Automated Traffic Signal Performance Measures: A Program Approach L By Justin R. Effinger, P.E. (M) ake County, situated in the northeastern most corner Shutterstock/ ZASIMOV YURII CASE STUDY of Illinois, USA, has a current population of more than 700,000-a population growth of 36 percent since 1990. The Illinois Department of Transportation (IDOT) found that there was an increase of approximately 875,000 daily vehicle miles (1.4 million kilometers [km]) of travel in Lake County (six percent growth) from 2010 to 2017, and this growth is expected to continue. Traffic congestion impacts the quality of citizens' daily lives-time spent frustrated in traffic backups means less time with one's family. The Lake County Division of Transportation (LCDOT) has been using Synchro traffic analysis software to evaluate intersection operations and performance. Table 1 summarizes the levels-of-service (LOS) for each of the county-involved, signalized intersections and roundabouts currently modeled in the Synchro model. LCDOT recognizes that effectively addressing congestion issues is not simply adding new lanes to our highway system, but making the roads work better. Automated Traffic Signal Performance Measures (ATSPMs) became more popular in the United States through the Every Day Counts - 4 Innovations.1 ATSPMs consist of logging high-resolution data from modern traffic signal controllers utilizing the "Indiana Traffic Signal Hi Resolution Data Logger Enumerations" for data analysis and to proactively identify and correct any deficiencies if they exist.2 LCDOT created an ATSPM program to address the following: 1. Improving traffic signal operations; 2. Quicker response time to citizen concerns; 3. Evaluation of adaptive signal control; 4. Transportation Management Center (TMC) Operations; 5. Planning selection process of improvement (modernization/ expansion) projects. Automated Traffic Signal Performance Measures (ATSPM) Program Table 1. Intersection Level of Service (From Synchro) 2018. Note: Levelof-Service for signalized intersections is defined in the 2010 Highway Capacity Manual. 44 Ma rch 2020 ite j o u rn al The established Lake County Passage program made a larger scale ATSPM implementation possible. Traffic signal and other roadway data are collected and returned to the Transportation Management Center (TMC) through the field communications