Contributor(s): National Academies of Sciences, Engineering, and Medicine; Transportation Research Board; National Cooperative Highway Research Program; Xiao Qin; Yang Li; Habib Tabatabai; Andrew Graettinger; Mohammad Wael Amer; Frank Gross; Bob Scopatz; Sam Arnold; Jason J. Bittner; Dan D'Angelo; Hannah Silber; Neil Janes

Bridge and tunnel strikes inflict serious damage to vehicles, highway bridges, and tunnels; cause injuries and fatalities; and impose detours and costly delays on highway users. Attempts by state departments of transportation (DOTs) and other bridge and tunnel owners to prevent bridge and tunnel strikes include signing, lighting, height detection systems, and actuated warning devices.

NCHRP Research Report 1132: Bridge and Tunnel Strikes: A Guide for Prevention and Mitigation, from TRB's National Cooperative Highway Research Program, presents state-of-the-art information to assist state DOTs in the prevention and mitigation of bridge and tunnel strikes by overheight motor vehicles.

Supplemental to the report is NCHRP Web-Only Report 411: Prevention and Mitigation of Bridge and Tunnel Strikes. (2025).

NCHRP. 2025.

By Thaddeus L. Johnson, Natasha N. Johnson, William J. Sabol, Megan A. Hartman and David T. Snively

This study examines the interaction effects of police collective bargaining authorization and police pay on racial differences in police-related fatalities. Using data from Fatal Encounters, the Bureau of Justice Statistics, and other publicly available databases, we applied entropy-weighted regressions to a balanced panel of 282 local police departments from 2000 to 2013 in the United States. We found that collective bargaining authorization is not directly associated with police-caused deaths. However, results indicate that higher median salaries for city police officers directly and meaningfully contribute to fewer people killed by police actions. When considering interactive effects, our findings suggest that police unionization offsets the life-saving benefits of higher relative pay, leading to more Black citizens dying from police intervention as salaries increase in agencies with collective bargaining authorization. Our findings demonstrate authorities should consider the potentially fatal and inequitable consequences for citizens during collective bargaining and salary-setting negotiations.

Police Practice and Research,  An International Journal May 2024.