In the future, the commute time between Jerusalem and Tel Aviv is supposed to be shorter than it is today. Will this have an effect on residential choices? Will more people opt to live in Tel Aviv and work in Jerusalem, or maybe vice versa? When planning for the future, it’s usually a good idea to start with the present and look at the current trends.
According to the Central Bureau of Statistics’ Workforce Survey, in 2013 Jerusalem was the workplace of 293,000 workers, the majority of whom (224,700) also resided in the city. Most of the 68,600 workers commuting from outside of Jerusalem reside in its periphery (Jerusalem and Judea and Samaria districts). This sums up to 48,100 commuters. Meanwhile, 16,600 workers come to Jerusalem from the Center (Central and Tel Aviv Districts), and the rest commute from the South, the North, and Haifa. We may assume that people commuting from the Center make up most of the potential riders of the train and the upgraded Route 1 to Jerusalem.
What about travel in the opposite direction? Will the trains from Jerusalem in the morning leave full? Will they carry more passengers than those arriving from Tel Aviv? The number of workers residing in Jerusalem and commuting to localities outside of the city stands at 34,000, or about half of the number of people commuting into the city. Of this group, 10,300 work in the Center (2,900 of them in Tel Aviv proper), making up the potential riders from Jerusalem to Tel Aviv. If the train were to open today, the Tel Aviv-to-Jerusalem direction would be the busier one. 
Car counts from roads connecting Jerusalem to the Center reveal a somewhat similar trend. From 6:00—10:00, some 9,300 cars entered Jerusalem via road no. 1 (the measuring point was located between Sha’ar Hagai and Shoresh; data are averages of the years 2012-13), and about 6,600 cars entered via road no. 443 (the measuring point was located between Modi’in and Giv’at Ze’ev; data are for 2015). Measuring these together, there are approx. 15,900 cars driving from the Center towards Jerusalem during these four hours. During the same hours, some 13,300 cars were traveling in the opposite direction on the same road segments. An opposite trend occurs in the afternoon, as commuters return from work. Between 14:00—18:00, some 17,200 cars were traveling in the direction of Tel Aviv, compared to 15,300 cars traveling in the direction of Jerusalem.
It appears that there is a substantial travel demand in both directions, a trend which stems from the fact that different people want different things. We can assume that this trend will continue to prevail and that the commute direction from Tel Aviv to Jerusalem will remain stronger even when the commute time will be shorter. The number of commuters in both directions will likely grow substantially.