for a double junction with diamond. Examples include Harris Park railway station, Sydney. Single lead left hand A single lead junction is used where traffic density is lower, and moves one of the turnouts on the main line onto the branch. This reduces the number of turnouts on the main line that are subject to wear. Space permitting, a single lead junction may be a stage towards construction of a higher speed ladder junction. This is shown as blue dashed line on the diagram. Risk However, unlike in the ladder, branch trains in opposite directions can collide head-on at 32 if either one passes a signal at danger (SPAD). This has contributed to fatal accidents, e.g. in the UK at: Glasgow Bellgrove on 6 March 1989 and Newton on 21 July 1991. These risks can be reduced by trap points, ATP or TPWS. Wear and Tear The diamond crossing is a high wearing and undesirable component: gaps in the K-crossings, and V-crossing. vibration at gaps caused by wheels jumping over these gaps. small parts which allow the joins to bend. insulated block joints, if needed for Track circuits, create more joints to bend. inconvenience when trying to tamp the track. inconvenience of speed limits to reduce vibration. difficulty of obtaining "track possession" to allow maintenance to be carried out. often the existing tracks do not have space to allow the alternative to be built as an afterthought. when starting on a "green field" site, the opportunity to install two high-speed turnouts to replace each diamond should not be missed. the insulated block joint problem can be reduced if axle counters can replace the track circuits over the crossings. switched diamonds are only suitable for limited range of crossing angles, and they have their own problems. say 1:5 (too coarse) to 1:10 (too coarse). the tracks through diamonds needed to be co-planar, and if not poor geometry and poor speeds may result. the legs of the diamond should be straight if possible. Trains (magazine) devoted an issue to diamonds, which, in their opinion, are NOT a railroad's best friend where traffic over a diamond crossing is heavier in one direction than the other, special measures can be taken to improve performance in the heavier traffic direction. See Trains. Single lead Right Hand A right hand single lead junction cannot protect against a collision should the Q-P train overrun the signal protecting