Guideline for Survey, Investigation, and Design of Black Spot Location (SID-BSL) and Its Application in Lampung Province, Indonesia

: In connection with the government's obligation to take responsibility for ensuring the safety of traffic and road transport for road users, it is necessary to conduct Surveys, Investigations, and Design of Black Spot Location (SID-BSL) to reduce traffic accident. Hence a guideline in conducting SID-BSL is needed. In this study, the author compiled a simple technique of prioritization for SID-BSL procedure and applies it to a research on National Roads in the Lampung Province. The technique of prioritization is simplified with four phase activities namely Preparation, Initial Analysis, Detail Survey, and Detail Analysis. The analysis technique is based on the ranking of Black Spot Locations using weighted accident number (WAN). Application procedure is applied on 237 events of accident on the National Roads in Lampung Province resulting five selected BSLs to be treated according to the availability of funds.


Introduction
Traffic accident is one of the enormous problems faced by the Indonesian Government. Data from the Police Department shows that each year more than 30,000 people died in traffic accidents and over 70,000 people suffered permanent injuries that cause many people become invalid and unable to work properly [1].
In Indonesia, increasing number of vehicles and human errors become major factors in the increase in traffic accidents. Data from the Police Department showed that in 2011, there were 109,776 accidents causing the deaths of 31,185 people, while in 2012 there were 109,038 accidents causing the deaths of 27,441 people, with the potential socio-economic loss of about 203 trillion to 217 trillion IDR per year (2.9% -3.1% of Indonesian GDP) or around 17.5 billion USD [2].
In connection with the responsibility of the government to ensure the safety of traffic and road transport for road users [3], it is necessary to conduct Surveys, Investigations, and Design concerning Black Spot Locations [4]. 1. Civil Engineering Department, Maranatha Christian University, Jl. Suria Sumantri 65, Bandung 40164, INDONESIA. E-mail: budiharsus@yahoo.com Therefore, there is a need to develop a guideline in conducting Surveys, Investigations, and Design Concerning Black Spot Location (SID-BSL) [5]. Black Spot Location (BSL) is the location that has a high accident rate in the same place and relatively at the same time frame [

Technical Requirements Black Spot Location Identification based on Accident Frequency
Identification of 20 or at least ten BSLs is based on the highest number of accident. The BSL should at least has two events of accident in a year. The data is taken from previous years and synchronized with secondary data from Police or Department of Transportation.

Number of Selected Black Spot Locations
The number of selected BSL is determined by counting the number of BSL with WAN higher than the average in all BSL. The calculation of the average value of WAN (UCL) from n number of BSL is as follows: The number of selected BSL that will be treated also depends on the availability of funds.

Detail Engineering Design
Detail Engineering Design, which is also referred to as Final Engineering Design, is a set of detailed technical design drawings related to the black spot location or accident-prone location treatments [7].

Estimation of Construction Cost
Estimation of construction cost is based on the various treatments of the Black Spot Location selected. The method of calculating the cost of a volume or quantity is derived from the design drawings multiplied by the unit cost (which consists of wages, tools, and materials) so that the amount of the estimated cost can be calculated [8].

General Procedures
The procedure consists of four stages, which can be seen in Figure 1.

Case Study
The procedure is applied on the National Roads in Lampung Province as a practical example. There were 237 events of accidents occurred during January 2014 to August 2014 [9]. Due to limited funds, the government has to prioritize which BSLs should be treated first.

Preparation Phase
Several things have to be prepared in the implementation of SID-BSL, namely: a. Collecting traffic accident data for at least the previous year. The accident data can be obtained from various sources, for example from the internet.
The procedure consists of four stages, which can be seen in Figure 1.

Initial Analysis Phase
The initial analysis phase consists of ranking process of 11 identified BSLs based on the survey on the degrees of accident and WAN as illustrated in Table  2. 1320 Description: Jalinteng = Central Trans-Sumatra Highway; Jalintim = East Trans-Sumatra Highway; Jalinbar = West Trans-Sumatra Highway. Table 3. Examples of Detail Survey Results on Selected BSLs [13] No.
Location Survey Results 1 Jalinteng KM 14 1) Road geometry forms a curve; 2) Road side consists of pit-run.

Detail Survey Phase
Detail survey of the BSL is done as follows: a. Observing road and environmental conditions on selected BSLs using a video camera or a photo, as illustrated in Table 3. b. Recording and sketching each selected BSL maps in detail. c. Marking and determining the GPS of each selected BSL on the base map of the road network/topography/geography [14].
Results in BSL selected sketches based on conditions of the ground and geographical map can be seen in Figures 2 and 3.

Phase Analysis Details
Detail analysis includes the following: a. Developing an alternative treatment proposal on selected BSLs. The examples are shown in Table 4    1) Road Geometric forms a curve; 2) Road side consists of pit-run.
3) Sharp cornering with limited visibility; 4) Good condition of road pavement.

> < (head-on)
A vehicle enforced to overtake at the curve resulting in a crash with the opposite vehicle 1) Installation of road signs: left curve warning (Table II (1a)*) and left chevrons (Table II (11d)*) (for direction towards Bandar Lampung), right curve warning (Table II (1b)*) and right chevrons (Table II (

Application Summary
Based on the general procedure above, it is necessary to take the following steps in detail, namely Survey, Investigation, and Design (SID) concerning Black Spot Location (BSL). The analysis carried out on the National road in the Province of Lampung began with the collection of secondary data from the previous year. Then the determination of selected BSL was based on the number of occurrences of BSL > 2 events per location. The data from the Police Department furthermore was matched with the data from the Department of Transportation and Highways in Lampung, resulting in identification of 11 BSLs. Then EAN analysis was used to rank the 11 BSLs resulting in the five selected BSLs. Further activities and analysis of the five selected BSLs were conducting survey details, developing alternative proposal of treatment, preparing Detail Engineering Design, preparing construction cost estimates, and preparing Draft Guidelines for SID-BSL and DED. Visually, the description and analysis of the survey work are shown in Figure 7. Recording, monitoring, and evaluating activities related to SID-BSL after physical construction works are only recommendations and not included in this study.

Recommendations
Based on the analysis of SID-BSL in Lampung Province, implementation of the alternative treatments on five BSLs will reduce traffic accidents. In addition, SID-BSL Guideline is expected to be immediately distributed to other provinces in Indonesia, so that Indonesia can work together to reduce the number and severity of accidents in accordance with the expectations of Presidential Instruction No. 4 of 2013, on the Decade of Action for Safety, within the period of 2011-2020. There should be adequate budget for continuous multi-year programme so that within six years, there is a 50% decrease in the number of accidents in accordance with the Presidential Instruction.
not included in this study. Analysis:  Developing alternative treatments proposal on 5 BSLs  Developing Detail Engineering Design on 5 BSLs  Estimating Construction Cost on 5 BSLs  Developing Drafts for SID Guidelines, [19]  Monitoring & evaluating work after physical construction work (Not included in the research).

Secondary Data from the Previous
Year from Directorate of Traffic of Polda Lampung, [11] (237 accidents, between January and August 2014)