Freeway lighting can substantially reduce accident frequency and increase capacity. Lighting is of additional benefit in freeway operations by providing motorists additional warning time of stalled or disabled vehicles on the roadway. A listing of the specific conditions considered by most authorities to warrant lighting is included below.
7.16.1 Warranting Conditions for Continuous Freeway Lighting
Continuous lighting along the freeway is warranted in the following cases:
Case CFL-1. On those sections in or near cities where the current average daily traffic (ADT) is 30,000 or more.
Case CFL-2. Where three or more successive interchanges are located with an average spacing of 1!/> mi (2.4 km) or less and adjacent areas outside the right-of — way are substantially urban.
Case CFL-3. Where for a length of 2 mi (3.25 km) or more the freeway passes through a developed suburban or urban area in which at least one of these conditions exists: (1) local traffic operates on a complete street grid having some form of street lighting, parts of which are visible from the freeway; (2) the freeway passes through a series of developments that are lighted; (3) separate cross streets with or without connecting ramps occur with an average spacing of L mi (0.8 km) or less, some of which are lighted as part of the local street lighting system; (4) the freeway crosssection elements, such as median and borders, are substantially reduced in width.
Case CFL-4. Where the ratio of night accidents to day accidents is at least 2.0 or higher than the statewide average for all unlighted similar sections and lighting may be expected to result in a significant reduction in the night accidents [3].
