Complete lighting of freeway interchanges is warranted under the following circumstances:
Case CIL-1. Where total current ADT ramp traffic entering and leaving the freeway within the interchange area exceeds 10,000 for urban conditions, 8000 for suburban conditions, or 5000 for rural conditions.
Case CIL-2. Where current ADT on the crossroad exceeds 10,000 for urban conditions, 8000 for suburban conditions, or 5000 for rural conditions.
Case CIL-3. Where existing substantial commercial or industrial development, which is lighted, is located in the immediate vicinity of the interchange; or where the crossroad approaches are lighted for at least L mi (0.8 km) on each side of the interchange.
Case CIL-4. Where the ratio of night accidents to day accidents within the interchange area is at least 1.5 times higher than the statewide average for all unlighted similar interchanges and lighting may be expected to result in a significant reduction in the night accident rate.
7.16.2 Warranting Conditions for Partial Interchange Lighting
Partial lighting of freeway interchanges (Fig. 7.58) is warranted when the following circumstances exist:
Case PIL-1. Where the total current ADT ramp traffic entering and leaving the freeway within the interchange area exceeds 5000 for urban conditions, 3000 for suburban conditions, or 1000 for rural conditions.
Case PIL-2. Where the current ADT on the freeway through traffic lanes exceeds 25,000 for urban conditions, 20,000 for suburban conditions, or 10,000 for rural conditions.
■ c Safety
Clearance
Paved Shou der
Shou der Nose
Safety
Cearance
=-____
Optional
Unit
(b) ENTRANCE RAMP
FIGURE 7.58 Typical luminaire locations for partial interchange lighting.
Case PIL-3. Where the ratio of night accidents to day accidents within the interchange area is at least 1.25 times higher than the statewide average for all unlighted similar sections and lighting may be expected to result in a significant reduction in the night accident rate.
