New development and changing land use in many urban areas call for increases in street capacity. Frequently, the additional capacity must be provided without an increase in curb-to-curb street width. Lane-width reductions through restriping to provide more lanes, used either alone or in combination with parking prohibitions, median removal, and intersection improvements are among the strategies used to provide additional capacity. Research was needed to document the operational effects of narrower lane widths on congestion reduction and related accident impacts.

The objective of this project was to determine the relationship between capacity and safety for various lane widths and allocations for a given street width. This relationship was quantified for both street segments and intersections. Such factors as volume-to-capacity ratios, prevailing speeds, vehicle type and volume, alignment quality, service to adjacent property, classification of streets, and environmental factors are among the important operational considerations.

All research has been completed and the final report has been published as NCHRP Report 330, "Effective Utilization of Street Width on Urban Arterials."