street design contexts

People have commented on my series of street design posts, online and Twitter and in person, with many questions about how to fix existing streets. My focus so far has been on new and reconstructed streets. Obviously fixing existing streets is a critical issue, and I’m not wanting to neglect it, but part of my approach is summed up as “don’t build stupid”, in other words, don’t ever again design or construct a single transportation infrastructure that prioritizes motor vehicle traffic over access and safety for walkers and bicyclists. The best time for better design was 50 years ago, the second best time is today. But the City of Sacramento, and most cities and counties and state agencies, are continuing to build things that are hostile to people walking and bicycling. Traffic engineering is a remarkably regressive profession, sticking with what was once thought to work, even though it never did, and even though it is absolutely clear that it does not meet our needs today. Transportation infrastructure is meant to last 30 to 50 years, and may be in place longer than that, so everything we do wrong today will be around for a long time. We won’t ever have the money to fix everything (a lot of our transportation investment is basically money we’ve flushed down the toilet), and the Vision Zero or Safe Systems approach of identifying and fixing the locations with the highest fatality and severe injury crashes is right.

My thinking about street design has four contexts:

  • New streets: When we build new streets, we need to do it right. We need to prioritize walkers, bicyclists, and transit, and accommodate motor vehicles within that context (if at all – not every transportation route even needs motor vehicles). I don’t see a lot of new streets coming. Development should be infill, not greenfield development low density sprawl. Most infill doesn’t need new streets, it already has the streets but needs better land use. The railyards and river districts areas in Sacramento are sort of infill. They did not have existing streets, and have had new streets constructed, unfortunately wider and faster than was necessary, though there are some elements of good design there. So the importance of new streets is not that they will be common, but that they must be done right.
  • Reconstructed streets: When we have the opportunity to envision a new function for streets, with different transportation allocation and supporting different land use, then we can make great streets. These projects are often called Complete Streets projects, though I have always been uncomfortable with the concept because the designs often neglect safe crossings of streets (there are no standards for how frequent safe crossings should be), and the pedestrian and bicyclist facilities often end up being tokenism. Some space is reserved for these uses, but it is clear that the design started with motor vehicle traffic and parking, and then including something for walking and bicycling. Raised crosswalks and raised intersections could be considered reconstructions because they involve pavement changes, and many times require drainage changes, but they can also be considered mitigations. The key aspect of reconstructed streets is that the curb line is not fixed, it can be moved to shift the allocation to motor vehicles, walking, and bicycling. Though obtaining right of way is expensive, changing the width should always be considered. And conversely, when street right of way is too wide, give the land back to the adjacent property owners! Speed limits are also not static, they can be lowered to the design speed, which is based on the desired function and feeling of the street, not on past use. The city has refused to consider lowering the speed limit of reconstructed streets, and this is engineering malfeasance.
  • Reallocated streets: These are streets where the curb line is not changed, other than installing curb extensions at intersections, but the use of the street area is reallocated from current use to desired use. General purpose lanes and parking may be converted to bicycle facilities and transit. General purpose lanes would be narrowed to reduce vehicle speeds. Parking might be eliminated where there are higher uses, but parking in and of itself is not bad. In fact, one of the solutions for overly wide streets in Sacramento is converting parallel parking to diagonal parking, leaving a narrower area for motor vehicle travel and significantly slowing traffic.
  • Mitigated streets: Problematic areas of the street system can be fixed even when the street length is not changed. High injury locations (which includes fatalities and severe injury) can be fixed without changes along the corridor. Note that this is not the city’s approach, which is to focus on corridors and ignore intersections crashes. The most prominent fix is curb extensions (bulb-outs) which reduce crossing distance for walkers, increase visibility between walkers and drivers, and reduce speeds. These can be installed immediately as temporary installations with paint and vertical delineators (also called soft hit posts, and often mis-called bollards), and later made permanent with hard curbs. Converting old non-compliant ADA ramps to modern designs (and perpendicular rather than diagonal) is another fix, with or without curb extensions. Street trees, where they are absent or sparse, is another fix.

Of all the street changes, mitigation will be the most common, if for budgetary reasons if nothing else. We have invested billions of dollars in the wrong transportation system, and we are unlikely to have the billions it would require to re-do everything the right way. But we can make changes. Now is the time, and better street design standards are one of the tools.

3 thoughts on “street design contexts

  1. This is a useful framework. I definitely get caught up in the latter three context, but I have been continuing to think about what an updated street design standard might look like for the next larger street(s) after the local one, mostly through the lens of reconstruction/reallocation.

    These are the 2 or 3 lane streets that many of us use the most–schools, parks, and storefronts are on them. When cycling, these are the lowest-stress through routes. I find the complete streets and NACTO designs pretty uncompelling in this size. If we are going to spend money, we should at least make something that people will find useful for another 50 years. I don’t think green turn boxes in the midst of traffic are going to cut it.

    Getting acceptance from the city on the possibility of changing a street classification (and thus speed limit) seems like a huge hurdle. Do you know how to find out the current classification of streets? I haven’t found a map or any data sets on the city web page.


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