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and gradients must be gentle to permit reasonable operating speeds. They arenormally only justified when traffic volumes reach over 20 000 passenger per hourone-way but can handle volumes of up to 80-90 000 per hour.7.3.7 Light rail systems are cheaper, being mostly at-grade and able to tolerate tightercurvatures and steeper grades. Capacity is normally limited to between 20 000 and30 000 passengers per hour (depending on the character of the system) but can beoperated economically at lower volumes.7.3.8 The distinctions between light and heavy rail blur when considering inter-urbanrailways. For example, on the Northwest New Territories urban link discussed inSection 7.6 later in this chapter, the light rail and heavy rail alternatives previouslyproposed for this line (in studies by MTRC and KCRC) both required relatively fasttrains on segregated tracks with full signalling systems. The light rail alternativeshould be somewhat cheaper to build by permitting sharper curves and steepergradients but the principal difference lies in the trains used and passenger carryingcapacity offered.7.3.9 This report considers inter-urban light rail to be limited to 4-car trains using similarvehicles to those used in the recently opened North West Railway, and heavy rail tobe similar in characteristics to the current MTR 8-car trains. Detailed feasibilitystudies could profitably investigate intermediate designs.7.3.10 Apart from variations in the light and heavy rail options, a wide variety of alternativeguided transit systems are available, such as monorails and magnetic levitationsystems. Some have been advocated in Hong Kong in the last decade, but nonehave been implemented. Such systems are unlikely to have sufficient capacity toserve the main urban corridors, but could find a role for some specialised applicationsat the district level. These should be investigated, where appropriate, in regional anddistrict studies.Rai/^Capsnity.7.3.11 The capacity of a rail line to carry passengers depends on four critical factors:(1) Passenger carrying capacit/of a rail car(2) Maximum train lengtjv'(3) Minimum operating headway"(4) Proportion of passenger demand-occurring in the peak7.3.12 These factors vary according to the type of rail system under consideration anddepend entirely on the assumptions made on passenger comfort. The Studyassumptions are specified below for the main systems of MTR, KCR main line, andLRT:DesignNormalOne-way Two-way One-way Two-way(per hr) (per day) (per hr) (per day)MTR (urban area)—low 60 000 570 000 75 000 700 000MTR (urban area)—high 60 000 670 000 75 000 830 000MTR (urban link to NWNT) 60 000 545 000 75 000 680 000KCR (current) 1 50 000 455 000 58 000 530 000KCR (future) 1 76 000 690 000 86 000 780 000LRT (region system) 1 19200 215000 22800 250000LRT (urban link to NWNT) 1 1.9 200 175J300- 22 800 21QJMXX1 These capacities could be further increased by reducing seating provision7.3.13 Low and high capacities are indicated for MTR since much depends on passengermovement characteristics, The low values indicate strong directional bias by time of123