Procedure For Marking Position Of Diamond Loops Prior To Slot Cutting; Chevron Type Loops - Marking Of Loops - Siemens BH17 7ER Installation Manual

2.3.5 Procedure for Marking Position of Diamond Loops Prior to Slot Cutting

These notes are to be read in conjunction with Figure 1 and Figure 2 but
kerbs and distances from carriageway centre lines are subject to any standing
Local Authority instructions.
Refer to the STS drawing and mark the distance of the loop from the stop line,
at the road edge.
1) From this point, mark a datum line to the road centre at right angles to the
road edge.
2) Measure in from the road edge 0.3 metres and mark this point on the
datum line. This point is referred to as the datum point.
3) Measure in 1 metre from the road centre and mark this point on the datum
line. This point is referred to as the end point.
4) Measure the distance between the datum point and the end point.
Reference to Figure 2 will determine the appropriate loop configuration to
be constructed.
5) Determine the length of the loop diagonal as follows:
i) For single loop configuration, the loop diagonal is the distance
between the datum point and end point.
ii) For double loop configuration, the loop diagonal is the distance
between the datum point and the end point divided by 2.
iii) For the triple loop configuration, the loop diagonal is the distance
between the datum point and the end point divided by 3.
iv) For the quad loop configuration, the loop diagonal is the distance
between the datum point and the end point divided by 4.
6) Starting at the datum point, mark the length of the loop diagonal along the
datum line for as many diamonds as are required in the configuration.
Figure 1 shows a double loop configuration by way of example.
7) Refer to Figure 2 to determine the length of the loop side.
8) Anchor a measuring tape at the datum point and using the tape and chalk,
strike arcs either side of the datum line, whose radius equals the length of
the loop side.
9) Strike similar arcs from the point on the datum line indicating the length of
the loop diagonal. The intersection of these arcs on either side of the
datum line fixes the position of the loop corners.
10) Repeat this procedure along the datum line for the required number of
diamonds in the configuration.
11) Join up the points with chalk to form the loop configuration required.
2.3.6 Chevron type loops – marking of loops
These notes are to be read in conjunction with Figure 3 but distances from
kerbs and carriageway centre lines are subject to any local authority
instructions.
667/HE/20663/000 Issue 13
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