Caltrans has agreed to monitor evening and nighttime noise in residential areas near the west portal of the Caldecott Tunnel. To see a graphical representation of the nighttime noise levels click here.

Sound levels are measured by hourly Leq, Level equivalent, the average level of sound, and by Lmax, the loudest sound.

Over a period of fourteen nights prior to the start of construction, an independent sound engineer recorded the ambient sound levels at eight residential locations near the west tunnel portal. This recording provided a baseline Leq and Lmax levels in the area.

The daily charts are compiled on the files below. One chart shows the summary of the evenings sound levels, the other chart shows the exceedance of the baseline Leq and Lmax and gives a description of the noise.

Of course, the monitors are sensitive to all sounds, not just the sound of construction.