Bicycle LTS & Connectivity Analysis

What is Level of Traffic Stress (LTS)?

This table summarizes LTS in terms of the cyclist type that would be comfortable on certain levels and the characteristics of those levels. Generally, as the colors indicate, the higher the LTS, the more dangerous or the greater the perceived danger, and the more confident the cyclist needs to feel on their bike to consider riding on that type of road.

LTS is a road classification scheme based on the estimated comfort of bicyclists in the traffic stream. DVRPC's LTS assignment is based on the number of lanes, effective vehicle speed, and the presence and type of bicycle facility on the road segment.

A few surveys have shown that the Interested but Concerned group is the largest, and therefore, a lot of bicycle infrastructure planning is done with them in mind.

Sources: Lowry et al, Dill and McNeil

LTS	Comfortable Enough	Characteristics
1	Most People	Lowest Stress Comfortable for most ages and abilities
2	Interested, but Concerned	Suitable for most adults Presenting little traffic stress
3	Enthused and Confident	Moderate traffic stress Comfortable for those already biking in American cities
4	Strong and Fearless	High traffic stress Multilane, fast moving traffic

Regional LTS

The map shows the DVRPC Region's road segments colored by their LTS assignment. As indicated by the colors on the map, divided highways and major arterials are often higher stress, while local, residential streets often present the lowest stress. Trails and off-road paths are considered non-stressful in this analysis.

This is a regional screening tool built on the most accurate representation of the road network attributes available. Since it is impossible for DVRPC staff to verify the attributes of every road in the region, there is always room for improvement. Road attribute errors resulting in inaccurate LTS values are being collected here.

Using the Data

Zooming in, here is an example of a downtown area in a suburban county in Pennsylvania with LTS assigned to the road network.

Low-Stress Areas

If we look at just the LTS 1 and 2 roads, those that are comfortable for most cyclists, you start to see gaps in the network, creating low-stress islands. If an interested but concerned cyclist starts their trip on one of these islands, and they are uncomfortable using the higher LTS roads that connect them, this person is limited to their island. If they want to travel off their island, they are unlikely to ride their bike.

Connecting Low-Stress Areas

What if we made LTS 3 roads more comfortable by making changes to them to lower their stress level to the point that they become LTS 1 or 2 roads? You can see that the islands are larger and much more connected.

We know that in reality, there is no way to make improvements to all the LTS 3 roads in the region at the same time. Thus, the point of our connectivity analysis was to be able to rank the LTS 3 roads and compare them to each other, to see which would enable the most low stress connections; essentially give us the most bang for our buck.

Low-Stress Bike Network Connectivity Analysis

The goal was to compare the connectivity benefit of each of the LTS 3 roads. Using a shortest path algorithm, we identified the shortest path from every census block in the region, to every other census block within five miles. Since we were focused on interested but concerned cyclists, we only let our paths use LTS 1, 2, and 3 roads.

For example, the purple line shows the shortest path between the two census blocks highlighted in orange .

Connectivity Analysis Results

We tallied the number of shortest paths that use each road segment.

The thicker the purple line, the more shortest paths use that road segment. Using these results, we can identify the LTS 3 road segments that would be used to enable the most low-stress connections if made more comfortable. The segments highlighted in brown are the LTS 3 roads used by the most shortest paths. These results are relative to the rest of the LTS 3 roads. Since shortest paths were calculated on a network including all LTS 3 roads, the number of connections enabled by each segment is based on every LTS 3 road being part of the low-stress network.

Since we know this is impossible, these results serve to rank the LTS 3 roads by their relative potential impact and serve as a pipeline of realistic beneficial projects. Essentially, the results are a screening tool that can help us narrow down where to look to make improvements.

Equity-Focused Connectivity Analysis

In an effort to be more intentional about considering equity in our work, we also created a version of the results incorporating information about the populations that live near the origin or destination.

DVRPC maintains an Indicators of Potential Disadvantage (IPD) analysis that identifies populations of interest under Title VI and Environmental Justice (youth, older adults, female, racial minority, ethnic minority, foreign-born, limited english proficiency, disabled, low-income). The IPD score classifies the concentration of the population groups of interest on a scale from "well below average" (yellow areas) to "well above average" (blue areas) in every census tract in the region.

To allow us to view the connectivity results through an equity lens, IPD scores were converted to a numerical scale and origins and destinations were weighted by their corresponding numerical IPD score. Paths connecting two places with above average concentrations of IPD populations were worth more than those connecting places with below average concentrations. Thus, these results can help identify the road segments that would have the greatest potential impact on potentially disadvantaged communities if made more comfortable for bicyclists.

Low-Stress Network Connectivity Priorities

These lines represent the LTS 3 roads that would allow for the most connections - the top 10% in each county. Since the shortest paths were calculated between census blocks, more shortest paths started and ended in more dense places, therefore inflating the number of paths in urban areas. We chose to prioritize the top 10% in each county to ensure there would be a mix of candidate locations throughout the region.

Equity-Focused Low-Stress Network Connectivity Priorities

The IPD weighted analysis is still primarily a connectivity analysis, so the results are similar to the original results. The IPD weighted top 10% is shown in blue , while the original results are shown in brown . Segments that fall in the top 10% for both analyses appear purple . Looking closely reveals more "priority" segments in areas with higher concentrations of populations of interest (IPD Score).

Connections to Trails

Using the shortest path method, we calculated paths from trail access points to census blocks within 2.5 miles. We tallied the number of paths using each road segment and weighted them by the IPD score of the origin and destination. The results highlight the LTS 3 segments with the greatest potential to enhance low-stress connectivity to trails.

Connections to Transit

Similarly, we calculated paths from bus, rail, and trolley stops to census blocks within 3 miles (based on FTA bike to transit guidance). We tallied the number of paths using each road segment and weighted them by the IPD score of the origin and destination. The results highlight the LTS 3 segments with the greatest potential to enhance low-stress connectivity to transit stops.

Connections to Schools

To support Safe Routes to School efforts, we calculated paths from schools (up to high school) to census blocks within 2 miles. We tallied the number of paths using each road segment and weighted them by the IPD score of the origin and destination. The results highlight the LTS 3 segments with the greatest potential to enhance low-stress connectivity to schools.

Welcome to DVRPC's Bicycle LTS & Connectivity Analysis