Road performance analysis due to Sayung Industrial Park development

This study aims to analyze the impact of Sayung Industrial Park development to the surrounding road network. The study merely relies on available secondary data, including recent transport study in Semarang Raya, trip rate, and previous research related on industrial area occupancy growth. Road performance in the terms of degree of saturation and travel speed are analyzed using a simplified four-step model using CUBE software. The results show that in 2023, assuming 50% occupancy of the industrial park, the average travel speed decreases by 8.5% and the average degree of saturation increases by 18.7%. While in 2030, assuming 100% occupancy, the road performance is worsened, the average travel speed decreases by 46.4% and the average degree of saturation increases by 45.5%. A new additional lane in each direction on Semarang–Demak main corridor is simulated to anticipate the full operational of Sayung Industrial Park in the future. The result shows an improvement on road performance.


Introduction
Sayung Industrial Park is an industrial area in Demak Regency managed by JatengLand.The site is conveniently situated next to Semarang-Demak national road, as well as the Semarang-Demak toll road.In addition, there are several infrastructure facilities in the vicinity that support distribution operations for industries.These include Tanjung Emas Port, Ahmad Yani Airport, and Tawang Station [1].
The road network is crucial for industrial activities.Industrial activities process raw materials into goods production [2].The demand for goods by consumers leads to increased trips in industrial areas.The trips are carried out for the distribution of raw materials and marketing of products to consumers.
The activities taking place in Sayung Industrial Park are predicted to generate trips that affect the performance of nearby roads.To determine the impact and anticipation, it's necessary to conduct an analysis of road performance.The CUBE program is used to analyze the traffic model.

Degree of saturation (V/C ratio)
The ratio of traffic flow to capacity is the main factor in determining the performance level of a road segment.The degree of saturation is a tool for examining traffic patterns in terms of speed.The degree of saturation plays a crucial role in determining whether there are issues with the capacity of a particular road segment [3].

Travel speed
According to Indonesia Highway Capacity Manual (IHCM) 1997, travel speed refers to the average speed of light vehicles on a road segment, expressed in km/h.Travel speed is the primary measure of road segment performance because it is easy to measure.In addition, the value of speed plays an essential role in economic analysis related to road user costs [3].

Route selection
The weighted amount or function of time, distance, and cost are used as the generalized cost as shown in equation (1).The equation is used in the CUBE model of the Transportation Laboratory of the Faculty of Engineering, Universitas Indonesia, in making toll road traffic models or other sources from the CUBE manual.

Capacity restrained
According to the capacity restrained assignment approach, if the traffic on a particular stretch of road increases but the capacity remains constant, then the time taken to travel on it will also increase.The volume-delay function used during traffic assignment in this study adopts the BPR formula.The equation used is as follows:

Methodology
The study solely relies on available secondary data, including recent transport study in Semarang Raya, trip rate, and previous research related on industrial area growth.The modeling process involves a simplified four-step model, which includes trip generation, trip distribution, and trip assignment-mode choice is not part of this research model since the secondary trip data used is already in vehicle trip unit.The processing of data for road capacity and free flow speed follows the guidelines set out in IHCM 1997.
To determine the number of trips generated by industrial park activities, a trip rate calculation is used along with several assumptions.Afterwards, a set of origin-destination matrices (ODM) is developed using the Furness method.The results of the ODM iteration are then used as input into the CUBE program for the assignment stage.These results are then analyzed to determine the impact of industrial park development.

Road/link data
Geometric data consists of main roads outside and within the industrial park.The geometry of the roads outside the area is obtained from the Transportation Laboratory of the Faculty of Engineering, while the roads inside the area are measured with the help of Google Earth.The calculation of free flow capacity and speed refers to the IHCM 1997.Urban roads have four adjustment factors: carriageway width, directional split, side friction, and city size.For freeways, adjustments are only made to the carriageway width.

Traffic analysis zone
There are 48 traffic analysis zones in total, comprising 41 internal zones (zone 1-41) and 7 external zones (zone 42-48).In the scenario without the industrial park development, there are four internal existing zones (zone 38-41), and in the scenario where the industrial park exists/developed, the number of zones increases to 48.The region's zones are numbered from 1 to 37.However, this amount increased to 10 ha in 2023 [4].The occupancy rate in 2016 was 3% [5], in 2020 was 30% [6], in 2021 was 47% [7], and in 2023 was 80% [4].According to the estimates, the occupancy rate for all upcoming constructions in 2023 is predicted to be 50%.The occupancy rate for phase 1 is 80%, and for phase 2 is 50%.It is assumed that the area will be fully occupied by the year 2030.

Vehicle composition.
Vehicle composition data is used to calculate the number of vehicles in passenger car units (pcu).In general, the composition of vehicles within the area is assumed to be the same as that outside the area because other industries have been established in the vicinity.In certain zones, the composition of vehicles needs to be adjusted according to their function.

Trip distribution assumptions
There are four ODM prepared for each scenarios: the 2023 scenario without industrial park (2023-TKI), the 2023 scenario with industrial park (2023-KI), the 2030 scenario without industrial park (2030-TKI), and the 2030 scenario with industrial park (2030-KI).The transportation information for trips outside the industrial zone is sourced from the Transportation Laboratory.For industrial zones, it is only expected that some particular zones (zone 1, 2, 5, 8, 35, and 36) those will generate trips (produce and attract) with other zones within the industrial zone itself.The distribution of trips in the industrial park refers to the proportion of trips generated by each zone in the area.Distribution of trips outside the industrial park refers to the proportion of trips from zone 40.
The available study on Tegineneng Industrial Park was used as a reference to estimate the increase in the number of trips resulting from the development of the industrial park.Before the area was developed, there were 186,876 vehicles per day on trips.After the development, the number increased 1294 (2024) 012003 IOP Publishing doi:10.1088/1755-1315/1294/1/0120035 to 279,441 vehicles per day [9].Based on the data, it can be inferred that 33.1% of trips originate from industrial areas.This value is used for the distribution of trips.

Assignment
The assignment process is carried out with generalized cost.To calculate travel time, the capacity restrained method with equation ( 2) is used during the traffic assignment.The values of coefficients α and β used in this method are 0.15 and 4.0, respectively.To assign traffic on the CUBE, the coefficients in the table below are utilized.In addition, the validation process includes data on the number of vehicles observed along Semarang-Demak Road.According to the survey, the number of vehicles recorded was 2,404 veh./h.However, the CUBE results showed 2,830 veh./h.Based on the percentage of modeling data errors compared to the actual data, which is 17.7%.

Road performance
By 2030, travel speed on multiple roads near the entrance of Sayung Industrial Park will decrease.By 2023, the development of industrial park will cause a decrease in travel speed on Semarang-Demak Road and Onggorawe Road.This decrease in speed will extend to all road segments by 2030 due to continued development.The degree of saturation on roads in industrial zones is increasing, especially near the entrances to these areas.The degree of saturation of roads located outside the industrial park increases significantly in each road segment.The most significant changes are observed on the toll road and Semarang -Demak Road.
The road performance in the area has declined from 2023 to 2030, as indicated by the decrease in travel speed from 47.39 km/h to 45.47 km/h.The degree of saturation has also decreased from 0.05 to 0.28.Despite this, drivers still have some freedom in determining the speed of their vehicle based on the degree of saturation value.In 2023, when the industrial park is developed and 50% of the area is occupied, the average travel speed will change by 8.54% and the degree of saturation will increase by 18.68%.In 2030, the impact of industrial park will be greater when the occupancy rate is at 100%.At full occupancy, there will be a 46.39% increase in the degree of saturation and the average travel speed will be 65.54% lower.

Do-something scenario (DS)
In the year 2030, the performance of roads is expected to decrease due to development and traffic growth.Therefore, it is necessary to change the road geometry to improve road performance.
-Lane addition on the Semarang-Demak Toll Road from 4/2D to 6/2D -Lane addition on Semarang-Demak Road from 4/2D to 6/2D -Road widening on Onggorawe and Guntur roads to 3.5 m By increasing the road capacity according to the improvement scenario (DS) as proposed above, the average performance on roads outside the area and toll roads increases.The travel speed on the toll road has gone up to 73.1 km/h, and the degree of saturation has decreased to 1.14.On roads outside the area, the travel speed increases to 34.2 km/h, and the degree of saturation decreases to 0.99.In addition to increasing the capacity of the road, other alternative solution could be proposed to minimize the use of private vehicles by providing public transportation to limit the movement of private vehicles.The presence of adequate and reliable public transportation services could reduce the dependence on private vehicles.In Central Java, the government has been developing bus rapid transit (BRT) system, but currently the service has not yet reach Sayung Regency [10].The nearest Trans Semarang BRT stop is at Genuk Market, which is 8.2 km away, while the nearest Trans Jateng BRT stop is at Godong Terminal, which is 30.8 km from the industrial area.Therefore, additional BRT routes are needed by considering passenger needs.Moreover, another solution that could be done is to limit the movement of private vehicles.Private vehicle movement can be limited during peak hours.Further analysis with related data is needed to determine the detailed calculations of these two solutions.

Conclusion
-The development of Sayung Industrial Park with an assumption of 50% occupancy in 2023 will result in an average decrease in speed of 8.54% and an average increase in degree of saturation of 18.68%.-The development of the Sayung Industrial Park with the assumption of 100% occupancy in 2030 will result in an average decrease in speed of 46.39% and an average increase in the degree of saturation of 66.06%.-Road performance inside the industrial area has decreased.Vehicle speed decreased from 47.39 km/h to 45.47 km/h, while the road degree of saturation increased from 0.05 to 0.28.-The do-something scenario can improve road performance by 2030.

=
Total cost of type k vehicles to cross the segment in unit time (minutes)  = Time taken by the vehicle to cross the segment (minutes)  = Coefficient of type k vehicle operating costs (minutes/km)  = Segment length (km)   = Toll fee for type k vehicles (Rp); on a closed system toll road, the rate is converted in advance according to the length of the segment (Rp/km × the length of the section in km)   = Time value of vehicle type k (Rp/minute)

==
Vehicle travel time in traffic flow conditions of V (minutes)  0 Vehicle travel time in free flow conditions (minutes)  = Traffic volume (pcu/h)  = Road capacity (pcu/h)

4. 3 . 3 .
Industrial park trip generation.To obtain the building floor area, the land area in the industrial park is multiplied by 0.5.The number of trips generated by each zone is determined by multiplying the trip rate by the number of units measured based on its land function.This results in trips being measured in units of trips per hour for each zone[8].

Figure 4 .
Figure 4. Travel time inside the industrial park.

Figure 5 .
Figure 5. Travel speed outside the industrial park.

Figure 6 .
Figure 6.Degree of saturation inside the industrial park.

Figure 7 .
Figure 7. Degree of saturation outside the industrial park.

Table 1 .
Road type, widths, capacity, and free flow speed (outside the industrial park).
Source: Authors' own elaboration based on Google Street View

Table 2 .
Typical road type, widths, capacity, and free flow speed plan (inside the industrial park).
Source: Authors' own elaboration based on Google Street View and Sayung Industrial Park Masterplan The occupancy level assumption is obtained from interpolating the Kendal Industrial Park occupancy level.The pandemic condition affects the level of occupancy in industrial areas.Between 2018 and 2022, the typical company investment was between 1-3 ha.

Table 4 .
Coefficient (A).Validation of travel time is conducted by comparing the model results and actual travel time (based on Google Maps) on two road segments, segment 1 is Semarang -Demak Road and segment 2 is Manageng Road and Ki Godek Road.

Table 5 .
Travel time validation.
*) Actual travel time are based on Google Maps

Table 7 .
Road type, capacity, and free flow speed improvement.

Table 8 .
Road performance outside the industrial park (do-something scenario).