\r\nThe population of Leipzig, which has the fastest growth rate of any major German city, is expected to increase by 150,000 to 720,000 within the next 15 years. In addition, around 4500 new cars are being registered in Leipzig each year which is increasing road congestion and pollution.\r\nThe existing tram and bus network carries around 145 million passengers per annum and has the capacity to grow to 180,000 per year. \u201cIf there are more than 180,000 then the system could collapse,\u201d Jung says, which is when a new tram or S-Bahn tunnel would be needed.\r\nThe proposed S-Bahn tunnel would run east-west and interchange with the existing north-south S-Bahn tunnel at Leipzig main station. The tunnel would run from Lindenauer Markt in the west via Sportforum\/Arena\/University to the main station where it would split with one branch heading north via Friedrich-List-Platz to Leipzig East and the other heading east to Wilhelm-Leuschner-Platz.\r\nLeipzig has published an 88-page Mobility Strategy 2030 which puts forward six options:\r\n\u2022 Continuation model whereby congestion and air quality worsen despite an investment of \u20ac600m and increase in the annual public transport subsidy from \u20ac51m to \u20ac56m\u2022 Continuation model without price increase: this is the same scenario as above but the annual subsidy would increase to \u20ac115m\u2022 Sustainability model: fewer cars on the roads, low noise, and environmental targets are met with an investment of \u20ac1.4bn and an annual subsidy of \u20ac83m\u2022 Bicycle model: a network of cycle lanes would be constructed which would produce the highest CO2 reductions and increase public transport usage slightly for an investment of \u20ac1bn and annual subsidy of \u20ac76m\u2022 Public transport model: priority would be given to the S-Bahn, tram and bus networks with an investment of \u20ac1.2bn and an annual subsidy of \u20ac57m, and\u2022 Citizen ticket model: community funding to enable either very low fares to be charged or even free travel to be provided for an investment of \u20ac2-4.5bn and annual subsidy of \u20ac141m.\r\n\u201cSafe. Clean and affordable for everyone \u2013 that\u2019s how I wish Leipzig\u2019s mobility to be in the future,\u201d Jung says. He also wants the federal government to provide more money to help German cities meet their climate protection targets.