Incorporating safety into transportation planning for small and medium-sized communities

Abstract

The City of Ames, in Iowa is a typical small-sized urban area. In 2008, the city had an estimated population of 56,500 and covered an area of 21.6 square miles. In 2003, the Ames Area Metropolitan Planning Organization (AAMPO) was designated with a planning area of 36 square miles. Ames hosts Iowa State University with an enrollment of 27,900 as of Fall 2009. During the period 20022008, on average 1,000 traffic crashes (of property damage over $1,000 worth) occurred. To meet the requirement of future development and solve the transportation problem facing today, city planners and engineers are seeking additional ways to explicitly consider safety in the transportation planning process. Historically, the approach to safety problem identification and mitigation has been reactive; ―black spots or hot spots‖ have been identified by ranking locations based on the crash frequency and severity, mainly at the corridor-level and without considering the exposure rate (vehicle miles traveled) and socio-demographics of the study area. To address safety in planning process, a larger study analysis area at the Transportation Analysis Zone (TAZ) level or the network planning-level should be used to address the needs of development of the community in the future and incorporate safety into long-range transportation planning process. This thesis examines how existing planning models (for example, the PLANSAFE models presented in NCHRP Report 546) can be used for forecasting safety in the future in small and medium-sized communities, due to changes in socio-demographics, traffic demand, road network and countermeasures. The thesis also evaluates the applicability of the Empirical Bayes (EB) method to network-level analysis for small planning areas. Finally, application of US Road Assessment Program (usRAP) protocols at the local urban road network is investigated. It is anticipated that incorporating safety methods into the long-range transportation planning process can assist city decision-makers in setting and monitoring progress towards transportation safety goals.