Park Tiles Standard road revision, November 2023

Published on: Wed Nov 15 2023

by Jake Coolidge, Web Cartographer

Recently we’ve investigated how to boost the contrast of roads against the light background colors of Park Tiles Standard. In recent years we’ve used the colors yellow, white, and off-white to indicate descending road hierarchy from grade-separated expressways down to service roads, coupled with slightly darker casing to boost figure/ground contrast. But even with the use of casing, we’ve encountered difficulty maintaining an appropriate amount of contrast that works in both rural and urban areas. This was particularly an issue at small scales (when the map is zoomed out). Conversations with park staff prompted us to prioritize a revision of road symbols, an item that had been waiting on our design backlog.

screenshot of a portion of Park Tiles map in its previous condition, showing low figure/ground contrast between roads and map background in a rural area

Roads displayed with low levels of contrast in rural areas prior to the update to Park Tiles

screenshot of a portion of Park Tiles map in its previous condition, showing a dense network of thoroughfares in an urban area

One of the features of the previous road symbolization scheme was that they did not overwhelm the map in dense urban areas

The problem originates with light road colors on a light background with a very thin and slightly darker casing serving as an intermediary. Boost the visibility of the casing, and the roads become more visible, but also with a messy, stripe-like appearance that causes some visual vibration at low zooms. The solution is to give roads slightly darker colors that need little or no casing to stand out from a variety of background colors. Major roads are slightly darker than the rest of the network. Aside from that, hiearchy is indicated by line width. The roads stand out from the background nicely and also read the same for persons with color vision disabilities.

screenshot of a portion of Park Tiles map in its revised state, showing improved figure/ground contrast between roads and map background in a rural area

This is the same rural area shown above with the revised road symbols applied; note the improved contrast with the background

screenshot of a portion of Park Tiles map in its revised state, showing a dense network of thoroughfares in an urban area

In urban areas, the revised road symbols improve contrast with the background without overwhelming the map

There is another advantage to shifting from yellow-white-off-white roads to gray roads: it smooths out discrepancies in the various data sources we use in Park Tiles. For example, a road designated a primary road in OpenStreetMap (OSM) is marked a secondary road in the NPS road dataset. The OSM-based road is superceded at the park boundary by NPS data. When this happens, the road symbol changes from yellow to white, even though the road itself does not change in any substantial way. A more uniform color scheme better approximates on-the-ground conditions.

screenshot of a portion of Park Tiles map in its previous state that shows how two data sources can classify the same road differently, leading to inconsistent road symbolization

The previous road symbol scheme drew unnecessary attention to data discrepancies between data sources, like this road classified as primary in OSM and classified as a secondary road in the NPS road dataset

screenshot of the same portion of Park Tiles map as shown above in its revised state that demonstrates how the new road symbols visually smooth out data discrepancies between data sources

The revised road symbols smooth out these discrepancies by applying a uniform gray color to a variety of road classes across both datasets.

We’ll begin by rolling out an update to Park Tiles Standard. Soon after we’ll update the Park Tiles legend to reflect these changes, and finally we’ll attend to a few variations on Park Tiles Standard we currently support: Park Tiles Standard OSM, Park Tiles Standard SL, and Park Tiles Standard SLSB.

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