menu.png|The ''Half-Life 2'' leak menu, featuring the previous image.
FileMobile wall citadel houses van.jpg|Concept art for the retail version near destroyed buildings.
FileGunship bays concept.jpg|Smart Barriers in the cut Gunship Bays, at the foot of the Depot.
FileSensor gate01.jpg|Sensor Gate with fixed textures in the map "combine_gallery_002".
FileSensor gate03.jpg|Ditto, seen from behind.
FileCitadel c17 soldiers early.jpg|Early Overwatch Soldiers near a prototype City 17 Inner Wall.
FileD4 streetwar01 04.jpg|Possible early Smart Barrier, mostly made of concrete in the map "d4_streetwar_01".
FileD4 streetwar01 07.jpg|Ditto.
FileProto innerwall randy fixed1.jpg|The Citadel beyond a prototype City 17 Inner Wall.
FileProto innerwall randy fixed2.jpg|Ruined City 17 street along the prototype City 17 Inner Wall.
FileLeak d2 coast 070002.jpg|Smart Barrier on the Bridge Point bridge in the leak, instead of a Force Field gate in the retail game.
FileLeak d2 coast 080009.jpg|Ditto.
FileLeak d2 coast 080011.jpg|Ditto, behind an Overwatch Soldier.
===Retail===
FileCafeteria combine wall.jpg|Smart Barriers replacing C3 block in Nova Prospekt, seen from the cafeteria.
FileCombine wall np.jpg|Smart Barriers in the destroyed C3 block of Nova Prospekt, seen from the block itself.
FileSmart Barrier plaza.jpg|Smart Barrier on the Trainstation Plaza.
FileTrainstation plaza breencast uprising.jpg|Ditto, with Rebels taking down the Breencast screen.
FileOverwatch Nexus1.jpg|Smart Barrier parts around the Overwatch Nexus building.
FileEp1 railway combine checkpoint.jpg|Smart Barrier at a checkpoint above the railway leading out of City 17, near the Technical Trainstation.
==List of appearances==
*https//www.youtube.com/watch?v=4ycFteRUQPM ''Half-Life 2'' at E3 2003 Barricade {{1st}} {{Nc}}
*''Half-Life 2''
*''Half-Life 2 Raising the Bar''
*''Half-Life 2 Deathmatch'' {{Nc}}
*''Half-Life 2 Episode One''
==References==
{{Reflist}}
{{Technology}}
{{Combine}}
CategoryCombine technologyCategoryTechnologyCategoryViktor Antonov designsCategoryEric Kirchmer designs
