Linear Referencing

Does roads condition have an effect on number of accidents that occur along Pitt County roads?

Problem Statement

Greenville city in North Carolina has observed an increase in the accidents on roads in Pitt County. It is not yet known whether this is due to the road conditions or just some random events affected by other variables. The objective of this assignment is therefore to investigate whether there is a relationship between the roads conditions and the number of accidents involved in these routes.

Analysis procedure

To address the problem, I used virtual computing lab’s ERIS ArcGIS Pro 2.9.1 which is hosted on Remote Desktop Web Client. Main tools used were Make Route Event Layer Tool, Overlay Route Events Layer Tool, export to table tool, select by attributes, as well as summarize statistics. Provided by the course instructor, and this included a geodatabase containing routes for Pitt County, tables including accidents and pavements data, and shapefiles including cities and country boundaries.

In Part A, I started with customizing the Linear Referencing tab using the Customize Ribbon tool. Three main groups were added to this tab, Routes (which had Calibrates Routs, Create Routes, and Locate Features Along Routes), Events (which had Dissolve Route Events, Make Route Event Layer, Overlay Route Events and Transform Route Events add to it), and finally Add-In Tools. The Add-In Tool is not yet available in AcrGIS Pro, hence I downloaded an LRSToos, esriAddinX from the GitHub and installed it in the computer. Using this installation, I added the Ser From/To Measures and Identify Route Locations to the Add-In Tool. This completed the customization of the Linear Referencing tab.

In Part B, I used the Some Routes layer to create layers from the accidents and pavements tables. I started with adding the Accidents table to the map. Then I used Make Route Event Layer tool to create an Accident Event Layer from the accident table and some routes layer as an input feature. Since accident events is a point dataset, I used point as an event type, and “MEAURE” field as a measure field. I also used the same tool to make a features layer from the pavements events table. This has linear segments, and which required to use line as events type. Measure Fields used were BEGIN_MP and END_MP. Next step involved exporting the table from the Pavement Event Layer as a way of preparing it for making a combined table of accident events and the pavement events. The exported table was named Pavement Events2.

Using the Overlay Route Events tool from the Linear Referencing tan, I combined attributes from the Pavement Events 2 table and the accidents events table, to make an intersect overlayed table called Accidents and Pavements. Then I used Make Route Event Layer tool to transform this combined table into a features layer which can be displayed on a map. To answer the question on the hypothesis, I created a new field called Segment Length in the created layer, and calculated length in the field using absolute values, targeting BEGIN_MP and END_MP for selected route 30000030. Then I looked at number of accidents for all segments of the route with less than or equal to 75 rating, compared that with number of accidents per mile of all routes within the same route of rating quality of greater than 75. There was no significant difference observed, as all had a 0.333 accidents per mile, hence concluded that there was no relationship between the road quality and the number of accidents occurrence.

Figure 1: Process Diagram

Results

Application and Reflection

Problem Statement: Malawi roads have a lot of potholes, and to some extent they are blamed for the increased road accidents which occur along the M1 road stretch. There is data about the number of accidents that happen along the roads of Malawi. What is missing is to help the government isolate the real reason why there is an increase in these accidents especially during December holidays.

Data needed: I will work hand in hand with the roads authority and the police, to get all the data on road conditions, and the police database on the number of accidents and the perceived reasons for each.

Analysis procedure: Using Make Route Event Layer, I will make a features layer of the accident data table to give it spatial properties. Then, I will examine the stretches to see where there are a lot of potholes, or poor road conditions, and the number of accidents that occur, to see whether there is any correlation between the number of accidents and the road conditions, and then will recommend accordingly for the government to take necessary action