Colorado State Highway 470 (SH 470) is a staple of transportation for the Denver Metropolitan Area as it was originally envisioned as Interstate 470, which was supposed to be a fully continuous beltway around Denver. While the full beltway was never completed, when SH 470 is combined with the toll road E-470 it forms a beltway that encircles roughly 75% of the way around Denver, leaving only the North-Western quadrant disconnected. With its place as a major freeway connecting the suburbs to the South and South-West of Denver, it is a key player for commuting and quickly moving around a significant portion of the Denver Metro Area. With this in mind, I became curious about what I could find from the recorded traffic data for the freeway. How has the Covid-19 pandemic and subsequent lockdown affected traffic on SH 470 and to what extent have traffic numbers subsequently recovered?
In order to answer this question, I thought it would be best suited to use the data from cdot_traffic.csv. Since I was only interested in the traffic data on SH 470, I also searched through the cdot_stations.csv file in order to find out which station ID numbers were the ones on SH 470. From this, I found that numbers 3, 512, and 105548 were the ones located on the freeway and were located in Littleton, Morrison, and Lone Tree respectively. From there, I aggregated the traffic data by grouping by the ID numbers, year, and month and aggregating on the counts. I did this so that the data for eastbound and westbound traffic would be added together to get total traffic for each station each month. I then filtered the stations to only get the data for stations with the ID numbers of 3, 512, and 105548. I also used .pct_change() in Pandas in order to calculate the percentage change in traffic numbers each month compared to the previous month. I then concatenated the data for all three stations to help facilitate creating visualizations using Seaborn. The line plot below was created showing the count of traffic from 2019 to 2021.
From this, a significant drop in traffic for all three stations can be seen in April of 2020. This is not surprising as this was the time that Colorado Governor Jared Polis’s stay-at-home lockdown orders were in effect. Specifically, the orders were in effect from March 26 until April 26. One thing that does surprise me is that the increase in traffic after April 2020 is about the same as, or even slightly greater than, the sharp decrease in traffic just preceding it. After the orders were lifted, traffic sharply increased and it seems that it continued to steadily increase ever since except for a dip in the winter months between 2020 and 2021. While it is difficult to definitively identify what the cause of this dip may be, the US experienced increased rates of Covid-19 infections during this time and surpassed 4 million deaths in November 2020. But now, traffic on SH 470 is generally slightly greater than most periods in 2019.
The above plot shows the percentage change of traffic month-to-month from 2019 to 2021. The percentage change from April to May 2020 is also shown here to be quite drastic as the three stations increased traffic by roughly 50% to over 100%. Also, the change after this drastic increase seems to hover relatively close to 0 while still staying above 0 more often than below it. This shows that even after the sharp increase after the lift of the stay-at-home orders, traffic has still slowly increased.
In this table, you can see that traffic in 2021 has increased to a level that is greater than traffic in 2019, which was before the Covid-19 pandemic hit the US. This table was created by grouping the data for all three stations by just the years so that the traffic counts for all stations would just be aggregated by year. Percent change was also calculated for how much traffic is changed in comparison to the preceding year. While traffic in 2020 decreased by 5.8 million from 2019, traffic in 2021 increased by 19.6 million from 2020. That makes total traffic for SH 470 in 2021 greater than in 2019 by 13.8 million.
From this analysis, it can be seen that there is evidence that traffic on SH 470, while definitely impacted by the Covid-19 pandemic, did not suffer any long-lasting negative impacts. A significant drop in traffic occurred in April of 2020 near when the pandemic first affected the US and the overall traffic numbers on the freeway were lower in 2020 than either in 2019 or 2021. But, the recovery was extremely rapid as traffic grew at a rate that exceeded the drop in April 2020. SH 470 has experienced slow and steady growth from July 2020 to December 2021 to the point where post-lockdown traffic numbers on SH 470 are greater than previous to it.
