Evaluation of Los for national road network in Rwanda

Abstract

The quality of service in transport is mostly linked to satisfaction of road users and the benefits they should get in using a given road. It has a direct effect on economy considering the losses for any travel and the improvement of that service which should transform these losses into benefits. The Rwanda paved network have a total length of 1,172.609 Km, they are in generally in good riding condition in terms of measured IRI. The performance of network in terms of level of service remains lower. The objective of this research put emphasize on service provided by traffic as well as economic implication and tend to provide solution of how it should be improved over 20 years of the analysis period. This should be done by introduction of passing or climbing lanes in order to provide passing opportunities. The current research is based on several documentation developed so far and used by researchers, Level of Service (LOS) have been used to measure the road performance or quality of service. USA has developed a manual (HCM) which has performed around the world, Asia also has developed manual refereeing to HCM. In Africa especially in region, a manual has been developed and have to guide for selection of design levels of service (DLOS) for the different classes of roads and to guide all country members of EAC in their design to get harmonized road network in region so that a well-balanced, economical road system will result. This manual refers on American standards, HCM and AASHTO. The HCM was chosen because it is the best practice, are feasible by using available data (field data) and some default data where field data are not available. To obtain LOS of a certain section, Average Travel Speed (ATS) varying between 40 to 110 Km/h and Percent Time Spent Following (PTSF) ranging from 0 to 100% are determined from calculations. The LOS level range from A to F where ATS for LOS “A” vary from 90 to 110 Km/h, PTSF is >40% and ATS for “E” range from 40 to 110 Km/h where PTSF for “E” varies 0 to 100%. The worst LOS “F” applies whenever the flow rate exceeds the segment capacity. An excel sheet was developed using VBA programming to determine LOS. vii The methodology of HCM, 2000 has been adopted to evaluate the current and future LOS over 20 years of analysis taking into consideration the base year (2010) and growth rate of 6.5%. Used data which were collected in 2010 on 54 sections of paved national road network, on which AADT varies between 115 and 5,412 including heavy vehicles. The study was carried out on 8 chosen roads of paved national highway having higher AADT varying between 1,730 and 17,844. The chosen growth rate 6.5 % produced increment of AADT showed the worst LOS within the analysis period. The results has shown that the national road network is operating at undesirable levels of service between D and E and service will be worst all along the analysis period which is 20 years. An economic analysis were also carried out on the proposed passing or climbing roads sections to be constructed in order to maintain the good LOS on the network. This has shown that the construction to improve LOS will not be economically viable. There will be no savings in VOC, but in VOT and pollution cost. The NPV is negatives (- 658,559,922 to - 4,197,936,942 Rwf) as well as IRR (- 0.03 to – 0.20) due to the investment cost ranging from 2 to 4 Billion introduced in do-something scenario. Finally, considering the poor LOS on national road network while the riding quality is good, passing or climbing lane should be introduced to facilitate the overtaking operations, but this is not economically viable. However, a further research is needed show the sections on national road network where freedom will be allowed to driver, this will be achieved by keeping the data collection process as well as data management to facilitates such kind of researches to improve the LOS of national network as the most important mean to satisfy the demand of road users.