# Efficiency Analysis of Roadway Lighting Replacement in a Selected Polish Municipality
## 1 Introduction
To determine an approximation of the relevant road surface illuminance parameters, the authors [14] conducted photometric simulations of road lighting with photometric data tables of high-pressure sodium (HPS) and LED lights. The tests were performed for different power ratings for a given set of luminaire mounting height, road width, pole spacing, sag and slope values, and a mathematical model consisting of six equations derived by multiple linear regression with appropriate predictor variables was presented. The study, which focused on investigating the possibility of retrofitting conventional road lighting luminaires with LEDs, ultimately demonstrated environmental and economic benefits, primarily a short payback period, a high savings-to-investment ratio and electricity savings. The researchers in [15] note that the initial cost of LED luminaires is significantly higher than that of other technologies and that investment costs can be a barrier to implementation. The paper discusses the adoption of LED luminaires to replace conventional lamps in public lighting systems in Rome (Italy), calculating possible energy and cost savings. The authors [16] compared the lighting quality between the HPS and the LED luminaires and found that the LED luminaires have higher overall and longitudinal uniformity and higher threshold increment values than the HPS luminaires due to better light distribution efficiency. They found that LED luminaires can achieve better visual and comfort performance. The results of the road lighting quality study conducted by the authors [16] indicate that the average illuminance and surround ratio values are not completely different when the properties of road surfaces change. The energy evaluation results demonstrate that the LED luminaire achieves the best energy efficiency--significantly better than a conventional HPS luminaire. In another paper [17], the authors estimated the national benefits of energy efficiency improvements in street lighting systems based on a pilot project in the city of Jakartaand energy audits in the other three cities. The research results showed that electricity consumption reduction potential through energy efficiency improvements could reach even 2.1 terawatt-hours annually. As part of their research, the authors analysed the effectiveness of road lighting replacement in a selected municipality in Poland. The scope of the topic covers the following issues:  
* Analysis of the technical condition of the original lighting system, based on an assessment of the wear and tear of the lighting network;
* Time and cost analysis of variants of the technological concept of replacing the above-mentioned system with a new one;
* Light intensity analyses were performed using Building Information Modelling (BIM) software;
* Estimate and description of possible benefits resulting from the lighting system replacement and analysis concerning the advisability of this undertaking. The following objectives will therefore be fulfilled in the paper:  
1. Development of a design for the street lighting system replacement in terms of the construction work;
2. Cost-effectiveness analysis of considered variants of the construction project, including time and cost of retrofitting, as well as the road user comfort due to the selection of spacing, the height of poles and luminaires influencing light intensity. The unique element of the paper is a comprehensive approach to the topic of road lighting replacement involving the demonstration of a decision-making system based on time and cost variants with lighting analysis. All analyses are based on a BIM model of the road section concerned, including lighting, which provides information on time, construction and operating costs.