The ultimate solution to traffic congestion may be to build an air traffic network.

This article comes from WeChat WeChat official account:Engineering（ID：engineering2015）, Author: Wu Zhiqiang, etc., original title: "Integrated Network Design and Demand Forecasting Engineering of Urban On-Demand Air Traffic", the first picture comes from vision china.

Traffic congestion is the primary problem that affects the sustainable development of global traffic. According to a report released by INRIX, in 2018, Americans spent an average of 97 hours in traffic jams, which cost nearly 87 billion US dollars, and each driver spent an average of 1,348 US dollars. At the same time, the positive effects brought by the capacity expansion of traditional roads have been affected by the growth of population and vehicles and the mileage of vehicles caused by urban expansion.（VMT）Offset by the increase in. Recent research focuses on the use of emerging technologies and concepts to alleviate congestion by using the existing road system more effectively.

For example, self-driving and networked vehicles are expected to alleviate traffic congestion, reduce vehicle travel time and expand the capacity of existing road systems. Transportation network company（TNC）The shared traffic and merging function of encourages customers to share traffic. Micro-traffic that can use sidewalks and bicycle lanes, including shared bicycles, electric motorcycles and electric bicycles, has been applied, which is expected to reduce VMT. Government agencies and research groups are aware of the necessity and possibility of developing and utilizing low-altitude space, which is a valuable resource that has not been fully utilized at present.

In 2017, NASA（NASA）Put forward urban air traffic.（UAM）And calls for market research on this mode of transportation. Since then, different units, including government agencies, manufacturers and research teams, have invested a lot of energy in this mode of transportation.

The concept of UAM can be traced back to 1960s, when several companies provided point-to-point commuting services by plane in metropolitan areas such as Los Angeles, San Francisco, new york and Chicago. Due to the low acceptance of these commuter services in the community, the high incidence of casualties and serious financial problems, these transportation companies were finally forced to significantly reduce or terminate the operation of these commuter services, which still limit the large-scale development of UAM today.　

In recent years, the concept of UAM is based on a new type of vertical takeoff and landing electric aircraft.（eVTOL）Based on. At present, this new type of aircraft is in the mature stage, which integrates advanced autonomous and distributed electric propulsion technology and can provide safer, quieter and more efficient air transportation services in low-altitude space. Some industrial companies are relatively optimistic about this prediction. They believe that their service prices can be controlled through economies of scale, and the potential acceptance is high. Some studies claim that the annual turnover of air taxi and airport shuttle service is close to $2.5 billion considering different limiting factors, and as long as there is enough market penetration, its service cost will be comparable to UberX.

However, public awareness, availability and accessibility of infrastructure, service quality and service cost, and many other factors may have great uncertainty on the potential demand of UAM. Therefore, researchers are not so optimistic about the adoption rate of UAM. They think that the proportion of trips to switch from the current ground mode to UAM service is limited, because the maintenance of UAM needs high cost, and the operation based on the site needs to use ground transportation, and its reliability is low when the weather conditions are bad.

Although various uncertain factors will affect the popularity of UAM, the government authorities and academic circles have reached a consensus that UAM will overcome the geographical restrictions of ground transportation modes and provide passengers with a greatly improved mobility. For example, Antcliff and others take Silicon Valley as an example to prove that UAM service can "door-to-door" passengers’ daily long distance.（DtD）The traffic time is shortened to one third of the ground traffic.　

Many efforts have been put into promoting the development of new UAM services. NASA and the federal aviation administration（FAA）Led the market feasibility study and the promotion of UAM. More than 70 manufacturers around the world, including Boeing, Airbus and Bell Helicopter, have been committed to designing better eVTOL aircraft. As of September 2018, they have invested more than 1 billion US dollars. The United States, China, the United Arab Emirates, Singapore and other places have carried out various types of aircraft test flights. In addition, some high-profile activities have been organized around the world to discuss the problems and solutions of UAM application, such as Uber Elevate Summit and Los Angeles Mayor’s Meeting. The potential market of UAM includes but is not limited to ambulance service, air taxi service, airport shuttle service, tourism, investigation and inspection, and cargo transportation.　

Recently, great progress has been made in the concept definition, potential market analysis and application constraint identification of UAM. One of the biggest challenges facing UAM’s on-demand service is the need to establish a well-distributed ground infrastructure to support the operation of eVTOL aircraft. In order to meet the needs of UAM passengers, the main ground infrastructure is the vertical take-off and landing airport used by eVTOL aircraft to take off and land, get on and off passengers and pay fees.(or helicopter airport). The intensive land use, aircraft operation demand and community acceptance in urban areas severely limit the number of vertical take-off and landing airports, making it difficult to provide door-to-door services only by pure air transportation. Therefore, the network design of UAM needs to integrate various modes of transportation: ground traffic in and out of vertical take-off and landing airports and air traffic between vertical take-off and landing airports. This multi-modal feature increases the complexity of UAM network design. In addition, the number and location of vertical landing sites will also attract users of different levels. The interaction between supply and demand needs to be clearly considered in UAM network design.

Wu Zhiqiang research team of the University of South Florida mainly studies the network design of UAM on-demand service. While considering the interaction between the location of vertical take-off and landing airport and the potential traffic demand of UAM, integer programming and a solution algorithm are used to determine the optimal location of vertical take-off and landing airport, user allocation and the choice of access mode. In addition, the key promoting factors of UAM’s potential demand and the different pricing strategies of UAM operators are analyzed from the supply side, and the effectiveness of the model is verified by a case study based on the simulated decomposition of traffic demand data in Tampa Bay, Florida, USA.

Figure 1. On-demand urban air traffic network design model. TBRPM: regional planning model of Tampa Bay; OD: starting point and ending point

Figure 2. Urban air traffic hub-and-spoke network

Keywords: advanced air traffic; Roof apron; The choice of transportation mode; Low altitude airspace; Unmanned driving system

The above contents are excerpted from: zhiqing Wu, Yu Zhang. Integrated network design and demand forecast for on-demand urban air mobility [J]. Engineering, 2021,7 (4): 473-487.

This article comes from WeChat WeChat official account:Engineering（ID：engineering2015）, Author: Wu Zhiqiang et al.