I first loaded the data into r using read_csv

bridges <- read.csv('https://archive.ics.uci.edu/ml/machine-learning-databases/bridges/bridges.data.version1')

I then created a data frame:

bridges_df <- data.frame(bridges)

I used the view command to see what the data looked like in the two different formats:

View(bridges)
View(bridges_df)

Next I renamed the rows of the Data Frame to be more discriptive. This was based on the website: https://archive.ics.uci.edu/ml/datasets/Pittsburgh+Bridges

N.B., that some of the data lacks context. Identifier is not explained in any detail. Nor is location, prehaps these makes sense in how the city records are kept. No measurement units are given for length, they could be feet or yards. As for River, A = Allegheny, M = Monongahela, O = Ohio

bridges_df <- setNames(bridges_df, c("ID", "River", "Location", "Year_Erected", "Purpose", "Length", "Lanes", "Clear", "T_or_D", "Material", "Span", "Rel-L", "Type"))

I was interest in how many bridges had more than 2 lanes

multi_lane_df <- subset(bridges_df, as.numeric(Lanes) > 3, select= c("Lanes", "Year_Erected", "Purpose", "Material"))
multi_lane_df
##     Lanes Year_Erected Purpose Material
## 21      4         1876 HIGHWAY     WOOD
## 56      4         1904      RR    STEEL
## 66      4         1915 HIGHWAY    STEEL
## 70      4         1923 HIGHWAY    STEEL
## 71      4         1924 HIGHWAY    STEEL
## 72      4         1926 HIGHWAY    STEEL
## 73      4         1926 HIGHWAY    STEEL
## 76      4         1927 HIGHWAY    STEEL
## 77      4         1927 HIGHWAY    STEEL
## 78      4         1928 HIGHWAY    STEEL
## 80      4         1928 HIGHWAY    STEEL
## 82      4         1931 HIGHWAY    STEEL
## 83      4         1931 HIGHWAY    STEEL
## 84      4         1931 HIGHWAY    STEEL
## 85      4         1937 HIGHWAY    STEEL
## 86      4         1939 HIGHWAY    STEEL
## 87      4         1945 HIGHWAY    STEEL
## 94      4         1951 HIGHWAY    STEEL
## 95      4         1951 HIGHWAY    STEEL
## 96      4         1951 HIGHWAY    STEEL
## 97      4         1955 HIGHWAY    STEEL
## 100     6         1959 HIGHWAY    STEEL
## 101     4         1961 HIGHWAY    STEEL
## 102     4         1962 HIGHWAY    STEEL
## 103     6         1969 HIGHWAY    STEEL
## 104     6         1975 HIGHWAY    STEEL
## 105     6         1978 HIGHWAY    STEEL

Suumarize the multilane subset:

summary(multi_lane_df)
##  Lanes   Year_Erected      Purpose    Material 
##  ?: 0   Min.   :1876   AQUEDUCT: 0   ?    : 0  
##  1: 0   1st Qu.:1926   HIGHWAY :26   IRON : 0  
##  2: 0   Median :1931   RR      : 1   STEEL:26  
##  4:23   Mean   :1938   WALK    : 0   WOOD : 1  
##  6: 4   3rd Qu.:1953                           
##         Max.   :1978

From this summary we can see that there are 23 four lane bridges and 4 six lane bridges. The earliest built was in 1876 which was the only wooden bridge in the group. The only railroad bridge in the subset was built in 1904, the rest are highway bridges.

Here is a barplot for the year each multilane bridge was built.

barplot(table(multi_lane_df$Year_Erected), main = "Multilane Brigdes by Year Erected")