Level Crossings & Track Maintenance

Level crossings

A level crossing (LC) is a place where a road crosses a railway at the same level. Road vehicles and pedestrians share the track area with trains, so LCs are a major cause of railway accidents. Every LC has to balance the convenience of road users with the safety of the train.

Classification

• Manned level crossings — a gate and a gateman protect the crossing. Gates close the road when a train approaches. They may be interlocked with the railway signals, so that the signal cannot be cleared until the gate is closed and locked.
• Unmanned level crossings — no gate or staff. Once common on secondary routes; Indian Railways has eliminated unmanned crossings on the broad-gauge network by closing them, building subways, or manning them.
• Interlocked and non-interlocked manned crossings.
• Classification by traffic: crossings are classed by the Train Vehicle Units (TVU) — the number of trains multiplied by the number of road vehicles per day — and by the visibility and the type of road; heavy-traffic crossings are candidates for grade separation.

Safety features

• Gates and boom barriers, warning lights, bells and signs on both sides of the road; whistle boards for the driver.
• Interlocking with signals so that the train's signal is cleared only when the gate is closed.
• Adequate sight distance on the road for the driver to see the approaching train, and a level or gently sloping approach on the road (a flat area for vehicles to stop).
• Check rails or rubber slabs and concrete panels for a smooth surface and to keep the track steady.
• Lighting and road markings.

Elimination

Replacing a level crossing by grade separation is the surest safety measure:

• ROB — Road Over Bridge — for busy roads and heavy train traffic; more land and cost.
• RUB — Road Under Bridge or Limited-Height Subway (LHS) — for lightly used roads; quicker and cheaper, installed by box pushing under traffic.
• Closing and diversion of the road where an alternative route exists.

Track maintenance

Why maintain

A track deteriorates constantly under the pounding of trains — the ballast is crushed and fouled, the level and alignment drift, the fastenings loosen, the rails wear and crack, drains get blocked. Neglected track causes speed restrictions, discomfort, rapid wear of rolling stock and — in the worst case — derailments. The aim of maintenance is to keep the track safe, comfortable, economical and reliable at the least total cost.

Types of maintenance

Staff

• Gangmen — do the manual work of maintenance.
• Keyman — walks his length of track daily, checking it and tightening fastenings; a key person for the safety of the track.
• Mate — supervises a gang.
• Patrolman — patrols at night and in monsoon, and keeps a look-out for defects or washouts.
• Permanent Way Inspector (PWI) / Section Engineer (P.Way) — responsible for a length of track (about 30–40 km) and carries out inspections and maintenance planning.
• Assistant Engineer, Divisional Engineer — for supervision and planning.

Machines

Inspection and recording

• Foot-plate inspection, push-trolley and motor-trolley inspections by the PWI and officers, with checks of gauge, alignment, cross-level, twist and unevenness.
• Track recording car (TRC) and oscillograph — measure geometry and vertical acceleration, giving a track quality index and identifying weak lengths.
• Ultrasonic testing of rails and welds at regular intervals.
• Bridge inspections before and after the monsoon.
• Records — track registers, rail failure records and works registers.

Track parameters and permitted deviations

The tolerances for gauge, alignment, cross-level, twist and unevenness are given in the Permanent Way Manual, with tighter limits at higher speed. When the limits are exceeded, a speed restriction is imposed until the defect is repaired.

Renewal

• Rail renewal — rails are replaced when the wear exceeds a limit, when they develop defects, or after they have carried a stipulated gross tonnage.
• Sleeper renewal (TSR) — replacing worn or damaged sleepers in a section.
• Complete Track Renewal (CTR) — replacing rails, sleepers and ballast together, often in the form of Through Sleeper Renewal or a full relaying with new materials.
• Deep screening of ballast, and formation rehabilitation, where the subgrade is troublesome.

LWR and CWR maintenance

Long welded rail needs special care: the stress-free temperature must be maintained by adjusting the rails if they are cut or when work is done; no track work (lifting, packing, sleeper renewal) is allowed when the rail temperature is outside the safe range without special precautions. Destressing re-fixes the rail at the right temperature. Buckling in hot weather (sun kink) and fracture in cold weather (pull-apart) are the dangers; the ballast shoulder and anchoring are kept in full condition.

Monsoon precautions

Before the monsoon: clear drains and culverts, check bridges (waterway, scour), retaining walls, cuttings and embankments, and vulnerable points (landslides, flood-prone reaches). During the monsoon: round-the-clock patrolling at critical locations, speed restrictions as required, and emergency stores (sleepers, ballast, boulders, sandbags) kept ready. After the monsoon: repair damage and re-tamp the track.

Rail welding

Flash-butt welding (in the plant) and alumino-thermic welding (on site) join rails to form panels and LWR; the welds are tested by ultrasonic testing and their geometry is checked.