SU0007300 - Laserfiche WebLink

Home Browse Search

Methodology for Assessing Off-Site Heavy Truck Noise Levels Project Heavy Truck Trip Generation According to project representatives, the 325 ton-per-hour capacity of the asphalt plant at the Munn & Perkins facility is capable of filling 13 trucks per hour. In addition, because 500 tons of asphalt products can be stockpiled an hour or two in advance of paving projects in storage silos, an additional 20 truck loads could be generated during the first hour of a nighttime paving project. Each truck load represents two (2) truck trips, consisting of an empty truck arriving and a loaded truck departing, The theoretical total project truck trip generation during the proposed expanded hours of operations would, therefore, be 66 truck trips during the first hour and 26 truck trips per hour thereafter. Assuming this level of activity was to continue for the entire duration of the night paving project (worst-case assumption), a total of 248 nighttime truck trips would be generated during that period (66 + 7*26). Noise Generation of Individual Truck Passages and Observations of "Jake Brake" Usage To quantify the noise generation of individual passages of heavy trucks on East River Road, BAC conducted single-event noise monitoring at locations X and Y (shown on Figure 2), on the morning of October 23, 2008. The measurements, which were conducted between 5:45 a.m. and 8 a.m., were intended to specifically quantify noise levels generated by individual truck passages near the existing residences to East River Road, and to observe the frequency of engine brake usage (Jake Brakes) as the trucks slowed approaching McHenry Avenue. A total of 46 and 52 individual heavy truck passages were monitored at Sites X and Y, respectively, which were located approximately 900 and 1,500 feet from the McHenry Avenue intersection. There was no discernible difference between the truck passby noise generation between the two locations, with the average noise level at both locations computed to be 86 dB SEL at the reference measurement distance of 40 feet from the centerline. Regarding Jake Brake usage, five (5) of the 46 trucks monitored at Site X (the site nearest the intersection of McHenry) utilized Jake Brakes for slowing as they approached the intersection, whereas only one (1) of the 52 passages observed at Site Y utilized Jake Brakes for slowing as it approached McHenry Avenue. This represents a very low percentage of Jake Brake usage as the trucks approach McHenry Avenue. The noise level of the trucks observed to be using Jake Brakes was computed to be 88 dB SEL, which is 2 dB higher than those not using Jake Brakes. The low percentage of observed Jake Brake usage as the truck slowed approaching the intersection of McHenry Avenue is expected since there are no sharp turns or hills which would obstruct the drivers view as they approach the intersection, thereby necessitating a heavier application of brakes than normal. Given the roadway geometry and observed Jake Brake usage by existing heavy trucks, there is no reason to expect the percentages of Jake Brake usage would increase with the proposed expanded hours of operation. Environmental Noise Analysis Munn&Perkins Expanded Hours of Operations- San Joaquin County Page 26