A unique attribute of cities - and a key distinction among cities, rural areas and many suburbs - is that city dwellers live and work in proximity to so many other people. Despite electronic networking, cities still thrive on proximity and daily physical interaction with a diverse group of people whose skills and abilities are complementary. Therefore think of a street as a context-sensitive, place-making platform or engine for wealth creation - it is an outdoor room that adds value to the surrounding properties, by providing safe and pleasant access. A well-designed, aesthetically appealing street network, that in its totality serves vehicles, walkers and bikers, facilitates social and economic interactions and a commitment to place, and delivers other benefits to a city and its people:
Improved safety for all users
Improved access for transit users, bicyclists and pedestrians
Increased walking, biking and thus community health
The potential for a household to cut transportation costs by selling a car
Reduced travel - and emergency response - times due to multiple nearly equivalent options for traversing the street network
A healthy tree canopy and reduced and cheaper stormwater management
More inviting public spaces that facilitate public art and increase the economic viability of businesses
While road restriping and mill-and-overlay projects afford an opportunity at least once every 10 years to make road improvements, make sure to plan ahead for the once-in-50-years road reconstruction opportunity to make significant road improvements.
The 2010 Legislature passed into law a complete streets policy governing state-owned roads and state-aided local road projects.
The Statewide Health Improvement Program (SHIP ) distributes funding to Community Health Boards and tribal governments across Minnesota to increase active transportation by means of, among other actions, adopting a complete streets policy.
93% of MN adults believe transportation projects should accommodate walkers and bikers, and 72% of MN adults believe in policies supporting sidewalks and bike paths (MN Physical Activity Survey, MN Dept. of Health: 2010). 61% of Minnesotans who have two or more community features to help them be physically active (sidewalks, parks, trails) report exercising 3 or more days/week, more than the 42% who have fewer community features. (Center for Prevention: 2015)
Connected street networks—grids or modified grids—disperse rather than concentrate traffic as do hierarchical streets networks (with with loop roads and cul-de-sacs branching off of arterials) and provide a perfect corrective for congestion. Modest street and lane reconfigurations, attending to context sensitive street design principles and adding traffic-calming measures, can reduce speeding by 40%, auto crashes by more than 50% and increase the number of walkers and bikers. In urban areas the least severe crashes are achieved when lane width is between 10.5 and 11 feet.Narrower vehicle lanes also carry more cars up to 40 m.p.h. See Safer Streets, Stronger Economies (Smart Growth American: 2015) for data analysis of benefits from 37 complete streets projects. See also The National Association of City Transportation Officials Street Design Guide. Note that a car hitting a pedestrian at 20 m.ph. kills the pedestrian 10% of the time, but at 40 m.ph. kills the pedestrian 90% of the time.
A 2010 Metropolitan Council analysis of the effects of land planning and urban design on travel demand documented that changes in vehicle miles traveled are most strongly related to (1) accessibility to destinations, especially jobs, and (2) street network design variables. Those variables - street connectivity and intersection density - correlate with improved public health outcomes. These variables are the key attributes of the old-fashioned grided networks that allow multiple ways to travel from A to B. Recent research shows that hierarchical street systems (the dendritic pattern of freeways, arterials, collectors and local streets) are less resilient to disruption and have less capacity than the grided network of streets. Arterials and collectors are also especially hostile to non-automotive modes of travel such as bikes and pedestrians.
Quantitative measures of walkability, the degree to which a neighborhood or city facilitates people to walk/shop in it, include Walk Score. Property values increase between $700 and $3,000 for each point increase in the Walk Score of a property. In cities walkability, facilitated by small blocks and a higher proportion of land area devoted to streets, is in tension with efficiency (large blocks with few streets and higher speed traffic). Like Walk Score and Transit Score, Bike Score provides an easy way to evaluate bikeability at a specific location.
The energy savings from no signals and no/little idling at roundabouts, compared to signalized intersections, has been estimated to be about 9% (averaging $84,000/yr.). As for safety benefits of roundabouts, a 2017 study by MnDOT documented a reduction of as much as 90% in fatal or incapacity injuries, a 75% decrease in injury-producing crashes, and a 39% decrease in all types of auto crashes. Roundabouts also slow traffic, reducing the need for police patrols, are cheaper (by roughly $150,00) to build than signalized intersections, and increase hourly traffic flow in excess of 65%. Safety for bikes and pedestrians in dense urban areas is an open question.