Feasibility study on intersection in North Sumatera

Traffic congestion is one of the problems faced by big cities, One of them is Binjai city and Medan city in North Sumatera. One of the causes of congestion is intersection of roads with highway and roads with railroads. To ensure the smooth movement of vehicles, technical handling at the intersection is needed. Therefore, it is necessary to pre-study the feasibility of level crossing in Binjai and Medan to be able to assess the investment needs and the level of importance of road development in the region. The development of transportation infrastructure and facilities is based on the thought of improving the transportation network system. The necessity of systemical integrated transportation system handling is needed in creating a transportation efficiency. The purpose of this study is to identify and prioritize the needs of the railway crossings. The objective which we want to be achieved is to obtain a document that contains technical, economic and environmental ability indicators as a reference in the feasibility and planning studies. The methodology used is collecting the primary data, secondary data, introduction of study area as the initial analysis of the problem. From the study it can be concluded that the existence of railway interchange will move the movement through traffic so it will not interfere the movement of traffic within urban areas and it keeps the national road network performance is still good.


1.1Basic Legal Reviews
The development of transportation infrastructure and facilities is based on the thought of improving the transportation network system. The transportation system evolves to provide a balance between demand and supply. The need for integrated transportation system handling systemically is needed in creating a transportation efficiency [1]. Normative reference in the preparation of this study is the law of each sub-sector of transportation, especially the land Transport sub-sector. 1. The number of trains crossing to the location is at least 25 train/day and at most 50 trains/day; 2. The average daily traffic volume is 1,000 to 1,500 vehicles on city roads and 300 to 500 vehicles on the road outside the city; or 3. The multiplication result between the average daily traffic volume and the train frequency is between 12,500 to 35,000. Then it should be upgraded into an interchange.

Figure 1.
Graph of intersection area according to train traffic per day and average daily traffic volume

Delay
When the train passes through the interline, all vehicles must stop, this is because the train crossing gate is closed so travel time increases longer than the normal condition (delay occurs).
The delay occurring at the intersection of the highway and the railroad consists of two parts: A. The delay that occurred when the closing of the crossing gate (see Figure 2.2). B. The geometric delay as a result of crossing by rail when the crossing gate is opened. So the delay experienced by any vehicle passing through the railway crossing can be stated as follows: Delay = (delay when the railway crossing gate is closed) + (geometric delay, delay when the railway crossing gate is closed) Meanwhile, Robertson (1994), defined the delay as follows: -Delay is the time lost when driving due to things beyond the ability of the driver.
-Waiting time is a part of the delay process where the vehicle can not run or run slower than planned speed.

Crosses Flow
In calculating the number of currents and the length of the queue on the railway crosses with the road, there are some times that need to be considered, i.e.: a. When the train begin to be seen by the driver b. When the vehicle is slowing down c. When the traffic flows start running the vehicle again d. When traffic flows back to normal where the influence of the railway crossing gate is gone By the time a train passes an intersection between railway and road without crossing gate, the driver can only detect by hearing first and then eyesight. When the train starts to be detected, the driver slows down the vehicle speed. As the train begins to pass through the crossings, the vehicle begins to stay motionless. This situation is prevailing during the time of rail traffic. For an intersection with a crossing gate, the train is detected with a automatic signal and then the driver sees the door of the train that began to close. After the train passed the crossing, the vehicle begins to move through the intersection, causing currents to change gradually until a certain time. After passing through the crossing, the speed will gradually rise so that the flow will return to normal conditions. The condition can be shown in Figure 3. The shaded part of Figure 3 is the amount of delay due to the closing of the railway crossing.

Preparation
a. Consolidating the Methodology, planning detailed implementation phases, collecting relevant agency data, introducing study areas, establishing modelling and analysis, developing technical analysis structures and survey plans. b. The Literature Study, by reviewing implementation methods, maximizing data usage, and analytical methods. c. Read the relevant Regulations, by preparing the pre-feasibility study concept, knowing the layout plan and developing some assessment indicators. d. Identify initial conditions and problems on an intersection with the road network system and the impact on the overall road network system

Collecting Primary and Secondary Data
Secondary data includes socio-economic, document related to research and road network database. While the primary data are road network survey, condition and soil structure survey, topographic survey, and traffic counting.

Stages of analysis
Analyzes conducted in this study include: -Conditions for existing traffic conditions (delay), creating a handling scenario and putting the analytical prediction basis in the planned "time horizon." -Do Nothing Conditions, predicting traffic performance without changes in network conditions, and then the analysis results will be used as a benchmark for the benefits of various handling scenarios. -Do something condition, traffic performance prediction performed with changing the network conditions (FO / UP) and the benefits reviewed is a benefit to users and society. The environmental analysis examines the implementation feasibility of the environment, including estimation of the benefits of air pollution reduction caused by vehicle emissions due to reduced congestion, assessing the hydrological side of the study area and the possible social impacts.
Project Cost Analysis is a calculation of all components of project costs incurred for the project, in this case, carried out on: land acquisition, construction, and maintenance.
The Project Benefit Analysis is a cost calculation that will be a benefit if the upgrading project is built, in this carried out on BOK and time value.

Research Result
The survey result of the condition of intersection based on its use of the land can be seen in Table 1.   The result of transportation modelling obtained from ATTN data in 2011 is calibrated and estimated into 2016 data with Furness method to obtain Ei and Ed value equal to 1 with an accuracy of 3 decimal digits.