Thailand Ranks Second in the World for Number of Road Accidents under Thailand's Codes of Geometrical Design and Traffic Engineering Concept When Compared with AASHTO

. Traffic problems in Bangkok have an influence on road users during peak hours. Especially, the traffic bottleneck on curves under the saturation flow situation must be remedied in order to increase the roadway capacity and speed. However, the appropriate speed for heavy vehicles is taken into consideration during off peak after the increasing lanes. This leads to the Rollover of heavy truck and rear-end collisions which are the main causes of vehicles accidents on curves. In addition, road accidents on curves account for the majority of all accidents in Thailand. According to the road accidents data collected in Thailand, 44 road deaths per 100,000 people, the country ranks second in the world for road accidents. When Thailand’s Code of Geometrical Design is compared with AASHTO (The American Association of State Highway and Transportation Officials), the super elevation length of Thailand’s Code is more than AASHTO. As a result, drivers are not made aware of the appropriate speed and the stooping sight distances (SSD) on curves. Therefore, the Design of Traffic Signage under the Perception and Reaction Times (PRT) for Thai Drivers will be taken into account.


Introduction
The Development of ITS (Intelligent Transportation System) has been developed since 2009.Image Sensing Technique by VLD (Virtual Loop Detector) for Checking Speed of Vehicles and LPR (License Plate Recognition) for Traffic Classified Counts in Thailand are taken into account.The traffic volumes on road curve are over saturation situation or F -Level of Service (L.O.S.).In case of Roadway Capacity, the increasing lanes on curve are taken into consideration.Although the traffic problem can be solved by this method, the over speed on curve must be controlled and the appropriate speed needs to be informed to drivers by the warning signage.In addition, the researcher is concerned with the geometrical design factors such as, super-elevation length on curves and Stopping Sight Distances (SSD) of PRT for Thai drivers.The Traffic Signage will also be calculated and installed on curved roads under the design factors as mentioned above.However, the number of traffic accidents on curves rises dramatically when Super Elevation Length of Thailand's Codes is more than AASHTO's Length.This is owing to the fact that sizes of letters on the traffic signage have an effect on road users.

Traffic collected data by ITS
There are two cases of applied ITS for collected data.One is a measurement of vehicle speed and the other is vehicle classification count by LPR off-line method as described in the following paragraph.

Measurement of speed
The positions of Lane Changing, which are 3 points, are located on Fig. 2. The first curve of Lane Changing and Speed of circular curve is composed of coordinates among points (x1,y1), (x2,y2), and (x3,y3) respectively.The calculation of angle, length of Lane Changing and speed used the concepts of geometrical design under the specific times as shown in Fig. 2 and Fig. 3.

Traffic collected data and evaluated existing situation
The Existing Traffic Volumes from LPR Method are input in the Trafficware Software [7].As a result, the traffic situation is a stop and go model as presented in Fig. 5.

Roadway capacity and number of lanes on curve (exit lane)
Roadway Capacity is very important for Highway Planners when considering traffic lanes on curve [6].The solution of this case study is to increase the number of lanes from 2 lanes to 3 lanes as can be seen in the Figure ) respectively.Therefore, the increasing of roadway capacity is tested on curve to improve the traffic flow.As a result, it can also raise the average speed of vehicles when driving on curve (see Fig. 6, Fig. 7).

The geometrical design factors on curve
There are two Geometrical Design Factors as compared between Thailand's Codes and AASHTO.The Super Elevation Length on Curve and Stopping Sight Distances lead to the traffic accidents and these factors under Thailand's Codes are of higher values than AASHTO.Furthermore, Fatalities in Thailand rank second out of all the road accidents in the world, which is the rate of 44 road deaths per 100,000 people in Thailand.The first Ranking of 45 road deaths per 100,000 occurs in Namibia [1].The traffic factors will be described in the following parts.

Super elevation curve length
The comparison of Super Elevation between AASHTO and DRR (Thailand's Codes) will be described in the Fig. 8, Fig. 9 and Table 1, Table 2 and Table 3.

Table 1. Comparison between super elevation length of
Thailand's code and AASHTO.As can be seen from the above Tables, the Length of Curve -Y+Z in the case of Thailand's Codes is dramatically more than AASHTO.However, the length of X in case of Thailand's Codes is equal to AASHTO.In case of C.G. of Vehicle, the Running Speed during testing with C.G. Equipment is illustrated in Fig. 10  According to Running Speed, the researcher will give the Safety Speed of Heavy Vehicle as based on Equation (2, 3 and 4).For example, the Design Speed is about 60 KPH and the Safety Speed will be 44 KPH.Therefore, the installation of traffic signs and sizes of letters will be located before the point of curve (PC) as described in the following parts.The Table 4 presents 30 cm. of Height, Thickness and Syllable of Letters in a Traffic Sign at various Running or Safety Speed.For example, speed at urban area (60 KPH) will be proposed 30 cm. of letters, two rows of Letters with 5 Syllables per row at a traffic sign under 101.77meters of the L+A+K Distances.

Mitigation of traffic accidents
Thai drivers use the SSD which is lower than the SSD of ASSHTO as based on the Equation (2, 3 and 4).Therefore, the Traffic Signage by ITS can warn Thai's Drivers to increase the length of SSD in order to operate their vehicles safely by using VMS (Variable Message Sign) as described in Fig. 13 and Table 5.

Conclusion
The increasing of traffic volumes by the decreasing of normal lane width and the increasing of lanes from 2 lanes to 3 lanes are taken into consideration.In addition, the application of Thailand's Code for Road -Curve Design Length is longer than AASHTO.However, the number of Traffic Accidents has substantially increased.The important mitigation is to install traffic signage and to focus on various sizes of letters when compared with speed.This is pointed out in the message on the traffic sign to warn drivers to drive on curve safely.Strict and Severe Law Enforcement is the best solution for Thai people who disobey the traffic laws.The researcher wishes to decrease the number of accidents as soon as possible.
FG/BG Detection module performs foreground/ background segmentation for each pixel.Blob Entering Detection module uses the result (FG/BG mask) of FG/BG Detection module to detect new blob object entered to a scene on each frame.Blob Tracking Module initialized by Blob Entering Detection results and tracks each new entered blob.Trajectory Generation module performs a saving function.It collects all blobs positions and saves each whole blob trajectory to hard disk when finished.Trajectory post processing module performs a blob trajectory smoothing function.The application of Blob Entering Detection Techniques is shown in Fig. 1.

Figure 1 .
Figure 1.Results of the Application of Blob Entering Detection Techniques.

Figure 2 .
Figure 2. Three points of lane changing and speed concept.

Figure 4 .
Figure 4. Traffic classified survey by LPR method.

Figure 6 .
Figure 6.Increasing of lane capacity on curve.

Figure 7 .
Figure 7.The raised speed after mitigation.

3 )
Figure 12.L, A and K Distance for Reading the words in the Traffic Sign.

Figure 13 .
Figure 13.Controlled Speed by the Size of Letter in Variable Message Sign (VMS).

Table 3 .
Results of super elevation length of AASHTO.

Table 4 .
30 CM, Height, thickness and syllable of letters on traffic sign based on speed.

Table 5 .
7 Collected Traffic Changing Lane and Speed Data during Installed VMS.