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would reduce the number of streetlights to approximately 40 lights, or $400,000 in estimated construction costs. Additional Construction Cost: $1,600,000* *Table 3.3 of the TRC does allow for adjustments to the applicable code of up to 10%. Maximizing the permitted adjustment would reduce the required streetlights to 180 lights. In this scenario the additional construction cost is reduced to $1,400,000. In addition to the initial capital investment of installing the streetlights, long-term maintenance and operation costs should also be considered. Maintenance and operations costs would be proportionally (per light) more expensive for the more intensive lighting approach. Design Standards/Justification for Proposed Code Amendment: Roundabout Lighting: MnDOT and FHWA design guidance recommends that all roundabouts be lit to provide adequate visibility for all modes of transportation during non - daylight hours. This guidance is consistent with past precedence for roundabouts constructed by Ramsey County and the City of Arden Hills. Vehicular Lighting: Street lighting is designed based on various physical factors of the lighting pole, trajectory, and luminaire intensity. The City of Arden Hills Public Works Design Manual (Draft) specifies the light type and design parameter for the lighting to be installed along Rice Creek Boulevard. Application of MnDOT photometrics design guidance, the specified lighting units would result in recommended spacing of approximately 200-ft. Detailed design of the lighting system would prioritize light locations at intersections and pedestrian crossings which reduce the space between lights in those locations. The following information is attached to this memo in the appendices providing further detail of the vehicular lighting design: • Appendix A: Photometric layouts for 40-ft vehicular lighting per current TRC code. Appendix B: Photometric layouts for the proposed vehicular lighting meeting standards established in the MnDOT Roadway Lighting Design Manual. The table below summarizes the design criteria of the MnDOT Roadway Lighting Design Manual and the performance of each of the two options against the standards. Design Alternative Minimum Avg Design Avg Minimum Design Illuminance Illuminance Uniformity Uniformity (Fc) (Fc) (Avg/Min) (Avg/Min) 40-ft Light Spacing (Current TRC) 1.0 7.32-8.11 4.0 1.29-1.44 Proposed Light Spacing (MnDOT) 1.0 1.05-1.20 4.0 3.0-3.5 Local Area Precedence (Vehicular Lighting): The following corridors/intersections have been constructed with streetlighting within the project vicinity. Design parameters for those systems are provided for reference. Kimley >>> Horn