Transportation network design for maximizing space–time accessibility

Tong, L., Zhou, X.  and Miller, H.J. (in press) “Transportation network design for maximizing space–time accessibility,” Transportation Research Part B: Methodologicaldoi:10.1016/j.trb.2015.08.002

Abstract.  One of the goals of transportation system construction and management is to improve individuals’ accessibility or the ease of reaching desired activities, destinations and services. However, many transportation network design models instead focus on maximizing individuals’ mobility or the ease of movement within the network. By adapting a space–time prism analysis framework, this paper aims to address a new urban network design problem to maximize the system-wide transportation accessibility between major activity locations, subject to a given highway construction budget. By constructing a time-dependent space–time network, we formulate the problem as a linear integer programming model to maximize the number of accessible activity locations within travel time budget for road users. A Lagrangian relaxation solution framework effectively decomposes the original complex problem into classical subproblems such as knapsack and time-dependent least cost problems. Various examples and discussions are provided to consider the effectiveness of the proposed method in modeling accessibility-enhancement strategies such as congestion mitigation and land use policies.

Road diets in the Cbus

Back on September 12, I posted about the magic of road diets – a relatively inexpensive way to achieve many good outcomes in urban transportation such as walkability, bikeability, increased safety and traffic calming.

A great example of a road diet is the Nationwide Boulevard project in the Arena District of Columbus (my fair city): Nationwide Boulevard Road Diet on Track for Fall Completion.  This project is also a great example of public-private partnerships, with funding coming from the City of Columbus and adjacent property owners.

Way to go, Cbus!  Now let’s talk again about protected bike lanes in downtown…

Access without ownership: Mobility as a service

A transport engineer in Helsinki is pioneering the real-world implementation of on-demand mobility services.  [A 24-Year-Old Transport Engineer Is About To Free Her City From Car Ownership.]

Sonja Heikkilä wants to create a sustainable mobility service ecosystem where Helsinki citizens can configure mobility services from a wide range of providers – public, private and shared – via smartphone apps.  In the future, users may be able to purchase monthly mobility plans that are tailored to their activity patterns and needs,  much like current mobile phone voice + data plans.

Helsinki is demonstrating that you can have access without ownership.  The average automobile is stationary and parked for 95% of its existence – a tremendously inefficient use of a valuable mobility resource.  Ownership also leads to overuse and binge mobility.

Social media, location-based services (LBS) and smart cities can help facilitate transportation polycultures that are not only more efficient but more effective and sustainable.  We must use these technologies to cultivate mobility services and collaborative mobility rather than the fight the futile battle of easing congestion through expanding roads and highways.  It has never worked, and it never will.