Lesson 1Track tolerances and geometry limits (gauge, twist, alignment, cant, and cant deficiency) for 90 mphThis lesson defines track geometry tolerances for 90 mph running, covering gauge, alignment, crosslevel, twist, cant, and cant deficiency, plus inspection methods, limits, and corrective actions suited to local conditions.
Regulatory geometry limit frameworksGauge and alignment tolerance bandsCrosslevel, twist, and warp limitsCant and cant deficiency constraintsGeometry inspection and recording carsLesson 2Rail types and profiles: UIC/AREMA standards, head-hardened and premium railsThis lesson explains rail steel grades, profiles, and standards, comparing UIC and AREMA sections, and when to use head-hardened or premium rails for curves, heavy loads, and faster passenger services.
Comparison of UIC and AREMA rail profilesRail steel grades and cleanlinessHead-hardened rail properties and usesPremium rail in curves and turnoutsRail wear, corrugation, and defect risksLesson 3Ballast composition, drainage, subgrade preparation, and formation stabilizationThis lesson reviews ballast, drainage, and formation design, including material choices, gradation, fouling prevention, subgrade prep, and stabilisation for lasting higher-speed track in varied Kenyan terrains.
Ballast gradation and quality criteriaBallast depth and shoulder designDrainage layers and underdrain systemsSubgrade assessment and improvementFormation stabilization and geosyntheticsLesson 4Track stiffness, transition zones, and track modulus effects on ride qualityThis lesson covers track stiffness, modulus, and transition zones, illustrating how support changes impact ride comfort, dynamic forces, and upkeep on faster lines.
Track modulus definition and estimationEffects of stiffness on vehicle responseBridge approaches and culvert transitionsEmbankment to cutting transition designMitigating differential settlement impactsLesson 5Rail geometry and alignment principles for 80–100 mph operationsThis lesson outlines horizontal and vertical alignment for 80–100 mph, including curves, spirals, gradients, and links to vehicle dynamics, comfort, and maintenance needs.
Minimum curve radius for target speedsTransition spirals and comfort criteriaVertical curves, grades, and sag crestsInteraction with vehicle dynamics limitsGeometry design for maintainabilityLesson 6Standards and reference documents to consult (AREMA, UIC leaflets, national track standards)This lesson reviews key global and local track standards, how AREMA, UIC, and Kenyan rules align, and how engineers apply them to higher-speed mainlines.
Structure of AREMA track-related chaptersMain UIC leaflets for track and geometryNational standards for 80–100 mph linesReconciling conflicting standard requirementsUsing standards in specifications and contractsLesson 7Continuous welded rail (CWR): benefits, restraint methods, stressing procedures, and neutral temperature conceptsThis lesson details CWR behaviour, advantages, risks, restraint, stressing/destressing, neutral temperature, and records for safe faster service.
Thermal forces and rail buckling riskFastening and ballast restraint needsCWR installation and welding stepsStressing and destressing proceduresNeutral temperature records and controlLesson 8Jointed track remediation: approaches to replacement, transition details, and temporary fixesThis lesson outlines jointed track fixes for faster routes, including replacement plans, CWR transitions, temporary repairs, and risk management during works.
Condition assessment of jointed trackPrioritizing segments for remediationDesigning jointed-to-CWR transition zonesTemporary joint and bar repair methodsManaging speed restrictions during worksLesson 9Turnouts and passing loop track design for mixed traffic and higher speedsThis lesson addresses turnout and loop design for mixed traffic at higher speeds, covering geometry, parts, speed limits, and layouts for capacity, safety, and ease of upkeep.
Turnout geometry and speed classesSwitch, crossing, and closure rail typesHigher-speed diverging route designLoop length and siding arrangementTurnout maintenance and inspection needsLesson 10Sleepers/ties selection: timber, concrete, prestressed concrete, and fastening systemsThis lesson discusses sleeper and fastening choices for faster lines, comparing timber vs concrete, prestressing, and how they manage gauge, stiffness, noise, and maintenance.
Timber sleeper benefits and limitationsMonoblock and twin-block concrete tiesPrestressed concrete design basicsElastic fastenings and rail padsFastening choice and track stiffness
