Gauntlet track or interlaced track (also gantlet track) is an arrangement in which railway tracks run parallel on a single track bed and are interlaced (i.e. overlapped) such that only one pair of rails may be used at a time. Since this requires only slightly more width than a single track, all rails can be carried on the same crossties/sleepers. Trains run on the discrete pair of rails appropriate to their direction, track gauge or loading gauge.
The term gauntlet is derived not from gauntlet meaning a type of glove, but from the expression running the gauntlet (originally running the gantlope) which means running between two confining rows of adversaries; gauntlet in this sense is a "corrupt form".
Gauntlet tracks can be used to provide horizontal clearance to a fixed obstruction adjacent to a track such as a cutting, bridge, or tunnel. Frog gauntlets are also commonly used when a rail line's capacity is increased by the provision of an additional track, but cost or other factors prevent the widening of the bridges. They are typically used for short stretches of track where it is cheaper to provide extra rails than to provide switches and reduce the line to single track. This also eliminates the problem of switch failures.
In a frog gauntlet, one rail crosses over a rail on the adjacent track. A frog is used to provide the flangeway for the crossing tracks. The train taking the gauntlet runs over the frog onto the parallel rails, passes through the gauntlet area, and passes over another frog to return to the original line. Since there are no points or other moving parts on a frog gauntlet track, a train operating on one of the tracks cannot be routed onto the other.
Because two trains cannot use the gauntlet at the same time, scheduling and signalling must allow for this restriction.
In a point gauntlet track, the rails for the two tracks do not need to cross, so no frog is required. The train taking the gauntlet runs over a set of switch points onto the parallel rails, passes through the gauntlet area, and passes over another set of switch points to return to the original line. This arrangement is used at the Roselle Park Station referenced below.
At a small number of locations on single track lines in Britain, interlaced loops had been provided where sprung catch points were required because of the steep gradient. The points at either end of the loop were set according to the train's direction of travel. Trains running uphill were routed via the loop incorporating the sprung catch point. Trains running downhill used the opposite loop, bypassing the catch point.
Where tracks diverge, a section of gauntlet track may be provided where the switches require to be located remote from the actual divergence. This arrangement is most commonly used on tram systems, to move the switches away from a heavily trafficked road.
An arrangement similar to gauntlet track is sometimes used to allow trains of different gauges to use the same track. In that case, the two interlaced tracks will have different gauges, sometimes sharing one of the rails for a total of three rails.
In Sydney, the bridge over the Georges River between Oatley and Como was built as single line in the 1880s. The line was duplicated soon after, except for that bridge. The bridge was fitted with gauntlet track, which needs no turnouts, and hence needs no signal box at the far end. The bridge was replaced with a double-track bridge in 1972.
Another example is visible in the tunnel under George Street, Railway Square, as part of the spur which leads from the connection between Redfern and the Darling Harbour goods station. This was a two-track tunnel (one of the oldest on the New South Wales railways) but became gauntlet track when the line was electrified to allow electric locomotive-hauled freight trains to access the former Darling Harbour. There was insufficient clearance in the tunnel to install overhead catenary above both tracks. A single track now continues on to the PowerHouse Museum and can be visited as part of the Ultimo Pedestrian Network. This track formerly served the Darling Harbour goods yards and was disconnected from the rest of the corridor which now forms part of the Sydney Light Rail network.
In Melbourne, Victoria broad and standard dual gauge gauntlet track is located to the north of Southern Cross Station. The northern section of the Upfield line between the Ford Sidings and Somerton is also dual gauge gauntlet track.
In Brisbane the dual gauge track for the CountryLink XPT service to Sydney runs from Roma Street railway station across the Merivale Bridge through the suburban rail network until it splits off at Acacia Ridge, Queensland.
The Gemmenich Tunnel (German: Gemmenicher Tunnel, French: Tunnel de Botzelaer) passing under the Dreiländerpunkt (Three country point) has a special track layout to enable the passage of wide military loads. The double-track tunnel has a third set of rails interlaced with one of the normal tracks. Active points (switches) at each end of the tunnel allow a train to divert along the central track, whilst other trains are blocked by signalling. The third track is rarely in use, so there is no limitation of capacity through the tunnel for standard-sized trains.
Close to where the borders of Belgium, Germany and the Netherlands come together, the interlaced tunnel section provides an important connection between Germany and the Belgian harbour at Antwerp. After completing the installation in 1991, trains with an oversize loading gauge were rerouted over this line, and the lightly used (but tunnel-free) secondary line between Stolberg and Welkenraedt (crossing the border at Raeren) was closed to freight traffic. Trains requiring use of the central track must be diesel hauled as electrification only currently reaches the tunnel mouth on the German side to allow for banking.
The Charleroi Pre-metro's Metro sections are entirely double-track, save for a short section along the Route de Mons, where a rail bridge abutment should have been moved to facilitate double track of premetro passing under it. Instead, a short section of gauntlet track is used. Behind the Anderlues depot of the Charleroi pre-metro there is an old-section of dual-gauge track, having both metro (tram/metro) and standard (railway) gauge. This section is no longer used by tram nor rail.
Gauntlet track exists on the Perry Island Canadian Pacific Railway Bridge across the Rivière des Prairies between Montreal and Laval (Parc subdivision, mile 10.0) because the structure gauge is not sufficiently wide for double track. This bridge is used by freight trains of the Canadian Pacific Railway (CPR), the Chemins de Fer Québec-Gatineau (CFQG) and by the Blainville–Saint-Jérôme Line suburban trains of the Metropolitan Transportation Agency.
On tram networks, gauntlet tracks are used to pass through a narrow passage through a building in Prague's historic Malá Strana and similarly on a narrow bridge in Ostrava. In addition, they are used in various places in Prague and Brno where interlacing is used to shift the switches away from high-traffic intersections, in order to improve traffic flow.
In the rail system, it is used to overlap metro and normal rail lines; these use the same gauge, but the metro's third rail would otherwise intrude upon the standard railway kinematic envelope.
In Mannheim, gauntlet track is used to shift the switch out of the road to prevent the switch from being driven over by cars and trucks. Mannheim also uses gauntlet track to run trams within less space.
In Stuttgart, gauntlet track was used extensively by the Stuttgarter Straßenbahnen in order to run services using the newer Stadtbahn, or light rail system, on route sections previously served by the older narrow-gauge tram system. The trams have now been completely phased out, save for occasional "old-timer" special runs, and all platforms are being converted from street-level to raised in order to accommodate the higher floors of the new vehicles.
To overcome space constraints, Amsterdam's tram network uses gauntlet track to increase space for shoppers in the 12 m (39 ft)-wide Leidsestraat in the city centre. In this busy and otherwise pedestrianised shopping street, the tram stops are located on the bridges over the canals, where more lateral space is available, permitting passing loops that can just accommodate two trams in each direction. Intermediate sections are gauntlet track. As service is frequent on routes 1, 2 and 5 which use this line, this arrangement often leads to delays. However, on line 10 in Czaar Peterstraat, the situation is reversed, and a short section of gauntlet track occurs in a line that is otherwise double, to make room for the platforms at the Eerste Leeghwaterstraat tram stop. Oddly, in a second radial route, at Utrechtsestraat, the passing places on the bridges are served by preset points with single track between them, rather than by gauntlet track. Amsterdam has two other short permanent sections of gauntlet track: opposite a loading bay in Amstelstraat (route 14) and preceding the points entering the eastern terminal loop outside Amsterdam Centraal railway station. In addition, during the rebuilding of the bridge over the Amstel at Hoge Sluis, the temporary bridge that carries tramlines 7 and 10 has been equipped with gauntlet track on the diagonal section at the eastern end, so as to leave enough room for the cycle path.
The Interislander rail-ferry ramps at Wellington and Picton have triple gauntlet track. At the ferry end of the ramp the outer tracks curve to the left and right to align with the tracks on the ferry rail deck.
The Lisbon tram system interlaces to negotiate several particularly narrow streets and tight corners.
The "Metrocentro T1" tram line of the Seville Metro that opened in 2007 features a 300 m section of interlaced track along the city's main pedestrian street. The section runs down Avenue de la Constitución, past the Seville Cathedral and World Heritage Site.
In Britain, gauntlet track was often used where street tramways had to pass through narrow streets and even archways in ancient city walls.
Roselle Park and Union Station on the Raritan Valley Line in New Jersey, have gauntlet tracks. The gauntlet track, with active switches, is used for passing high-level platforms, where the track is shared by both passenger and freight trains. The gauntlet track allows freight trains the extra clearance they may require, by moving the train further away from the platform edge. This type of point gauntlet is also used on the South Shore Line (NICTD) railroad at stations in Hegewisch in Illinois and Hammond and East Chicago in Indiana. (SouthShore Freight runs freight trains on the NICTD line.) A frog gauntlet section on the NICTD line in Gary, Indiana, was removed in 1997 after a 1993 fatal near head on accident where the tracks diverged.
The Westside Express Service (WES) regional rail line in the Portland, Oregon, suburbs has gauntlet track at its three intermediate stations, Hall-Nimbus, Tigard and Tualatin. These locations are along a stretch of track that WES trains shares with freight trains of the Portland and Western Railroad. Gauntlets at the stations allows freight cars to clear the high-level platforms.
The Delaware, Lackawanna and Western Railroad used gauntlet track to allow two sets of track to be placed in the centre-line through the Oxford Tunnel in New Jersey.
Amtrak's B&P Tunnel, underneath Baltimore on the Northeast Corridor, was equipped with a point gauntlet on one of its two tracks. Installed by the Pennsylvania Railroad in the mid-1950s to allow TOFC trains to fit through the tunnel, Amtrak removed it in the mid-1990s after most freight trains had been routed away from the Northeast Corridor.
The San Francisco Cable Car system features gauntlet track on some tight corners, where the outer rail of the inner track is shared as the inner rail of the outer track.
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