Intersection Layout
Layout controls
Intersection layout translates plan geometry into field positions. Establish control from the baseline or centerline, curb line, right-of-way, benchmark, and stop line. Signal faces, pedestrian push buttons, controller cabinet, detection, and conduit runs are then tied to those controls. MUTCD Part 4 governs signal face placement and visibility; ADA governs push button reach and ramp landings; the clear-zone policy governs pole offsets.
Field checks
- Overhead signal heads should be centered over the lanes they control; post-mounted heads need a clear view for the required distance.
- Push buttons must be reachable from a firm, stable surface and located near the ramp landing, not behind it.
- Poles must stay outside the clear zone or use breakaway design.
- Detection zones should be placed where vehicles actually stop, not where the plan stylizes them.
Worked example: A pole is at station 12+37, offset 12 ft from the curb. The nearest even station is 12+00, so the station distance is 37 ft. Pull 37 ft along the baseline, turn 90 degrees, and pull 12 ft to the pole center. Set a hub and tack, then check the offset from the actual curb, not the pavement edge. If the curb is 0.8 ft inside the plan line, the field offset changes; record the check shot before excavation. The reasoning is that layout is referenced to surveyed control, so a field discrepancy must be resolved before staking becomes construction.
Traps: measuring from the edge of pavement instead of the surveyed curb; ignoring ADA landing slope; placing a push button where a wheelchair user cannot reach it; assuming plan scale is exact; missing a sight-distance conflict.