Safety Effectiveness of High-Speed Expressway Signals, 2005

The safety benefit of signalizing intersections of high-speed divided expressways is considered. Analyses were conducted on 50 and 55 mph and on 55 mph only intersections, comparing unsignalized and signalized intersections. Results of the 55 mph analysis are included in this report. Matched-pair analysis indicates that generally, signalized intersections have higher crash rate but lower costs per crash. On the other hand, before-and-after analysis (intersections signalized between 1994 and 2001) indicates lower crash rates (~30 percent) and total costs (~10 percent) after signalization. Empirical Bayes (EB) adjusted before-and-after analysis reduces estimates of safety benefit (crash rate) to about 20 percent. The study shows how commonly used analyses can differ in their results, and that there is great variability in the safety performance of individual signalized locations. This variability and the effect of EB adjustment are demonstrated through the use of innovative graphics.

Iowa Individual Income Tax School District, Tax Year 1997

Iowa School District Surtax Report 1997

Iowa Individual Income Tax School District, Tax Year 1998

Iowa School District Surtax Report 1998

Iowa Individual Income Tax School District Report, Tax Year 1999

Iowa School District Surtax Report 1999

Iowa Individual Income Tax School District Report, Tax Year 2000

Iowa School District Surtax Report 2000

Iowa Individual Income Tax School District Report, Tax Year 2001

Iowa School District Surtax Report 2001

Iowa Individual Income Tax School District Report, Tax Year 2002

Iowa School District Surtax Report 2002

Iowa Individual Income Tax School District Report, Tax Year 2003

Iowa School District Surtax Report 2003

Iowa Individual Income Tax School District Report, Tax Year 2004

Iowa School District Surtax Report 2004

Iowa Individual Income Tax School District Report, Tax Year 2005

Iowa School District Surtax Report 2005

Iowa Individual Income Annual Tax Statistical Report 1997

Iowa Individual Income Tax Statistical Report 1997

Iowa Individual Income Tax Annual Statistical Report 1998

Iowa Individual Income Tax Statistical Report 1998

Iowa Individual Income Tax Annual Statistical Report 1999

Iowa Individual Income Tax Statistical Report 1999

Iowa Individual Income Tax Annual Statistical Report 2000

Iowa Individual Income Tax Statistical Report 2000

Iowa Individual Income Tax Annual Statistical Report 2001

Iowa Individual Income Tax Statistical Report 2001