CEMP-E
TI 850-02
AFMAN 32-1125(I)
1 MARCH 2000
(6) The following should be considered in selecting an appropriate road crossing surface:
(a) Vehicle traffic volume, type and speed.
(b) Road use road or street.
(c) Use by industrial traffic or special vehicles.
(d) Railroad traffic volume, type and speed.
(e) Accident history for existing crossings where the crossing surface may have contributed to the
accident.
(f) Cost initial construction cost, replacement cost, and maintenance cost.
(g) Expected service life.
(7) Type 1 Gravel Crossing with Timber Flangeway Header. These crossings are appropriate in
locations with very low traffic volumes and where a crossing is not often used by large trucks or tracked
vehicles.
(8) Type 2 Timber Crossing. These crossings generally have a medium life span of about 10 to 15
years. They are often chosen due to long familiarity and experience with their design. If removed for
track or road maintenance, however, the warping stresses that commonly build up in wood long exposed
to weathering elements can make replacement difficult and may result in a rougher riding surface.
Timber is subject to wear, that may gradually lead to exposure of fastenings to vehicle tires. Timber is
also subject to damage by plow blades during snow removal.
(9) Type 3A Asphalt Crossing. These are expediently and inexpensively constructed, but the
absence of a separate header to form a flangeway typically leads to difficulty in keeping the flangeway
clear and to pavement breaking adjacent to the rail.
(10) Type 3B Asphalt Crossing with Timber Flangeway Header. The presence of a separate
flangeway header, compared with Type 3A, typically results in reduced flangeway maintenance and less
pavement breakage near the flangeway. Expected life may average 8 to 10 years under moderate traffic
and where freeze-thaw cycles are common.
(11) Type 3C 4-Rail Asphalt Crossing. This design may be less subject to plow blade damage during
snow removal operations than a Type 3B crossing. It uses scrap rail turned on its side to form a solid
flangeway, that tends to reduce the amount of water entering the track and can also be cleaned without
damaging the flangeway.
(12) Type 3D 6-Rail Asphalt Crossing. The protective rails on each side of the running rails take
some of the lateral impacts from passing vehicles and thus reduce the tendency of the running rail to be
loosened over time by vehicle traffic. This design may be useful where heavy trucks or tracked vehicles
commonly cross the track. The design does require cutting many scrap tie plates to act as supports or
shims, but, as with Type 3C, material costs are typically inexpensive.
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