Post-implementation evaluation of the CMAQ program in Northeastern Illinois. Phase 2 final report

Thakuriah, P., Lin, J., Blasie, E.T., Vassilakis, W. and Gan, L. (2011) Post-implementation evaluation of the CMAQ program in Northeastern Illinois. Phase 2 final report. Technical Report. Chicago Metropolitan Agency for Planning, Chicago, IL.

Abstract

This study evaluates a random sample of eighteen bicycle and pedestrian facilities, sixteen of which were funded by the Congestion Mitigation and Air Quality (CMAQ) program in the Chicago metro area. Users of these facilities were surveyed in intercept mode during specific intervals of time starting in the summer of 2009 and ending in the spring of 2011, leading to 376 responses. Usage levels were also enumerated in all sites. The study showed varying levels of use at the different facilities and that motorized mode substitution (change from personal car use to bicycle and pedestrian modes) resulted after the facilities became available to users, potentially leading to improved air quality outcomes. There is also evidence of latent mode substitution, i.e., respondents self-reported that the current non-motorized trip could have been made by using motorized modes, but that they chose not to. The majority of users cited recreation and exercise to be the primary reason for using the facilities. Site-level factors play an important role in the propensity to switch from being exclusively Single Occupant Vehicle (SOV) users to bicycle and pedestrian users, controlling for individual sociodemographic factors. Users of bicycle paths were less likely than pedestrians to have been SOV users for their trip purpose prior to starting use of the non-motorized facility. Bicyclists are more likely to self-report using public transportation or bicycles on alternative facilities prior to using the CMAQ-funded facility. Respondents surveyed in high density areas were also more likely to have been non-car users for the current trip prior to using the facility. Respondents surveyed in areas farther away from the center of the City of Chicago are more likely to have switched from SOV modes. Finally, respondents surveyed in areas with lower levels of car ownership are less likely to have used SOV modes for the current trip prior to using the facility. The propensity to switch from being exclusively SOV users is positively correlated with the higher levels of Average Daily Traffic in highway links in surrounding census tracts and with the percent of population who speak limited or no English in surrounding areas. Finally, the ability to connect directly to a transit station is positively correlated while the recreational usage is negatively correlated with the propensity to switch from being previously exclusively SOV users for the trip purpose. Our analysis also found that depending on the location and overall sociodemographic, transportation and other characteristics of the surrounding areas, there are likely to be at least four groupings of CMAQ-funded projects that exhibit various combinations propensity to switch and overall use levels. Although data on 4 randomly selected intersection improvement and 4 randomly selected signal interconnect projects (“roadway projects”) were collected for the “before” period of a before-andafter evaluation of traffic outcomes, only two projects, both signal interconnect projects, were completed within the timeline of the project. The field observations reveal that there is a 7.15% and 10.68% improvement on the southbound and northbound direction respectively in one of the signal interconnect sites, which equates to a 2.8 mph and 3.2 mph increase in the southbound and northbound respectively. Field observations in the other location revealed that while there is a 5.81% improvement in speed (representing a 2mph increase) on the southbound direction, the northbound direction incurred a speed reduction of almost 11%, i.e., a 4.2 mph decrease in speed. Due to the extremely small sample size of completed before-and-after cases, we do not consider the results of the roadway project analysis to be conclusive or generalizable.

• Item Type: Research Reports or Papers (Technical Report)
• Keywords: Congestion Mitigation and Air Quality (CMAQ) program, travel behavior effects, motorized mode substitution, latent demand, evaluation, intercept survey, before-and-after study, air quality impacts, emissions, bicycling, walking, non-motorized, neighborhood design, street connectivity, signal interconnect, intersection improvement
• Status: Published
• Glasgow Author(s) Enlighten ID: Thakuriah, Professor Piyushimita
• Authors: Thakuriah, P., Lin, J., Blasie, E.T., Vassilakis, W., and Gan, L.
• Subjects: G Geography. Anthropology. Recreation > G Geography (General); G Geography. Anthropology. Recreation > GE Environmental Sciences; H Social Sciences > H Social Sciences (General); H Social Sciences > HE Transportation and Communications
• College/School: College of Social Sciences > School of Social and Political Sciences > Urban Studies
• Publisher: Chicago Metropolitan Agency for Planning