Chapter 14 - Lighting

14.3. Illumination Requirements

If lighting is included in the project then the design shall be based upon AASHTO and IESNA guidelines, the designer should then determine the uniformity ratios and Light Loss Factors (LLF) for each specific lighting project.  For roadways, tunnels, rest areas, welcome centers and park &ride lots, the guidance is as follows:

14.3.1. Roadway

The roadway maintained average illuminance, uniformity ratio and veiling luminance ratio shall be in accordance with the AASHTO Roadway Lighting Design Guide and the IESNA RP-8.  A LLF of 0.7 shall be used to compute the maintained iIlluminance values.  The lighting designer may use a lower LLF if necessary but the designer shall document the reasons in the lighting calculations.

14.3.2. Vehicular Tunnels

The maintained average luminance values in the tunnel threshold and interior zones shall be in accordance with the AASHTO Roadway Lighting Design Guide and the IESNA RP-22.  A LLF of 0.5 shall be used to compute the maintained luminance values.  The lighting designer may use a lower LLF if necessary but the designer shall document the reasons in the lighting calculations.

14.3.3. Rest Areas and Welcome Centers

The maintained average illuminance values for the parking and pedestrian areas shall be in accordance with the AASHTO Roadway Lighting Design Guide and the IESNA G-1.  A LLF of 0.7 shall be used to compute the maintained illuminance values.  The lighting designer may use a lower LLF if necessary but the designer shall document the reasons in the lighting calculations.

14.3.4. Park & Ride Lots and Pedestrian Tunnels

The illuminance values for pedestrian tunnels shall be in accordance with IESNA G-1. A LLF of 0.7 shall be used to compute the maintained illuminance values.