TRAFFIC SHIFTING AND ECONOMICAL VALUE STUDY OF SEMARANG-DEMAK TOLLROAD TOWARDS TIDAL FLOOD DISASTER ON SEMARANG NORTH COAST

• Main Author: Windra Kusumowardani, Estiyani
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/73815
• Institution: Institut Teknologi Bandung

<p align="justify"> Tidal floods have caused various health, environmental, socioeconomic, and infrastructural losses. In general, flood conditions impacted transportation infrastructure directly as physical damage and indirectly as congestion, disruption of business activities, and increased emissions. The direct impact of flooding on road infrastructure has caused infrastructural damage due to the cost of reconstructing roads, and the indirect result includes costs due to congestion and delays in logistics delivery. Traffic disruption due to tidal flooding on the north coast of Semarang has caused long traffic jams, especially on the Semarang-Demak road section, which is part of the Pantura route. In addition, tidal floods have impacted economic activities because of traffic disruptions that accommodated national logistics. As a form of physical adaptation strategy to tidal flood conditions, road operators are constructing the Semarang-Demak Toll Road. The aim is to complement road network connectivity and maintain traffic flow serviceability in the network. The toll road operation should reduce congestion in the North Central Java area and reduce delays when tidal flooding occurs. This study focuses on traffic shifting analysis and benefit estimation of the Semarang- Demak toll road operation. The traffic is modeled macroscopically at the North Semarang road network level. User equilibrium algorithm applied on traffic assignment process. Furthermore, the value of benefits in terms of mobility is analyzed based on traffic performance with average travel speed and travel time savings parameters. Economic benefits are estimated using vehicle operating cost savings parameters (BKBOK) for normal traffic conditions and time-saving parameters when traffic conditions have been affected by floods. This study explores speed reduction caused by inundation, based on previous studies (i.e., Pregnolato et al., 2017), to be modeled within a road network framework. The network is modeled based on a 4-stage modeling approach, with the capacity of the Semarang- Demak national road section based on the basic speed-density model derived from field data. The height variations of the modeled tidal inundation were 100, 125, 150, 175, 200, 225, and 250 mm. No vehicles pass on the national road at a tidal inundation height of 300 mm, considering the safety threshold and passenger vehicle stability during a flood. Based on field data analysis results, the Semarang-Demak national road section has high traffic volume characteristics and a relatively low average travel speed. New infrastructure existence naturally causes a shift in movement from the national road to the toll road. Results of traffic modeling under normal traffic conditions show that when section 2 of the Semarang-Demak toll road section was in service, the number of vehicles shifting was 13%. It is generally due to the 40% in travel time saving for trips from Semarang-Demak or vice versa by passing the Semarang-Demak toll road. Addition of the section 1 toll road network in the Semarang-Demak toll road sections 1 and 2 operations (constant demand), shifting increased by 9% to 22% due to an increase in travel time to 64%. In addition, traffic demand growth from 2023 to 2025 in the Semarang-Demak toll road when sections 1 and 2 operating results in a shifting increment of 4% from 22% to 26% The presence of tidal inundation significantly reduces vehicle speed and has been estimated resulting a further trigger for the shifting process toward the toll road. In general, there is no significant impact on speed reduction during inundation with a height of less than 125 mm. Vehicle speed decreases significantly when the inundation exceeds 150 mm. Under 200 mm inundation conditions, the decrease in travel speed on the Semarang-Demak national road reached 50%, and the increment in travel time reached 200%. Even at 250 mm inundation, the speed reduction reached 80% compared with the non-inundated condition. However, the speed reduction by traveling through the toll is manageable by 28%. This output illustrates that the operation of the Semarang-Demak toll road is a form of road infrastructure resilience against tidal floods that inundated the Semarang-Demak national road. In terms of benefits for road users (consumer surplus), the addition of the Semarang- Demak toll road network (i.e., section 1 toll roads) with a fixed demand scenario results in a 133% increase in vehicle operational cost saving (BKBOK) under normal traffic conditions. Overall, tidal flood conditions that inundated the Semarang-Demak national road caused a decrease in vehicle speed and caused road user losses due to delays and a rise in vehicle operating costs. However, the impact of this loss can be minimized by the operation of the Semarang-Demak toll road, although its use is limited to four or more wheeled vehicles.